Motor performance score: a new algorithm for accurate behavioral testing of spinal cord injury in rats.

To evaluate the usefulness of standard neurological tests in predictin g the neurological outcome after photochemically induced spinal cord lesions in rats, we inflicted injuries of different severity to adult female rats. The behavior of the rats was followed for 6 weeks and the results of the behavioral tests were correlated with morphological indicators of tissue destruction at the end of this period. We found many behavioral tests to be highly correlated with the loss of tissue, whereas some tests were inaccurate in correlating with degree of tissue destruction. Motor score, beam walk, and righting reflect were all highly correlated with the volume of the lesion as well as the depth of the lesion cavity at its epicenter. We propose a protocol for neurological evaluation of this type of spinal cord injury consisting of six individual tests, hierarchally organized such that injured rats can be divided into 11 groups ofn eurological deficit, scored from 10 to 0. This so-called motor performance score is fast and easy to perform and shows high correlation with the lesion volume, and is thus suitable for neurological evaluation of photochemically induced spnial cord injury.