Cerebral blood flow after experimental basal ganglia hemorrhage

The effect of cerebral hemorrhage on regional cerebral blood flow (RCBF) in awake, unrestrained rats was studied by comparing intracaudate injections of whole blood (N = 14), centrifuged blood (N = 2), and inert plastic (N = 1). RCBF was measured by the polarographic hydrogen clearance technique using chronically implanted electrodes in the cortex and caudate bilaterally. After hemorrhage, animals became comatose and flows diminished 23 to 30% (p less than 0.01) below baseline values. Recovery of RCBF to prehemorrhage values was accompanied by awakening and survival while persistently low RCBF in all regions occurred only in the 2 animals died, suggesting that physiological changes which lower RCBF in after hemorrhage may be harmful. Transient hyperperfusion of the contralateral cortex occurred in 6 of 10 animals during the first 10 minutes after hemorrhage. In all 8 animals tested daily there was significant hyperperfusion of one or both cortical regions during the second or third day after hemorrhage (mean increase in right cortex RCBF, 30%, p less than 0.05; left, 45%, p less than 0.01). Injection of an identical volume of plastic was not accompanied by hyperperfusion, suggesting that destruction of the caudate or addition of an intracerebral mass was not responsible for the increase in blood flow. However, injection of centrifuged blood components caused immediate hyperperfusion, which persisted in some cortical regions on the following day. A substance in cerebral hemorrhage clot may cause increased cortical RCBF.