The effect of electrical and mechanical stimulation on the regenerating rodent facial nerve

Investigators have long sought realistic methods to accelerate regeneration following nerve injury. Herein, we investigated the degree to which manual target muscle manipulation and brief electrical stimulation of the facial nerve, alone or in combination, affects recovery following rat facial nerve injury.

Prospective, randomized animal study.

Sixty rats were randomized to three groups: brief electrical stimulation (BES), mechanical stimulation of the whisker pad (MEC), or both (COMBO). Animals underwent facial nerve transection and immediate microsurgical repair. In BES and COMBO groups, transection was preceded by 1-hour (3 V, 20 Hz square wave) electrical stimulation. Animals were tested weekly, with 5-minute recording sessions of whisker movement. In the MEC and COMBO groups, animals received 5 minutes of daily massage to the left whisker pad throughout the recovery period. Whisking behavior was analyzed for comparisons.

The BES and MEC groups demonstrated improved functional recovery in all whisking parameters compared with the COMBO group or historical controls at most time points between postoperative weeks 1 and 7. After 12 weeks, functional recovery remained superior in the BES and MEC groups compared with the COMBO and control groups, although the effect was no longer statistically significant.

We observed an accelerative recovery effect of either electrical nerve stimulation or massage of the whisker pad on whisking behavior. The combination of both interventions had a negating effect on the acceleration of recovery. The potential clinical utility of these modalities bears consideration, and their negating interaction warrants further study.