Dysphagia in Duchenne muscular dystrophy assessed objectively by surface electromyography

Objective swallowing assessment is indicated in the management of patients with Duchenne muscular dystrophy (DMD). Surface electromyography (sEMG) provides a non-invasive, objective method of quantifying muscle activity. It was hypothesised that the measurement of sEMG activity during swallowing would distinguish between preserved and disordered swallow function in DMD. This comparative study investigated the peak, duration, and relative timing of muscle activity during swallowing of four muscle groups: orbicularis oris, masseter, submental, and infrahyoid. The study included three groups of participants: Nine DMD patients with dysphagia (mean age = 21.7 ± 4.2 years), six DMD patients with preserved swallow function (21.0 ± 3.0 years), and 12 healthy controls (24.8 ± 3.1 years). Dysphagic DMD participants produced significantly higher normalised peak amplitude measurements than the healthy control group for masseter (61.77 vs. 5.07; p ≤ 0.01) and orbicularis oris muscles (71.87 vs. 26.22; p ≤ 0.05). Intrasubject variability for masseter peak amplitude was significantly greater for dysphagic DMD participants than the other groups (16.01 vs. 5.86 vs. 2.18; p ≤ 0.05). There were no differences in timing measurements between groups. Different characteristic sEMG waveforms were observed for the three groups. sEMG provides useful physiological information for the evaluation of swallowing in DMD patients, justifying further study.