The role of hemoglobin in the etiology of cerebral vasospasm. An in vivo study of baboons.

Oxyhemoglobin was injected intracisternally into three baboons, and methemoglobin into one baboon, in an attempt to mimic the prolonged cerebral arterial spasm sometimes seen after subarachnoid hemorrhage due to aneurysm rupture. Cerebral angiography was performed for up to 7 days after injection of hemoglobin, and the degree of vasospasm was estimated from the angiograms. Oxyhemoglobin caused slight arterial narrowing, which lasted for 3 days. Methemoglobin had no significant effects. Motor neurological deficits and histopathological signs, characteristic of prolonged cerebral vasospasm, were not observed. It was concluded that hemoglobin alone is not capable of causing the cerebral vasospasm syndrome in these experimental animals.