Fisher et al identified certain features that indicated severe vasospasm in patients following a subarachnoid hemorrhage. The authors are from the Massachusetts General Hospital.
Features:
(1) decrease in the residual lumen of the artery
(2) delayed blood flow (compared to flow in normal arteries)
(3) influx of collateral blood flow from across a border zone
(4) occurrence of delayed ischemic neurologic deficits corresponding to the distribution of the involved artery (delayed deficits never developed in patients with mild to moderate vasospasm)
Artery
Code
Luminal Diameter in Severe Vasospasm
intracranial portion of the internal carotid artery
ICA
< 2.0 mm
middle cerebral artery from the origin to the bifurcation
M1
<= 1.0 mm
middle cerebral artery from the bifurcation to the emergence from the sylvan fissure
M2
<= 0.5 mm
anterior cerebral artery from the origin to the anterior communicating artery (ACA)
A1
<= 1.0 mm
anterior cerebral artery from the anterior communicating artery to the superior surface of the corpus callosum 3 cm posterior to the genu
A2
<= 0.5 mm
posterior cerebral artery proximal to the posterior communicating artery (PCA)
P1
<= 0.5 mm
distal branches
<= 0.5 mm
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