Kawamura, Yasuo, Kihara, Mikihiro, Nishimoto, Kazuhiro et al. · Pathophysiology : the official journal of the International Society for Pathophysiology · 2003 · DOI
This small study looked at three ME/CFS patients who had problems with both nerve-muscle communication and autonomic nervous system dysfunction (how the body regulates heart rate, sweating, and other automatic functions). All three patients improved significantly when given low doses of a medication called pyridostigmine, which helps acetylcholine (a chemical messenger in the nervous system) work better. The authors suggest that some ME/CFS fatigue might be caused by a combination of these two problems working together.
This study provides preliminary evidence that some ME/CFS symptoms may stem from objective physiological defects in neuromuscular and autonomic function—defects that may be treatable with existing medications. If validated in larger studies, this could identify a physiological subgroup of ME/CFS patients who might benefit from targeted pharmacological intervention, moving the field toward mechanism-based treatment strategies.
This case series does not prove that pyridostigmine is effective for ME/CFS broadly, nor that neuromuscular transmission defects cause CFS in the general population—only that these three patients showed the findings and responded to treatment. There is no control group to account for placebo effect, and the small sample size means results cannot be generalized. Correlation between these physiological findings and CFS symptoms does not establish causation.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Kawamura, Yasuo, Kihara, Mikihiro, Nishimoto, Kazuhiro, & Taki, Mayumi (2003). Efficacy of a half dose of oral pyridostigmine in the treatment of chronic fatigue syndrome: three case reports.. Pathophysiology : the official journal of the International Society for Pathophysiology. https://doi.org/10.1016/s0928-4680(03)00007-5
BibTeX
@article{mecfsatlas-kawamura-2003-efficacy-half,
author = {Kawamura, Yasuo and Kihara, Mikihiro and Nishimoto, Kazuhiro and Taki, Mayumi},
title = {Efficacy of a half dose of oral pyridostigmine in the treatment of chronic fatigue syndrome: three case reports.},
journal = {Pathophysiology : the official journal of the International Society for Pathophysiology},
year = {2003},
doi = {10.1016/s0928-4680(03)00007-5},
note = {PubMed: 14567934},
url = {https://www.mecfsatlas.com/evidence/kawamura-2003-efficacy-half},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-29. https://www.mecfsatlas.com/evidence/kawamura-2003-efficacy-half
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