It is well known that cerebral vasospasm following ruptured cerebral aneurysm affects the prognosis very seriously after direct surgery. However, the pathogenesis of cerebral vasospasm remains obscure. Furthermore, the precise brain damage following it has not been made clear histopathologically.
The histopathological postmortem studies of intracranial arteries with angiographycally demonstrated arterial narrowing have been carried out in 44 cases.
The cerebral arterial wall corresponding to the angiographic vasospasm showed various structural changes, which could be divided into five groups according to histological findings.
In Group 1, the intraluminal size of arterial wall was reduced even though the medial thickening, marked corrugation of the internal elastic lamina and intimal edema were demonstrated. In Group 2, necrosis of smooth muscle cells in the tunica media, partial break of internal elastic lamina and the profuse deposition of acid mucopolysaccharides were seen. In Group 3, marked intimal thickening and the medial atrophy were seen. In Group 4, dilatation of luminal size with improvement of the intimal thickening and the remarkable medial atrophy were noted. In Group 5, regeneration of smooth muscle cell in the tunica media was observed.
These histological findings suggest the time course of cerebral arterial spasm from onset to remission.
