Abstract
Six hundred and eight carotid angiograms of 266 patients with ruptured intracranial aneurysms were analyzed to investigate the sequential changes of the type and severity of vasospasm. Furthermore, the present study was undertaken to analyze the effects of vasospasm upon clinical states, cerebral blood flow and prognosis of the patients.
Vasospasm was simply classified according to its extent into four types; diffuse (narrowing of intraarterial diameter over 2 cm in length including at least one part of C1, A2 and M1), peripheral (narrowing of the diameter over 2 cm in length in the distal parts), multi-local (multiple, localized narrowing) and local (single, localized narrowing). Diffuse type of vasospasm was further divided into two groups by its degree of severity. Namely, vasospasm reducing the caliber of an artery by more than 50% was defined as severe (diffuse severe), while mild vasospasm represented reduction in the caliber of 25 to 50% (diffuse mild). In order to obtain an indicator of objective measure of vasospasm, a ratio between each diameter of the arteries (C1, A2, M1) to the diameter of the canalicular portion of the internal carotid artery was calculated from 32 normal carotid angiograms (A-P projection). Fifty or 75% of the normal ratio were used as measurement controls.
The results were as follows : 1) Vasospasm which occurred within 3 days after the onset was seen in only 3 of 79 cases (3.8%). However, the incidences of vasospasm increased as the time passed and reached its peak at the period between 8th and 15th day, when vasospasm was seen in 83 of 106 cases (78%). The type of narrowing was diffuse in most of these cases. Thereafter, the occurrence of vasospasm gradually decreased and the type of narrowing tended to change from diffuse to local or multi-local types. Only few cases showed vasospasm after 50th day. 2) It was noted that in all of the 8 preoperative patients, on whom carotid angiography was performed more than twice, vasospasm changed from diffuse to local or multi-local types. 3) Most of the patients with diffuse type of vasospasm, especially with diffuse severe type, showed decreased values of mean CBF, and showed focal ischemia in the regions supplied by the involved arteries. In patients with multi-local or local types of vasospasm, there was little difference in mean CBF as compared to the patients without vasospasm, though there frequently existed focal ischemia in patients with multi-local type of vasospasm. 4) Diffuse type of vasospasm tended to have effects on the clinical state and outcome of patients. It was evident that narrowing of the arterial lumen by more than 50% and diffuseness of vasospasm (diffuse-severe type of vasospasm) caused cerebral ischemia.
It was concluded that the present method of classifying the degree of vasospasm was useful in determining the clinical significance of vasospasm.
