THE EFFECT OF AGE ON PERIPHERAL MOTOR-NERVE FUNCTION AFTER CRUSH INJURY IN THE RAT

Objective: To determine the ontogeny of functional recovery after peri pheral nerve crush injury. Design: Comparative study in rats of varyin g ages. Materials and Methods: Sixty-second crush injury was performed on the left posterior tibial nerve, Control animals underwent either nerve transection or sham procedure, Nerve function was evaluated 2, 4 , and 8 weeks following injury by walking track analysis, Print length ratio (PLR), (ratio of normal right-sided print length to experimenta l left-sided print length), was used to evaluate functional recovery. Measurements and Main Results: Two weeks after crush injury, adult rat s experienced significantly greater functional impairment than both 4- day-old and 3-week-old animals (p < 0.05), Four weeks after injury, th e difference in function between 4-day-old and adult rats and between 3-week-old and adult rats became insignificant, Complete recovery had been achieved by 8 weeks in all groups. Conclusions: These results dem onstrate faster functional recovery after nerve injury in immature rat s than in adults.