Cerebrovascular Surgery
Core concepts
Distinguish aneurysmal subarachnoid hemorrhage (aSAH) from other causes and know the Hunt-Hess and modified Fisher grading systems - Fisher grade predicts vasospasm risk. Understand the phases: early brain injury, vasospasm (days 3–14, delayed cerebral ischemia), and hydrocephalus. Know nimodipine's role (improves outcomes; it is not purely an anti-vasospasm drug). Understand aneurysm treatment principles: clipping vs coiling vs flow diversion, and when each is favored (wide neck, blister aneurysms, posterior circulation). Know the vascular territories and classic syndromes of ischemic stroke, the time windows for thrombolysis and thrombectomy, and the concept of penumbra. Understand arteriovenous malformation grading (Spetzler-Martin) and hemorrhage risk, plus cavernous malformation and moyamoya basics.
Traps
A common trap is treating vasospasm with induced hypertension before confirming delayed ischemia, or misreading a normal initial CT in a patient with a thunderclap headache (send for LP/xanthochromia if delayed). Another trap: assuming all aneurysms need immediate treatment regardless of grade. Watch for confusion between nimodipine (oral, improves outcome) and vasopressors (for symptomatic vasospasm).
Worked rule of thumb
A thunderclap headache with a negative CT within 6 hours in a low-risk patient may still warrant LP if there is clinical concern; xanthochromia confirms aSAH. For vasospasm, the sequence is eu volemia → nimodipine → induced hypertension for symptomatic delayed ischemia → endovascular therapy.