A primate model of chronic cerebral vasospasm.

Fourteen experiments have been completed to develop an improved primate model of chronic cerebral vasospasm. Results show that by placing a 0.4 mm needle through the intracranial internal carotid artery and percutaneously removing it the following day, cerebral vasospasm is regularly present five days later. There has been no mortality. The results of two monkeys followed with serial angiograms suggest that spasm first appears four days following the subarachnoid hemorrhage and lasts at least eleven days. The results of all experiments show that the most affected vessel in each experiment is reduced to 62% of control diameters. Vasospasm involves cerebral arteries both ipsilateral and contralateral to the site of hemorrhage and extends to the most distal vessels which can be measured. Finally, a neurological defect has been regularly demonstrated on the side contralateral to the site of hemorrhage.