[Epidemiology, clinical study and pathology of vasospasm].

Symptomatic vasospasms or delayed cerebral ischemia associated with arteriographic evidence of arterial constriction is currently the most important cause of morbidity after acute subarachnoid hemorrhage. Symptomatic vasospasm usually develops between 4 and 12 days after subarachnoid hemorrhage. There is typically a gradual deterioration of the level of consciousness accompanied by focal neurological deficits. 30% of patients who survived aneurysmal SAH develop delayed cerebral ischemia secondary to vasospasm. Vasospasm produces cerebral ischemia and infarction by hemodynamic mechanisms. Vasospasm is an important independent predictor of poor outcome after aneurysmal SAH. Other conditions than aneurysmal subarachnoid hemorrhage such as trauma, tumors, unruptured aneurysms, meningitis and ruptured AVM may be associated with vasospasm.