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Brody myopathy demonstrates a pseudo‐increment on repetitive nerve stimulation
Author(s) -
Masingue Marion,
Arzel Marianne,
Sternberg Damien,
Stojkovic Tanya,
Behin Anthony,
Bassez Guillaume,
Vicart Savine,
Péréon Yann,
Magot Armelle,
Kuntzer Thierry,
Eymard Bruno,
Fournier Emmanuel
Publication year - 2020
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.26809
Subject(s) - myopathy , medicine , stimulation , neuroscience , physical medicine and rehabilitation , anatomy , psychology , pathology
Brody myopathy (BM) is a recessive condition caused by mutations in the ATP2A1 gene and usually induces impaired muscle relaxation during and after exercise. Diagnosis relies on needle electromyography showing electrical silence, muscle biopsy with decreased sarcoplasmic reticulum calcium adenosine triphosphatase activity, and genetic analysis. Electrodiagnostic functional analyses are useful in the diagnosis of channelopathies, and thus may be impaired in BM. Methods We performed exercise tests and repetitive nerve stimulation (RNS; 10 supramaximal stimuli at 3 Hz) in 10 patients with BM. Results All participants showed incremental responses on RNS. Compound muscle action potential amplitude was increased and duration was decreased, especially in the ulnar nerve (+30.2 ± 7.1% and − 30.3 ± 2.8%, respectively; both P < .001). Discussion Easily accessible, this sign, referred to as the Arzel sign, could prove to be a very useful tool in BM diagnosis and in broadening its phenotype.