Effect of muscle strengthening on peripheral facial palsy: A randomized controlled trial

OBJECTIVE To evaluate the effect of muscle strengthening intervention in peripheral facial palsy (PFP). METHODS A randomized controlled trial was conducted at five hospitals. Fifty-one subjects with PFP who showed a response of less than 20% on electroneurography (ENoG) were enrolled. Subjects in a muscle-strengthening-intervention group (MS Group) underwent a selective muscle contraction intervention (SMCI). Subjects in another group not receiving muscle strengthening intervention (Non-MS Group). Both groups underwent three interventions: Prohibition of maximum effort movements, Stretching of the affected facial muscles, and Mirror biofeedback therapy. The outcomes were measured by the Sunnybrook Facial Grading System (FGS) at 6 months after onset (primary endpoint) and at 12 months after onset (secondary endpoint). The subjects in the MS Group and Non-MS Group were further divided into subgroups showing ENoG responses of 10% or less and ENoG responses of over 10%, as a sub-analysis. RESULTS No significant differences between the MS Group and Non-MS Group at either the primary endpoint or secondary endpoint. Among the subjects in the treatment group with an ENoG response of over 10% at the primary endpoint, the FGS Composite Score and FGS Voluntary Movement score were both significantly higher in the MS Group than in Non-MS Group. Although the MS Group had a significantly lower FGS Resting Symmetry Score, there was no significant difference between the two groups in the FGS Synkinesis Score. CONCLUSIONS SMCI improved paralysis in subjects exhibiting an ENoG response of over 10% within the 6 months from onset without any deterioration of synkinesis.