Acute, post-ischemic sensorimotor deficits correlate positively with infarct size but fail to predict its occurrence and magnitude after middle cerebral artery occlusion in rats

This study investigated whether sensorimotor deficits measured soon after reperfusion could predict the occurrence and magnitude of cerebral infarct following middle cerebral artery occlusion (MCAO). Rats were subjected to left MCAO for 2 h according to the intraluminal thread method. At 0, 1, 2, and 3 h after reperfusion, the animals were examined for neurological deficits using an expanded scale comprising the following tests: (A) postural reflex, (B) circling motion, (C) falling to contralateral side, (D) placement of the contralateral forelimb during motion, and (E) general state of alertness or consciousness. Deficits were graded from 0 (normal) to 2 or 3 (severe), and the final neuro-score was a summation of these scores over the various time points and among the various tests. The neuro-score of the animals that survived up to 24 h after MCAO ranged from 0 to 8.2 and positively correlated with infarct size ( p = 0.0002–0.001). However, at least three animals with moderate neuro-scores (4.5–6.0) did not exhibit any sign of infarcted brain tissue. Other animals having a distinct neuro-score (3.2 and 8.2, respectively) exhibited cerebral infarct with the same size (235 mm 3 ). These data indicate that the extent of neurological deficit assessed within the first 3 h after reperfusion does not reliably correspond to the occurrence and magnitude of cerebral infarct. Therefore, the neuro-score, when measured acutely within the first few hours after reperfusion, does not serve as a reliable criterion for preselecting animals with similar infarct size following transient MCAO.