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Brain arteriovenous malformation (AVM) and cavernoma
An AVM is graded on the Spetzler-Martin scale by size, eloquence and deep venous drainage — grades 1 and 2 are operated on, grades 4 and 5 are usually observed — whereas a cavernoma is a "popcorn" lesion invisible on angiography and best detected on SWI.
Why it matters in the exam
AVM questions ask for the grade: size under 3 cm — 1 point, 3 to 6 cm — 2, over 6 cm — 3; eloquent area — 1; deep venous drainage — 1. The haemorrhage risk of an unruptured AVM is about 2 to 4% per year, higher after a first bleed, with deep drainage, a deep location or an associated aneurysm. ARUBA showed that for unruptured malformations medical management led to less stroke or death in the short term (10.1% versus 30.7% with intervention), so the tendency for an unruptured AVM is conservative, especially at higher grades, and the decision is made jointly by a neurosurgeon, an interventional radiologist and a radiosurgery specialist. Radiosurgery suits an AVM under 3 cm in an eloquent or deep area; obliteration takes 2 to 3 years, during which the bleeding risk remains.
A cavernoma (cavernous malformation) is a cluster of venous caverns with no brain tissue between them, surrounded by a haemosiderin ring; MRI shows "popcorn" with a dark rim, and SWI or GRE is the most sensitive sequence. Angiography is normal. The familial form is linked to CCM1 (KRIT1), CCM2 and CCM3, with multiple lesions. Presentations: seizure, haemorrhage and neurological deficit. Surgery suits an accessible lesion with epilepsy or repeated haemorrhage, and a brainstem cavernoma is operated on after a second symptomatic bleed when it reaches the surface. A developmental venous anomaly (DVA) is often adjacent — it must not be resected, because it drains normal brain. Carotid-cavernous fistula (CCF) is discussed separately.
Key points
- Spetzler-Martin: size, eloquence, deep drainage.
- Grades 1 to 2 — surgery; 4 to 5 — usually observation.
- ARUBA: unruptured AVM — conservative tendency.
- Cavernoma — "popcorn", SWI, normal angiography.
- The DVA is preserved.
Summary table
| Spetzler-Martin component | Value | Points |
|---|---|---|
| Size | Under 3 cm / 3 to 6 / over 6 | 1 / 2 / 3 |
| Eloquent area | No / yes | 0 / 1 |
| Venous drainage | Superficial only / deep | 0 / 1 |
| Decision by grade | 1 to 2 surgery; 3 individual decision; 4 to 5 usually observation | Sum of points |
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Sources
- AHA/ASA Scientific Statement: Management of Brain Arteriovenous Malformations, 2017 — Natural history and treatment
- Angioma Alliance consensus guidelines on cerebral cavernous malformation, 2017 — Imaging, surgery and familial disease
- ARUBA randomised trial, 2014 — Medical management versus interventional therapy for unruptured AVM
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.