Arteriovenous Malformation (AVM)

Know the lesion before induction - The catheter angiogram and MRI give nidus size, location, feeding and draining vessels, and any associated aneurysm; pair that with a documented baseline neuro exam and look for signs of cerebral ischemia or raised ICP.

Spetzler-Martin grade - Nidus size, eloquence of adjacent brain, and superficial versus deep venous drainage predict surgical morbidity. A high grade means a longer, bloodier case.

Continue antiepileptics - Keep them going through the perioperative period. Up to 50% of patients seize postoperatively and prophylactic anticonvulsants are typically given.

Staged embolization - Large AVMs are often embolized days before resection to cut flow, reduce intraoperative blood loss, and let the surrounding parenchyma adjust to the new perfusion.

Arterial line before induction - Place it pre-induction. Blood pressure swings during laryngoscopy, pin placement, and incision are the events that matter, and you want beat-to-beat pressure through all of them.

Blunt the stimulating moments - Adequate anesthetic depth with a balanced hypnotic-analgesic combination, then titrate esmolol or clevidipine for hypertensive surges and pressors or inotropes for hypotension.

Do not let the pressure fall - Strict control keeps cerebral perfusion pressure up without worsening bleeding from the resection bed. These patients already run ischemic from steal, so hypotension buys a new deficit.

Bleeding is the main event - Surgical hemostasis is hard because arterial and especially venous vessels are poorly visualized. Secure large-bore IV access, have blood products immediately available, and consider central access for volume status, rapid transfusion, and vasoactive infusions.

Fluid choice - Skip hypotonic and glucose-containing solutions. The first worsens cerebral edema, the second worsens outcomes after neurologic ischemia.

Brain relaxation - Hypertonic saline or mannitol, mild hyperventilation to a PaCO2 of 30-35 mm Hg, CSF drainage, and head elevation all improve exposure.

Neuromonitoring and awake mapping - SSEP and MEP monitoring is increasingly used for AVM resection, so pick a maintenance regimen that preserves signals. For eloquent-region lesions, an awake craniotomy with intraoperative brain mapping is an option in selected patients.

Normal perfusion pressure breakthrough - After resection, hold blood pressure at low-normal. The chronically dilated arterioles next to the resected nidus cannot vasoconstrict, so hyperemia, edema, and hemorrhage can occur even at normal perfusion pressures. Beta blockers and calcium channel blockers (clevidipine, nicardipine) are usually what you reach for.

Emergence - Hypertension on emergence is the thing to prevent. Aim for a rapid, controlled wake-up so a neuro exam is possible right away, then hand off to an ICU set up for close hemodynamic and neurologic monitoring.

Talk to the surgeon - In large or high-flow lesions the hemodynamic ask changes stage by stage. Keep the conversation open rather than defending a fixed number.

An arteriovenous malformation (AVM) is a tangle of direct artery-to-vein connections — the nidus — with no intervening capillary bed and no neural tissue inside it. The feeding arteries lack a normal muscular layer and the draining veins dilate under high-velocity arterial flow, making the lesion a high-flow, low-resistance shunt whose internal pressure sits below systemic arterial pressure.

Two consequences drive the anesthetic. First, the abnormal vessels bleed — into brain parenchyma, the subarachnoid space, or the ventricles. Second, blood shunted away from adjacent brain ("steal") leaves the surrounding arterioles chronically, maximally vasodilated with lost autoregulation, so once the AVM is excluded those vessels cannot vasoconstrict and hyperemia, edema, and hemorrhage can follow at normal pressures — normal perfusion pressure breakthrough. About 70% are supratentorial, most surface between ages 10 and 40, and 4-25% carry an aneurysm on a feeding artery.