EFFECT OF PULSED ELECTROMAGNETIC STIMULATION ON FACIAL-NERVE REGENERATION

Objective: To determine if exposure to electromagnetic fields influenc es regeneration of the transected facial nerve in the rat. Design and Methods: The left facial nerve was transected in the tympanic section of the fallopian canal in 24 rats randomly assigned to 2 groups. The c ut ends of the facial nerve were reapproximated without sutures within the fallopian canal to maximize the potential for regeneration. Rats in the experimental group (n=12) were then exposed to pulsed electroma gnetic stimulation (0.4 millitesla at 120 Hz) for 4 hours per day, 5 d ays per week, for 8 weeks. Rats in the control group (n=12) were handl ed in an identical manner without pulsed electromagnetic stimulation. Four other rats were given sham operations in which all surgical proce dures were carried out except for the actual nerve transection. Two of these rats were placed in each group. Nerve regeneration was evaluate d using electroneurography (compound action potentials), force of whis ker and eyelid movements, and voluntary facial movements before and at 2-week intervals after transection. Histological evaluation was perfo rmed at 10 weeks after transection. Each dependent variable was analyz ed using a 2-way analysis of variance with 1 between variable (groups) and 1 within repeated measures variable (days after transection). Res ults: Statistical analysis indicated that N1 (the negative deflection of depolarization phase of the muscle and/or nerve fibers) area, N1 am plitude, and N1 duration, as well as absolute amplitude of the compoun d action potentials, were all significantly greater 2 weeks after tran section in the experimental than in the control group of rats. The for ce of eye and whisker movements after electrical stimulation was stati stically greater in the experimental group of rats 4 weeks after trans ection. Voluntary eye movements in the experimental group were signifi cantly better at 5 and 10 weeks, while whisker movements were better a t 3 and 10 weeks. There was no statistical difference between the 2 gr oups for any histological variable. Conclusion: Results of this study indicate that pulsed electromagnetic stimulation enhances early regene ration of the transected facial nerve in rats.