Objective: This study investigated the effects of a combinatorial treatment, consisting of a brief period of nerve electrical stimulation (ES) and systemic supraphysiologic testosterone, on functional recovery following a crush of the recurrent laryngeal nerve (RLN).
Study design: Prospective, controlled animal study.
Methods: After a crush of the left RLN, adult male Sprague-Dawley rats were divided into four treatment groups: 1) no treatment, 2) ES, 3) testosterone propionate (TP), and 4) ES + TP. Each group was subdivided into 1, 2, 3, or 4 weeks post-operative survival time points. Groups had an n of 4- 9. Recovery of vocal fold mobility (VFM) was assessed.
Results: Brief ES of the proximal nerve alone or in combination with TP accelerated the initiation of functional recovery. TP administration by itself also produced increased VFM scores compared to controls, but there were no statistical differences between the ES-treated and TP-treated animals. Treatment with brief ES alone was sufficient to decrease the time required to recover complete VFM. Animals with complete VFM were seen in treatment groups as early as 1 week following injury; in the untreated group, this was not observed until at least 3 weeks post-injury, translating into a 66% decrease in time to complete recovery.
Conclusions: Brief ES, alone or in combination with TP, promise to be effective therapeutic interventions for promoting regeneration following RLN injury.
Keywords: Axotomy; androgen; electrical stimulation; functional recovery; rat; recurrent laryngeal nerve; regeneration; vocal fold.