Small nerve fiber involvement in patients referred for fibromyalgia

Muscle Nerve. 2014 May;49(5):757-9. doi: 10.1002/mus.24156. Epub 2014 Jan 28.


Introduction: Fibromyalgia (FM) is a chronic syndrome characterized by widespread pain often accompanied by other symptoms suggestive of neuropathic pain. We evaluated patients for small fiber neuropathy (SFN) who were referred for fibromyalgia (FM).

Methods: We studied 20 consecutive subjects with primary FM. Patients underwent neurological examination, nerve conduction studies, and skin biopsies from distal leg and thigh.

Results: Electrodiagnostic studies were normal in all patients. SFN was diagnosed in 6 patients by reduced epidermal nerve fiber density. These patients also showed abnormalities of both adrenergic and cholinergic fibers.

Conclusions: A subset of FM subjects have SFN, which may contribute to their sensory and autonomic symptoms. Skin biopsy should be considered in the diagnostic work-up of FM.

Keywords: autonomic dysfunction; fibromyalgia; neuropathic pain; skin biopsy; small fiber neuropathy.

MeSH terms

  • Adrenergic Neurons / pathology*
  • Adult
  • Biopsy
  • Cholinergic Neurons / pathology*
  • Cohort Studies
  • Electrodiagnosis*
  • Erythromelalgia / complications
  • Erythromelalgia / pathology*
  • Erythromelalgia / physiopathology
  • Female
  • Fibromyalgia / complications
  • Fibromyalgia / pathology*
  • Fibromyalgia / physiopathology
  • Humans
  • Leg / innervation
  • Male
  • Middle Aged
  • Nerve Fibers / pathology*
  • Neural Conduction / physiology
  • Neurologic Examination
  • Skin / innervation
  • Skin / pathology*