Prevalence of denervation in the intrinsic foot muscles in patients with distal predominantly small fiber neuropathy

Muscle Nerve. 2020 May;61(5):595-599. doi: 10.1002/mus.26829. Epub 2020 Feb 24.

Abstract

Background: We aimed to evaluate the significance of electromyographic findings in the intrinsic foot muscles (IFMs) of patients with skin biopsy proven small fiber neuropathy (SFN).

Methods: This was a single-center retrospective analysis of patients who underwent skin biopsy for intra-epidermal nerve fiber density (IENFD) measurement and electrodiagnostic (EDX) study for evaluation of polyneuropathy.

Results: A total of 1416 patents with normal lower extremity EDX studies proximal to the foot were included. Active denervation was seen in 16.1% of IFMs in patients with skin biopsy proven SFN and 4.1% of patients without SFN (P < .0001). Reinnervation changes without active denervation were observed in 30.4% of SFN patients and 23.8% of patients without SFN (P = .01). IENFD was lower in SFN patients with active denervation in IFMs than without (P < .0001).

Conclusions: Evaluation of active denervation in the IFMs can reveal large fiber dysfunction in SFN patients with otherwise normal routine EDX findings.

Keywords: denervation; electromyography; intra-epidermal nerve fiber density; large fiber neuropathy; skin biopsy; small fiber neuropathy.

MeSH terms

  • Action Potentials
  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Electrodiagnosis
  • Electromyography
  • Epidermis / pathology
  • Female
  • Foot / innervation*
  • Foot / physiopathology
  • Humans
  • Male
  • Middle Aged
  • Muscle, Skeletal / innervation*
  • Muscle, Skeletal / physiopathology
  • Nerve Fibers / pathology
  • Neural Conduction / physiology*
  • Retrospective Studies
  • Small Fiber Neuropathy / pathology
  • Small Fiber Neuropathy / physiopathology*
  • Sural Nerve / physiopathology*
  • Thigh
  • Young Adult