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The role of electrodiagnosis with long exercise test in mcardle disease
Author(s) -
Semplicini Claudio,
Hézodearzel Marianne,
Laforêt Pascal,
Béhin Anthony,
LeonardLouis Sarah,
Hogrel JeanYves,
Petit François,
Eymard Bruno,
Stojkovic Tanya,
Fournier Emmanuel
Publication year - 2018
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.26074
Subject(s) - isometric exercise , medicine , compound muscle action potential , cardiology , exercise intolerance , physical medicine and rehabilitation , physical therapy , physical exercise , electrophysiology , heart failure
: In this study we evaluated the role of an electrodiagnostic provocative test (long exercise test) in McArdle disease. Methods : Twenty‐five McArdle patients and 2 control groups underwent an electrodiagnostic protocol with long exercise test (LET), consisting of recording the compound muscle action potential (CMAP) before and after 5 minutes of isometric contraction. Results : The LET disclosed a postexercise decrease in CMAP amplitude in 23 of 25 McArdle patients. The immediate and long‐lasting decrease differentiated McArdle patients from controls. Patients with a normal LET demonstrated milder symptoms and/or residual myophosphorylase activity. Discussion : The LET is a sensitive, safe, and noninvasive provocative test that may guide clinicians toward molecular analysis of the myophosphorylase gene. The abnormalities observed on LET point toward complex biochemical mechanisms determined by the absence of myophosphorylase, beyond simple glycolytic blockade (ionic pump dysfunction, sarcolemmal inexcitability). The normal LET in patients with milder symptoms indicates a relationship of the LET with clinical severity, thus identifying it as a potential outcome measure. Muscle Nerve 58 : 64–71, 2018