The changes in EEG, evoked potentials and neurological recovery after global brain ischemia in dogs

Electroencephalography (EEG), evoked potentials and neurological recovery score were compared between 10 min and 15 min transient global brain ischemia in 18 dogs. The transient global brain ischemia was induced by occluding aorta, superior and inferior caval veins. The grade of EEG (1: normal approximately 5: flat) 2 hrs after ischemia was significantly lower with the 10 min ischemic group (n = 9) than with the 15 min group (n = 9) (3.7 +/- 0.5 vs 4.1 +/- 0.3, P less than 0.05). The rate of reappearance in evoked potential waves 2 hrs after ischemia was higher with the 10 min ischemic group than with the 15 min group (auditory brainstem response 5 wave: 100% vs 33%, middle latency response Pa wave: 80% vs 0%, somatosensory evoked potential N2 wave: 83% vs 78%, N3 wave: 67% vs 33%). The neurological recovery score (0: death approximately 100: normal) 7 days after ischemia was significantly higher with the 10 min group than with the 15 min group (58 +/- 34 vs 27 +/- 23, P less than 0.05). In both groups, there was a significant correlation (r = +0.85, P less than 0.01) between the total score of EEG and evoked potential waves (0: no wave appeared approximately 6: all waves appeared) 2 hours after ischemia and the neurological recovery score 7 days after ischemia. These results suggest that the neurological recovery after transient global brain ischemia would be estimated by EEG and evoked potential waves.