The purpose of this study was to comprehensively evaluate respiratory muscle function in adults with facioscapulohumeral muscular dystrophy (FSHD).14 patients with FSHD (9 men, 53±16 years) and 14 matched controls underwent spirometry, diaphragm ultrasound, and measurement of twitch gastric and transdiaphragmatic pressures (twPgas and twPdi; n=10) following magnetic stimulation of the lower thoracic nerve roots and the phrenic nerves. The latter was combined with recording of diaphragm compound muscle action potentials (CMAP; n=14).
RESULTS
The following parameters were significantly lower in patients vs. controls: forced vital capacity (FVC), maximum inspiratory and expiratory pressure, peak cough flow, diaphragm excursion amplitude and thickening ratio on ultrasound, twPdi (11±5 vs. 20±6 cmH
2 O), and twPgas (7±3 vs. 25±20 cmH
2 O). Diaphragm CMAP showed no group differences. FVC correlated inversely with the clinical severity scale score (r=-0.63, p=0.02).
In FSHD, respiratory muscle weakness involves both the diaphragm and the expiratory abdominal muscles. This article is protected by copyright. All rights reserved.