The effect of age on peripheral motor nerve function after crush injury in the rat.

OBJECTIVE

To determine the ontogeny of functional recovery after peripheral nerve crush injury.

DESIGN

Comparative study in rats of varying ages.

MATERIAL 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 experimental left-sided print length), was used to evaluate functional recovery.

MEASUREMENTS AND MAIN RESULTS

Two weeks after crush injury, adult rats experienced significantly greater functional impairment than both 4-day-old and 3-week-old animals (p < 0.05). Four weeks after injury, the 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 demonstrate faster functional recovery after nerve injury in immature rats than in adults.