Clinical Significance of Repetitive Compound Muscle Action Potentials in Patients with Myasthenia Gravis: A Predictor for Cholinergic Side Effects of Acetylcholinesterase Inhibitors.
10.3988/jcn.2016.12.4.482
- Author:
Hyo Eun LEE
1
;
Yool Hee KIM
;
Seung Min KIM
;
Ha Young SHIN
Author Information
1. Department of Neurology, Keimyung University Kyungju Dongsan Hospital, Gyeongju, Korea.
- Publication Type:Original Article
- Keywords:
myasthenia gravis;
acetylcholinesterase inhibitor;
repetitive compound muscle action potential
- MeSH:
Acetylcholinesterase*;
Action Potentials*;
Americas;
Cholinesterase Inhibitors*;
Humans;
Hypersensitivity;
Immunotherapy;
Myasthenia Gravis*;
Neostigmine;
Pyridostigmine Bromide;
Retrospective Studies
- From:Journal of Clinical Neurology
2016;12(4):482-488
- CountryRepublic of Korea
- Language:English
-
Abstract:
BACKGROUND AND PURPOSE: Acetylcholinesterase inhibitors (AChEIs) are widely used to treat myasthenia gravis (MG). Although AChEIs are usually tolerated well, some MG patients suffer from side effects. Furthermore, a small proportion of MG patients show cholinergic hypersensitivity and cannot tolerate AChEIs. Because repetitive compound muscle action potentials (R-CMAPs) are an electrophysiologic feature of cholinergic neuromuscular hyperactivity, we investigated the clinical characteristics of MG patients with R-CMAPs to identify their clinical usefulness in therapeutic decision-making. METHODS: We retrospectively reviewed the clinical records and electrodiagnostic findings of MG patients who underwent electrodiagnostic studies and diagnostic neostigmine testing (NT). RESULTS: Among 71 MG patients, 9 could not tolerate oral pyridostigmine bromide (PB) and 17 experienced side effects of PB. R-CMAPs developed in 24 patients after NT. The highest daily dose of PB was lower in the patients with R-CMAPs (240 mg/day vs. 480 mg/day, p<0.001). The frequencies of PB intolerance and side effects were higher in the patients with R-CMAPs than in those without R-CMAPs [37.5% vs. 0% (p<0.001) and 45.8% vs. 12.8% (p=0.002), respectively]. The MG Foundation of America postintervention status did not differ significantly between MG patients with and without R-CMAPs, and the response to immunotherapy was also good in both groups. CONCLUSIONS: Side effects of and intolerance to AChEIs are more common in MG patients with R-CMAPs than in those without R-CMAPs. AChEIs should be used carefully in MG patients with R-CMAPs. The presence of R-CMAPs after NT may be a good indicator of the risks of PB side effects and intolerance.
