28 Cerebral Arteriovenous Malformation

Case 28 Cerebral Arteriovenous Malformation

Pascal M. Jabbour and Erol Veznedaroglu

Fig. 28.1 Computed tomography scan of the head showing a right basal ganglia bleed.

Fig. 28.2 Magnetic resonance imaging scan of the head showing a basal ganglia arteriovenous malformation.

Any intracerebral hemorrhage in a young patient without any past medical history should raise the suspicion of a vascular malformation.

What is the next test to order?

The CT of the head showed a basal ganglia bleed in a young patient; the next test to be ordered should be an imaging modality that is able to demonstrate any vascular abnormality, like a CT angiogram, MRI, or magnetic resonance angiography.

What is the most common AVM grading system used? And what is the patient’s grade?
- The Spetzler–Martin grading system (Table 28.1).¹
- The patient’s grade is 2 (size) + 1 (eloquence) + 1 (venous drainage) = 4
What is the risk of rupture of an AVM and the lifetime cumulative risk for this patient?
- The risk of rupture of this AVM is ~4% per year.²
- Risk is 1 (risk of not hemorrhaging) raised to the power of years left to live.
- In a 36-year-old patient, at an average life expectancy of 79 years, the years left to live can be calculated to be 43 years.
- Risk = 1 – (1 – risk of hemorrhage) ⁴³
- Risk = 1 – (0.96) ⁴³ = 83
- The patient has a lifetime risk of hemorrhage of 83%.
What are the diff erent treatment options for this patient?
- The diff erent options are^1,3,4
  - No intervention if the risk of intervening is higher than the natural history risk of the AVM rupturing.
  - Embolization in preparation for surgical resection
  - Embolization with the goal of reducing the volume of the AVM in preparation for radiosurgery
  - Surgery alone
  - Radiosurgery alone with possible volume fractionation
What are some important steps of AVM surgery?
- Furosemide + mannitol prior to dural opening
- Proximal temporary occlusion can be performed with aneurysm clips.
- Smaller vessels are occluded with AVM mini-clips.
- Large draining veins are clipped with large aneurysm clips.
- Do not commit on vessel occlusion until the vessel is seen to enter the AVM.
- “If it looks like it may be AVM, it probably is.”
- Difficult-to-control bleeding during this dissection is commonly an indication that the AVM–brain interface has been breached on the side of the AVM.
- As a safety measure, before taking the major draining vein, an aneurysm clip is placed across it for 10–15 minutes and dissect out in a diff erent area.
- Always obtain a postoperative angiogram and CT scan.⁵
What is normal perfusion pressure breakthrough and how is it treated?
- It is a disorder of autoregulation of the brain vasculature.
- May present with sudden onset of brain swelling and bleeding from multiple sites
- May be due to draining vein that was taken too soon
- Also occurs from raw normal brain surfaces, that have lost autoregulatory capacity
- Close inspection of the operative field will identify any residual AVM.
- Treatment
  - Elevation of the patient’s head
  - Administration of mannitol and furosemide
  - Barbiturate- or etomidate-induced coma
  - Hypotension may be beneficial.
  - Focal hypotension by means of proximal vessel occlusion with temporary clip⁵