Possible involvement of the autonomic nervous system in cervical muscles of patients with myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS)

BACKGROUND: Patients with myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS) sometimes present with stiffness of the cervical muscles. To investigate the pathophysiology of ME/CFS, this observational study compared patients with versus without recovery from ME/CFS through local modulation of the cervical muscles. METHODS: Over a period of 11 years, a total of 1226 inpatients with ME/CFS who did not respond to outpatient care were enrolled in this study. All patients received daily cervical muscle physical therapy during hospitalization. Self-rated records documenting the presence or absence of ME/CFS, as well as the representative eight symptoms that frequently accompany it at admission and discharge, were compared. Pupil diameter was also measured to examine autonomic nervous system function involvement. RESULTS: The recovery rate of ME/CFS after local therapy was 55.5%, and did not differ significantly by sex, age strata, and hospitalization period. The recovery rates of the eight symptoms were variable (36.6-86.9%); however, those of ME/CFS in the symptom subpopulations were similar (52.3-55.8%). The recovery rates of all symptoms showed strong associations with that of ME/CFS (p < 0.001). The pupil diameter was more constricted in the ME/CFS-recovered patients than in the ME/CFS-unrecovered patients in the total population and the subpopulations stratified by sex, age, and hospitalization period. CONCLUSIONS: There was a strong association between the recovery of ME/CFS and other related whole-body symptoms. The recovery of ME/CFS may be partly linked to amelioration of the autonomic nervous system in the cervical muscles. TRIAL REGISTRATION: UMIN000036634 . Registered 1 May 2019 - Retrospectively registered.