title: Nerve compression, membrane excitability, and symptoms of carpal tunnel syndrome.
abstract: BACKGROUND
  In this study we investigated the changes in axonal excitability and the generation of neurological symptoms in response to focal nerve compression (FNC) of the median nerve in carpal tunnel syndrome (CTS).
  
  
  METHODS
  Sensory excitability recordings were undertaken in 11 CTS patients with FNC being applied at the wrist using a custom-designed electrode.
  
  
  RESULTS
  During FNC, refractoriness increased significantly (62.4 ± 3.4%; P < 0.001), associated with a rapid reduction in superexcitability (16.9 ± 2.8%; P < 0.001) and sensory nerve action potential amplitude (SNAP) (32.4 ± 3.9%; P < 0.001), consistent with axonal depolarization. Associated with these changes, paresthesiae steadily increased throughout FNC, as did numbness. Reductions in SNAP amplitude and superexcitability developed more rapidly for CTS patients during FNC compared with controls, and these changes were associated with more marked symptoms.
  
  
  CONCLUSIONS
  Axonal responses to compression are impaired in CTS. This may suggest a greater reliance on axonal membrane Na(+) /K(+) -ATPase function.
authors: Neuroscience Research Australia & Prince of Wales Clinical School, University of New South Wales, Barker Street, Randwick, New South Wales 2031, Australia.
authors: S Eric
authors: SE
authors: Han
authors: Cindy S-Y
authors: CS
authors: Lin
authors: Robert A
authors: RA
authors: Boland
authors: Matthew C
authors: MC
authors: Kiernan
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000368:Aged; D002349:Carpal Tunnel Syndrome / Q000503:physiopathology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology*; D008564:Membrane Potentials / Q000502:physiology*; D008875:Middle Aged; D009408:Nerve Compression Syndromes / Q000503:physiopathology*; D009431:Neural Conduction / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D011984:Sensory Receptor Cells / Q000502:physiology; D000254:Sodium-Potassium-Exchanging ATPase / Q000502:physiology
chemical_list: D000254:Sodium-Potassium-Exchanging ATPase