American Society for Peripheral Nerve

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Effectiveness and Safety of Dynamic Gracilis Muscle Smile Restoration in Facial Paralysis: a Systematic Review and Meta-Analysis
Mélissa Roy, MDCM1; Joseph Corkum, MD2; Prakesh S Shah, MBBS, DCH, MRCP, MRCPCH1; Gregory H. Borschel, MD, FAAP, FACS3; Emily S. Ho, BSc OT Reg (Ont), MEd3; Ronald M. Zuker, MD, FRCSC, FACS, FAAP3; Kristen M Davidge, MD, MSc, FRCS(C)3; (1)University of Toronto, Toronto, ON, Canada, (2)Dalhousie University, Halifax, NS, Canada, (3)The Hospital for Sick Children, Toronto, ON, Canada

Introduction: Smiling is a fundamental component of social interactions and a window to one’s emotions. For patients suffering from facial palsy, significant challenges arise socially, cosmetically, and functionally. One of the key procedures for dynamic smile restoration is the microneurovascular transfer of a free muscle unit. Our objective was to review the effectiveness and safety of dynamic smile reanimation surgery using the free gracilis muscle unit in patients with facial paralysis.

Methods: A systematic review was conducted and relevant studies reporting surgical outcomes of dynamic smile restoration using free gracilis transplants were identified from EMBASE, Medline, and Web of Science databases from inception to May 23rd 2017. Only studies reporting the use of the gracilis as a free muscle transplant in both pediatric and adult patients were included. All facial paralysis etiologies were eligible for inclusion. Two-stage screening and data extraction were performed by two independent reviewers. Data on sample size, smile excursion, complications, revisions, and quality of life were extracted and analyzed. Pooled proportions estimates were calculated using random-effects models when reported outcomes were not too heterogeneous.

Results: A total of 1,623 abstracts were screened, 472 articles were reviewed and 21 met inclusion criteria. Included studies comprised 19 case series and 2 cohorts (1 retrospective, 1 prospective) published between 1991 and 2015. 1,295 patients ages on average 26.5 (range 4-80) including a ratio of female to male of 1:0.91 and at least 254 (19.6%) congenital cases and 309 (23.9%) tumor resections underwent 1,446 gracilis muscle transplantations. Of these, 977 flaps were coapted to the facial nerve, 379 to the masseter, 48 to the spinal accessory, 14 to the hyploglossal, and 21 had dual innervation. Only 12 (57.1%) studies attempted to estimate smile excursion outcomes change using 10 different tools and pooling of four studies revealed a mean estimate of 7.0mm (95%CI 5.2-8.8; I293.4%, p<0.001). Three (14.3%) studies explored patients’ change in quality of life and all showed improvement. Fifteen (71.4%) studies reported operative complications and six (28.6%) reported subsequent revision procedures. Pooled proportions estimates of flap failures and revision procedure rates were revealed to be 4.5% (95%CI 1.8-7.2, I268.7%, p<0.001), and 23.0% (95%CI 8.1-37.8, I287.5%, p<0.001) respectively.

Conclusions: In conclusion, dynamic smile restoration using a free gracilis muscle has a low rate of failure but does require revision procedures to optimize final cosmetic outcomes. A need for more homogeneous reporting of smile excursion and patient-reported outcome measures is clear.

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