Experimental cerebral vasospasm

✓The authors describe a model for making an experimental subarachnoid hemorrhage that closely simulates human aneurysmal rupture. A needle previously inserted into the posterior communicating artery is subsequently withdrawn by traction on a thread. Using this model they demonstrate biphasic spasm by measurement of cerebral blood flow and angiography after rupture of the artery; the early spasm lasted 60 minutes and the late spasm began 3 or 4 hours after subarachnoid hemorrhage and continued for several days. The authors discuss the pathogenesis of early and late spasm.