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Research Original Investigation

Powering the Gracilis for Facial Reanimation

Consistent with prior studies, our results support the use of themasseteric nerve and CFNG together, rather than either alone, as the best option for neurotizing the gracilis flap for fa cial reanimation in adults. Several experienced facial reani mation surgeons have postulated that achieving spontaneity is only likely with use of the CFNG. 9,27,38,39 Unfortunately, as noted in the past by several independent groups, the limita tion of CFNG may be the decreased axon count that reaches the transplantedmuscle aftermultiple anastomoses. 40,41 Thus, the added robust axonal input from themasseteric nervemay help augment the excursion beyond what the CFNG can achieve alone. 10,11,41,42 Though the mechanism for this phe nomenon is not known, the previously described “babysit ter” procedure is one possible explanation. 43 Aswith the origi nally described “minihypoglossal” graft during the first stage of a CFNG, themasseteric nervemay serve this purpose by pro viding neural input while the CFNG is maturing. Though our meta-analysis was limited to the masseteric nerve and CFNG, there is some compelling evidence that the masseteric nerve may be the best nonfacial nerve to use for this purpose. Researchers have theorized that, owing to the proximity of the smile and jaw-clenching areas of control in the premotor and primary motor area, it may be easier for pa tients to achieve spontaneity after reinnervationwith themas seteric nerve. 44,45 In addition, there is normal activation of the masseteric nerve during smiling, 46 which further supports the case for the masseteric nerve because this is the gesture used to trigger a smile by patients after reanimationwith this nerve. Opportunities for Future Research It is clear from our systematic review that spontaneity is the most heterogeneously reported measure in facial reanima tion. Unfortunately, noexistingpatient-reportedoutcomemea sure addresses this specific issue of standardizing how spon taneity is measured. A standard protocol for measuring spontaneity postoperatively would likely require a video as sessment with independent, blinded raters, and would re quire a patient to fall within a defined upper limit for the amount of time allowed to elapse after exposure to a smile stimulus to be called spontaneous. Hadlock’s group has pro posed a smile spontaneity assay to address this problem, and recently showed that the correlation between the assay and clinician-graded spontaneity was unfortunately quite low (R = 0.35). 47,48

A related issue is that of preoperative patient factors such as age and severity of paralysis. Though facial reanimation sur geons would likely agree that younger age is a positive prog nostic factor for subsequent spontaneity, and a nonflaccid pa ralysis will likely have a better result than a flaccid paralysis owing to better postoperative resting tone, neither of these fac tors are well-controlled for in published studies. As reporting standards improve over time, we expect that the impact of age, flaccidity, and other patient factors will become better under stood in a more quantitative fashion. Limitations Despite a thorough systematic search, our study is some what limited in that there were a small number of donor nerve options to use for our meta-analysis, which precluded our ability to make definitive conclusions. Unfortunately, we were limited to previously published studies, which do not capture all the possible donor nerves that have been used in facial reanimation with alternative techniques. For example, others have obtained successful outcomes with a hypoglos sal nerve transfer. 9,49,50 Because those studies did not use a gracilis free flap, however, they were excluded from this study. In addition, our meta-analyses were largely driven by the study by Bhama et al 11 because it was the largest of the included studies. Furthermore, all of the studies included in our meta-analyses were done in the United States at 1 of 2 centers. Though this does limit the generalizability of our findings, this helps to highlight the need for compatible out come measures and improved results reporting in facial reanimation. Conclusions Owing to the heterogeneity in reported outcomes from facial reanimation, we were unable to make definitive conclusions regarding the optimal donor nerve for this purpose. Establish ing a reporting standard at peer reviewed journals to improve results reporting is onemethod to allow for improved collabo ration in the future. Standardizing follow-up times, assessing spontaneity in an objective and reproducible fashion, and use of consistent outcomemeasures would allow for futuremeta analyses and better understanding of options for facial reani mation for this challenging patient population.

2 . Bradbury ET, Simons W, Sanders R. Psychological and social factors in reconstructive surgery for hemi-facial palsy. J Plast Reconstr Aesthet Surg . 2006;59(3):272-278. doi:10.1016/j.bjps.2005.09. 003 3 . Harii K, Ohmori K, Torii S. Free gracilis muscle transplantation, with microneurovascular anastomoses for the treatment of facial paralysis. a preliminary report. Plast Reconstr Surg . 1976;57 (2):133-143. doi:10.1097/00006534-197602000 00001 4 . O’Brien BM, Franklin JD, Morrison WA. Cross-facial nerve grafts and microneurovascular free muscle transfer for long established facial

ARTICLE INFORMATION Accepted for Publication: January 10, 2020.

Statistical analysis: Vila, Kallogjeri. Administrative, technical, or material support: Chi. Study supervision: Vila, Chi. Conflict of Interest Disclosures: Dr Kallogjeri reported grants from Potentia Metrics outside the submitted work. No other disclosures were reported. REFERENCES 1 . Nellis JC, Ishii M, Byrne PJ, Boahene KDO, Dey JK, Ishii LE. Association among facial paralysis, depression, and quality of life in facial plastic surgery patients. JAMA Facial Plast Surg . 2017;19(3): 190-196. doi:10.1001/jamafacial.2016.1462

Published Online: March 26, 2020. doi:10.1001/jamaoto.2020.0065

Author Contributions: Drs Vila and Chi had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Vila, Chi. Acquisition, analysis, or interpretation of data: All authors. Drafting of the manuscript: Vila, Chi. Critical revision of the manuscript for important intellectual content: Vila, Kallogjeri, Yaeger .

434 JAMA Otolaryngology–Head & Neck Surgery May 2020 Volume 146, Number 5 (Reprinted)

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