The Tinel Sign and Myelinated Axons in the Cross-Face Nerve Graft: Predictors of Smile Reanimation Outcome for Free Gracilis Muscle Transfer?

Introduction: During a two-stage free gracilis muscle transfer (FGMT) to restore smile to patients with facial paralysis, some surgeons assess nerve regeneration through the cross-face nerve graft (CFNG) with the Tinel sign and a nerve biopsy. Objective: To test whether ultimate smile reanimation outcomes are correlated with (1) the Tinel sign or (2) myelinated axons of the biopsied CFNG at the time of FGMT. Methods: Retrospective case series was performed at a tertiary care facial nerve center. Dynamic smile outcomes were quantified with Emotrics analysis of pre- and postoperative photographs. Results: Of the 113 FGMT surgeries by CFNG performed since 2002, 92 patients had pre- and postoperative photo-documentation. Most patients (89%, N = 82) had a positive Tinel sign at the time of FGMT; however, 14 patients with positive Tinel signs were deemed failures. Interestingly, 4 patients with a negative Tinel sign went on to have successful dynamic outcomes and 16 patients lacking myelinated axons in their CFNG biopsy ultimately achieved successful smile outcomes. Conclusion: Although the majority of patients had a positive Tinel sign and myelinated axons in the CFNG at the time of FGMT, the presence or absence of either factor did not predict ultimate smile outcome in this series.