RT Journal Article
SR Electronic
T1 Template-operated quantitative motor unit potential analysis in diaphragm of patients with myotonic dystrophy
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP P2150
VO 44
IS Suppl 58
A1 Lea Leonardis
A1 Simon Podnar
YR 2014
UL http://erj.ersjournals.com/content/44/Suppl_58/P2150.abstract
AB The diaphragm is the main inspiratory muscle. Template-operated quantitative motor unit potential (MUP) analysis (qEMG) has been shown to be useful in the diagnosis of myopathy in limb muscles. Diaphragmatic MUPs in a healthy population are much smaller than in limb muscles and due to the waxing and waning respiratory EMG pattern, MUP sampling is difficult.The aim of our study was to evaluate feasibility and utility of the quantitative MUP analysis in the diagnosis of myopathy of the diaphragm.qEMG of the diaphragm and the biceps brachii muscles, phrenic nerve conduction studies and respiratory function tests were performed in 30 patients with myotonic dystrophy (DM) type 1 (DM1) and 17 patients with DM type 2 (DM2). Findings in both disorders were compared to reference ranges and correlated with respiratory function studies.Low diaphragm MUP amplitude precluded MUP analysis in 21% of DM1 patients. Only a single DM1 patient had qEMG findings consistent with myopathy. In this patient, and another 4 DM1 and 3 DM2 patients, findings consistent with neuropathy were demonstrated. By contrast, in the biceps brachii muscles of the same DM population, 67% of patients had MUPs consistent with myopathy. Phrenic compound motor action potential amplitudes correlated with respiratory function tests, whereas diaphragm MUP parameters did not.Diaphragm myopathic MUPs are very small and as such they skip from qEMG analysis. Template-operated quantitative MUP analysis is therefore inadequate for sampling diaphragm MUPs in patients with DM.