Prevention of denervated muscle atrophy with accelerated nerve‐regeneration by babysitter procedure in rat facial nerve paralysis model

Abstract

Purpose The “babysitter” procedure is a reconstruction technique for facial nerve complete paralysis and uses the movement source from the healthy facial nerve with a cross‐nerve graft. First, an end‐to‐side neurorrhaphy is performed between the affected facial nerve trunk and hypoglossal nerve for continuously delivering stimuli to the mimetic muscles for preventing the atrophy of mimetic muscles. Despite favorable clinical results, histological and physiological mechanisms remain unknown. This study attempted to establish a model for the “babysitter” procedure and find its efficacy in rats with facial nerve complete paralysis. Materials and Methods A total of 16 Lewis rats were used and divided into 2 groups; cross nerve graft (n = 8) and babysitter groups (n = 8). The facial nerve trunk was transected in both groups. Babysitter group underwent a two‐stage procedure. Cross nerve graft group underwent only the transfer of nerve graft from the healthy side to affected side. The animals were assessed physiologically by compound muscle action potential (CMAP), and the regenerated nerve tissues were evaluated histopathologically at 13 weeks after surgery. Results Facial nucleus stained with retrograde tracers proved the re‐innervation of affected facial muscle by the babysitter procedure. In CMAP, the amplitude of babysitter group was significantly higher than that of the cross‐facial nerve graft group (p < .05). Histological examination found a significant difference in myelin g‐ratio between two groups (p < .05). Conclusion This study investigated the “babysitter” procedure for rat facial nerve palsy. Babysitter procedure shortened the denervation period without mimic muscle atrophy.

Current Treatments and Future Directions for Facial Paralysis

“…A babysitter procedure is the process of coapting an additional donor nerve to a nerve graft, distal to the primary neurorrhaphy 40 . This procedure has been described in situations, such as in parotidectomies, where a segment of the facial nerve requires excision due to tumor involvement [41][42][43][44] . In this scenario, a nerve graft is typically used to bridge the nerve gap.…”

“…40 This procedure has been described in situations, such as in parotidectomies, where a segment of the facial nerve requires excision due to tumor involvement. [41][42][43][44] In this scenario, a nerve graft is typically used to bridge the nerve gap. To minimize irreversible end-plate degeneration, an alternative donor motor nerve can be used such as hypoglossal nerve.…”

The Regenerative Potential of Facial Nerve Motoneurons following Chronic Axotomy in Rats

“…For years, researchers have never stopped looking for effective treatments to promote facial nerve regeneration [10][11][12][13].…”

“…Previous studies have shown that nerve injuries induce a variety of molecular responses that may be involved in the regeneration of injured neurons [ 11 , 13 – 16 ]. In the neurons, the efficacy and the specificity of neurotrophic factors to support regeneration depend on the presence of their respective receptors and their number.…”