Cortical-evoked potentials and cerebral infarction in temporary middle cerebral artery occlusion in the cat.

Somatosensory-evoked potentials (SSEP) and cerebral infarct size were measured in nine cats in which the middle cerebral artery (MCA) was clip-occluded for 3 h followed by an equal period of recirculation. During MCA occlusion, there was a reduction in the mean amplitude of the major cortical wave (MCW) to less than 50% of the pre-occlusion value. There was no significant improvement in this amplitude after clip release. Cerebral infarction was detected in eight of the animals and the mean (+/- s.d.) infarct size was 27.8 +/- 19.6%. A good negative correlation between the MCW amplitude and infarct size was apparent as early as 15 min into the period of occlusion (r = -0.87, P less than 0.01). In this model of focal cerebral ischaemia, the 15-min MCW amplitude is a good predictor of cerebral infarction.