Cerebral artery spasm. A histological study at necropsy of the blood vessels in cases of subarachnoid hemorrhage.

From a larger series of autopsies with subarachnoid hemorrhage (SAH), 20 cases were selected for the known complication of cerebral vasospasm. Evidence for vasospasm was radiological and pathological in 17 cases and pathological alone in three. A systematic histological examination of the large arteries in places known formerly to have been in spasm showed that, in the 12 early cases (death before 3 weeks), there were relevant changes in all the layers of the arterial wall, the most significant being evidence of necrosis in the tunica media. In the eight late cases (death after 3 weeks), in addition to the sequelae of the earlier acute changes, there was marked concentric intimal thickening by subendothelial fibrosis, again located in the segments of arteries formerly in spasm. Changes were also found in the small arteries, capillaries, and veins, both in the early and late cases but these changes, although striking, were thought to be caused by the ischemia due to the vasospasm; similar changes were also seen in the control cases with ischemia from arterial occlusion.