Diaphragm involvement in Facioscapulohumeral dystrophy: insights from phrenic nerve stimulation studies

Abstract

Background: Cervical and cortical magnetic stimulation (CEMS and COMS) of the phrenic nerves using surface electrodes and transnasally inserted balloon catheters allows evaluation of contractile and electrophysiological properties of the diaphragm. Facioscapulohumeral muscular dystrophy (FSHD) is characterized by progressive weakness of facial and limb muscles but diaphragm involvement has been insufficiently explored. Methods: 12 patients with genetically proven FSHD (8 men, 4 women; 52±17 years) and 12 healthy controls matched for age and gender (7 men, 5 women; 51±14 years) underwent COMS and CEMS of the phrenic nerves with simultaneous recording of twitch oesophageal and gastric pressures (twPes, twPgas). Diaphragm motor evoked (dMEP) and compound muscle action potential (dcMAP) were simultaneously recorded from the lower costal margin using surface electrodes. Results: In FSHD patients (FVC 74.25 ±29.76 % vs. 111.50 ± 17.26 %, p Conclusions: There is diaphragm involvement in patients with FSHD, and it appears to be exclusively myopathic in nature.