Subarachnoid hemorrhage and cerebrovascular spasm. Morphological study of intracranial arteries based on animal experiments and human autopsies.

Artificial subarachnoid hemorrhage (SAH) produced by injection of autologous blood into the cisterna magna in dogs gave rise to considerable narrowing or spasm of the basilar artery and its branches, including the posterior cerebral arteries, as demonstrated by cerebral angiography. Repeated cisternal injections of blood at various intervals produced more severe spasm than a single injection. After perfusion-fixation of the brain, the cerebral arteries were examined by light and electron microscopy. None of the animals showed abnormalities in the intima or media of the vessel walls. Previously reported findings of morphological changes due to spasm could not be confirmed. Postmortem examination of brain vessels from nine patients with SAH and arterial spasm showed no specific changes that could be ascribed to spasm.