Handbook of Neurosurgery 8th Edition-4

Contents 49 Vascular Malform at ions 82 Vascu lar Malfo rm at ion s . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1238 82.1 General inform at ion and classificat ion . . . . . . . . . . . . . . . . . . . 1238 82.2 Art eriovenous m alform at ion (AVM) . . . . . . . . . . . . . . . . . . . . . . 1238 82.3 Ve n ou s an gio m as . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1245 82.4 Angiographically occult vascular m alform at ions . . . . . . . . . . 1246 82.5 Osler-Weber-Re ndu syndrom e . . . . . . . . . . . . . . . . . . . . . . . . . . . 1246 82.6 Cavernous m alform at ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1247 82.7 Dural art eriovenous fist ulae (DAVF) . . . . . . . . . . . . . . . . . . . . . . 1251 82.8 Vein of Galen m alform at ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1255 82.9 Carot id-cavernous fist ula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1256 82.10 Sigm oid sinus divert iculum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1258 Stroke and Occlusive Cerebrovascular Disease 83 General Inform at ion and St roke Physiology . . . . . 1264 83.1 De fin it ion s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1264 83.2 Cerebrovascular hem odynam ics . . . . . . . . . . . . . . . . . . . . . . . . . 1264 83.3 Collat eral circulat ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1265 83.4 “Occlusion ” syndrom es . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1265 83.5 St roke in young adult s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1269 83.6 At herosclerot ic carot id art ery disease . . . . . . . . . . . . . . . . . . . . 1271 84 Evaluat ion and Treat m e nt for St roke . . . . . . . . . . . . . 1280 84.1 Rat ionale for acut e st roke t reat m ent . . . . . . . . . . . . . . . . . . . . . 1280 84.2 Evalu at ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1280 84.3 Managem ent of TIA or st roke . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1282 84.4 Carot id endart erect om y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1290 84.5 Carot id angioplast y/st ent ing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1297 85 Sp e cial Co n d it io n s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1301 85.1 Tot ally occluded int ernal carot id art ery . . . . . . . . . . . . . . . . . . 1301 85.2 Cerebe llar infarct ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1302 85.3 Malignant m iddle cerebral art ery t errit ory infarct ion . . . . . 1303

50 Contents 85.4 Cardiogenic brain em bolism . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1304 85.5 Ve rt e brobasilar insu ciency . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1305 85.6 Bow hunt e r’s st roke . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1307 85.7 Cerebrovascular venous t hrom bosis . . . . . . . . . . . . . . . . . . . . . 1308 85.8 Mo yam o ya dise ase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1313 85.9 Ext racranial-int racranial (EC/IC) bypass . . . . . . . . . . . . . . . . . . 1317 86 Ce re b ral Art e rial Disse ct io n s . . . . . . . . . . . . . . . . . . . . . . 1322 86.1 Ge ne ral inform at ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1322 86.2 No m e nclat ure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1322 86.3 Pat hop h ysiolog y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1322 86.4 Epide m io lo gy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1323 86.5 Sit e s of disse ct ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1323 86.6 Clinical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1323 86.7 Evaluat io n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1324 86.8 Ove rall ou t com e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1324 86.9 Ve sse l specific inform at ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1324 Int racerebral Hem orrhage 87 Int race re b ral He m o rrh ag e . . . . . . . . . . . . . . . . . . . . . . . . . 1330 87.1 Ge ne ral Inform at ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1330 87.2 Int race rebral he m orrhage in adult s . . . . . . . . . . . . . . . . . . . . . . 1330 87.3 Epide m io lo gy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1330 87.4 Locat ions of hem orrhage w it hin t he brain . . . . . . . . . . . . . . . 1331 87.5 Et io lo gie s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1332 87.6 Clinical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1336 87.7 Evaluat io n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1338 87.8 Init ial m anagem ent of ICH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1339 87.9 Surgical t re at m e nt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1342 87.10 Ou t com e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1345 87.11 ICH in young adult s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1345 87.12 Int racerebral hem orrhage in t he new born . . . . . . . . . . . . . . . 1346 87.13 Ot her causes of int racerebral hem orrhage in t he new born 1352

Contents 51 Out com e Assessm ent 88 Ou t co m e Asse ssm e n t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1358 88.1 Cance r . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1358 88.2 He ad in ju r y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1358 88.3 Cerebrovascular e ve nt s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1358 88.4 Sp in al cord in ju r y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1362 Di erent ial Diagnosis 89 Di erent ial Diagnosis by Locat ion or Radiographic Finding – Int racranial . . . . . . . . . . . . . . . 1364 89.1 Diagnoses covered out side t his chapt er . . . . . . . . . . . . . . . . . . 1364 89.2 Post erior fossa le sions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1364 89.3 Mult iple int racranial lesions on CT or MRI . . . . . . . . . . . . . . . . 1368 89.4 Ring-enhancing lesions on CT/MRI . . . . . . . . . . . . . . . . . . . . . . . 1369 89.5 W hit e m at t e r le sions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1371 89.6 Sellar, suprasellar and parasellar lesions . . . . . . . . . . . . . . . . . . 1371 89.7 Int racranial cyst s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1374 89.8 Orbit al le sio n s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1375 89.9 Cavernous sinus lesions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1376 89.10 Sku ll le sio n s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1376 89.11 Com bined int racranial/ext racranial lesions . . . . . . . . . . . . . . . 1380 89.12 Int racranial hyperdensit ies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1380 89.13 Int racranial calcificat ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1380 89.14 Int ravent ricular lesions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1381 89.15 Perivent ricular lesions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1384 89.16 Meningeal t hicke ning/e nhancem ent . . . . . . . . . . . . . . . . . . . . . 1385 89.17 Ependym al and subependym al enhancem ent . . . . . . . . . . . . . 1385 89.18 Int ravent ricular hem orrhage . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1386 89.19 Medial t e m poral lobe le sions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1386 89.20 Basal ganglion abnorm alit ies . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1386 89.21 Th alam ic le sio ns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1386 89.22 Int ranasal/int racranial lesions . . . . . . . . . . . . . . . . . . . . . . . . . . . 1387

52 Contents 90 Di erent ial Diagnosis by Locat ion or Rad io g rap h ic Fin d in g – Sp in e . . . . . . . . . . . . . . . . . . . . . 1390 90.1 Diagnoses covered out side t his chapt er . . . . . . . . . . . . . . . . . . 1390 90.2 At lant oaxial subluxat ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1390 90.3 Abnorm alit ies in ve rt ebral bodie s . . . . . . . . . . . . . . . . . . . . . . . 1390 90.4 Axis (C2) vert e bra lesions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1391 90.5 Pat hologic fract ures of t he spine . . . . . . . . . . . . . . . . . . . . . . . . 1391 90.6 Spinal epidural m asses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1392 90.7 De st ruct ive le sions of t he spine . . . . . . . . . . . . . . . . . . . . . . . . . 1392 90.8 Ve rt e bral hyperost osis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1393 90.9 Sacral le sio ns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1393 90.10 Enhancing ner ve root s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1394 90.11 Nodular enhancing lesions in t he spinal canal . . . . . . . . . . . . 1394 90.12 Int raspinal cyst s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1394 90.13 Di use enhancem ent of nerve root s/cauda equina. . . . . . . . 1394 91 Di erent ial Diagnosis (DDx) by Signs and Sym pt om s – Prim arily Int racranial . . . . . . . . . . . . . . . 1395 91.1 Diagnoses covered out side t his chapt er . . . . . . . . . . . . . . . . . . 1395 91.2 Ence p h alo pat hy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1396 91.3 Syncope and apoplexy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1396 91.4 Transient neurologic deficit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1398 91.5 At axia/balance di cult ie s. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1398 91.6 Diplop ia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1399 91.7 An osm ia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1399 91.8 Mult iple cranial nerve palsies (cranial neuropat hies) . . . . . . 1399 91.9 Binocular blindne ss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1401 91.10 Monocular blindne ss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1401 91.11 Exo ph t h alm os. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1402 91.12 Pt osis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1403 91.13 Pat hologic lid ret ract ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1403 91.14 Macro ce ph aly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1403 91.15 Tin nit us . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1404 91.16 Facial sensory changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1405 91.17 Language dist urbance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1406

Contents 53 92 Di erent ial Diagnosis (DDx) by Signs and Sym pt om s – Prim arily Spine and Ot her . . . . . . . . . . 1407 92.1 Diagnoses covered out side t his chapt er . . . . . . . . . . . . . . . . . . 1407 92.2 Mye lop at h y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1407 92.3 Sciat ica . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1410 92.4 Acut e paraplegia or quadriple gia . . . . . . . . . . . . . . . . . . . . . . . . 1413 92.5 Hem iparesis or he m iple gia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1414 92.6 Lo w b ack pain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1414 92.7 Foo t dro p . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1416 92.8 Weakness/at rophy of t he hands/UEs . . . . . . . . . . . . . . . . . . . . . 1419 92.9 Radiculopat hy, upper ext rem it y (cervical) . . . . . . . . . . . . . . . . 1420 92.10 Neck pain (ce rvical pain) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1420 92.11 Burning hands/fe e t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1421 92.12 Muscle pain/t e nd erness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1421 92.13 Lh e rm it t e’s sig n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1421 92.14 Sw allow ing di cult ie s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1421 Procedures, Int ervent ions, Operat ions 93 Ge n e ral In fo rm at io n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1426 93.1 Int ro du ct io n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1426 93.2 Int raope rat ive dye s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1426 93.3 Ope rat ing room equipm ent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1426 93.4 Surgical he m ost asis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1428 93.5 Craniot om y gene ral inform at ion . . . . . . . . . . . . . . . . . . . . . . . . . 1428 93.6 Int raoperat ive cort ical m apping (brain m apping) . . . . . . . . . 1432 93.7 Craniop last y. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1436 93.8 Bon e graft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1437 93.9 St e reot act ic surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1441 94 Sp e cific Cran io t o m ie s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1445 94.1 Post erior fossa (suboccipit al) craniect om y . . . . . . . . . . . . . . . 1445 94.2 Pt erional craniot om y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1453 94.3 Te m poral craniot om y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1456

54 Contents 94.4 Front al craniot om y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1459 94.5 Pe t rosal craniot om y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1460 94.6 Approache s t o t he lat eral vent ricle . . . . . . . . . . . . . . . . . . . . . . 1461 94.7 Approache s t o t he t hird ve nt ricle . . . . . . . . . . . . . . . . . . . . . . . . 1461 94.8 Int e rhem ispheric approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1466 94.9 Occipit al craniot om y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1466 94.10 De com pressive cranie ct om y . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1467 95 Sp in e, Ce r vica l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1472 95.1 Ant erior approaches t o t he cervical spine . . . . . . . . . . . . . . . . 1472 95.2 Transoral approach t o ant erior craniocervical junct ion . . . . 1472 95.3 Occipit ocer vical fusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1474 95.4 Ant erior odont oid scre w fixat ion . . . . . . . . . . . . . . . . . . . . . . . . 1476 95.5 At lant oaxial fusion (C1–2 art hrodesis) . . . . . . . . . . . . . . . . . . . 1479 95.6 C2 scre w s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1483 95.7 Ant erior vert ebral body screw -plat e fixat ion . . . . . . . . . . . . . 1486 95.8 Zero profile int e rbody devices. . . . . . . . . . . . . . . . . . . . . . . . . . . 1487 96 Sp in e, Tho racic and Lu m bar . . . . . . . . . . . . . . . . . . . . . . . 1489 96.1 Ant erior access t o t he cervico-t horacic junct ion/upper 1489 t ho racic spine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1489 96.2 Ant erior access t o m id and low er t horacic spine . . . . . . . . . . 1489 96.3 Thoracic pedicle screw s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1493 96.4 Ant erior access t o t horacolum bar junct ion . . . . . . . . . . . . . . . 1493 96.5 96.6 Ant erior access t o t he lum bar spine . . . . . . . . . . . . . . . . . . . . . 1494 Inst rum ent at ion/fusion pearls for t he lum bar and 1494 96.7 lum bo sacral spin e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96.8 Lum bosacral pedicle screw s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1498 1501 96.9 Minim ally invasive lat eral ret roperit oneal t ranspsoas 1502 96.10 int e rbo dy fu sion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1502 96.11 Transface t pedicle screw s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1502 96.12 1502 96.13 Face t fu sion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S2 scre w s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Iliac scre w s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Post -op clinic visits – lum bar and/or t horacic spine fusion .

Contents 55 97 Miscellane ous Surgical Procedure s . . . . . . . . . . . . . . . 1504 97.1 Percut aneous vent ricular punct ure . . . . . . . . . . . . . . . . . . . . . . 1504 97.2 Percutaneous subdural tap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1504 97.3 Lu m b ar pu nct ure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1504 97.4 Lum bar cat he t er CSF drainage . . . . . . . . . . . . . . . . . . . . . . . . . . . 1510 97.5 C1–2 punct ure and cist ernal t ap . . . . . . . . . . . . . . . . . . . . . . . . . 1511 97.6 CSF diversionar y procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1512 97.7 Vent ricular access device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1518 97.8 Sural ne rve biopsy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1520 97.9 Ne r ve b lo cks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1521 98 Fu n ct io n al Ne u ro su rg e ry. . . . . . . . . . . . . . . . . . . . . . . . . . . 1524 98.1 Dee p brain st im ulat ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1524 98.2 Typical t arget s used in funct ional brain surgery . . . . . . . . . . . 1524 98.3 Surgical t reat m ent of Parkinson’s disease . . . . . . . . . . . . . . . . 1524 98.4 Dyst on ia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1528 98.5 Sp ast icit y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1528 98.6 To rt icollis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1533 98.7 Neurovascular com pression syndrom es . . . . . . . . . . . . . . . . . . 1534 98.8 Hyp e rh id ro sis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1537 98.9 Tre m or . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1537 98.10 Sym p at h e ct o m y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1537 99 Pain Pro ce d u re s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1541 99.1 Ge ne ral inform at ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1541 99.2 Choice of pain procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1541 99.3 Types of pain procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1541 99.4 Cordo t o m y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1542 99.5 Com m issural m yelot om y. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1544 99.6 Punct at e m idline m ye lot om y . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1545 99.7 CNS narcot ic adm inist rat ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1545 99.8 Spinal cord st im ulat ion (SCS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1547 99.9 Dee p brain st im ulat ion (DBS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1550 99.10 Dorsal root ent ry zone (DREZ) lesions . . . . . . . . . . . . . . . . . . . . 1550

56 Contents 100 Se izu re Su rg e r y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1553 100.1 General inform at ion, indicat ions . . . . . . . . . . . . . . . . . . . . . . . . 1553 100.2 Pre -surgical e valuat ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1553 100.3 Surgical t e chnique s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1554 100.4 Surgical proce dure s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1555 100.5 Risks of seizure surge ry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1557 100.6 MRI guided laser int erst it ial t herm al t herapy (MRGLITT) . . 1557 100.7 Post operat ive m anagem ent for seizure surgery (epilepsy surgery) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1557 100.8 Ou t com e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1557 101 Rad iat io n Th e rapy (XRT) . . . . . . . . . . . . . . . . . . . . . . . . . . . 1560 101.1 Int ro du ct ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1560 101.2 Convent ional ext ernal beam radiat ion . . . . . . . . . . . . . . . . . . . 1560 101.3 St ereot act ic radiosurgery and radiot herapy . . . . . . . . . . . . . . 1564 101.4 Int e rst it ial brachyt herapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1571 102 En d ovascu lar Ne uro su rg e ry . . . . . . . . . . . . . . . . . . . . . . . 1575 102.1 Ge ne ral inform at ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1575 102.2 Pharm acologic agent s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1576 102.3 Neuroendovascular Procedure Basics . . . . . . . . . . . . . . . . . . . . 1582 102.4 Diagnost ic angiography for cerebral subarachnoid hemorrhage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1583 102.5 Disease -specific int er vent ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1584 Ap p e n d ix 103 Quick Reference Tables and Figures . . . . . . . . . . . . . . 1604 In d e x . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1633

Part I 1 Gross Anatom y, 58 Cranial and Spine 75 Anat om y and Physiology 2 Vascular Anatom y 90 3 Neurophysiology and Regional Brain Syndrom es I

58 Anatom y and Physiology 1 1 Gross Anat om y, Cranial and Spine 1.1 Cort ical surface anat om y 1.1.1 Lat eral cort ical surface Fig. 1.1. For abbreviation s, see Table 1.1 an d Table 1.2. Th e m iddle fron tal gyrus (MFG) is usu- ally m ore sin uous th an th e IFG or SFG, an d it often con n ects to th e pre-cen tral gyrus via a th in isth - m us.1 Th e cen tral sulcus join s th e Sylvian fissure in on ly 2% of cases (i.e. in 98% of cases th ere is a “subcen t ral” gyrus). Th e in traparietal sulcus (ips) separates th e superior an d in ferior parietal lobules. Th e IPL is com posed prim arily of th e AG an d SMG. Th e Sylvian fissure term in ates in th e SMG (Brod- m an n’s area 40). Th e superior tem poral sulcus term in ates in th e AG. 1.1.2 Brodm ann’s areas Fig. 1.1 also iden tifies th e clin ically sign ifican t areas of Brodm an n’s (Br.) m ap of th e cytoarch itec- ton ic fields of th e h um an brain . Fun ction al sign ifican ce of th ese areas is as follow s: 1. Br. areas 3, 1, 2: prim ar y som atosen sor y cortex 2. Br. areas 41 & 42: prim ar y auditor y areas (tran sverse gyri of Hesch l) 3. Br. area 4: precen tral gyrus, prim ary m otor cortex (AKA “m otor strip”). Large con cen tration of gian t pyram idal cells of Bet z 4. Br. area 6: prem otor area or supplem en tal m otor area. Im m ediately an terior to m otor strip, it plays a role in contralateral m otor program m ing 5. Br. area 44: (dom in an t h em isph ere) Broca’s area (m otor speech ) 6. Br. area 17: prim ar y visual cortex CENTRAL S ULCUS Br. 3 (Rola ndic fis s ure ) Br. 1 Br. 2 Br. 8 Br. 6 Br. 4 Br. 40 Br. 44 SPL Br. 39 prcs pof PreCG pocs ips PostCG SMG IPLAG tos SFG IFG MFG ios PT POp sfs POr STG sts los ifs MTG OG pocn ITG Br. 42 Br. 17its LATERAL Br. 41 S ULCUS (Sylvian fissure) Fig. 1.1 Left lateral cerebral cortical surface anatomy. Br. = Brodmann’s area (shaded). See Table 1.1 and Table 1.2 for abbreviations (lowercase = sulci, UPPERCASE= gyri).

Gross Anatom y, Cranial and Spine 59 Table 1.1 Cerebral sulci (abbreviations) 1 Abbreviat ion Su lcu s cins cingulate sulcus cs central sulcus ips-ios intraparietal-intraoccipital sulcus los lateral occipital sulcus pM pars marginalis pocn pre-occipital notch pocs post-central sulcus pof parieto-occipital fissure pos parieto-occipital sulcus prcs pre-central sulcus sfs, ifs superior, inferior frontal sulcus sps superior parietal sulcus sts, its superior, inferior tem poral sulcus tos trans occipital sulcus Table 1.2 Cerebral gyri and lobules (abbreviations) Abbreviat ion Gyrus / lobule AG angular gyrus CinG cingulate gyrus Cu cuneus LG lingual gyrus MFG, SFG m iddle & superior frontal gyrus OG orbital gyrus PCu precuneous PreCG, PostCG pre- and post-central gyrus PL paracentral lobule (upper SFG and PreCG and PostCG) IFG inferior frontal gyrus ● POp ● pars opercularis ● PT ● pars triangularis ● POr ● pars orbitalis STG, MTG, ITG superior, middle & inferior temporal gyrus SPL, IPL superior & inferior parietal lobule SMG supramarginal gyrus

60 Anatom y and Physiology 1 CT prcs CENTRALSULCUS SFG PL pM sps cins cins CinG PCu MRI corpus callosum pos Cu LG pons Fig. 1.2 Medial aspect of the right hem isphere. Table 1.1 and Table 1.2 for “CT” & “MRI” bars depict t ypical axial slice orientation for CT & MRI scans. See a b b re via t io n s. 7. Wern icke’s area (lan guage): in th e dom in an t h em isphere, m ost of Br. area 40 an d a por tion of Br. area 39 (m ay also in clude ≈ posterior th ird of STG) 8. th e st riped port ion of Br. area 8 in Fig. 1.1 (fron tal eye field) in itiates volun tar y eye m ovem en ts to the opposite direct ion Brodm an n’s area 44, Wern icke’s area: Lan guage fun ction can n ot be reliably localized on an atom ic groun ds due to in dividual variabilit y in its exact location ; in order to perform m axim al brain resec- t ion s w ith m in im al risk of aph asia, tech n iques such as in t ra-operat ive brain m appin g2 or lookin g for ph ase reversal on in traoperative cort ical SSEP3 sh ould be em ployed. 1.1.3 Medial surface Fig. 1.2. Th e cin gulate sulcus term in ates posteriorly in th e pars m argin alis (pM) (plural: partes m argin ales). On axial im agin g, th e pMs: are visible on 95% of CTs an d 91% of MRIs,4 are usually th e m ost prom inent of the paired grooves straddling the m idline, and they extend a greater distan ce into th e h em isph eres.4 On axial CT, th e pM is located sligh tly posterior to th e w idest biparietal diam eter4; on th e t ypically m ore h orizon tally orien ted MRI slices th e pM assum es a m ore posterior position. Th e pMs cur ve posteriorly in low er slices an d an teriorly in h igh er slices (h ere, th e paired pMs form th e “pars bracket” – a ch aracteristic “h an dlebar” con figuration straddlin g th e m idlin e). 1.2 Cent ral sulcus on axial im aging See Fig. 1.3. Iden tificat ion of th e central sulcus is im por tan t to localize th e m otor strip (con tain ed in th e PreCG). Th e cen tral sulcus (CS) is visible on 93%of CTs an d 100%of MRIs.4 It cur ves posteriorly as it approach es th e in terh em isph eric fissure (IHF), an d often term in ates in th e paracen tral lobule, just an terior to th e pars m argin alis (pM) w ith in th e pars bracket (see above)4 (i.e. th e CS often does not reach the m idlin e).

Gross Anatom y, Cranial and Spine 61 Fig. 1.3 Retouched axial FLAIR MRI with labels for 1 gyri/sulci shown in the left hem isphere, and an SSFFGG unlabeled mirror image shown as the right hem i- sphere for reference. The inverted Ω illustrates the PPLL hand “knob” (see text). See Table 1.1 and Table 1.2 for abbreviations. Ω p rcs PreCG “motor strip” cs PostCG PM hand “knob” pocs Po in t e rs: ● parieto-occipital sulcus (pos) (or fissure): m ore prom in en t over th e m edial surface, an d on axial im agin g is longer, m ore com plex, an d m ore posterior than the pars m arginalis5 ● post-cen t ral sulcus (pocs): usually bifurcates an d form s an arc or paren th esis (“lazy-Y”) cupping th e pM. Th e an terior lim b does n ot en ter th e pM-bracket an d th e posterior lim b cur ves beh in d th e pM to en ter th e IHF Han d “Kn ob”: Th e alph a m otor n euron s for h an d m otor fun ct ion are located in th e superior aspect of th e prefron tal gyrus.6 On axial im agin g, th is appears as a kn ob-like protrusion (sh aped like an inverted greek letter om ega Ω) of th e precen tral gyrus project in g posterolaterally in to th e cen tral sulcus7 Fig. 1.3. On sagittal im aging it h as a posteriorly project in g h ook-like appearan ce an d is even w ith th e posterior lim it of th e Sylvian fissure.7 1.3 Surface anat om y of t he cranium 1.3.1 Craniom et ric point s See Fig. 1.4. Pterion : region w h ere th e follow in g bon es are approxim ated: fron tal, parietal, tem poral an d sph enoid (greater w in g). Estim ated as 2 finger-breadth s above th e zygom atic arch , an d a th um b’s breadth beh in d th e fron tal process of th e zygom atic bon e (blue circle in Fig. 1.4). Asterion : jun ction of lam bdoid, occipitom astoid an d parietom astoid sutures. Usually lies w ith in a few m illim eters of th e posterior-in ferior edge of th e jun ct ion of th e tran sverse an d sigm oid sin uses (n ot alw ays reliable8 – m ay overlie eith er sin us). Vertex: th e topm ost poin t of th e sku ll. Lam bda: jun ct ion of th e lam bdoid an d sagittal sut ures. Steph an ion : jun ction of coron al suture an d superior tem poral lin e. Glabella: th e m ost for w ard project in g poin t of th e foreh ead at th e level of th e supraorbital ridge in th e m idlin e. Opisth ion : th e posterior m argin of th e foram en m agn um in th e m idlin e. Bregm a: th e jun ct ion of th e coron al an d sagittal sut ures. Sagittal suture: m idlin e suture from coron al suture to lam bdoid suture. Alth ough often assum ed to overlie th e superior sagittal sin us (SSS), th e SSS lies to th e righ t of th e sagittal suture in th e m ajor- it y of specim en s9 (but n ever by > 11 m m ). Th e m ost an terior m astoid poin t lies just in fron t of th e sigm oid sin us.10 1.3.2 Relat ion of skull m arkings t o cerebral anat om y – Taylor-Haught on lin e s Taylor-Haugh ton (T-H) lin es can be con structed on an an giogram , CT scout film , or sku ll x-ray, an d can th en be recon structed on th e patien t in th e O.R. based on visible extern al lan dm arks.11 T-H lin es are sh ow n as dash ed lin es in Fig. 1.5.

62 Anatom y and Physiology 1 vertex b re g m a st e p h a n io n FRONTAL cs PARIETAL p t e rio n stl ophyron sqs lam bda glabella nasion GWS TEMPORAL ls rhinion sms pms OCCIPITAL MASTOoImD s NASAL ZYG ast e rio n p ro st h io n MAXILLA o p ist h io n inion in fe rio r gonion alveolar point g n at h io n MANDIBLE or menton Fig. 1.4 Craniometric points & cranial sutures. Named bones appear in all upper case letters. Abbreviations: GWS = greater wing of sphenoid bone, NAS = nasal bone, stl = superior temporal line, ZYG = zygo- m atic. Sutures: cs = coronal, ls = lambdoid, om s = occipitomastoid, pms = parietom astoid, sm s = squam om astoid, sqs = sq uam osal 1. Fran kfurt plan e, AKA baselin e: lin e from in ferior m argin of orbit th rough th e upper m argin of th e extern al auditor y m eat us (EAM) (as distin guish ed from Reid’s base lin e: from in ferior orbital m argin th rough th e cen ter of th e EAM)12 (p 313) 2. th e distan ce from th e n asion to th e in ion is m easured across th e top of th e calvaria an d is divided in to quar ters (can be don e sim ply w ith a piece of tape w h ich is th en folded in h alf t w ice) 3. posterior ear line: perpendicular to the baseline through the m astoid process 4. condylar line: perpendicular to the baselin e through th e m an dibular condyle 5. T-H lin es can th en be used to approxim ate th e sylvian fissure (see below ) an d th e m otor cortex (also see below ) Sylvian fissure AKA lat eral fissure Approxim ated by a lin e con n ectin g th e lateral can th us to th e poin t 3/4 of th e w ay posterior alon g th e arc run n in g over convexity from n asion to in ion (T-H lin es). Angular gyrus Located just above th e pin n a, im por tan t on th e dom in an t h em isph ere as part of Wern icke’s area. Note: th ere is sign ifican t in dividual variabilit y in th e location .2

Gross Anatom y, Cranial and Spine 63 1/2 2 cm 1 N-I 3/4 N-I c e n tra l s u lc u s N s ylvia n fis sure ©2001 Ma rk S Gre e nbe rg, M.D. All rights re s e rve d. Una uthorize d us e is prohibite d. I EAM Fra nkfurt pla ne pos te rior e a r line condyla r line Fig. 1.5 Taylor-Haughton lines and other localizing methods Angular art ery Located 6 cm above th e EAM. Mot or cort ex Num erous m eth ods utilize extern al lan dm arks to locate th e m otor st rip (pre-cen t ral gyrus) or th e cent ra l sulcus (Rolan dic fissure) w h ich separates m otor st rip an teriorly from prim ar y sen sor y cortex posteriorly. Th ese are just approxim ation s sin ce in dividual variabilit y causes th e m otor strip to lie anyw h ere from 4 to 5.4 cm beh in d th e coron al sut ure.13 Th e cen tral sulcus can n ot even be reliably iden tified visually at surger y.14 1. m eth od 1: th e superior aspect of th e m otor cortex is alm ost straigh t up from th e EAM n ear th e m idline 2. m eth od 215: th e central sulcus is approxim ated by connecting: a) th e poin t 2 cm posterior to th e m idposition of th e arc exten din g from n asion to in ion (illus- trated in Fig. 1.5), to b) th e poin t 5 cm straigh t up from th e EAM

64 Anatom y and Physiology 1 cs B DF1 FM AO V3 T Aq D2 Twining V4 D3 D4 opis thion ba s e line s igmoid s inus s e lla turcica Fig. 1.6 Relationship of ventricles to skull landm arks Abbreviations: (F= frontal horn, B= body, A= atrium, O = occipital horn, T= tem poral horn) of lateral ventricle. FM = foram en of Monro. Aq = sylvian aqueduct. V3 = third ventricle. V4 = fourth ventricle. cs = coronal suture. Dim ensions D1–4 see Table 1.3 3. m eth od 3: usin g T-H lin es, th e cen t ral sulcus is approxim ated by con n ecting: a) th e poin t w h ere th e “posterior ear lin e” in tersects th e circum feren ce of th e sku ll ( Fig. 1.5; usually about 1 cm behind the vertex, and 3–4 cm behin d th e coronal suture), to b) th e poin t w h ere th e “con dylar lin e” in tersects th e lin e represen ting th e sylvian fissure 4. m eth od 4: a lin e draw n 45° to Reid’s base lin e start in g at th e pterion poin ts in th e direct ion of th e m otor str ip 16 (p 584–5) 1.3.3 Relat ionship of vent ricles t o skull Fig. 1.6 sh ow s th e relation sh ip of n on -hydroceph alic ven tricles to th e skull in th e lateral view. Som e dim en sion s of in terest are sh ow n in Table 1.3.17 In th e n on -hydroceph alic adult , th e lateral ven tricles lie 4–5 cm below th e outer skull surface. Th e center of th e body of th e lateral ven t ricle sits in th e m idpupillar y lin e, an d th e fron tal h orn is in ter- sected by a lin e passing perpen dicular to th e calvaria alon g th is lin e.18 Th e an terior h orn s exten d 1– 2 cm an terior to the coronal suture. Average len gth of th ird ven tr icle≈ 2.8 cm . Th e m idpoin t of Tw in ing’s lin e (• in Fig. 1.6) sh ould lie w ith in th e 4th ven tr icle.

Gross Anatom y, Cranial and Spine 65 Table 1.3 Dim ensions from Fig. 1.6 1 Dim ension Descript ion Lower lim it Ave ra g e Upper lim it ( Fig. 1.6) (m m ) (m m ) (m m ) 25 D1 length of frontal horn anterior to FM 36.1 40.0 D2 distance from clivus to floor of 4th ventricle at level 33.3 14.6 19.0 of fastigium a 32.6 40.0 D3 length of 4th ventricle at level of fastigiuma 10.0 D4 distance from fastigiuma to opisthion 30.0 athe fastigium is the apex of the 4th ventricle within the cerebellum Table 1.4 Cervical levels19 Landm ark Le ve l angle of m andible C1–2 1 cm above thyroid cartilage (≈ hyoid bone) C3–4 level of thyroid cartilage C4–5 crico-thyroid m em brane C5–6 carotid tubercle C6 cricoid cartilage C6–7 1.4 Surface landm arks of spine levels Est im ates of cer vical levels for an terior cer vical spin e surger y m ay be m ade using th e lan dm arks sh ow n in Table 1.4. In tra-operative C-spin e x-rays are essen tial to verify th ese estim ates. Th e scapular spin e is located at about T2–3. Th e in ferior scapular pole is ≈ T6 posteriorly. In tercristal lin e: a lin e draw n bet w een th e h igh est poin t of th e iliac crests across th e back w ill cross th e m idlin e eith er at th e in terspace bet w een th e L4 an d L5 spin ous processes, or at th e L4 spi- n ous process itself. 1.5 Cranial foram ina and t heir cont ent s 1.5.1 Sum m ary Table 1.5 Cranial foramina and their contentsa Foram en Co n t e n t s nasal slits anterior ethm oidal nn., a. & v superior orbital fissure Cr. Nn. III, IV, VI, all 3 branches of V1 (ophthalm ic division divides into nasociliary, frontal, and lacrimal nerves); superior ophthalm ic vv.; recurrent meningeal br. from lacrimal a.; orbital branch of middle m eningeal a.; sym pathetic filam ents from ICA plexus inferior orbital fissure Cr. N. V-2 (m axillary div.), zygomatic n.; filam ents from pterygopalatine branch of m axillary n.; infraorbital a. & v.; v. between inferior ophthalm ic v. & pterygoid venous plexus foramen lacerum usually nothing (ICA traverses the upper portion but doesn’t enter, 30% have vidian a.) carotid canal internal carotid a., ascending sym pathetic nerves

66 Anatom y and Physiology Table 1.5 continued Cont ent s 1 Foram en incisive foram en descending septal a.; nasopalatine nn. greater palatine foram en greater palatine n., a., & v. lesser palatine foram en lesser palatine nn. internal acoustic m eatus Cr. N. VII (facial); Cr. N. VIII (stato-acoustic) – see text & Fig. 1.7 hypoglossal canal Cr. N. XII (hypoglossal); a m eningeal branch of the ascending pharyngeal a. foram en m agnum spinal cord (medulla oblongata); Cr. N. XI (spinal accessory nn.) entering the skull; vertebral aa.; anterior & posterior spinal arteries foram en cecum occasional sm all vein cribriform plate olfactory nn. optic canal Cr. N. II (optic); ophthalmic a. foram en rotundum Cr. N. V2 (m axillary div.), a. of foram en rotundum foram en ovale Cr. N. V3 (m andibular div.) + portio m inor (motor for CrN V) foram en spinosum m iddle m eningeal a. & v. jugular foram en internal jugular v. (beginning); Cr. Nn. IX, X, XI stylomastoid foram en Cr. N. VII (facial); st ylom astoid a. condyloid foram en v. from transverse sinus m astoid foram en v. to mastoid sinus; branch of occipital a. to dura m ater aAbbreviations: a. = artery, aa. = arteries, v. = vein, vv. = veins, n. = nerve, nn. = nerves, br. = branch, Cr. N. = cranial nerve, fm n. = foramen, div. = division 1.5.2 Porus acust icus AKA in tern al auditor y can al ( Fig. 1.7) Th e filam en ts of th e acoust ic portion of VIII pen etrate t iny open in gs of th e lam in a cribrosa of th e coch lear area.20 Tran sverse crest: separates superior vestibular area an d facial can al (above) from th e in ferior ves- t ibular area an d coch lear area (below ).20 Vert ical crest (AKA Bill’s bar – n am ed after Dr. William House): separates th e m eatus to th e facial canal an teriorly (con tain in g VII an d n er vus in term edius) from th e vest ibular area posteriorly (con - tainin g th e superior division of vest ibular n er ve). Bill’s bar is deeper in th e IAC th an th e tran sverse crest. Th e “5 n er ves” of th e IAC: 1. facial n er ve (VII) (m n em on ic: “7-up” as VII is in superior port ion ) 2. n er vus in term edius: th e som at ic sen sor y bran ch of th e facial n er ve prim arily in n er vatin g m ech a- n oreceptors of th e h air follicles on th e in n er surface of th e pin n a an d deep m ech an oreceptors of nasal an d buccal cavities and ch em oreceptors in the taste buds on the anterior 2/3 of th e tongue 3. acoustic por tion of th e VIII n er ve (m n em on ic: “Coke dow n ” for coch lear por tion ) 4. superior bran ch of vestibular nerve: passes through the superior vestibular area to term inate in the utricle and in th e am pullæ of the superior and lateral sem icircular canals (m nem onic superi- or = LSU (Lateral & Superior sem icircular can als an d th e Ut ricule)) 5. in ferior bran ch of vest ibular n er ve: passes th rough in ferior vestibular area to term in ate in th e saccule

Gross Anatom y, Cranial and Spine 67 facial canal (Cr. N. VII with NI*) Fig. 1.7 Right internal auditory canal (porus acusti- 1 cus) & nerves vertical crest (“Bill’s bar”) * NI= nervus interm edius superior vestibular area (superior (to utricle & superior & vestibular lateral sem icircular canals) nerve) transverse crest (crista falciform is) inferior vestibular area (in fe rio r (to saccule) ve st ib u la r n e r ve ) foramen singulare (to posterior sem icircular canal) cochlear area (acoustic portion of Cr. N. VIII) lateral ventricle }- genu INTERNAL CAPSULE head of caudate frontopontine tract }INTERNAL CAPSULE (A) - anterior limb corticobulbar tract }anterior thalamic radiation face (B) shoulder superior thalamic arm hand }radiation hip trunk foot (C) putamen }posterior thalamic globus pallidus }radiation corticorubral tract corticospinal tract (D) auditory }INTERNAL CAPSULE radiation - posterior limb optic radiation thalamus ascending thalamocortical fibers lateral geniculate body medial geniculate body descending corticofugal fibers third ventricle Fig. 1.8 Internal capsule schematic diagram (left side shows tracts, right side shows radiations) 1.6 Int ernal capsule 1.6.1 Archit ect ural anat om y For a sch em at ic diagram , Fig. 1.8; Table 1.6 delin eates th e th alam ic subradiation s. Most IC lesion s are caused by vascular acciden ts (th rom bosis or h em orrh age). 1.6.2 Vascular supply of t he int ernal capsule (IC) 1. an terior ch oroidal: all of retrolen ticular part (in cludes optic radiation ) an d ven t ral part of pos- terior lim b of IC 2. lateral striate bran ch es (AKA capsular bran ch es) of m iddle cerebral arter y: m ost of an terior AND posterior lim bs of IC 3. gen u usually receives som e direct bran ch es of th e in tern al carotid arter y 1.7 Cerebellopont ine angle anat om y For n orm al an atom y of righ t cerebellopon tin e an gle, see Fig. 1.9.

68 Anatom y and Physiology 1 Table 1.6 Four Thalam ic “subradiations” (AKA thalamic peduncles) , labeled A-D in Fig. 1.8 Radiat ion Co n n e ct io n Com m ent s a n t e rio r m edial & anterior thalam ic ↔ frontal lobe (A) nucleus superior rolandic areas ↔ ventral thalam ic nuclei general sensory fibers from (B) body & head to term inate in postcentral gyrus (areas 3,1,2) posterior occipital & posterior parie- ↔ caudal thalam us (C) tal inferior transverse tem poral gyrus ↔ MGB (sm all) includes auditory radia- (D) of Heschl t io n re tra ctor V on ce re be lla r Me cke l's he mis phe re ca ve fora me n of pons Lus chka flocculus fora me n of choroid Ma ge ndie ple xus ce re be lla r VII tons il IAC P ICA VIII IX jugula r fora me n X XI XII olive me dulla Fig. 1.9 Normal anatomy of right cerebellopontine angle viewed from behind (as in a suboccipital approach)20 1.8 Occipit oat lant oaxial-com plex anat om y Ligam en t s of t h e occip it oat lan t oaxial com p lex. Stabilit y of th e occipitoatlan tal join t is prim arily due to ligam en ts, w ith lit tle con tribution from bony articulation s an d join t capsules (see Fig. 1.10, Fig. 1.11, Fig. 1.12): 1. ligam en ts th at con n ect th e atlas to th e occiput: a) an terior atlan to-occipital m em bran e: ceph alad exten sion of th e an terior lon gitudin al liga- m en t. Exten ds from an terior m argin of foram en m agn um (FM) to an terior arch of C1

Gross Anatom y, Cranial and Spine 69 clivus ascending 1 band right alar ligament C1 accessory CRUCIATE (deep) portion LIGAMENT of tectorial membrane C2 transverse band descending band Fig. 1.10 Sagit tal view of the ligaments of the craniovertebral junction (Modified with permission from “In Vitro Cervical Spine Biom echanical Testing” BNI Quarterly, Vol.9, No. 4, 1993) apical odontoid ligament cruciate ligament, posterior ascending band C1 atlantooccipital anterior membrane atlantooccipital ligamentum membrane flavum C2 anterior transverse longitudinal ligament C3 ligament cruciate ligament, spinal descending band cord tectorial membrane posterior longitudinal ligament Fig. 1.11 Dorsal view of the cruciate and alar ligaments Viewed with tectorial m em brane rem oved. (Modified with permission from “In Vitro Cervical Spine Biom echanical Testing” BNI Quarterly, Vol.9, No. 4, 1993)

70 Anatom y and Physiology right alar Fig. 1.12 C1 viewed from above, showing the trans- ligam ent verse and alar ligaments (Modified with perm ission 1 odontoid t ra n sve rse from “In Vitro Cervical Spine Biom echanical Testing” process ligam ent BNI Quarterly, Vol.9, No. 4, 199) t u b e rcle t e c t o ria l m e m brane posterior arch C1 b) posterior atlan to-occipital m em -bran e: con n ects th e posterior m argin of th e FM to posterior arch of C1 c) th e ascen ding ban d of th e cruciate ligam en t 2. ligam en ts th at con n ect th e axis (viz. th e odon toid) to th e occiput: a) tectorial m em bran e: som e auth ors dist in guish 2 com pon en ts ● superficial com pon en t: ceph alad con tin uat ion of th e posterior lon gitudin al ligam en t. A st ron g ban d con n ecting th e dorsal surface of th e den s to th e ven tral surface of th e FM above, an d dorsal surface of C2 & C3 bodies below ● accessor y (deep) por t ion : located laterally, con n ects C2 to occipital con dyles b) alar (“ch eck”) ligam en ts21 ● occipito-alar portion : connects side of the dens to occipital condyle ● atlan to-alar port ion : con n ects side of th e den s to th e lateral m ass of C1 c) apical odon toid ligam en t: con n ects tip of den s to th e FM. Lit tle m ech an ical stren gth 3. ligam en ts th at con n ect th e axis to th e atlas: a) t ran sverse (atlan toa xial) ligam en t: t h e h or izon t al com p on en t of t h e cr u ciate ligam en t . Tr ap s t h e d e n s again st t h e an t e r ior at las via a st r ap - like m ech an ism ( Fig. 1 .1 2). Pr o - vid es t h e m ajor it y of t h e st ren gt h (“t h e st ron gest ligam en t of t h e sp in e ”22) b) atlan to-alar portion of th e alar ligam en ts (see above) c) descen din g ban d of th e cruciate ligam en t Th e m ost im portan t st ructures in m ain tain in g atlan to-occipital stabilit y are th e tectorial m em bran e an d th e alar ligam en ts. W ith out th ese, th e rem ain ing cruciate ligam en t an d apical den tate ligam en t are insu cient. 1.9 Spinal cord anat om y 1.9.1 Dent at e Ligam ent Th e den tate ligam en t separates dorsal from ven tral n er ve roots in th e spinal n er ves. Th e spinal accessory n er ve (Cr. N. XI) is dorsal to th e den tate ligam en t. 1.9.2 Spinal cord t ract s Anat om y Fig. 1.13 depicts a cross-section of a t ypical spin al cord segm en t, com bin ing som e elem en ts from di eren t levels (e.g. th e in term ediolateral grey n ucleus is on ly presen t from T1 to ≈ L1 or L2 w h ere th ere are sym path et ic (th oracolum bar outflow ) n uclei). It is sch em atically divided in to ascendin g an d descen din g h alves, h ow ever, in actualit y, ascen din g an d descen din g path s coexist on both sides. Fig. 1.13 also depicts som e of th e lam in ae according to th e sch em e of Rexed. Lam in a II is equiv- alen t to th e substan tia gelatin osa. Lam in ae III an d IV are th e n ucleus proprius. Lam in a VI is located in the base of the posterior horn .

Gross Anatom y, Cranial and Spine 71 S = s ac ral 1 T = tho rac ic MOTOR bi-directional C = c e rvic al SENSORY (descending paths (ascending paths) paths) {{{ 78 6 S TC 9 I 10 5 S TC III II intermediolateral IV grey nucleus 4 (sympathetic) 3 V 11 VI 12 VII IX CTS X dentate VIII ligament IX 13 14 2 2.5-4 cm 15 1 anterior spinal anterior motor artery nerve root Fig. 1.13 Schem atic cross-section of cervical spinal cord. See Table 1.7, Table 1.8 and Table 1.9 for path nam e s. Table 1.7 Descending (motor) tracts (↓ ) in Fig. 1.13 Num ber Pat h Funct ion Side of body ( Fig. 1.13) 1 anterior corticospinal tract skilled m ovementa o p p o sit e 2 m edial longitudinal fasciculus ? sam e 3 vestibulospinal tract facilitates extensor muscle tone sam e 4 m edullary (ventrolateral) reticulospinal automatic respirations? sam e t ract 5 rubrospinal tract flexor muscle tone sam e 6 lateral corticospinal (pyram idal) tract skilled m ovem ent sam e aThe term inal fibers of this uncrossed tract usually cross in the anterior white com missure to synapse on alpha motor neurons or on internuncial neurons. It is true that some of these fibers do stay on the same side, but it is felt to be a minority. Also, the anterior corticospinal tract is easily identified only in the cervical and upper thoracic regions.

72 Anatom y and Physiology 1 Table 1.8 Bi-directional tracts in Fig. 1.13 Funct ion Num ber Pat h ( Fig. 1.13) 7 dorsolateral fasciculus (of Lissauer) 8 fasciculus proprius short spinospinal connections Table 1.9 Ascending (sensory) tracts (↑ ) in Fig. 1.13 Num ber Pat h Funct ion Side of body ( Fig. 1.13) 9 fasciculus gracilis joint position, fine touch, vibration same 10 fasciculus cuneatus 11 posterior spinocerebellar tract stretch receptors sam e pain & temperature o p p o sit e 12 lateral spinothalam ic tract whole limb position o p p o sit e unknown, ? nociceptive o p p o sit e 13 anterior spinocerebellar tract light touch o p p o sit e 14 spinotectal tract 15 anterior spinothalamic tract Sensat ion Pain and tem perature: body Receptors: free n er ve en din gs (probable). 1st order n euron : sm all, fin ely m yelin ated a eren ts; som a in dorsal root gan glion (n o syn apse). En ter cord at dorsolateral t ract (zon e of Lissauer). Syn apse: substan t ia gelatin osa (Rexed II). 2nd order n euron axon cross obliquely in the anterior w hite com m issure ascending ≈ 1–3 seg- m en ts w h ile crossing to en ter th e lateral spin oth alam ic t ract . Syn apse: VPL th alam us. 3rd order n euron s pass th rough IC to postcen tral gyrus (Brodm an n’s areas 3, 1, 2). Fine touch, deep pressure and proprioception: body Fin e touch AKA discrim in ative touch . Receptors: Meissn er’s & pacin ian corpuscles, Merkel’s disks, free n er ve en din gs. 1st order n euron : h eavily m yelin ated a eren ts; som a in dorsal root gan glion (n o syn apse). Sh ort bran ch es syn apse in n ucleus proprius (Rexed III & IV) of posterior gray; lon g fibers en ter th e ipsilat- eral posterior colum n s w ith out syn apsing (below T6: fasciculus gracilis; above T6: fasciculus cu n e at u s). Syn apse: n ucleus gracilis/cun eat us (respect ively), just above pyram idal decussat ion . 2n d order n euron axon s form in tern al arcuate fibers, decussate in low er m edulla as m edial lem n iscus. Syn apse: VPL th alam us. 3rd order n euron s pass th rough IC prim arily to postcen tral gyrus. Light (crude) touch: body Receptors: as fin e touch (see above), also perit rich ial arborization s. 1st order neuron : large, heavily m yelinated a erents (Type II); som a in dorsal root ganglion (no synapse). Som e ascend uncrossed in post. colum ns (w ith fine touch ); m ost syn apse in Rexed VI & VII. 2n d order n euron axon s cross in an terior w h ite com m issure (a few don’t cross); en ter an terior spinothalam ic tract. Syn apse: VPL th alam us. 3rd order n euron s pass th rough IC prim arily to postcen tral gyrus. 1.9.3 Derm at om es and sensory nerves Derm atom es are ares of th e body w h ere sen sation is subser ved by a sin gle n er ve root. Periph eral n er ves gen erally receive con tribution s from m ore th an on e derm atom e.

Gross Anatom y, Cranial and Spine 73 Lesion s in periph eral n er ves an d lesion s in n er ve roots m ay som etim es be dist in guish ed in part 1 by th e pattern of sen sor y loss. A classic exam ple is splitt in g of th e ring fin ger in m edian n er ve or uln ar n er ve lesion s, w h ich does n ot occur in C8 n er ve root injuries. Fig. 1.14 sh ow s an terior an d posterior view, each sch em atically separated in to sen sor y derm a- tom es (segm en tal) and peripheral sensory ner ve distribution. ANTE R IO R P O S TE R IO R {trigeminalV1 C2 nerve V2 V3 superior clavicular occipitals C2 C3 C3 INTERCOSTALS C4 posterior T2 C4 lateral T4 C5 T3 medial T6 C5 T4 axillary T8 T2 RADIAL T10 T6 T12 T1 T2 post. cutaneous C6 dorsal cutan. clunials S5 T8 musculocutan. S3 T10 T12 medial cutan. C6 T1 ©2001 Ma rk S Gre e nbe rg, M.D. S4 radialAll rights reserved. L1 Una uthorize d us e is prohibite d. C8 L2 ilio- median L3 L4 C8 inguinal S1 C7 C7 L3 lateral cutan. ulnar L4 nerve of thigh posterior FEMORAL cutaneous anterior cutaneous L5 saphenous L4 L5 SCIATIC COMMON PERONEAL lat. cutan. sup. peroneal deep peroneal TIBIAL {sural S1 S1 med. lat. plantars D E R MAT O ME S C UTANE O US D E R MAT O ME S (a n te rio r) NE RVE S (p o s te rio r) Fig. 1.14 Dermatomal and sensory nerve distribution (Redrawn from “Introduction to Basic Neurology”, by Harry D. Pat ton, John W. Sundsten, Wayne E. Crill and Phillip D. Swanson, © 1976, pp 173, W. B. Saunders Co., Philadelphia, PA, with perm ission)

74 Anatom y and Physiology 1 References [1] Naid ich TP. MR Im agin g of Brain Su rface An atom y. [11] W illis W D, Grossm an RG. In : Th e Brain an d Its En vi- Neurorad iology. 1991; 33:S95–S99 ron m en t . Med ical Neurobiology. 3rd ed. St. Lou is: C [2] Ojem an n G, Ojem an n J, Lettich E, Berger M. Cor tical V Mosby; 1981:192–193 Lan guage Localization in Left, Dom in an t Hem i- [12] Warw ick R, W illiam s PL. Gray's An atom y. Philadel- sph ere. An Elect rical Stim ulat ion Mapp in g Invest i- phia 1973 gation in 117 Patients. J Neurosurg. 1989; 71:316– [13] Kid o DK, LeMay M, Levin son AW , Ben son W E. Com - 326 puted tom ograph ic localization of th e precen tral [3] Suzuki A, Yasui N. In t raoperative Localization of th e gyrus. Radiology. 1980; 135:373–377 Cen tral Su lcus by Cort ical Som atosen sory Evoked [14] Mart in N, Grafton S, Viñ uela F, Dion J, et al. Im agin g Poten tials in Brain Tum or: Case Repor t. J Neurosurg. Tech n iqu es for Cor tical Fu n ct ion al Localization . Clin 1992; 76:867–870 Neurosurg. 1990; 38:132–165 [4] Naid ich TP, Brigh tbill TC. Th e pars m argin alis, I: A [15] An derson JE. Grant's Atlas of An atom y. Baltim ore: \"bracket\" sign for the cen tral sulcus in axial plan e William s an d Wilkin s; 1978; 7 CT an d MRI. In t J Neurorad iol. 1996; 2:3–19 [16] W ilkin s RH, Ren gach ar y SS. Neurosurger y. New [5] Valen te M, Naidich TP, Abram s KJ, Blum JT. Di eren- York 1985 t iatin g th e pars m argin alis from th e p arieto-occipi- [17] Lusted LB, Keats TE. Atlas of Roen tgen ographic tal sulcus in axial com puted tom ography section s. Measu rem en t . 3rd ed . Ch icago: Year Book Medical In t J Neuroradiol. 1998; 4:105–111 Publish ers; 1972 [6] Pen field W , Boldrey E. Som atic m otor and sensor y [18] Gh ajar JBG. A Guide for Ven tricular Cath eter Place- representation in the cerebral cortex of m an as m en t: Tech n ical Note. J Neurosurg. 1985; 63:985– st u died by electrical stim u lation . Brain . 1937; 986 60:389–443 [19] Watkin s RG. In : Anterior Cer vical Approach es to the [7] Yousr y TA, Sch m id UD, Alkadhi H, Sch m idt D, Per- Spine. Surgical Approaches to th e Spin e. New York: aud A, Bu ettn er A, W in kler P. Localization of th e Sprin ger-Verlag; 1983:1–6 m otor hand area to a knob on the precentral gyrus. [20] Rh oton AL, Jr. Th e cerebellopon tin e an gle an d pos- A n ew lan d m ark. Brain . 1997; 120 (Pt 1):141–157 terior fossa cran ial n er ves by th e retrosigm oid [8] Day JD, Tsch abitsch er M. Anatom ic posit ion of the ap proach . Neu rosu rgery. 2000; 47:S93–129 asterion . Neu rosu rger y. 1998; 42:198–199 [21] Dvorak J, Panjabi MM. Fun ct ional An atom y of the [9] Tubbs RS, Salter G, Elton S, Grabb PA, Oakes W J. Sag- Alar Ligam en ts. Spin e. 1987; 12:183–189 ittal su tu re as an extern al lan d m ark for th e su p erior [22] Dickm an CA, Craw ford NR, Bran tley AGU, Son n tag sagittal sin us. J Neurosurg. 2001; 94:985–987 VKH, Koen em an JB. In vitro cervical spin e biom e- [10] Barn ett SL, D'Am brosio AL, Agazzi S, van Loveren ch an ical test in g. BNI Qu arterly. 1993; 9:17–26 HR, Lee JH. In : Petroclival an d Upper Clival Menin gi- om as III: Com bin ed An terior an d Posterior Ap p roach . Men in giom as. Lon d on : Sp rin ger-Verlag; 2009:425–432

Vascular Anatom y 75 2 Vascular Anat om y 2.1 Cerebral vascular t errit ories 2 Fig. 2.1 depicts approxim ate vascular dist ribution s of th e m ajor cerebral arteries. Th ere is con sid- erable variabilit y of th e m ajor arteries1 as w ell as th e cen tral distribution . Th e len ticulostr iates m ay h ave origin s o of di eren t segm en ts of th e m iddle or an terior cerebral artery). Recurren t ar ter y of Heubn er (RAH) (AKA m edial st riate arter y) origin : jun ct ion of th e ACA an d a-com m in 62.3%, proxi- m al A2 in 23.3%, A1 in 14.3%.2 2.2 Cerebral art erial anat om y 2.2.1 General inform at ion Th e sym bol “ ” is used to den ote a region supplied by th e in dicated arter y. See An giography (cere- bral) (p. 236) for an giograph ic diagram s of th e follow in g an atom y. 2.2.2 Circle of Willis See Fig. 2.2. A balan ced con figuration of th e Circle of W illis is presen t in on ly 18% of th e popula- t ion . Hypoplasia of 1 or both p -com m s occurs in 22–32%, absen t or hypoplastic A1 segm en ts occurs in 25%. Key poin t: th e an terior cerebral arteries pass over th e superior surface of th e opt ic ch iasm . 2.2.3 Anat om ical segm ent s of int racranial cerebral art eries 1. carotid artery: th e t radition al n um berin g system 3 w as from rostral to caudal (coun ter to th e direct ion of flow, and to th e num bering schem e of the other arteries). A num ber of system s h ave been described to addresses this inconsistency and also to identify an atom ically im portant seg- m en ts of th e ICA th at w ere n ot origin ally delin eated (e.g. see Table 2.1 4). Also see below for m ore detail CORONAL VIEW AXIAL VIEW a nte rior ce re bra l a rte rymiddle ce re bra l a rte ry R AH MCA AC h A a nte rior choroida l a rte ry inte rna l ca rotid poste rior cere bra l PCommA a rte ry ba s ila r a rte ry Fig. 2.1 Vascular territories of the cerebral hemispheres. RAH = recurrent artery of Heubner.

76 Anatom y and Physiology optic n. central retinal a. (Cr. N. II) ophthalmic a. 2 ACAs ICA superior hypophyseal a. a-comm a. (hidden) MCA medial &lateral pituitary lenticulostriate aa. p-comm a. anterior choroidal a. P1 P2 choroid plexus pons PCA { oculomotor n. AICA (Cr. N. III) vertebral a. PICA SCA pontine aa. basilar a. anterior spinal a. Fig. 2.2 Circle of Willis viewed from in front of and below the brain 2. anterior cerebral5: a) A1 (precom m un icating): ACA from origin to ACoA b) A2 (postcom m un icat in g): ACA from ACoA to bran ch -poin t of callosom argin al c) A3 (precallosal): from bran ch -poin t of callosom argin al cur vin g aroun d th e gen u of th e corpus callosum to superior surface of corpus callosum 3 cm posterior to th e gen u d) A4: (supracallosal) e) A5: term in al bran ch (postcallosal) 3. m iddle cerebral6: a) M1: MCA from or igin to bifu rcat ion (h orizon t al segm en t on AP an giogram ). A classical bifu rcat ion in to relat ively sym m et r ical su p er ior an d in fer ior t r u n ks is seen in 50%, n o bifu rcat ion occu rs in 2%, 25% h ave a ver y p roxim al bran ch (m id d le t ru n k) ar isin g from t h e su p e rior (15%) or t h e in ferior (10%) t r u n k creat in g a “p seu d o-t r ifu rcat ion ”, a p seu d o -tet - rafurcation occurs in 5%

Table 2.1 Segm ents of the ICA Syst em of Fischer Vascular Anatom y 77 Cincinnati syst em C1 (cervical) Not described 2 C2 (petrous) C3 (lacerum ) C5 C4 (cavernous) C4 + part of C5 C5 (clinoid) C3 C6 (ophthalm ic) C2 C7 (comm unicating) C1 ● lateral fron to-orbital an d prefron tal bran ch es arise from M1 or superior M2 t run k ● precen tral, cent ral, an terior an d posterior parietal arteries arise from a superior (60%) or m iddle (25%) or in ferior (15%) trun k ● the superior M2 trunk does not give any bran ches to the tem poral lobe b) M2: MCA trun ks from bifurcat ion to em ergen ce from Sylvian fissure c) M3–4: distal branches d) M5: term in al bran ch 4. posterior cerebral (PCA) (several n om en clature sch em es exist5,7): a) P1: PCA from th e origin to posterior com m un icatin g ar ter y (AKA m esen ceph alic, precom m u- n icating, circular, pedun cular, basilar…). Th e lon g an d sh or t circum flex an d th alam operforat- in g ar teries arise from P1 b) P2: PCA from origin of p -com m to th e origin of in ferior tem poral arteries (AKA am bien t , post- com m un icatin g, perim esen ceph alic), P2 traverses the am bien t cistern , Hippocam pal, an terior tem poral, pedun cular perforatin g an d m edial posterior ch oroidal arteries arise from P2 c) P3: PCA from th e origin of th e in ferior tem poral bran ch es to th e origin of th e term in al bran ch es (AKA quadrigem in al segm en t). P3 t raverses th e quadrigem in al cistern d) P4: segm en t after th e origin of th e parieto-occipital an d calcarin e ar teries, in cludes th e cort i- cal bran ch es of th e PCA 2.2.4 Ant erior circulat ion Anat om ic variant s Bovin e circulation : th e com m on carotids arise from a com m on trun k o th e aorta. Ext ernal carot id 1. superior thyroid a.: 1st an terior bran ch 2. ascending pharyngeal a. a) n eurom en ingeal t run k of th e ascen din g ph ar yn geal a.: supplies IX, X & XI (im por tan t w h en em bolizin g glom us tum ors, 20%of low er cran ial n er ve palsy if th is bran ch is occluded) b) ph ar yn geal bran ch : usually th e prim ar y feeder for jugular foram en tum ors (essen tially th e only cause of hypertrophy of th e ascen din g ph ar yn geal a.) 3. lingual a. 4. facial a.: bran ch es an astam ose w ith oph th alm ic a.; im portan t in collateral flow w ith ICA occlu- sion (p.1265) 5. occipital a. posterior scalp 6. posterior auricular 7. superficial tem poral a) fron tal bran ch b) parietal branch 8. (in tern al) m axillar y a. – in itially w ith in parotid glan d a) m iddle m en ingeal a. ● an terior branch ● posterior branch

78 Anatom y and Physiology b) accessory m eningeal c) in ferior alveolar d) in fra-orbital 2 e) others: distal branch es of w hich m ay anastom ose w ith branches of oph thalm ic artery in the orbit Int ernal carot id art ery (ICA) Lies posterior & m edial to th e extern al carotid (ECA). Segm ents of the ICA and its branches See Fig. 2.3 for bran ch es, an d referen ce.4 1. C1 (cer vical): begin s in n eck at carotid bifurcat ion w h ere th e com m on carotid ar ter y divides in to in tern al an d extern al carot ids. Travels in carotid sh eath w ith IJV an d vagal n er ve, en circled w ith postganglion ic sym path etic n er ves (PGSN). C1 en ds w h ere th e ICA en ters carotid can al of petrous bon e. No bra nches 2. C2 (petrous): still surroun ded by PGSNs. En ds at th e posterior edge of th e foram en lacerum (f- Lac) (in ferom edial to th e edge of th e Gasserian gan glion in Meckel’s cave). Th ree division s: anterior cerebral anterior choroidal posterior parietal angular artery posterior temporal PCal central LS CM artery ACom RH ascending FP frontal anterior LS temporal orbitofrontal OF ophthalmic PCom internal carotid Fig. 2.3 Internal carotid arteriogram (AP view). ACom: anterior com municating artery CM: callosom arginal artery FP: frontopolar artery LS: lenticulostriate arteries OF: orbitofrontal artery PCal: pericallosal artery PCom : posterior com municating artery RH: recurrent artery of Heubner (Reprinted courtesy of Eastman Kodak Company)

Vascular Anatom y 79 a) vert ical segm en t: ICA ascen ds th en ben ds as th e… 2 b) posterior loop: an terior to coch lea, ben ds an tero-m edially becom ing th e… c) h orizon tal segm en t: deep an d m edial to greater an d lesser superficial petrosal n er ves, an teri- or to t ym pan ic m em bran e (TM) 3. C3 (lacerum ): th e ICA passes over (but n ot th rough ) th e f-Lac form ing th e lateral loop. Ascen ds in th e can alicular portion of th e f-Lac to juxtasellar position , piercin g th e dura as it passes th e pet- rolin gual ligam en t to becom e th e cavern ous segm en t. Bran ch es (usually n ot visible an giographically): a) caroticot ym pan ic (in con sisten t) t ym pan ic cavit y b) pter ygoid (vidian ) bran ch : passes th rough foram en lacerum , presen t in on ly 30%, m ay con tin - ue as artery of pterygoid canal 4. C4 (cavern ous): covered by vascular m em bran e lin in g sin us, still surroun ded by PGSNs. Passes an teriorly th en supero-m edially, ben ds posteriorly (m edial loop of ICA), t ravels h orizon tally, an d ben ds an teriorly (part of an terior loop of ICA) to an terior clinoid process. En ds at th e proxim al dural rin g (in com pletely en circles ICA). Many bran ch es, m ain on es in clude: a) m en in gohypophyseal trun k (MHT) (largest & m ost proxim al). 2 causes of a prom in en t MHT: 1) tum or (usually petroclival m en ingiom a – see below ), 2) dural AVM (p.1251) ● a. of ten torium (AKA ar tery of Bern ascon i & Cassin ari): th e blood supply of petroclival m en in giom as ● dorsal m en in geal a. (AKA dorsal clival a.) ● in ferior hypophyseal a. ( posterior lobe of pit uitar y): post-part um occlusion causes pit ui- tar y in farcts (Sh eeh an’s n ecrosis), h ow ever, DI is rare because th e stalk is spared b) anterior m eningeal a. c) a. to in ferior portion of cavern ous sin us (presen t in 80%) d) capsular aa. of McCon n ell (in 30%): supply th e capsule of th e pituitar y8 5. C5 (clin oid): begin s at proxim al dural rin g, en ds at distal dural rin g (w h ich com pletely en circles ICA) w h ere th e ICA becom es in t radural 6. C6 (oph th alm ic): begin s at distal dural ring, en ds just proxim al to p -com m . Bran ch es: a) oph th alm ic a.: th e origin from th e ICA is distal to th e cavern ous sin us in 89%(in t racavern ous in 8%, th e oph th alm ic ar ter y is absen t in 3%9) an d can var y from 5 m m an terior to 7 m m pos- terior to th e an terior clin oid.8 Passes th rough th e optic can al in to th e orbit (th e in tracran ial course is ver y sh ort , usually 1–2 m m 8). Has a ch aracteristic bayon et-like “kin k” on lateral a n gio gra m b) superior hypophyseal a. bran ch es an terior lobe of pituitar y & stalk (1st bran ch of supracli- n oid ICA) 7. C7 (com m un icating): begin s just proxim al to p -com m origin , t ravels bet w een Cr. N. II & III, term i- n ates just below an terior perforated substan ce w h ere it bifurcates in to th e ACA & MCA a) posterior com m unicatin g a. (p -com m ) ● few an terior th alam operforators ( optic tract, ch iasm & posterior hypoth alam us): below ● plexal segm ent: enters supracornual recess of tem poral horn, on ly this portion of ch oroid p le x u s ● cistern al segm ent: passes through crural cistern b) anterior ch oroidal arter y10: takeo 2–4 m m distal to p -com m (variable) por tion of optic t ract , m edial globus pallidus, gen u of in tern al capsule (IC) (in 50%), in ferior h alf of posterior lim b of IC, un cus, retrolen ticular fibers (optic radiation ), lateral gen iculate body; for occlusion syndrom es (p.1265) 8. “Carotid siph on ”: n ot a segm en t, but a region in corporatin g th e cavern ous, oph th alm ic an d com - m un icating segm en ts. Begin s at th e posterior ben d of th e cavern ous ICA, an d en ds at th e ICA b ifu r ca t io n Different iat ing p -com m from ACh on art eriogram 1. p-comm origin is proxim al to that of the anterior choroidal artery (ACh) 2. p-comm is usually larger than ACh 3. p-comm usually goes up or down a lit tle, then straight back & usually bifurcates 4. ACh usually has a superior “hump” (plexal point) where it pass through the choroidal fissure to enter the ventricle

80 Anatom y and Physiology Ant erior cerebral art ery (ACA) Passes bet w een Cr. N. II an d an terior perforated substan ce. See Fig. 2.4. Bran ches: 1. recurren t arter y (of Heubn er): t ypically arises from th e area of th e A1/A2 jun ct ion . Various statis- 2 tics can be foun d in th e literature regardin g th e percen tage th at arise from distal A1 vs. proxim al A2.11 It m ost im portan t to be m in dful th at th e takeo is variable, e.g. w h en treatin g an eur ysm s (on e of th e larger m edial len ticulostriates, rem ain der of len ticulostr iates m ay arise from th is artery) head of caudate, putam en , and an terior intern al capsule 2. m edial orbitofron tal ar ter y 3. fron topolar ar ter y 4. callosom arginal a) in tern al fron tal bran ch es ● anterior ● m iddle ● posterior b) paracentral artery 5. pericallosal arter y (con tin uation of ACA) a) superior internal parietal (precun eate) artery b) in ferior in tern al parietal arter y Anatom ic variants Hyp oid : having only one anterior cerebral artery (as in a h orse). Middle cerebral art ery (MCA) See Fig. 2.5 an d an atom y (p. 76). Bran ch es var y w idely, 10 com m on on es: 1. m edial (3–6 per side) an d lateral len ticulostriate ar teries 2. anterior temporal 3. posterior tem poral 4. lateral orbitofron tal 5. ascen din g fron tal (can delabra) 6. precentral (prerolan dic) 7. central (rolan dic) 8. anterior parietal (postrolan dic) 9. posterior parietal 10. angular Post erior circulat ion Anatom ic variants Fetal circulation : 15–35%of patien ts supply th eir posterior cerebral artery on on e or both sides pri- m arily from th e carotid (via p -com m ) in stead of via th e vertebrobasilar system . Vertebral artery (VA) Th e VA is th e first an d usually th e largest bran ch of th e subclavian ar ter y. Varian t: th e left VA arises o th e aor tic arch in ≈ 4%. Diam eter ≈ 3 m m . Mean blood flow ≈ 150 m l/m in . Th e left VA is dom in an t in 60%. Th e righ t VA w ill be hypoplastic in 10%, an d th e left w ill be hypoplastic in 5%. Th e VA is atretic an d does n ot com m un icate w ith th e BA on th e left in 3%, an d on th e righ t in 2%(th e VA m ay term i- n ate in PICA). Four segm en ts: ● V1 prevertebral: from subclavian ar tery, courses superiorly an d posteriorly an d en ters th e fora- m en transversarium , usually of the 6th vertebral body ● V2 ascen ds vertically w ith in th e tran sverse foram in a of th e cer vical vertebrae surroun ded by sym - path et ic fibers (from th e stellate gan glion ) an d a ven ous plexus. It is sit uated a nter ior to th e cervi- cal roots. It turn s laterally to en ter th e foram en w ith in th e t ran sverse process of th e axis ● V3 exits th e foram en of th e axis an d cur ves posteriorly an d m edially in a groove on th e upper sur- face of th e atlas an d en ters th e foram en m agn um ● V4 pierces th e dura (location som ew hat variable) an d im m ediately en ters th e subarach n oid space. Join s th e con tralateral VA at th e ver tebral con fluen s located at th e low er pon tin e border to form th e basilar arter y (BA)

Vascular Anatom y 81 paracentral }superior internal parietal Internal frontal (precuneate) 2 posterior inferior middle anterior calloso- pericallosal marginal anterior choroidal fronto- posterior communicating polar internal carotid medial orbitofrontal choroid crescent of eye ophthalmic tuberculum sellae Fig. 2.4 Anterior cerebral arteriogram (lateral view) (Reprinted courtesy of Eastm an Kodak Com pany) ascending central frontal posterior parietal angular posterior temporal lateral orbitofrontal anterior temporal internal carotid Fig. 2.5 Middle cerebral arteriogram (lateral view) (Reprinted courtesy of Eastman Kodak Com pany)

82 Anatom y and Physiology Br a n ch e s An t er ior m en in geal. Arises at body of C2 (axis), m ay feed ch ordom as or foram en m agn um m en - in giom as, m ay also act as collateral in vascular occlusion 2 Post er ior m en in geal. May be a source of blood for som e dural AVMs (p. 1251) Medullary (bulbar) aa Posterior spin al Post er ior in fer ior cerebellar ar t er y (PICA) (largest bran ch ). Usually arises ≈10 m m distal to poin t w h ere VA becom es in t radural, ≈ 15 m m proxim al to th e vertebrobasilar jun ct ion ( Fig. 2.6) 1. an atom ic varian ts: a) in 5–8%th e PICA h as an extradural origin b) “AICA-PICA”: origin is o basilar trun k (w h ere AICA w ould usually origin ate) 2. 5 segm en ts12 (som e system s som e describe on ly 4). Durin g surgery, th e first th ree m ust be pre- served, but the last 2 m ay usually be sacrificed w ith m inim al deficit13: a) an terior m edullary: from PICA origin to in ferior olivar y prom in en ce. 1 or 2 sh ort m edullary short circum flex branches ventral m edulla b) lateral m edullar y: to origin of n er ves IX, X & XI. Up to 5 bran ch es th at supply brain stem c) ton sillom edullar y: to ton sillar m idport ion (con tain s ca uda l loop on an gio) P-comm III left PCA SCA IV V AICA VI VII/VIII BA { lm tvt IX cs X tm XII am left PICA left VA XI Fig. 2.6 Intradural VA and PICA segments (lateral view) (Modified with perm ission from : Lewis SB, Chang DJ, Peace DA, Lafrentz PJ, Day AL. Distal posterior inferior cerebellar artery aneurysms: clinical features and managem ent. J Neurosurg 2002;97(4):756-66)

Vascular Anatom y 83 d) teloveloton sillar (supraton sillar): ascen ds in ton sillom edullar y fissure (con tain s cra nia l loop 2 on angio) e) cort ical segm ents 3. 3 branches a) ch oroidal a. (BRANCH 1) arises from cran ial loop (choroida l point), ch oroid plexus of 4th ve n t r icle b) term inal branches: ● ton silloh em isph eric (BRANCH 2) ● in ferior verm ian (BRANCH 3) in ferior in flect ion = copula r point on an gio An t er ior sp in al Basilar artery (BA) Form ed by th e jun ct ion of th e 2 vertebral arteries. Bran ch es: 1. an terior in ferior cerebellar arter y (AICA): from low er par t of BA, run s posterolaterally an terior to VI, VII & VIII. Often gives o a loop th at run s in to th e IAC an d gives o th e labyrin th in e artery an d th en em erges to supply th e an terolateral in ferior cerebellum an d th en an astom oses w ith PICA 2. internal auditor y (labyrinthine) 3. pontine branches 4. superior cerebellar a. (SCA) a) sup. verm ian 5. posterior cerebral: join ed by p -com m s ≈ 1 cm from origin (th e p -com m is th e m ajor origin of th e PCA in 15%an d is term ed “fetal” circulat ion , bilateral in 2%). 3 segm en ts (n am ed for surroun din g cistern ) an d th eir bran ch es: a) peduncular segm ent (P1) ● m esen ceph alic perforatin g aa. ( tectum , cerebral pedun cles, an d th ese n uclei: Edinger- Westphal, oculom otor and trochlear) ● in terpedun cular th alam operforators (1st of 2 groups of posterior th alam operforatin g aa.) ● m edial post . ch oroidal (m ost from P1 or P2) ● “ar ter y of Perch eron”: a rare an atom ic varian t14 in w h ich a solitar y arterial t run k arisin g from th e proxim al segm en t of on e PCA supplies th e param edian th alam i an d rostral m id- brain bilaterally b) am bient segm en t (P2) ● lateral post . ch oroidal (m ost from P2) ● th alam ogen iculate th alam operforators (2n d of 2 groups of posterior th alam operforatin g aa.) geniculate bodies + pulvinar ● an terior tem poral (an astam oses w ith an terior tem poral br. of MCA) ● posterior tem poral ● parieto-occipital ● calcarine c) quadrigem in al segm en t (P3) ● quadrigem inal & geniculate branches quadrigem inal plate ● post. pericallosal (splen ial) (an astom oses w ith pericallosal of ACA) Posterior cerebral artery (PCA) See Fig. 2.7. Carot id-vert ebrobasilar anast om oses P-com m artery: th e “n orm al” (m ost com m on ) an astom osis. Persisten t fetal an astam oses15 ( Fig. 2.8) result from failure to involute as th e VAs an d p -com m s develop (order of involution : otic, hypoglossal, prim itive trigem in al, proatlan tal). Most are asym pto- m at ic. How ever, som e m ay be associated w ith vascular an om alies such as an eur ysm s or AVMs, an d occasion ally cran ial n er ve sym ptom s (e.g. t rigem in al n euralgia w ith PPTA) can occur. Four t ypes (from cran ial to caudal – th e 1st 3 are n am ed for th e associated cran ial n er ve): 1. persisten t prim itive t rigem in al arter y (PPTA): seen in ≈ 0.6%of cerebral an giogram s. Th e m ost com m on of th e persisten t fetal an astom oses (83%). May be associated w ith trigem in al n euralgia (p. 479). Con n ects th e cavern ous carotid to th e basilar arter y. Arises from th e ICA proxim al to th e origin of th e m en in gohypophyseal t run k (50%go th rough sella, 50%exit th e cavern ous sin us & course w ith th e trigem in al n er ve) an d con n ects to th e upper basilar ar ter y betw een AICA & SCA. Th e VAs m ay be sm all. Saltzm an t ype 1 varian t: th e p -com m s are hypoplastic an d th e PPTA pro- vides sign ifican t blood supply to th e dist ribution s of th e distal BA, PCA an d th e SCAs (th e basilar

84 Anatom y and Physiology posterior lateral posterior pericallosal parieto-occipital {2 choroidals medial posterior cerebral calcarine superior cerebellar superior vermian thalamoperforators posterior posterior temporal communicating anterior temporal basilar hemispheric branches lateral marginal {AICAlateral branch lm tvt cs }choroidal branch medial branch am inferior vermian P ICA hemispheric branch bra nche s tm tonsillar branch vertebral arteries PICAsegments am = anterior medullary lm = lateral medullary tm = tonsillomedullary (w/caudal loop) tvt = telovelotonsillar (supratonsillar) (w/cranial loop) cs = cortical segments Fig. 2.7 Vertebrobasilar arteriogram (lateral view) (Reprinted courtesy of Eastman Kodak Com pany) P-Comm Fig. 2.8 Carotid-vertebrobasilar anastomoses PCA SCA trigeminal otic AICA PICA hypoglossal p ro a t la n t a l C1 C2 ICA VA artery is often hypoplastic). Salt zm an t ype 2: p -com m supplies PCA. Saltzm an t ype 3: PPTA join s th e SCA (in stead of th e BA). It is crit ical to recogn ize a PPTA before doing a Wada test (p.1553) because of the risk anesthetizing the brainstem , and in doing transsphenoidal surgery because of risk of arterial injur y. May rarely be an explan ation of posterior fossa sym ptom s in a patien t w ith carotid disease 2. otic: th e first to involute, an d th e rarest to persist (8 cases reported). Passes th rough IAC to con - nect petrous carotid to basilar artery 3. hypoglossal: con n ects petrous or distal cervical ICA (origin usually betw een C1-C3) to VA. Traver- ses th e hypoglossal can al. Does n ot cross foram en m agn um

Vascular Anatom y 85 4. proatlan tal in tersegm en tal: con n ects cer vical ICA to VA. May arise from : bifurcation of com m on 2 carotid, ECA, or ICA from C2-C4. An astom osis w ith VA in suboccipital region . 50%h ave hypoplas- t ic proxim al VA. 40 cases reported 2.3 Cerebral venous anat om y 2.3.1 Suprat ent orial venous syst em Major veins and t ribut aries See Fig. 2.9 for an giogram an d bran ch es. Th e left an d righ t in tern al jugular vein s (IJVs) are th e m ajor source of outflow of blood from th e in tracran ial com part m en t. Th e r ight IJV is usually dom in an t. Oth er sources of outflow in clude orbital vein s an d th e ven ous plexuses aroun d th e vertebral arteries. Diploic an d scalp vein s m ay act as col- lateral path w ays, e.g. w ith superior sagittal sin us obstruct ion .16 Th e follow in g outlin e t races th e ven ous drain age back from th e IJVs. Inferior petrosal sinus Term in ates (i.e. drain s to) ≤ 1 cm of jun ction of sigm oid an d tran sverse sin uses. Sigm oid sinus superior petrosal sinus Drain s to IJV n ear jun ct ion w ith sigm oid sin us anterior caudate vein inferior superior thalamostriate vein sagittal sagittal sinus sinus superior anastamotic vein (of Trolard) TC direct lateral v. internal cerebral v. IVs posterior septal v. septal vein great cerebral superficial middle vein (of Galen) vein of cerebral vein posterior horn sphenoparietal sinus straight sinus cavernous sinus Torcular herophili deep middle cerebral vein transverse sinus basal cerebral sigmoid sinus vein (of Rosenthal) inferior anastamotic TC = transverse caudate veins IVs = insular veins vein (of Labbé) Fig. 2.9 Internal carotid venogram (lateral view) (Reprinted courtesy of Eastman Kodak Com pany)

86 Anatom y and Physiology Transverse sinus R > L in 65%. V. of Labbe. (In ferior an astom ot ic v.) 2 Con flu en s of sin u ses. (Torcular h eroph ili) 1. occipital sinus 2. superior sagittal sinus a) v. of Trolard (superior an astom otic v.): th e prom in ent superficial vein on th e non-domina nt side (Labbé is m ore prom in en t on th e dom in an t side) b) cort ical veins 3. st raigh t sin us a) in ferior sagit tal sin us b) great cerebral v. (of Galen ) ● pre-cen t ral cerebellar v. ● basal vein of Rosen th al ● in tern al cerebral v.: join ed at th e foram en of Mon ro (ven ous an gle) by: an terior septal v. th alam ostriate v. Cavernous sinus Origin ally n am ed for its superficial resem blan ce to th e corpora cavern osa. Alth ough classical teach - in g depicts th e cavern ous sin us as a large ven ous space w ith m ultiple trabeculation s, inject ion stud- ies17 an d surgical experien ce18 in stead supports th e con cept of th e cavern ous sin us as a plexus of vein s. It is h igh ly variable betw een in dividuals an d from side-to-side. Fig. 2.10 is an oversim plified sch em atic of on e sect ion th rough th e righ t cavern ous sin us. 1. inflow ing veins: a) superior & in ferior oph th alm ic vein s b) superficial m iddle cerebral vein s c) sph enoparietal sinus d) superior & in ferior petrosal sin us 2. outflow : a) sph enoparietal sinus b) superior petrosal sinus c) basilar plexus (w h ich drain s to th e in ferior petrosal sin us) d) pterygoid plexus e) th e righ t an d left cavern ous sin uses com m un icate an teriorly an d posteriorly via th e circular sin u s 3. contents19 a) Oculom otor n . (III) b) Troch lear n . (IV) sDeiallapehragm a CAVERNOUS SINUS Optic chiasm Icnatreortnida la r t e r y Pit u it a r y Oculom otor (III) Outer layer (dura propria) Spaihresninouids Inner mem branous layer Trochlear (IV) } T(orifaPnagruklianrsospna)ce Abducent (VI) Ophthalm ic (V1) Maxillary (V2) Cords of Willis Fig. 2.10 Right cavernous sinus (coronal section)

Vascular Anatom y 87 c) Oph th alm ic division of t rigem in al (V1) 2 d) Maxillar y division of t rigem in al (V2): th e on ly n er ve of th e cavern ous sin us th at doesn’t exit th e skull th rough th e superior orbital fissure (it exits th rough foram en rotun dum ) e) Carotid arter y (ICA). 3 segm en ts w ith in th e cavern ous sin us ● posterior ascen din g segm en t: im m ediately after ICA en ters th e sin us ● h orizon tal segm en t: after ICA t urn s an teriorly (th e lon gest segm en t of th e in t racavern ous ICA) ● an terior ascen ding segm en t: ICA turn s superiorly f) Abducen s n . (VI): th e on ly n er ve NOT attach ed to lateral dural w all, som etim es referred to as th e on ly cran ial n er ve in side th e cavern ous sin us 4. t rian gular space (of Parkin son ): superior border form ed by Cr. N. III & IV, an d th e low er m argin form ed by V1 & VI (a lan d m ark for su rgical en tran ce to th e cavern ou s sin u s)20,21 (p 3007) 2.3.2 Posterior fossa venous anat om y See Fig. 2.11. 2.4 Spinal cord vasculat ure See Fig. 2.12. Alth ough a radicular arter y from th e aorta accom pan ies th e n er ve root at m any levels, m ost of th ese con tribute lit tle flow to th e spin al cord itself. Th e an terior spin al arter y is form ed from th e jun ction of t w o bran ch es, each from on e of th e ver tebral arteries. Major con tributors of blood supply to th e an terior spin al cord is from 6–8 radicular ar teries at th e follow in g levels (“radiculom edullar y arteries”, th e levels listed are fairly con sisten t, bu t th e sid e varies22 (p 1180–1)): 1. C3 – arises from vertebral ar ter y 2. C6 an d C8 (≈ 10%of population lack an an terior radicular artery in low er cervical spin e23) a) C6 – usually arises from deep cervical ar tery b) C8 – usually from costocervical t run k 3. T4 or T5 4. artery of Adam kiew icz AKA arteria radicularis an terior m agn a a) th e m ain ar terial supply for th e spin al cord from ≈ T8 to th e con us b) located on th e left in 80%24 c) sit uated betw een T9 & L2 in 85%(betw een T9 & T12 in 75%); in rem ain ing 15%betw een T5 & T8 (in th ese latter cases, th ere m ay be a supplem en tal radicular ar tery furth er dow n ) great cerebral vein (Galen) internal occipital v. precentral cerebellar v. superior vermian v. transverse sinus posterior mesencephalic v. lateral mesencephalic v. superior hemispheric v. straight sinus anterior ponto- mesencephalic v. tuberculum sellae transverse inferior hemispheric v. pontine vein inferior vermian v. brachial vein superior petrosal sinus anterior medullary v. petrosal vein vein of the lateral recess of the 4th ventricle Fig. 2.11 Vertebrobasilar venogram (lateral view) (Reprinted courtesy of Eastman Kodak Com pany)

88 Anatom y and Physiology 2 basilar artery spinal cord right vertebral left vertebral artery artery radicular artery at C3 anterior spinal artery right common left common radicular artery at C6 carotid carotid deep cervical artery right costocervical trunk subclavian radicular artery at C8 brachiocephalic trunk left subclavian left posterior spinal artery aorta }radicular artery at T5 posterior inter- intercostal arteries costal artery artery of (dorsal branch) Adamkiewicz posterior (arteria radicularis spinal arteries anterior magna) radicular arteria radicularis artery magna (posterior branch) posterior intercostal artery anterior spinal aorta artery Axia l vie w Fig. 2.12 Schem atic diagram of spinal cord arterial supply (Modified from Diagnostic Neuroradiology, 2nd ed., Volume II, pp. 1181, Taveras J M, Woods EH, editors, © 1976, the William s and Wilkins Co., Baltimore, with perm ission)) d) usually fairly large, gives o ceph alic an d caudal bran ch (latter is usually larger) giving a ch ar- acteristic hair-pin appearance on an giography Th e paired posterior spin al arteries are less w ell defin ed th an th e an terior spin al arter y, an d are fed by 10–23 radicular branches. Th e m idth oracic region h as a tenuous vascular supply (“w atersh ed zon e”), possessin g on ly th e above n oted arter y at T4 or T5. It is th us m ore susceptible to vascular in sults. An at om ic var ian t s. Arcade of Lazorth es: n orm al varian t w h ere th e an terior spinal artery join s w ith th e paired posterior spinal arteries at th e conus m edullaris.

Vascular Anatom y 89 Re fe r e n ce s [14] Perch eron G. Th e an atom y of th e ar terial sup p ly of 2 th e h um an th alam us an d its use for the in terpreta- [1] van der Zw an A, Hillen B, Tu lleken CAF, Du jovn y M, tion of th e th alam ic vascular path ology. Z Neurol. Dragovic L. Variability of th e Territories of th e Major 1973; 205:1–13 Cerebral Arteries. J Neurosurg. 1992; 77:927–940 [15] Luh GY, Dean BL, Tom sick TA, Wallace RC. Th e per- [2] Lou kas M, Louis RG, Jr, Ch ilds RS. An atom ical exam i- sisten t fetal carotid-vertebrobasilar an astom oses. n ation of th e recurren t artery of Heubner. Clin An at. AJR Am J Roen tgen ol. 1999; 172:1427–1432 2006; 19:25–31 [16] Sch m id ek HH, Au er LM, Kap p JP. Th e Cerebral [3] Fisch er E. Die Lageabw eich ungen d er Vorderen Hir- Ven ou s System . Neurosurger y. 1985; 17:663–678 n ar terie im Gefässbild. Zen tralbl Neurochir. 1938; 3:300–313 [17] Taptas JN. The So-Called Cavernous Sin us: A Review of the Cont roversy an d Its Im plication s for Neuro- [4] Bou th illier A, van Loveren HR, Keller JT. Segm en ts of the in tern al carotid artery: A new classification . surgeons. Neurosurgery. 1982; 11:712–717 Neu rosu rger y. 1996; 38:425–433 [18] Sekh ar LN, Sch ram m VL. In : Operative Man agem en t [5] Krayen bü h l HA, Yasargil MG. Cerebral An giograp hy. of Tum ors Involvin g th e Cavern ou s Sin us. Tu m ors of 2n d ed. Lon don : Bu t terw orth s; 1968:80–81 th e Cran ial Base: Diagn osis an d Treatm en t. Mou n t Krisco: Futura Publish in g; 1987:393–419 [6] Krayen bü h l H, Yasargil MG, Huber P. In : Ron tgen - [19] Um an sky F, Nath an H. Th e Lateral Wall of th e Caver- an atom ie un d Top ograp h ie der Hirn gefasse. Zere- n ous Sin us: w ith Special Referen ce to the Nerves brale An giograph ie fu r Klin ik un d Praxis. St uttgar t: Related to It. J Neurosurg. 1982; 56:228–234 Georg Th iem e Verlag; 1979:38–246 [20] van Loveren HR, Keller JT, El-Kallin y M, Scodary DJ, Tew JM. The Dolen c Tech n ique for Cavern ous Sin us [7] Ecker A, Riem en sch n eid er PA. An giograph ic Local- Exp loration (Cad averic Prosect ion ). J Neurosurg. ization of In t racran ial Masses. Sprin gfield, Illin ois: 1991; 74:837–844 Ch arles C. Th om as; 1955 [21] Youm an s JR. Neurological Surgery. Ph iladelph ia 1982 [8] Gibo H, Len key C, Rh oton AL. Microsurgical An ato- m y of th e Su praclin oid Port ion of th e In tern al Caro- [22] Taveras JM, Wood EH. Diagn ostic Neuroradiology. tid Artery. J Neu rosu rg. 1981; 55:560–574 2n d ed. Balt im ore: W illiam s an d W ilkin s; 1976 [9] Ren n W H, Rh oton AL. Microsurgical An atomy of th e [23] Turnbull IM, Breig A, Hassler O. Blood Supply of th e Sellar Region. J Neurosurg. 1975; 43:288–298 Cervical Spin al Cord in Man . A Microan giograph ic Cadaver Stu d y. J Neurosurg. 1966; 24:951–965 [10] Rh oton AL, Jr. Th e su praten torial ar teries. Neu rosu r- gery. 2002; 51:S53–120 [24] El-Kallin y M, Tew JM, van Loveren H, Du n sker S. Surgical approach es to th oracic disk h ern iation s. [11] An atom ical exam in ation of th e recurren t artery of Acta Neu roch ir. 1991; 111:22–32 Heubn er. Clin An at. 2006; 19:25–31 [12] Lister JR, Rh oton AL, Matsu sh im a T, et al. Microsu r- gical An atom y of the Posterior In ferior Cerebellar Artery. Neurosurgery. 1982; 10:170–199 [13] Getch CC, O'Sh augh n essy BA, Ben dok BR, Parkin son RJ, Batjer HH. Surgical m an agem en t of in tracran ial an eur ysm s involvin g th e p osterior in ferior cerebel- lar artery. Con tem p Neu rosu rg. 2004; 26:1–7

90 Anatom y and Physiology 3 Neurophysiology and Regional Brain Syndrom es 3.1 Neurophysiology 3 3.1.1 Blood-brain barrier General inform at ion Th e passage of w ater-soluble substan ces from th e blood to th e CNS is lim ited by t igh t jun ction s (zon - ulae occluden tes) w h ich are foun d bet w een cerebral capillar y en doth elial cells, lim itin g pen etrat ion of th e cerebral paren chym a (blood-brain barrier, BBB), as w ell as bet w een ch oroid plexus epith elial cells (blood-CSF barrier).1 A n um ber of specialized m ediated tran sport system s allow t ran sm ission of, am ong oth er th in gs, glucose an d certain am in o acids (especially precursors to neurotransm itters). Th e e cacy of th e BBB is com prom ised in certain path ological states (e.g. tum or, in fect ion , t rau- m a, st roke, h epatic en cephalopathy…), an d can also be m an ipulated ph arm acologically (e.g. hyper- ton ic m an n itol in creases th e perm eabilit y, w h ereas steroids reduce th e pen etrat ion of sm all hydrophilic m olecules). Th e BBB is absen t in th e follow in g areas: ch oroid plexus, hypophysis, t uber cin ereum , area post- rem a, pineal and preoptic recess. Mean s of assessing th e in tegrit y of th e BBB: ● visible dyes: Evan’s blue, fluorescein ● radioopaque dyes (im aged w ith CT scan 2): iodin e (protein -boun d con trast agen t) ● param agnetic (im aged on MRI): gadolin ium (protein -boun d con trast agen t) ● m icroscopic: horseradish peroxidase ● radiolabeled: album in, sucrose Cerebral edem a and t he blood brain barrier Th ree basic t ypes of cerebral edem a; di usion -w eigh ted MRI (p. 232) m ay be able to di eren tiate: 1. cytotoxic: BBB is closed, th erefore n o protein extravasation , th erefore n o en h an cem en t on CT or MRI. Cells sw ell th en sh rin k. Seen e.g. in h ead injur y 2. vasogen ic: BBB disrupted. Protein (serum ) leaks out of vascular system , an d th erefore m ay en h an ce on im agin g. Extracellular space (ECS) expan ds. Cells are stable. Respon ds to cort icostero- ids (e.g. dexam eth ason e). Seen e.g. surroun din g m etastat ic brain tum or 3. isch em ic: a com bin ation of th e above. BBB closed in itially, but th en m ay open . ECS sh rin ks th en expan ds. Fluid extravasates late. May cause delayed deterioration follow in g in t racerebral h em or- rhage (p.1337). 3.1.2 Babinski sign and Ho m ann sign Int roduct ion Alth ough th e Babin ski sign is regarded as th e m ost fam ous sign in n eurology, th ere is st ill disagree- m en t over w h at con stitutes a n orm al respon se an d w h en abn orm al respon ses sh ould occur.3 Th e follow in g represen ts on e in terpretation . The plantar reflex (PR) (AKA Babinski sign after Joseph François Félix Babinski (1857–1932) a French neurologist of Polish descent) is a prim itive reflex, present in infancy, consisting of extension of the great toe in response to a noxious stim ulus applied to the foot. The sm all toes m ay fan, but this is not a consis- tent nor clinically important component. The PR disappears usually at ≈ 10 m onths age (range: 6 m os to 12 yrs), presum ably under inhibitory control as myelination of the CNS occurs, and the norm al response then converts to plantarflexion of the great toe. An upper m otor neuron (UMN) lesion anyw here along the pyram idal (corticospinal) tract from the motor strip dow n to ≈ L4 w ill result in a loss of inhibition, and the PR w ill be “unm asked” producing extension of the great toe. With such an UMN lesion, there m ay also be exaggeration of flexor synergy resulting in dorsiflexion of the ankle, and flexion of the knee and hip (AKA triple flexor response) in addition to extension of the great toe. Neuroanatom y Th e a eren t lim b of th e reflex origin ates in cutan eous receptors restricted to th e first sacral derm a- tom e (S1) an d travels proxim ally via th e t ibial n er ve. Th e spin al cord segm en ts involved in th e reflex-arc lie w ith in L4-S2. Th e e eren t lim b to th e toe exten sors t ravels via th e peronea l ner ve.

Neurophysiology and Regional Brain Syndrom es 91 Di erent ial diagnosis 3 Et io lo g ie s Lesion s producin g a PR n eed n ot be structural, but m ay be fun ct ion al an d reversible. Th e roster of possible etiologies is exten sive, som e are listed in Table 3.1. Elicit ing t he PR, and variat ions Th e optim al st im ulus con sists of stim ulat ion of th e lateral plan tar surface an d t ran sverse arch in a sin gle m ovem en t lastin g 5–6 secon ds.4 Oth er m ean s for applyin g n oxious st im uli m ay also elicit th e plan tar reflex (even outside th e S1 derm atom e, alth ough th ese do n ot produce toe flexion in n or- m als). Described m an euvers in clude: Chaddock (scratch th e lateral foot; positive in 3%w h ere plan tar st im ulation w as n egative), Sch ae er (pin ch th e Ach illes ten don ), Oppen h eim (slide kn uckles dow n sh in ), Gordon (m om en tarily squeeze low er gastrocn em ius), Bing (ligh t pin pricks on dorsolateral foot), Gon da or St ron sky (pull th e 4th or 5th toe dow n an d out an d allow it to sn ap back). Ho m an’s (or Ho m ann’s or Ho m ann) sign Attributed to Joh an n Ho m an n , a Germ an n eurologist pract icin g in th e late 1800. May sign ify a sim - ilar UMN in terruption to th e upper extrem ities. Elicited by flicking dow nw ard on th e n ail of th e m id- dle or rin g fin ger: a positive (path ologic) respon se con sists of involun tar y flexion of th e adjacen t fin gers an d/or th um b (m ay be w eakly presen t in n orm als).5 Di ers from th e plan tar reflex sin ce it is m on osyn aptic (syn apse in Rexed lam in a IX). Can som etim es be seen as n orm al in youn g in dividual w ith di usely brisk reflexes & positive jaw jerk, usually sym m etric. W h en present path ologically, represen ts disin h ibition of a C8 reflex, in di- cates lesion above C8. Ho m ann sign was observed in 68% of patients operated for cervical spondylotic myelopathy.5 In 11 patients presenting with lum bar sym ptom s but no myelopathy, a bilateral Ho m an sign was associated w ith occult cervical spinal cord com pression in 10 (91%).5 The Ho m ann test has a sensitivity of 33-68%, specificity of 59-78%, a positive predictive value of 26-62%and negative predictive value of 67-75%.6 3.1.3 Bladder neurophysiology Cent ral pat hw ays Th e prim ar y coordin at in g center for bladder fun ct ion resides w ith in th e n ucleus locus coeruleus of th e pon s. Th is cen ter syn chron izes bladder con tract ion w ith relaxation of th e ureth ral sph incter dur- in g voidin g.7 Volun tary cort ical con trol prim arily involves in h ibition of th e pon t in e reflex, an d origin ates in th e an terom edial port ion of th e fron tal lobes an d in th e genu of th e corpus callosum . In an un in h ibited bladder (e.g. in fan cy) th e pon t in e voidin g center fun ct ion s w ith out cort ical in h ibition an d th e detru- sor m uscle con tracts w h en th e bladder reach es a crit ical capacit y. Volun tary suppression from th e cortex via th e pyram idal tract m ay con tract th e extern al sph in cter an d m ay also in h ibit detrusor contract ion . Cortical lesion s in th is location → urgen cy in con tin en ce w ith in abilit y to suppress th e m ict u rition reflex.8 (p 1031) E erents to the bladder travel in the dorsal portion of th e lateral colum n s of the spinal cord (shaded areas in Fig. 3.1). Table 3.1 Di erential diagnosis of the plantar reflex (PR) Et iologies ● spinal cord injuriesa ● cervical spinal m yelopathy ● lesions in motor strip or internal capsule (stroke, tumor, contusion…) ● subdural or epidural hem atom a ● hydranencephaly ● toxic-m etabolic coma ● seizures ● trauma ● TIAs ● hemiplegic m igraine ● motor neuron disease (ALS) ain spinal cord injuries, the PR m ay initially be absent during the period of spinal “shock” (p. 931)

92 Anatom y and Physiology Fig. 3.1 Location of spinal cord bladder efferents (sh a d e d ) 3 Mo t o r Th ere are t w o sph in cters th at preven t th e flow of urin e from th e bladder: in tern al (auton om ic, invol- untary control), and external (striated m uscle, voluntary control). Parasym pathet ics (PSN) Th e detrusor m uscle of th e bladder con tracts an d th e in tern al sph in cter relaxes un der PSN st im ula- t ion . PSN pregan glion ic cell bodies reside in th e in term ediolateral grey of spin al cord segm en ts S2–4. Fibers exit as ven t ral n er ve roots an d travel via pelvic splan ch n ic n er ves (n er vi erigen tes) to term i- n ate on ganglia w ith in th e w all of th e detrusor m uscle in th e body an d dom e of th e bladder. Som atic nerves Som atic volun tary con trol descen ds in th e pyram idal t ract to syn apse on m otor n er ves in S2–4, an d th en t ravels via th e puden dal n er ve to th e extern al sph incter. Th is sph in cter m ay be volun tarily con - t racted, but relaxes reflexly w ith open in g of th e in tern al sph in cter at th e in it iation of m icturit ion . Prim arily m ain tain s con tin en ce durin g ↑ vesical pressure (e.g. valsalva). Sym pathetics Sym path etic cell bodies lie w ith in th e in term ediolateral gray colum n of lum bar spin al cord from seg- m en ts T12 —L2. Preganglion ic axon s pass th rough th e sym path et ic ch ain (w ith out syn apsing) to th e in ferior m esen teric ganglion . Postganglion ic fibers pass th rough th e in ferior hypogast ric plexus to th e bladder w all an d in tern al sph incter. Sym path et ics h eavily in n er vate th e bladder n eck an d trig- on e. Sym path et ics h ave litt le e ect on bladder m otor activity, but alph a adren ergic stim ulation results in bladder n eck closure w h ich is n ecessar y for bladder filling. Pelvic n er ve stim ulation → in creased sym pathetic tone → detrusor relaxation & in creased bladder neck tone (allow in g larger volum e to be accom m odated). Se n so r y Less w ell un derstood th an m otor in n er vation . Bladder w all stretch receptors sen se bladder fillin g an d sen d a eren t sign als via pelvic, puden dal an d hypogastric n er ves to spin al cord segm en ts T10- L2 & S2–4. Fibers ascen d prim arily in th e spinoth alam ic t ract . Urinary bladder dysfunct ion Th e term n eurogen ic bladder describes bladder dysfun ct ion due to lesion s w ith in th e cen tral or periph eral n er vous system s. Som e use th e term syn onym ously w ith detrusor areflexia. Dorsal (sen sory) roots lesion s in terrupt th e a eren t lim b, producin g an aton ic bladder th at fills un til dribbling an d overflow in con tin en ce occur. No sen sation of bladder fulln ess is appreciated. Vol- untary voidin g is still possible, but is usually incom plete. Det rusor hyperreflexia Can result from in terruption of e eren ts anyw h ere from cortex to sacral cord. W h en a critical vol- um e is attain ed, reflex bladder em pt ying occurs. Clin ically associated w ith frequen t, un con trollable,

Neurophysiology and Regional Brain Syndrom es 93 precipitous voidin g. Cerebral lesion s in clude: st roke, h ead injur y, brain tum ors, hydroceph alus, Par- 3 kin son’s disease, various dem en tias, an d MS. Cord lesion s in clude anyth in g th at causes m yelopathy (p . 1 4 0 7 ). Detrusor areflexia Clin ically correlates w ith di cult y in itiatin g m icturit ion , in terrupted flow, an d sign ifican t residual urin e. In con tin en ce m ay result from over-disten tion of th e bladder (overflow in con t in en ce), or m ay be associated w ith absen ce of sph in cter ton e. Et iologies in clude: ch ron ic in fect ion , lon g-term bladder cath eterizat ion , certain drugs (especially ph en oth iazin es), injur y or tum or of th e cauda equin a or con us m edullaris, m yelom en ingocele, an d diabetes m ellitus (auton om ic n europathy). Specific injuries a ecting t he bladder In general, regarding discrete n eurologic lesion s a ect in g th e bladder9: 1. supraspin al (lesion s above th e brain stem ): loss of cent rally m ediated in h ibition of th e pon tin e voidin g reflex. Usually produces involun tar y bladder con tract ion s w ith sm ooth an d striated sph in cter syn ergy, often w ith preser ved sen sation an d volun tar y striated sph in cter fun ction . Sym ptom s: urin ar y frequen cy or urgen cy, urgen cy in con tin en ce, and n octuria.7 If sen sor y path - w ays are in terrupted, un con scious in con t in en ce occurs (in con tin en ce of th e un aw ares t ype). Sin ce m uscles are coordin ated, n orm al bladder pressures are m ain tain ed an d th ere is low risk of h igh -pressure related ren al dysfun ct ion . Volun tar y bladder em pt yin g is usually m ain tain ed, an d tim ed voiding together w ith antich olinergic m edications (see below ) are used in m anagem ent. Areflexia m ay som etim es occur 2. com plete (or n ear com plete) spin al cord lesion s: a) suprasacral (lesion a bove th e S2 spin al cord level, w h ich is ≈ T12/L1 vertebral body level in an adult): th e sacral voidin g center is located in th e con us m edullaris. Etiologies: spin al cord injuries, tum ors, transverse m yelit is. ● In itially follow in g spin al cord injur y, th ere m ay be spin al sh ock. Durin g spinal sh ock (p. 931), th e bladder is acon tract ile an d areflexic (detru sor areflexia); sph in cter ton e usually persists and urinary retention is th e rule (urinary incontinen ce generally does not occur except w ith overdistention) ● After spin al sh ocksubsides, m ost develop det rusor hyper reflexia → involun tar y bladder con - tract ion s w ith out sen sation (autom atic bladder), sm ooth sph in cter syn ergy, but st riated dyssyn ergy (involun tar y con traction of th e extern al sph in cter durin g voidin g w h ich produ- ces a fun ction al outlet obstruct ion w ith poor em pt ying an d h igh vesical pressures). Bladder fills and em pties spontaneously (or in response to low er extrem ity cutan eous stim ulation). Bladder com plian ce is often reduced. Man aged by in term itten t cath eterization s + anticholin ergics b) in frasacral lesion s (lesion below th e S2 spin al cord level): in cludes injur y to con us m edullaris, cauda equin a or periph eral n er ves (form erly referred to as low er m otor n euron lesion s). Etiol- ogies: large HLD, traum a w ith com prom ise of spin al can al. Usually develop detrusor areflexia, and do n ot h ave involun tar y bladder con traction s. Reduced urin ar y flow rate or reten tion results, an d volun tar y voidin g m ay be lost. Overflow in con tin en ce develops. Th ere m ay be reduced com plian ce durin g fillin g, an d paralysis of th e sm ooth sph incter (th e n eurologic basis of th is h as n ot been settled, an d m ay be due to sym path et ic or PSN involvem en t). Usually associated w ith loss of bulbocavern osus an d an al w in k reflex (preser ved in suprasacral lesions, except w hen spinal sh ock is present (p.931) ) and perin eal sensory loss 3. in terruption of th e periph eral reflex arc: m ay produce disturban ces sim ilar to low spin al cord injur y w ith det rusor areflexia, low com plian ce an d in abilit y to relax th e striated sph in cter 4. h ern iated lum bar disc (p. 1046): m ost con sist in it ially of di cult y voidin g, st rain ing, or urin ar y reten tion . Later, irritative sym ptom s m ay develop 5. spinal sten osis (lum bar or cervical): urologic sym ptom s vary, an d depen d on th e spin al level(s) involved an d th e t ype of involvem en t (e.g. in cer vical spin al sten osis, detrusor hyperact ivity or underactivit y m ay occur depending on w h ether the involvem ent of th e m icturition neural axis is com pression of the inhibitory reticulospinal tracts or m yelopathy involving the posterior fun iculus) 6. cauda equina syndrom e (p.1050): usually produces urinar y retention , although som etim es incontin ence m ay occur (som e cases are overflow incontin ence) 7. periph eral n europath ies: such as w ith diabetes, usually produce im paired detrusor activit y 8. n eurospin al dysraph ism : m ost m yelodysplastic patien ts h ave an areflexic bladder w ith an open bladder n eck. Th e bladder usually fills un til th e restin g residual fixed extern al sph in cter pressure is exceeded an d th e leakage occurs

94 Anatom y and Physiology 9. m ultiple sclerosis: 50–90%of pat ien ts develop voidin g sym ptom s at som e tim e. Th e dem yelin a- tion prim arily involves th e posterior an d lateral colum n s of th e cer vical spin al cord. Detrusor hyperreflexia is th e m ost com m on urodyn am ic abn orm alit y (in 50–99%of cases), w ith bladder areflexia bein g less com m on (5–20%) Urinary retent ion 3 Etiologies of urin ar y reten tion : 1. bladder outlet obstruction (a brief di eren tial diagn osis list is presen ted h ere) a) ureth ral stricture: reten tion tends to be progressive over tim e b) prostatic enlargem ent in m ales: ● ben ign prostatic hypertrophy (BPH) & prostate can cer: reten tion ten ds to be progressive over tim e ● acute prostatitis: onset of retention m ay be sudden ● rare: extruded prostatic stone c) w om en m ay develop a cystocele w hich can produce a urethral kink d) rare: urethral cancer 2. detrusor areflexia (p.93) or hypoton ia a) spinal cord injur y b) cauda equina syndrom e (p. 1050) c) ch ronic in fect ion d) lon g-term bladder cath eterization e) certain drugs (n arcotics, ph en oth iazin es) f) injur y of th e cauda equin a or con us m edullaris, or of th e spin al cord at or below th e sacrum ● trauma ● tumor ● m yelom en ingocele g) diabetes m ellitus (auton om ic n europathy) h ) h erpes zoster at th e level of th e sacral d orsal root ganglia9 (p 967) i) in com plete open in g of th e bladder n eck durin g voidin g: occurs alm ost exclusively in youn g an d m iddle-aged m ales w ith lon gstan ding obstruct ive an d irritative sym ptom s9 (p 968) j) in itially follow in g severe bladder over disten tion or w ith ch ronic disten tion an d decom pres- sion from any of th e above 3. postoperative reten tion : w ell-recogn ized but poorly un derstood. More com m on after low er uri- n ar y t ract , perin eal, gyn ecologic an d an orectal operat ion s. An esth esia an d an algesia m ay con trib- ute to a n u m ber of factors9 (p 969) 4. psychogenic Evaluat ion of bladder funct ion Urodynam ics Usually com bined w ith x-ray (cystom etrogram (CMG))or fluoro (videourodyn am ics). Measures in travesicular pressures durin g retrograde bladder filling th rough a ureth ral catheter, usually com - bin ed w ith sph in cter electrom yography. Presen ce or absen ce (detrusor areflexia, see below ) of de- t rusor reflex is detected. If presen t , procedure is repeated, askin g pat ien t to suppress th e urge to void. In abilit y to suppress is called an un in h ibited det rusor reflex (AKA detrusor hyperreflexia, see above). Sphincter electrom yography (EMG) Eith er via n eedle electrodes, or w ith extern ally m oun ted surface elect rodes. Volun tar y sph in cter con tract ion tests in tact n ess of supraspin al in n ervation . W h en com bin ed w ith CMG, detects elect rical act ivit y in sph in cters durin g associated ph ases of detrusor con tract ion . Voiding cystourethrogram and intravenous pyelography (IVP) Voidin g cystoureth rogram (VCUG) detect s urethral path ology (diverticula, strictures…), abn orm al- ities of bladder (divert icula, det rusor trabeculation s associated w ith lon gstan ding con tract ion s again st h igh resistan ce…), an d vesical-ureteral reflux.

Neurophysiology and Regional Brain Syndrom es 95 Pharm acologic Treat m ent 3 Goals are to preser ve ren al fun ct ion (w h ich usually involves preven tion of UTIs, ren al calculi, an d ureteral reflux due to h igh in t ravesicular pressures) an d opt im ization of urin ar y con tin en ce. Pat ien ts w ith in adequate em pt yin g or in creased bladder pressure are often m an aged by in term itten t cath e- terizat ion s an d an t ich olin ergics (see below ). An tich olin ergics an d beh avioral th erapy are used for patien ts w ith m ain tain ed volun tar y bladder em ptyin g w ith urin ar y frequen cy or urgen cy in con t in e n ce. Th e m ajorit y of th e n eurologic involvem en t in bladder con tract ion is ACh -m ediated stim ulation of postganglionic parasym pathetic m uscarin ic cholin ergic receptors on bladder sm ooth m uscle. Detrusor hyperreflexia Th e follow in g are all syn th et ic an tich olin ergics th at block postgan glionic syn apses (m uscarin ic act ion ) w ith out blockin g skeletal n eurom uscular or auton om ic ganglia (n icot in ic jun ct ion s). Th is increases the volum e at w hich autom atic (reflex) contraction occurs in the neurogenic (uninhibited) bladder, e ect ively in creasing bladder capacit y. Th ese agen ts in crease th e th resh old at w h ich invol- untary bladder contraction occurs, but th ey do not increase the w arning tim e and they do not in crease th e abilit y to suppress con tract ion , th erefore, urgen cy an d in con tin en ce w ill still occur u n less t reatm en t is com bin ed w ith a regim en of tim ed void in g.9 (p 972) All are con train dicated in glaucom a as th e an tich olin ergic e ects in clude m ydriasis. Overdosage results in th e classic an tich olin ergic sym ptom s (“red as a beet, h ot as a stove, dr y as a rock, m ad as a h atter”). Use is often lim ited by side e ect s such as dr y m outh . Drug info : Oxybut ynin (Dit ropan®) Probably the most widely prescribed agent. Com bines anticholinergic activit y with independent mus- culotropic relaxant e ect and local anesthetic activit y. Adults: usual dose is 5 m g BID-TID (maxim um 4 times daily). Peds: not recom mended for age < 5 years; usual dose is 5 m g BID (maximum 5 mg TID). Supplied: 5 mg tablets, 5 mg/5 ml syrup. Drug info : Tolt erodine (Det rol®) Milder side e ects than oxybut ynin, but m ay also be less e ective.10 2 m g PO BID. Can be lowered to 1 m g PO BID in som e patients. Supplied: 1 & 2 mg tablets. Detrol® LA 2 & 4 m g capsule Drug info : Flavoxat e HCl (Urispas®) Weak anticholinergic. Direct smooth muscle inhibitor. Few reported side e ects. Som e studies have shown no benefit in the elderly population.9 (p 974) Adult: 100–200 m g PO TID-QID. Drug info : Im ipram ine HCl (Tofranil®) A tricyclic antidepressant. Mechanism of beneficial e ect is controversial. Does possess som e anticho- linergic activit y as well as other porperties.9 (p 977) Appears to decrease bladder contractility and increase outlet resistance.

96 Anatom y and Physiology Det rusor areflexia Drug info : Bet hanechol (Urecholine®) A parasympathomimetic agent, primarily m uscarinic with lit tle nicotinic activit y; related to acet ylcho- line but not destroyed by cholinesterase. Increases the tone of the detrusor muscle, aiding bladder 3 emptying. Also increases gastric motilit y. Sub-Q administration produces a more intense e ect on the bladder than PO. Always have atropine available when giving by sub-Q route. E ects occur within 30–90 m inutes after PO dose, and within 15 m inutes of sub-Q dose. Indicated for acute post-op non-obstructive urinary retention and for neurogenic atony due to spi- nal cord injury or dysfunction. Side e ect s: sweating and diarrhea are not uncommon but of little danger. Can precipitate severe bronchospasm in asthm atics. Nausea may be reduced by giving with an empty stom ach. Atropine is a specific antidote for overdosage (atropine sub-Q: 0.6 mg in adults, or 0.01 mg/kg in children < 12 yrs). Start with 5–10 mg PO, and increase hourly until desired e ect obtained or 50 mg given. Then, continue minim um e ective dosage TID-QID (usual: 10–50 mg PO TID-QID). Sub-Q (have atropine available): 0.5–1 ml, repeat q 15 mins until desired response or 4 doses given; continue minimal e ec- tive dose TID-QID. Supplied: 5, 10, 25 & 50 mg tabs. Injection: 5.15 mg/ml (for sub-Q use only). Bladder m anagem ent aft er cauda equina com pression In situation s w h ere th ere is urin ar y reten tion w ith som e prospect of return of fun ct ion (e.g. follow - in g surger y for acute cauda equin a com pression ) th e follow in g bladder m an agem en t regim en m ay be em ployed: ● teach th e patien t or a fam ily m em ber to perform clean in term itten t cath eterizat ion s (CIC), if CICs can be done: ○ h ave th em m on itor post-void residuals (PVR) ○ start tam sulosin (Flom ax®) 0.4 m g PO q d (see below ) ○ if PVRs ever fall to < 75 cc, discon tin ue CICs ● if CICs can n ot be perform ed, m an age w ith an in dw ellin g Foley cath eter for a w eek, an d ch eck th e PVR after th at tim e ● if after 1 w eek th e PVR is ≥ 75 cc, D/C tam sulosin if used, an d refer th e patien t to a urologist for urodynam ics (urodynam ics earlier than th is tim e w ill usually n ot result in a change in m anagem ent) Drug info : Tam sulosin (Flom ax®) A prostate alpha1Aadrenoreceptor antagonist. Used to treat voiding di culties resulting from outlet obstruction due to benign prostatic hypertrophy (BPH). Has been shown to have som e e ectiveness in wom en via other mechanisms. Sim ilar to terazosin (Hytrin®) and doxazosin (Cardura®), but has an advantage for acute relief because the dose of tamsulosin does not need to be gradually ram ped up (it can be started at the therapeutic dose). It takes at least 5–7 days to work. Side e ect s : very few. Rhinitis, retrograde or dim inished ejaculation, or postural hypotension m ay occur.11 : 0.4 m g PO q d (usually given 30 minutes after the sam e meal each day). If there is no response by 2–4 weeks, a dose of 0.8 m g PO q d can be tried.11 3.2 Regional brain syndrom es Th is sect ion ser ves to briefly describe t ypical syn drom e associated w ith lesion s in various areas of th e brain . Un less oth erw ise n oted, lesion s con sidered are destr uctive. 3.2.1 Overview 1. fron tal lobe a) unilateral injury: ● m ay produce few clin ical fin dings except w ith ver y large lesion s ● bilateral or large un ilateral lesion s: apathy, abulia

Neurophysiology and Regional Brain Syndrom es 97 ● th e fron tal eye field (for con tralateral gaze) is located in th e posterior fron tal lobe (Br. area 3 8, sh ow n as th e st riped area in Fig. 1.1). Destructive lesion s im pair gaze to th e con trala- teral side (patien t looks towa rds th e side of th e lesion ), w h ereas irritative lesions (i.e. seiz- ures) cause th e cen ter to activate, producin g con tralateral gaze (patien t looks a wa y from th e side of th e lesion ). See also Ext raocu lar m u scle (EOM) system (p. 565) for m ore d e t a ils. b) bilateral injur y: m ay produce apathy, abulia c) olfactor y groove region : m ay produce Foster Ken n edy syn drom e (see below ) d) prefron tal lobes con trol “executive fun ct ion ”: plan n in g, prioritizing, organ izin g th ough ts, sup - pressin g im pulses, understan ding th e consequences of decisions 2. parietal lobe: m ajor features (see below for details) a) either side: cortical sensory syndrom e, sensory extinction, contralateral hom onym ous h em i- anopia, con tralateral n eglect b) dom in an t parietal lobe lesion (left in m ost): lan guage disorders (aph asias), Gerstm an n’s syn - drom e (p.98), bilateral astereognosis c) n on -dom in an t parietal lobe lesion s: topograph ic m em or y loss, an osogn osia an d dressin g a p r a x ia 3. occipital lobe: h om onym ous h em ian opsia 4. cerebellum a) lesion s of th e cerebellar h em isph ere cause ataxia in th e ipsila tera l lim bs b) lesions of the cerebellar verm is cause truncal ataxia 5. brain stem : usually produces a m ixture of cran ial n er ve deficits an d lon g tract fin din gs (see below for som e specific brain stem syn drom es) 6. pineal region a) Parin aud’s syn drom e (p. 99) 3.2.2 Pariet al lobe syndrom es See referen ce.12 (p 308–12) Pariet al lobe anat om y Th e parietal lobe is located beh in d th e cen tral sulcus, above th e Sylvian fissure, m ergin g posteriorly in to th e occipital lobe (th e border on th e m edial surface of brain is defin ed by a lin e con n ecting th e parieto-occipital sulcus to the pre-occipital notch ). Pariet al lobe neurophysiology ● either side: anterior parietal cortex organizes tactile precepts (probably con tralateral) and in tegra- tes w ith visual an d auditor y sen sation to build aw aren ess of body an d its spatial relation s ● dom in an t side (on left in 97%of adults): un derstan ding lan guage, in cludes “cross-m odal m atch - in g” (auditory-visual, visual-tactile, etc.). Dysph asia present w ith dom in an t lobe lesion s often im pedes assessm ent ● non-dom in ant side (right in m ost): integrates visual and proprioceptive sensation to allow m ani- pulation of body an d objects, an d for cer tain con struct ion al activit ies Clinical syndrom es of pariet al lobe disease Ove r vie w 1. unila tera l parietal lobe disease (dom in an t or n on -dom in an t): a) cortical sensory syn drom e (see below ) and sensory extinction (neglecting 1 of 2 sim ultane- ously presen ted st im uli). Large lesion → h em ian esth esia b) congenital injury → m ild hem iparesis & contralateral m uscle atrophy c) h om onym ous h em ian opia or visual in atten t iven ess d) occasion ally: an osogn osia e) n eglect of con tralateral h alf of body an d visual space (m ore com m on w ith righ t side lesion s) f) abolition of optokinetic nystagmus to on e side 2. addition al e ects of dom in an t parietal lobe lesion (left in m ost): a) lan guage disorders (aph asias) b) speech -related or verbally m ediated fun ct ion s, e.g. cross-m odal m atch ing (e.g. patien t un der- stan ds spoken w ords and can read, but cannot un derstand sen tences w ith elem ents of r ela t io n sh ip s)

98 Anatom y and Physiology c) Gerstm an n’s syn drom e, classically: ● agraph ia w ith out alexia (patien ts can read but can n ot w rite) ● left-righ t con fusion ● digit agn osia: in abilit y to iden tify fin ger by n am e ● acalculia d) tact ile agn osia (bilateral astereogn osis) 3 e) bilateral ideom otor apraxia (in abilit y to carr y out verbal com m an ds for act ivit ies th at can oth - erw ise be perform ed spon tan eously w ith ease) 3. addit ion al e ects of n on -dom in an t parietal lobe lesion s (usually righ t): a) topographic m em or y loss b) anosogn osia an d dressin g apraxia Cort ical sensory syndrom e Lesion of postcen tral gyrus, especially area th at m aps to h an d. ● sensor y deficits: a) loss of position sense an d of passive m ovem ent sense b) inabilit y to localize tact ile, therm al, and n oxious stim uli c) astereogn osis (in abilit y to judge object size, sh ape, an d iden tit y by feel) d) agraph esth esia (can n ot in terpret n um bers w rit ten on h an d) e) loss of t wo point discrim ination ● preser ved sensation s: pain , touch, pressure, vibration, tem perature ● oth er features a) easy fat igabilit y of sen sor y perception s b) di cult y distinguishing sim ultaneous stim ulations c) prolongation of superficial pain w ith hyperpath ia d) touch h allucin ation s Ant on-Babinski syndrom e A un ilateral asom atagn osia. May seem m ore com m on w ith n on -dom in an t (usually righ t) parietal lesion s because it m ay be obscured by th e aph asia th at occurs w ith dom in an t (left) sided lesion s. 1. an osogn osia (in di eren ce or un aw aren ess of deficits, patien t m ay deny th at paralyzed extrem it y is theirs) 2. apathy (in di eren ce to failure) 3. alloch eiria (on e-sided st im uli perceived con tralaterally) 4. dressin g apraxia: n eglect of on e side of body in dressin g an d groom in g 5. extin ction: patient is unaw are of contralateral stim ulus w h en presen ted w ith double-sided sim ultan eous stim ulation 6. in attent ion to an en tire visual field (w ith or w ith out h om onym ous h em ian opia), w ith deviation of head, eyes, and torsion of body to una ected side Pariet al lobe aphasias 1. Wern icke’s aph asia: lesion of auditor y association areas or th eir separat ion from an gular gyrus an d prim ar y auditor y cortex. A fluent aph asia (n orm al sen ten ce len gth & in ton ation , devoid of m ean in g). May in clude paraph asias. Lesion in region of Wern icke’s area (Brodm an n areas 40 & 39, Fig. 1.1) 2. Broca’s (m otor) aph asia: in realit y, “apraxia” of m otor sequen cin g for speech (speech an d ph on a- t ion m uscles aren’t paralyzed, an d fun ction for oth er act ivities), producin g falterin g, dysarth ric speech . Lesion in region of Broca’s area (Brodm an n area 44, Fig. 1.1) 3. global aph asia: usually due to lesion th at destroys large por tion of lan guage cen ter; all aspect s of speech an d lan guage a ected a) un able to speak except for som e clich és, h abitual ph rases, or explet ives b) an om ia (in abilit y to n am e objects or parts of objects) c) verbal and m otor perseveration d) un able to un derstan d all except for a few w ords e) inabilit y to read or w rite 4. con duction aph asia: due to disruption of con n ection s betw een fron tal an d tem poral speech areas, usually involving supram argin al gyrus. Sim ilar to Wern icke’s (fluen t spon tan eous speech an d paraph asias), but pat ien ts un derstan d spoken or w ritten w ords, an d are aw are of th eir defi- cit. Repetition is severely a ected