Deceleration of denervated facial muscle atrophy through functional electrical stimulation: a sonographic quantification in patients with facial nerve paralysis

Functional Electrical Stimulation (FES) is an established intervention for a range of muscular and neurological disorders that has already been studied in numerous publications. However, its application to Peripheral Facial nerve Paralysis (PFP) still needs to be sufficiently investigated. As the first approach known to the authors, this study examines the effect of FES on the facial muscles in complete PFP using ultrasonography as a means of observation. In a prospective single-center observational pilot study, ten patients with complete PFP, confirmed by needle-electromyography (EMG), performed FES of the affected lateral mouth region at home twice daily for 20 minutes. The facial muscles' Cross-Sectional Area (CSA) was regularly assessed using sonographic quantification. While the CSA of most non-stimulated muscles decreased considerably during ongoing paralysis, a significant CSA increase of the Zygomaticus Muscle (ZYG), which was regularly subjected to FES, could be demonstrated. FES can halt the atrophy of denervated ZYG and potentially other facial muscles. Further investigations with a more significant patient collective are recommended. From now on, FES could be established as an additive method in the non-invasive treatment of PFP.