Abnormality in the self-monitoring mechanism in patients with fibromyalgia and somatoform pain disorder

Psychosom Med. 2005 Jan-Feb;67(1):111-5. doi: 10.1097/01.psy.0000146327.73705.9c.

Abstract

Background: Auditory hallucinations and passivity experiences are associated with an abnormality in the self-monitoring mechanism that normally allows us to distinguish self-produced from externally produced sensations. It is unclear if chronic central pain disorders such as fibromyalgia and somatoform pain disorders also involve a defect of the self-monitoring mechanism.

Methods: Responses to tactile stimulation were assessed in four groups of subjects (N = 40): patients with fibromyalgia, patients with somatoform pain disorder, patients with schizophrenia with auditory hallucinations and/or passivity experiences, and normal control subjects. The subjects were asked to rate the perception of a tactile sensation on their left and right hands. The tactile stimulation was either self-produced by movement of the subject's right or left hand or externally produced by the experimenter.

Results: Normal control subjects experienced self-produced stimuli as less intense than identical, externally produced tactile stimuli. In contrast, patients with fibromyalgia, patients with somatoform pain disorder, and patients with schizophrenia with auditory hallucinations and/or passivity experiences gave the same perceptual ratings for tactile stimuli produced by themselves as those produced by the experimenter (intergroup difference, p = .043; 95% confidence interval [CI], 0.16-0.68). Post hoc tests revealed that this significance was mainly caused by the fibromyalgia (p = .046; 95% CI, -1.66-0.13) and the somatoform pain disorder group (p = .033; 95% CI, -1.71-0.06).

Conclusions: We conclude that central pain disorders such as fibromyalgia and somatoform pain disorders interfere with the correct functioning of the self-monitoring mechanism that normally allows us to distinguish self-produced from externally produced tactile stimuli.

Publication types

  • Comparative Study

MeSH terms

  • Acute Disease
  • Adult
  • Awareness / physiology*
  • Brief Psychiatric Rating Scale
  • Female
  • Fibromyalgia / diagnosis
  • Fibromyalgia / physiopathology*
  • Humans
  • Hyperalgesia / diagnosis
  • Hyperalgesia / physiopathology
  • Internal-External Control*
  • Male
  • Middle Aged
  • Pain Measurement / methods*
  • Pain Threshold / physiology*
  • Personality Inventory
  • Physical Stimulation
  • Schizophrenia / physiopathology
  • Somatoform Disorders / diagnosis
  • Somatoform Disorders / physiopathology*
  • Somatosensory Cortex / physiopathology
  • Touch / physiology*