Nimodipine and acceleration of functional recovery of the facial nerve after crush injury

Abstract

Objective: To establish whether nimodipine, a calcium channel blocker, accelerates or otherwise improves functional recovery of whisking after facial nerve crush injury in the rat.

Methods: Thirty rats underwent exposure of the left main trunk of the facial nerve followed by a standard crush injury and subsequent quantitative facial movement testing. Animals were randomized into an experimental group (n = 15) and a control group (n = 15). Four days prior to facial nerve manipulation, experimental animals underwent subcutaneous implantation of a nimodipine-secreting pellet. All animals were tested preoperatively and on postoperative days 2, 8 to 17, 20, 22, 24, and 31 using a validated, quantitative whisking kinematics apparatus. Whisks were analyzed for amplitude, velocity, and acceleration.

Results: Animals receiving nimodipine demonstrated significantly better whisking on 5 days (postoperative days 9, 11 to 13, and 20) compared with control animals (P < .001, P = .003, P = .009, P = .009, and P = .009, respectively; 1-tailed ttest). Overall, the nimodipine-treated animals showed earlier recovery compared with the untreated animals.

Conclusions: We demonstrate that nimodipine improves recovery of whisking after facial nerve crush. This finding corroborates the semiquantitative findings of others, and provides complete whisking kinematic data on its effects. Given the low adverse effect profile of nimodipine, there may be clinical implications in its administration in patients experiencing facial nerve injury.

Figure 1

Relative recovery of whisking amplitude over time. Curves represent the calculated average relative amplitude of the 3 largest amplitude whisks for each animal on each day of testing. The nimodipine treated group showed a statistically significant improvement on post-operative days 9, 11–13, and 20 as compared with the controls (p<.05, one-tailed t-test). Error bars indicate 2-tailed standard error.

Figure 2

Demonstrates the relative recovery of facial function for post-operative days 10–14, the days of rapid recovery of function. (Top) The nimodipine treated group showed a statistically significant improvement in relative amplitude on days 11–13 as compared with the controls (p<.05, one-tailed t-test). The nimodipine-treated group also showed significantly better relative whisking velocity on days 11–13 (middle) and relative acceleration on days 11–14 (bottom) as compared with the controls (p<.05, one-tailed t-test)