title: Axonal dysfunction, dysmyelination, and conduction failure in hereditary neuropathy with liability to pressure palsies.
abstract: BACKGROUND
  Patients with hereditary neuropathy with liability to pressure palsies (HNPP) manifest with episodes of focal paresis when exposed to mechanical stress, although the basis for vulnerability to conduction block remains relatively unexplained.
  
  
  METHODS
  Axonal excitability techniques were utilized to provide insights into pathophysiological mechanisms in 13 HNPP patients, stimulating median motor and sensory axons at the wrist.
  
  
  RESULTS
  In HNPP, distal latencies were prolonged, and motor and sensory amplitudes were reduced. Threshold was increased. Depolarizing and hyperpolarizing electrotonus was greater, and resting current-threshold slope was reduced. There were greater threshold changes in superexcitability, and refractoriness was decreased.
  
  
  CONCLUSIONS
  Taken together, excitability testing in patients with HNPP established axonal hyperpolarization in both motor and sensory axons that may be attributable to changes in nerve architecture. In turn, the hyperpolarized resting membrane potential in HNPP may be a major predisposing factor for development of conduction block with mechanical stresses.
authors.affiliation: Neuroscience Research Australia, Sydney, Australia; Department of Neurology, Sydney Children's Hospital, School of Women's and Children's Health, University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Farrar
authors.forename: Susanna B
authors.initials: SB
authors.lastname: Park
authors.forename: Arun V
authors.initials: AV
authors.lastname: Krishnan
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Kiernan
authors.forename: Cindy S-Y
authors.initials: CS
authors.lastname: Lin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001176:Arthrogryposis / Q000503:physiopathology*; D001369:Axons / Q000502:physiology*; D016022:Case-Control Studies; D002648:Child; D003711:Demyelinating Diseases / Q000503:physiopathology*; D004558:Electric Stimulation; D005260:Female; D015417:Hereditary Sensory and Motor Neuropathy / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology*; D010641:Phenotype; D011930:Reaction Time / Q000502:physiology; D013314:Stress, Mechanical; D014955:Wrist Joint / Q000294:innervation; D055815:Young Adult
keywords: axon; conduction block; demyelination; excitability; hereditary neuropathy