Sural sensory nerve action potential, epidermal nerve fiber density, and quantitative sudomotor axon reflex in the healthy elderly

Muscle Nerve. 2014 Apr;49(4):564-9. doi: 10.1002/mus.23971. Epub 2014 Jan 27.


Introduction: Polyneuropathy evaluation in older patients is often challenging due to conflicting data regarding normative values for peripheral nerve testing.

Methods: We characterized the results of sural nerve conduction studies, intraepidermal nerve fiber density (IENFD), and quantitative sudomotor axon reflex testing (QSART) in a prospective study of 50 healthy subjects aged ≥60 years.

Results: Of the 50 subjects, 48 (96%) had an obtainable sural sensory nerve action potential (SNAP). Using quantile regression, we estimated the lower limit of normal (LLN) for sural amplitudes to be 3 μV for patients 60-70 years, 1 μV for those 70-74 years, and <1 μV (absent) for those ≥75 years of age. IENFD and QSART volume were reduced with advancing age, although IENFD was lower in men and QSART volume was lower in women.

Conclusions: We propose that an absent sural SNAP in patients up to 75 years of age should be considered abnormal. Our findings also support age- and gender-stratified normative data for IENFD and QSART.

Keywords: IENFD; QSART; SNAP; healthy elderly; normative values; sural nerve.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials / physiology*
  • Aged
  • Aged, 80 and over
  • Axons / physiology*
  • Cohort Studies
  • Electromyography / methods
  • Epidermis / innervation*
  • Epidermis / physiology*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Nerve Fibers / physiology
  • Prospective Studies
  • Reflex / physiology*
  • Sural Nerve / physiology*