CORRELATION BETWEEN MOTOR IMPAIRMENT AND INFARCT VOLUME AFTER PERMANENT AND TRANSIENT MIDDLE CEREBRAL-ARTERY OCCLUSION IN THE RAT

Background and Purpose There have been a number of recent reports desc ribing the relationship between ischemic damage and various behavioral and functional measures, although there have been few studies that ha ve demonstrated a direct correlation between functional impairment and lesion volume. The purpose of the present study was to assess functio nal outcome by measurement of motor impairment and to determine whethe r this correlated to a range of infarct volumes induced by varying the duration of focal ischemic insult in the rat. Methods Male Sprague-Da wley rats were subjected to 0, 30, 60, or 120 minutes or permanent mid dle cerebral artery (MCA) occlusion by the intraluminal filament techn ique. Motor impairment was assessed by the accelerating rota-rod and g rid-walking tests, and the brains were perfusion-fixed for histologica l determination of infarct volume and brain swelling 24 hours after MC A occlusion. Results Marked impairment in performance of both motor te sts was recorded in the 60-minute, 120-minute, and the permanent MCA o cclusion groups when compared with sham-operated rats. There were sign ificant correlations between regional infarct volume, brain swelling, and all behavioral measurements (all r(2)>.5, P<.001). Conclusions The rota-rod and grid-walking tests of motor performance provide quantita tive, objective, and reproducible measures of functional impairment of rats following an ischemic insult. These impairments correlate direct ly with infarct volume and provide information integral to future stud ies evaluating the effects of potential neuroprotective agents.