The ReSolve study in facioscapulohumeral dystrophy (FSHD) is a multi-site, international study undertaken to refine study design for clinical trials. One goal of this study is to identify reliable assessment tools to document disease progression in orofacial musculature and function in readiness for clinical trials.
FSHD type 1 is a progressive neuromuscular disease caused by a repeat contraction to <10 repeats of the D4Z4 repeat which encodes for the DUX4 protein. This results in an aberrant reactivation of the gene in skeletal muscle.1 Facial weakness is usually the initial presenting symptom and 25% and 35% of patients reporting dysarthria and dysphagia, respectively.2
227 participants were enrolled across eight US and three European sites. Strength and endurance of lips, cheeks (bilaterally), and tongue (anteriorly and posteriorly) were assessed using the Iowa Oral Performance Instrument (IOPI). Participants repeat numbers were quantified and patients were also assessed using the FSHDHI, manual muscle testing (MMT), and a clinical rating of severity of symptoms.
Mean age of participants was 50.3 years (SD 14.1). Test-retest reliability across study sites for orofacial strength and endurance measures ranged from 0.66 – 0.85, indicating moderate to good reliability. Using Spearman’s rank correlation coefficient, bilateral cheek strength and lip strength had low positive correlations with repeat number (0.38, 0.49, 0.32) and MMT total score (0.47, 0.50, 0.37). Low negative correlation was seen with bilateral cheek (L, R) and lip strength with the impaired facial expression rating on FSHDHI (-0.34, -0.32, -0.37). Additionally, bilateral cheek strength (L, R) and lip endurance had low negative correlation with overall FSHD clinical score (-0.35, -0.45, -0.33). All correlations were significant at the ?<.01 level.
IOPI is a reliable tool measuring orofacial strength in FSHD. Correlations exist with clinical ratings of overall disease severity, specific rating of orofacial functioning, and overall manual muscle testing.