Quantitative Three-dimensional Scanning of Facial Movements in Facioscapulohumeral Dystrophy

A BSTRACT Background: Facioscapulohumeral dystrophy (FSHD) is the third prevalent neuromuscular disorder, particularly with facial and upper limb involvement. Due to its characteristics, quantitative assessment of facial function is challenging but essential for determining severity. We aimed to evaluate facial participation of patients with FSHD using three-dimensional (3D) scanning to determine whether 3D evaluations differed in patients with FSHD compared to healthy controls and if facial involvement was correlated with genetic mutation and clinical severity. Methods: Twenty-one healthy controls (57.1% of females) and 12 patients with FSHD (58.3% of females) were investigated using 3D facial scanning in a three-axis coordinate system to evaluate eyebrow elevation, maximal eye closing, maximal teeth showing, whistling, and happy facial expressions. These expressions were evaluated in terms of intensity and asymmetry. Genetic mutations were investigated to reveal the D4Z4 repeat (D4Z4-RU) on 4q35. Clinical severity scores (CSS) were determined through neurologic examinations. For Q1, 3D data were compared between patients with FSHD and controls. For Q2, the association of 3D variables with D4Z4-RU and CSS was examined. Results: Intensity of whistling, maximal eye closing, and happy expressions were significantly different in patients with FSHD compared with controls ( P < 0.001, P < 0.002). Asymmetry-related measurements were not different between groups. Facial movements did not correlate with CSS and D4Z4-RU in patients with FSHD. Conclusions: 3D estimations can provide quantitative data on the function of facial muscles. By converting 3D scans into colored face scales, additional information on facial parts affected by specific movements could be obtained. The use of 3D in FSHD has the potential to provide reliable quantitative data for routine, research, and follow-up studies.