Effect of Bumetanide on Facial Nerve Regeneration in Rat Model.

Objective: We investigated the effects of bumetanide alone and in combination with dexamethasone on facial nerve regeneration in rats with facial paralysis.

Study Design: A prospective controlled animal study.

Setting: An animal laboratory.

Subjects And Methods: Facial paralysis was induced in 32 Wistar rats that we then divided into 4 groups: group 1, control; group 2, bumetanide; group 3, dexamethasone; group 4, bumetanide and dexamethasone. Electroneurography was performed 1, 2, and 4 weeks later, and nerve regeneration was evaluated by electron and light microscopy and Western blotting in week 4.

Results: Regarding the comparison between preoperative values and week 4, the latency difference in group 1 (1.25 milliseconds) was significantly higher than those of groups 2 to 4 (0.56, 0.34, and 0.10 milliseconds, respectively; = .001). The latency increment in groups 2 and 3 was higher than that of group 4 ( = .002 and = .046) in week 4, whereas groups 2 and 3 did not differ significantly ( = .291). Amplitude difference was not statistically significant from week 4 among all groups (all .05). The number of myelinated axons was significantly higher in all treatment groups than in the control group ( = .001). Axon number and intensity were significantly higher in group 4 as compared with groups 2 and 3 ( = .009, = .005).

Conclusion: After primary neurorrhaphy, dexamethasone and bumetanide alone promoted nerve recovery based on electrophysiologic and histologic measures. Combination therapy was, however, superior.