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Sensory nerve excitability and neuropathy in end stage kidney disease
  1. A V Krishnan1,
  2. R K S Phoon2,
  3. B A Pussell2,
  4. J A Charlesworth2,
  5. M C Kiernan1
  1. 1Prince of Wales Medical Research Institute and Prince of Wales Clinical School, University of New South Wales, Sydney, Australia
  2. 2Department of Nephrology, Prince of Wales Hospital
  1. Correspondence to:
 Dr Matthew Kiernan
 Prince of Wales Medical Research Institute, Barker Street, Randwick, Sydney, NSW 2031, Australia; M.kiernan{at}unsw.edu.au

Abstract

Background: Peripheral neuropathy is present in 65% of patients with end stage kidney disease (ESKD) starting dialysis. Studies of membrane potential and axonal ion channel function may help explain the pathophysiology.

Objectives: To follow changes in median sensory axon excitability in patients with ESKD treated with haemodialysis, and correlate them with clinical rating scales and serum levels of potential neurotoxins.

Methods: Sensory nerve action potentials were recorded from the second digit following stimulation of the median nerve in 12 ESKD patients. Stimulus–response behaviour using two stimulus durations, threshold electrotonus to 100 ms polarising currents, a current–threshold relation, and recovery of excitability following supramaximal stimulation were recorded before, during, and after haemodialysis. Serum concentrations of potential neurotoxins were measured.

Results: Before dialysis, there were changes in nerve excitability consistent with axonal depolarisation: refractoriness was increased; superexcitability and depolarising threshold electrotonus were reduced. Following dialysis there were improvements in all indices, with correlations between excitability abnormalities and serum potassium measurements. Neuropathic symptoms correlated with excitability changes.

Conclusions: Nerves are depolarised before haemodialysis in ESKD patients. The correlation of excitability abnormalities with potassium indicates that the achievement of normokalaemia should be a priority in treating such patients.

  • ESKD, end stage kidney disease
  • Kt/V, ratio of clearance of urea to distribution volume
  • NCS, nerve conduction study
  • NSS, neuropathy symptom score
  • RRP, relative refractory period
  • SNAP, sensory nerve action potential
  • TEd, depolarising threshold electrotonus
  • TEh, hyperpolarising threshold electrotonus
  • T-NSS, total neuropathy symptom score
  • membrane potential
  • nerve excitability
  • threshold electrotonus
  • uraemic neuropathy

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Footnotes

  • Competing interests: none declared

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