Use of Objective Metrics in Dynamic Facial Reanimation: A Systematic Review.

IMPORTANCE: Facial nerve deficits cause significant functional and social consequences for those affected. Existing techniques for dynamic restoration of facial nerve function are imperfect and result in a wide variety of outcomes. Currently, there is no standard objective instrument for facial movement as it relates to restorative techniques. OBJECTIVE: To determine what objective instruments of midface movement are used in outcome measurements for patients treated with dynamic methods for facial paralysis. DATA SOURCES: Database searches from January 1970 to June 2017 were performed in PubMed, Embase, Cochrane Library, Web of Science, and Scopus. Only English-language articles on studies performed in humans were considered. The search terms used were ("Surgical Flaps"[Mesh] OR "Nerve Transfer"[Mesh] OR "nerve graft" OR "nerve grafts") AND (face [mh] OR facial paralysis [mh]) AND (innervation [sh]) OR ("Face"[Mesh] OR facial paralysis [mh]) AND (reanimation [tiab]). STUDY SELECTION: Two independent reviewers evaluated the titles and abstracts of all articles and included those that reported objective outcomes of a surgical technique in at least 2 patients. MAIN OUTCOMES AND MEASURES: The presence or absence of an objective instrument for evaluating outcomes of midface reanimation. Additional outcome measures were reproducibility of the test, reporting of symmetry, measurement of multiple variables, and test validity. RESULTS: Of 241 articles describing dynamic facial reanimation techniques, 49 (20.3%) reported objective outcome measures for 1898 patients. Of those articles reporting objective measures, there were 29 different instruments, only 3 of which reported all outcome measures. CONCLUSIONS AND RELEVANCE: Although instruments are available to objectively measure facial movement after reanimation techniques, most studies do not report objective outcomes. Of objective facial reanimation instruments, few are reproducible and able to measure symmetry and multiple data points. To accurately compare objective outcomes in facial reanimation, a reproducible, objective, and universally applied instrument is needed.