Facial--hypoglossal nerve end-to-side neurorrhaphy: anatomical study in rats

End-to-side neurorrhaphy (ESN) is presented as a sort of surgical technique for nerve repair that has the aim to obtain a good reinnervation of the recipient nerve and function preservation of the donor nerve. Several problems regarding this technique remain to be solved. Even if ESN could find some indications in particular cases of peripheral nerve surgery, we do not think that this technique can be first choice surgery for repairing a damaged facial nerve because of the complexity of the function of facial muscles and the necessity to offer an adequate number of motoneurons from the donor nerve for reinnervation of the recipient nerve.So, despite some reports about the clinical use of facial-hypoglossal nerve ESN, we studied experimentally such technique in the rat, having as recipient the facial nerve and as donor the hypoglossus. The purpose was to establish the number of motoneurons with which the donor hypoglossal nerve innervates the recipient facial nerve, and to compare the result with that obtained after facial-hypoglossus end-to-end neurorrhaphy (EEN). Beside other interesting findings, the key point of the obtained results was that motoneuron contribution given from the donor hypoglossus to the innervation of the recipient facial nerve was limited in ESN as compared to the classic EEN.