{"title":"Diaphragmatic Compound Muscle Action Potentials Correlate With the Clinical Severity of Myasthenia Gravis.","authors":"Hirotomo Suehiro, Kenji Sekiguchi, Yoshikatsu Noda, Shun Matoba, Shunsuke Watanabe, Masahiro Hayashi, Masaaki Yoshikawa, Ryosuke Sugisawa, Riki Matsumoto","doi":"10.1002/mus.28397","DOIUrl":null,"url":null,"abstract":"<p><strong>Introduction/aims: </strong>Patients with myasthenia gravis (MG) often experience impairment of respiratory function. Some case reports have explored the diaphragmatic compound muscle action potential (DCMAP) amplitudes in patients with MG using single-stimulus phrenic nerve conduction studies. Herein, we aimed to investigate whether the DCMAP amplitude correlated with the clinical severity of MG and whether this improved with treatment.</p><p><strong>Methods: </strong>We retrospectively evaluated patients with MG who underwent right phrenic nerve conduction studies. We evaluated the patients' clinical characteristics and the clinical severity of MG, as assessed by compound muscle action potential (CMAP) amplitudes, and compared the CMAP amplitudes before and after treatment in patients with generalized MG (gMG).</p><p><strong>Results: </strong>This study included 76 patients with MG (30 with ocular MG [OMG] and 46 with gMG). The median DCMAP amplitudes were significantly higher in OMG than in gMG (364 vs. 212 μV, p < 0.01). Receiver operating characteristic analysis showed that DCMAP amplitude < 256 μV distinguished gMG from OMG with 71.7% sensitivity and 93.3% specificity. The DCMAP amplitudes were moderately correlated with the MG activities of daily living score (p < 0.01, r = -0.52) and quantitative myasthenia gravis score (p < 0.01, r = -0.60). Median DCMAP amplitudes significantly increased in patients with gMG after treatment (from 184 to 336 μV, p < 0.01).</p><p><strong>Discussion: </strong>DCMAP amplitudes may correlate with the clinical severity of MG, differentiate gMG from OMG, and reflect the treatment response. We propose that DCMAP measurement be included in the evaluation of patients with MG.</p>","PeriodicalId":18968,"journal":{"name":"Muscle & Nerve","volume":" ","pages":"1043-1051"},"PeriodicalIF":2.8000,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Muscle & Nerve","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1002/mus.28397","RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2025/3/19 0:00:00","PubModel":"Epub","JCR":"Q2","JCRName":"CLINICAL NEUROLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Introduction/aims: Patients with myasthenia gravis (MG) often experience impairment of respiratory function. Some case reports have explored the diaphragmatic compound muscle action potential (DCMAP) amplitudes in patients with MG using single-stimulus phrenic nerve conduction studies. Herein, we aimed to investigate whether the DCMAP amplitude correlated with the clinical severity of MG and whether this improved with treatment.
Methods: We retrospectively evaluated patients with MG who underwent right phrenic nerve conduction studies. We evaluated the patients' clinical characteristics and the clinical severity of MG, as assessed by compound muscle action potential (CMAP) amplitudes, and compared the CMAP amplitudes before and after treatment in patients with generalized MG (gMG).
Results: This study included 76 patients with MG (30 with ocular MG [OMG] and 46 with gMG). The median DCMAP amplitudes were significantly higher in OMG than in gMG (364 vs. 212 μV, p < 0.01). Receiver operating characteristic analysis showed that DCMAP amplitude < 256 μV distinguished gMG from OMG with 71.7% sensitivity and 93.3% specificity. The DCMAP amplitudes were moderately correlated with the MG activities of daily living score (p < 0.01, r = -0.52) and quantitative myasthenia gravis score (p < 0.01, r = -0.60). Median DCMAP amplitudes significantly increased in patients with gMG after treatment (from 184 to 336 μV, p < 0.01).
Discussion: DCMAP amplitudes may correlate with the clinical severity of MG, differentiate gMG from OMG, and reflect the treatment response. We propose that DCMAP measurement be included in the evaluation of patients with MG.
期刊介绍:
Muscle & Nerve is an international and interdisciplinary publication of original contributions, in both health and disease, concerning studies of the muscle, the neuromuscular junction, the peripheral motor, sensory and autonomic neurons, and the central nervous system where the behavior of the peripheral nervous system is clarified. Appearing monthly, Muscle & Nerve publishes clinical studies and clinically relevant research reports in the fields of anatomy, biochemistry, cell biology, electrophysiology and electrodiagnosis, epidemiology, genetics, immunology, pathology, pharmacology, physiology, toxicology, and virology. The Journal welcomes articles and reports on basic clinical electrophysiology and electrodiagnosis. We expedite some papers dealing with timely topics to keep up with the fast-moving pace of science, based on the referees'' recommendation.