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Muscular consequences

Recently, abnormal lactate responses to exercise in patients with chronic fatigue syndrome (CFS) were correlated with the detection and characterization of enterovirus sequences in skeletal muscle, using the same techniques successfully used to demonstrate such sequences in the heart muscle. Enteroviral RNA was detected in 10 of 48 muscle biopsies (20.8%) of CFS patients, but not in 29 control tissue samples from normal subjects or patients with a variety of muscle diseases, demonstrating that the presence of enterovirus sequences in muscle is not typical of the general population. An abnormal lactate response to exercise occurred nine times more commonly in CFS patients with enterovirus sequences in muscle than in enterovirus-negative cases. PCRs were more closely related to Coxsackie B virus but were not made for herpesvirus. It may be that the remaining CFS patients with muscle problems gave positive PCR in muscle samples to other viruses that were not done in this study. Hence, CFS is heterogeneous depending on the infection that caused it in each patient.1

The EBV virus has also been related to dermatomyositis/polymyositis. The results of Der-Yuan Chen’s study showed a positive association of Epstein-Barr virus (EBV) with dermatomyositis/polymyositis and nasopharyngeal carcinoma. Patients with dermatomyositis or poliomyositis who have anti-EBNA-1 IgA positive or increased EBV DNA loads should be highly suspicious of occult nasopharyngeal carcinoma. However, other diagnostic markers that include antibodies against early antigen (EA) may provide additional data to serological tests to detect the presence of nasopharyngeal carcinoma.2

This association allows us to think that performing a muscle biopsy to determine the presence of dermatomyositis or polymyositis, together with a PCR to EBV in this tissue could help in the diagnosis, in case the pathogen causing CFS was this virus and had muscle problems.


  1. Lane R, Soteriou B, Zhang H, Archard L. Enterovirus related metabolic myopathy: a postviral fatigue syndrome.Journal of Neurology, Neurosurgery, and Psychiatry. 2003;74(10):1382-1386. Available in:
  2. Chen D.Y., Chen Y.M., LanJ.L., et al. Polymyositis/dermatomyositis and nasopharyngeal carcinoma: the Epstein-Barr virus connection?. J. Clin Virol. 20110 Dec; 49(4):290-5. Available in: