Tolerance to arrest of cerebral circulation in the rhesus monkey

Abstract

Twenty rhesus monkeys ( Macaca mulatta) were subjected to periods of arrest of cerebral blood flow varying from 4 to 15 min. Arrest was accomplished by placing ligatures around the carotid and vertebral arteries. A drainage cannula in one carotid artery served to remove blood reaching the circle of Willis via anastomotic routes. After clamping the vessels, electrocortical activity (EEG) ceased within 25 sec. After reestablishment of blood flow to the brain, the EEG reappeared anywhere from 30 min to 5 hr depending on the duration of the arrest period. Animals subjected to periods of cerebral arrest up to 13 min showed no neurologic or behavioral deficits on the second postoperative day. The animal subjected to 14-min arrest retained motor deficits even 2 months postsurgically. Three animals subjected to 15 min of arrest failed to survive. One of these lived for 20 hr, recovering normal EEG activity and consciousness. It was able to make uncoordinated body and limb movements, but could not sit or eat. Controlled cerebral arrest up to 12 or 13 min appears to be relatively safe in the primate. Periods longer than this result in permanent neurologic deficits or death.