Trial design Hypoglossal–facial nerve (HN-FN) neurorrhaphy is a method commonly used to treat facial palsy when the proximal stump of the injured FN is unavailable. Since the classic HN-FN neurorrhaphy method that needs to section the injured FN is not suitable for incomplete facial palsy, we investigated a modified method that consists of HN-FN ‘side’-to-side neurorrhaphy, retaining the remaining or spontaneously regenerated FN axons while preserving hemihypoglossal function.

Methods To improve axonal regeneration, we used for the first time a predegenerated sural autograft for performing HN–FN ‘side’-to-side neurorrhaphy followed by postoperative facial exercise. We treated 12 patients who had experienced FN injury for 1–18 months as a result of acoustic tumour removal. All patients experienced facial grade V–VI paralysis according to the House-Brackmann scale, but their FN was anatomically preserved. No spontaneous facial reinnervation was detected before repair.

Results Although we did not perform fresh nerve grafts and HN–FN ‘side’-to-end neurorrhaphy as controls for ethical reasons, the reparative outcomes after nerve reconstruction were remarkable: functional improvements were detected as soon as 3 months after repair, House-Brackmann grade II or III FN functions were achieved in five and four patients, respectively, and there were no apparent signs of synkinesis. The three patients who experienced less satisfactory outcomes had exhibited facial palsy for more than 1 year accompanied by muscle atrophy, consistent with a need for rapid surgical intervention.

Conclusions Based on fundamental concepts and our experimental results, this new surgical method represents a major advance in the rehabilitation of FN injury.

Trial registration number JS2013-001-02.