RECOVERY OF FUNCTION FOLLOWING ARREST OF THE BRAIN CIRCULATION

Abstract

Sudden complete arrest of blood flow in the brain for periods of 2 to 11 min. was produced in dogs. The corneal reflex disappeared in 10 sec. and respiration ceased in 20 sec. The course of recovery was qualitatively similar in all animals but differed depending on the duration of brain anemia. The effects of a certain period of brain anemia were constant from animal to animal. Brain stasis for 6 min. or less resulted eventually in complete recovery of function, while stasis for 8 min. or longer resulted in permanent severe brain damage. The course of recovery showed 6 stages: (1) Restoration of vital centers and simple reflexes occurred. (2) Hyperactivity and reflex hyperirritability appeared several hrs. after brain anemia. During this period there were vigorous coordinated running movements carried out by the comatose animal. No convulsions occurred. (3) Coma persisted for 24 hrs. after only 4 min. of arrest of the brain circulation. Coma was characterized by flexor rigidity, loss of auditory reflexes, vestibular and other righting reflexes and loss of cerebral function. Animals surviving 8 min. of brain anemia remained in coma permanently. (4) Following coma there was a transition period lasting several days during which righting mechanisms returned and function of the cerebral cortex was restored but cerebeller ataxia persisted. (5) The most persistent neurological dysfunction was cerebellar ataxia which gradually improved. (6) Complete recovery of function finally ensued. The brain neurons which are apparently most sensitive to arrest of circulation are the Purkinje cells of the cerebellar cortex.