Weighting of facial grading variables to disfigurement in facial palsy

Abstract

IMPORTANCE: A universal, health care professional-graded scale for facial assessment would be a useful tool for reporting, comparing, and assessing facial function among patients with facial paralysis. OBJECTIVES: To correlate scores of an assessment tool, the eFACE scale, with expert-rated facial disfigurement and to determine the relative contributions of facial features to facial palsy-related disfigurement. DESIGN, SETTING, AND PARTICIPANTS: The eFACE scale yields 15 individual variable scores, in addition to subscores for static, dynamic, and synkinesis elements, and a total score that is based on 100-point scales. Two hundred patients with varying degrees of unilateral facial palsy underwent independent eFACE assessment and assignment of a disfigurement score by 2 facial nerve surgeons. The mean scores were determined, and multivariate regression analysis was performed to fit eFACE subset scores (static, dynamic, and synkinesis) to disfigurement ratings. A hybrid regression model was then used to weight each of the 15 eFACE variables, using stepwise regression to control for the effect of the other variables. Scoring was performed during an 8-week period from March 16 to May 8, 2015. MAIN OUTCOME AND MEASURE: Use of the 100-point eFACE variables, together with a 100-point visual analog scale of disfigurement, with 0 representing the most extreme disfigurement possible from a facial nerve disorder and 100 representing no discernible facial disfigurement. RESULTS: In the 200 patients included in analysis (126 [63.0% female]; mean [SD] age, 46.5 [16.4] years]), predicted disfigurement scores based on eFACE subset scores demonstrated excellent agreement with surgeon-graded disfigurement severity (r2 = 0.79). Variable weighting demonstrated that the 6 key contributors to overall disfigurement were (in order of importance) nasolabial fold depth at rest (normalized coefficient [NC], 0.18; P < .001), oral commissure position at rest (NC, 0.15; P < .001), palpebral fissure width at rest (NC, 0.09; P < .001), nasolabial fold orientation with smiling (NC, 0.08; P = .001), and palpebral fissure width during attempts at full eye closure (NC, 0.06; P = .03). CONCLUSIONS AND RELEVANCE: A mathematical association between eFACE-measured facial features and overall expert-graded disfigurement in facial paralysis has been established. For those using the eFACE grading scale, predictions of the specific effects of various interventions on expert-rated disfigurement are now possible and may guide therapy.