Arteriovenous Malformations (AVMs)

FACTS

  • Congenital tangle of arteries and veins (nidus) without an intervening capillary bed → direct high-flow shunt.
    • vessel remodeling may also lead to intranidal aneurysms or aneurysms of feeding arteries.
  • Epidemiology: Incidence ~1/100,000; most present between ages 20–40.
  • Locations: Cerebral hemispheres (most common), brainstem, cerebellum, or spinal cord.
  • Annual hemorrhage risk ≈ 2–4%/year, higher if prior rupture or deep venous drainage.
  • Account for ~2% of all strokes and ~50% of intracerebral hemorrhages in young adults.

HPI

universal ROS
  • emphasis on seizures
  • Family history of AVMs or HHT (hereditary hemorrhagic telangiectasia).

PHYSICAL EXAM

  • universal exam

IMAGING

Modality
Findings / Utility
Non-contrast CT head
Rapid detection of acute ICH, intraventricular or subarachnoid extension.
CTA head/neck
Demonstrates nidus, arterial feeders, and venous drainage pattern; useful emergently.
MRI brain with MRA
Defines AVM anatomy, edema, old hemorrhage, and eloquent cortex involvement.
Digital Subtraction Angiography (DSA)
Gold standard for diagnosis and treatment planning — shows feeding arteries, nidus size, venous drainage, and associated aneurysms.
Spetzler–Martin grading
Guides surgical risk: based on size, eloquence of adjacent cortex, and venous drainage (superficial vs deep).

A/P

Ruptured presentation
  • Admit to Neuro ICU
  • BP control: maintain SBP <140–160 mmHg (institution-specific).
  • Reverse coagulopathy, correct platelets.
  • Seizure management: load with levetiracetam; continuous EEG if encephalopathic.
  • ICP management: HOB 30°, hypertonic saline or mannitol if needed.
  • Avoid aggressive BP lowering (maintain perfusion).
Modality
Indication / Notes
Microsurgical resection
Preferred for small, accessible AVMs (Spetzler–Martin I–II). Goal = complete nidus excision.
Endovascular embolization
Used as adjunct pre-surgery or radiosurgery; sometimes curative for small nidus.
Stereotactic radiosurgery (SRS)
Used for small–moderate AVMs (<3 cm) in eloquent/deep areas; gradual obliteration over 2–3 years.
Observation
For large, high-risk AVMs or elderly/asymptomatic patients. Regular MRI/MRA follow-up.

Notes

ARUBA (A Randomized Trial of Unruptured AVMs)

  • Design: RCT
  • Population: 226 patients with un-ruptured brain AVMs
  • Arms
    • Medical management alone (control)
    • Interventional therapy (surgery, embolization, radio-surgery, or a combination)
  • Median follow-up: ~33 months (trial was stopped early)
  • Outcome measured: Composite of death or symptomatic stroke (ischemic or hemorrhagic).
  • Results
      • At median 33 months:
    • Medical group: 10.1% (N=11) had stroke or death
    • Intervention group: 30.7% (N=35) had stroke or death
    • Hazard ratio: 0.27 (95% CI 0.14–0.54, p < 0.001)
  • Criticism
    • Conclusion: Medical management is superior to interventional therapy in preventing death or stroke over short-term follow-up.
    • Caveat: The study did not address long-term hemorrhage risk, and follow-up was short for a lifelong disease like AVM.
    • The trial was stopped early, limiting assessment of long-term benefit from definitive obliteration
Takeaway: Medical management wins early, but long-term debate continues.

Pathology

  • abnormally high flow often causes ectatic remodeling of the veins draining the AVM or of the arteries feeding it