Forelimb locomotor rating scale for behavioral assessment of recovery after unilateral cervical spinal cord injury in rats.

Background: Cervical spinal cord injury (SCI) models in rats have become increasingly useful because of their translational potential. The goal of this study was to design, develop and validate a quick and reliable forelimb locomotor rating scale for adult rats with unilateral cervical SCI injury.

New Method: Adult female rats were subjected to a C5 unilateral mild contusion (n=10), moderate contusion (n=10) or hemisection injury (n=9). Forelimb locomotion was evaluated before injury, four times during the first week (Days 2, 3, 4 and 7) and weekly for up to 8 weeks post-injury. Scoring categories were identified and animals were ranked based on their performance in these categories. The scale was validated for its usefulness by comparing animals with different injury models (dorsolateral funiculotomy C3/4), levels of injury (moderate contusion C4) and sex (male - moderate contusion C3/4) and also by correlating FLS scores with other established behavioral tests (grid walking and kinetic tests).

Results And Comparison With Existing Methods: Forelimb performance on both the grid-walking and kinetic tests was positively correlated with the forelimb locomotor rating scale (FLS). Histological analysis established a positive correlation between the spared tissue and the observed FLS score. Our results show that the new rating scale can reliably detect forelimb deficits and recovery predicted by other behavioral tests. Furthermore, the new method provides reproducible data between trained and naïve examiners.

Conclusion: In summary, the proposed rating scale is a useful tool for assessment of injury and treatments designed to enhance recovery after unilateral cervical SCI.