Nishikai, M · Nihon rinsho. Japanese journal of clinical medicine · 1992
This study examined 51 patients with ME/CFS to look for physical and immune system clues about the illness. Researchers found that most patients had tender points similar to those seen in fibromyalgia, elevated antibodies to Epstein-Barr virus (a common virus), and lower numbers of certain immune cells called NK cells. These findings suggest that viral infections and immune system problems may play a role in ME/CFS.
This study provides early evidence linking ME/CFS to specific immune abnormalities and past viral infection, supporting the biological basis of the illness rather than viewing it as purely psychological. Understanding these immune markers could eventually help with diagnosis and guide treatment approaches targeting viral or immune dysfunction.
This study does not prove that Epstein-Barr virus or reduced NK cells directly cause ME/CFS—only that these abnormalities are associated with the condition. The cross-sectional design cannot establish whether these immune changes are primary drivers of illness or secondary consequences. The study also does not explain why some people with similar immune markers develop ME/CFS while others do not.
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
Nishikai, M (1992). [Chronic fatigue syndrome--study of 51 cases treated at the Second Tokyo National Hospital].. Nihon rinsho. Japanese journal of clinical medicine. https://pubmed.ncbi.nlm.nih.gov/1337560/
BibTeX
@article{mecfsatlas-nishikai-1992-chronic-fatigue,
author = {Nishikai, M},
title = {[Chronic fatigue syndrome--study of 51 cases treated at the Second Tokyo National Hospital].},
journal = {Nihon rinsho. Japanese journal of clinical medicine},
year = {1992},
note = {PubMed: 1337560},
url = {https://www.mecfsatlas.com/evidence/nishikai-1992-chronic-fatigue},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/nishikai-1992-chronic-fatigue
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