IN A PRIOR study1 a relationship was demonstrated between change in cortical steady potential (SP) and extent of neurologic deficit that followed temporary occlusion of the middle cerebral artery (mca) in the dog. Observations were made in both anesthetized and unrestrained awake animals. In the latter, implanted electrodes were used and when an SP change developed it ordinarily appeared 1 to 12 minutes after occlusion. In general, a precipitous SP shift following occlusion portended severe neurologic impairment; slower shifts of lower voltage or no SP change at all were associated with lesser deficits or normal neurologic function. The neurologic status existing 24 hours after occlusion was the one that correlated well with the SP changes.
To further analyze the SP change we sought to determine if location and size of infarction was related to the magnitude of SP shift, and if these changes (SP and infarction), in