Intracranial Arterial Spasm: A Clinical Analysis

I T HAS become apparent during the past two decades that patients suffering from spontaneous subarachnoid hemorrhage frequently also have intracranial arterial spasm, a complicating factor that adversely affects their neurological status and prognosis, w-'''~''~,s,~ ~,16'z~ ,9,~3 ~,,,~7 Despite the common occurrence of this phenomenon, its exact etiology and pathogenesis are not known. Intracranial arterial spasm in humans can be induced by mechanical stimuli such as surgical trauma to the cerebral arteries, but the mechanisms that produce preoperative spasm are less well understood. This type of spasm has been found to have the following characteristics: it is seen most frequently in association with subarachnoid hemorrhage; it is usually most marked in the major cerebral arteries ipsilateral to a ruptured aneurysm and involves primarily the parent artery; it is almost exclusively an intradural phenomenon; it usually lasts for days to weeks and does not seem to vary in severity from minute to minute; and it does not appear to be caused by arteriography. Because of these clinical features, as well as the results of various laboratory investigations, 6,14,33,47,51'~7'59 it has been postulated that preoperative intracranial arterial spasm originates locally as a result of arterial distortion and irritation by aneurysmal rupture and perivascular clot formation, and is propagated to other areas by the nerves and smooth muscle fibers of the involved cerebral arteriesY ~ Our recent clinical experience with intracranial arterial spasm, as analyzed in the present paper, adds further support to this concept.