Hypoglossal-facial nerve "side-to-side" neurorrhaphy for facial paralysis resulting from closed temporal bone fractures

Background: Closed temporal bone fractures due to cranial trauma often result in facial nerve injury, frequently inducing incomplete facial paralysis. Conventional hypoglossal-facial nerve end-to-end neurorrhaphy may not be suitable for these injuries because sacrifice of the lesioned facial nerve for neurorrhaphy destroys the remnant axons and/or potential spontaneous innervation. Objective: we modified the classical method by hypoglossal-facial nerve "side-to-side" neurorrhaphy using an interpositional predegenerated nerve graft to treat these injuries. Methods: Five patients who experienced facial paralysis resulting from closed temporal bone fractures due to cranial trauma were treated with the "side-to-side" neurorrhaphy. An additional 4 patients did not receive the neurorrhaphy and served as controls. Results: Before treatment, all patients had suffered House-Brackmann (H-B) grade V or VI facial paralysis for a mean of 5 months. During the 12-30 months of follow-up period, no further detectable deficits were observed, but an improvement in facial nerve function was evidenced over time in the 5 neurorrhaphy-treated patients. At the end of follow-up, the improved facial function reached H-B grade II in 3, grade III in 1 and grade IV in 1 of the 5 patients, consistent with the electro-physiological examinations. In the control group, two patients showed slightly spontaneous innervation with facial function improved from H-B grade VI to V, and the other patients remained unchanged at H-B grade V or VI. Conclusions: We concluded that the hypoglossal-facial nerve "side-to-side" neurorrhaphy can preserve the injured facial nerve and is suitable for treating significant incomplete facial paralysis resulting from closed temporal bone fractures, providing an evident beneficial effect. Moreover, this treatment may be performed earlier after the onset of facial paralysis in order to reduce the unfavorable changes to the injured facial nerve and atrophy of its target muscles due to long-term denervation and allow axonal regrowth in a rich supportive environment.