Exercise test in muscle channelopathies and other muscle disorders

Citation
T. Kuntzer et al., Exercise test in muscle channelopathies and other muscle disorders, MUSCLE NERV, 23(7), 2000, pp. 1089-1094
Citations number
10
Categorie Soggetti
da verificare
Journal title
MUSCLE & NERVE
ISSN journal
0148639X → ACNP
Volume
23
Issue
7
Year of publication
2000
Pages
1089 - 1094
Database
ISI
SICI code
0148-639X(200007)23:7<1089:ETIMCA>2.0.ZU;2-I
Abstract
We studied the percentage change in compound muscle action potential (CMAP) amplitude and area during and after a 5-min maximal contraction of the mus cle. The exercise test (ET) was performed on 64 patients with different mus cle disorders and on 46 normal controls. The range of normal ET values was defined as the mean + 2 SD of the control values. The mean sensitivity of t he test was 63% in the whole group with ion channel muscle disorders, the h ighest sensitivity being seen in primary periodic paralysis (81%) and the l owest in chloride channelopathies (17%). In thyrotoxic periodic paralysis, the ET was abnormal in the three of the four patients studied. in patients with myotonic dystrophy, a smaller than normal increase in CMAP amplitude o ccurred during and after exercise, whereas in proximal myotonic myopathy a normal initial increase in CMAP amplitude was followed by an abnormal decre ment. We conclude that the ET can be of use in confirming abnormal muscle m embrane excitability in patients with calcium and sodium channelopathies an d thyrotoxic periodic paralysis. In chloride channelopathy, the test may al so be abnormal, but shows no, or only a small, increase in amplitude or are a in the immediate postexercise period. The test may also be abnormal in pr oximal myotonic myopathy, but is normal in myotonic dystrophy. (C) 2000 Joh n Wiley & Sons, Inc.