Axonal hyperexcitability: Mechanisms and role in symptom production in demyelinating diseases

Kenneth J. Smith, Paul A. Felts, Raju Kapoor

Research output: Contribution to journalReview articlepeer-review

20 Citations (Scopus)


Some of the symptoms associated with demyelinating disorders are believed to originate from spurious impulses arising ectopically in axons at the site of demyelination. This review describes such "positive" symptoms and the patterns of impulses that may be associated with them, including continuous trains of impulses, as well as spontaneous and triggered impulse bursts. The mechanisms underlying the generation of such trains by individual axons are described, including the roles of sodium and potassium currents, the composition of the extracellular fluid, impulse "reflection" at demyelinated sites, and stretch-sensitive ion channels. The contribution of ephaptic transmission to symptom production and its potential role in the generation of ectopic impulses are discussed. The factors involved in the generation of massed discharges are also examined as a basis for certain paroxysmal clinical phenomena.

Original languageEnglish
Pages (from-to)237-246
Number of pages10
Issue number4
Publication statusPublished - 1 Jul 1997


  • Axons
  • Demyelinating diseases
  • Ectopic action potentials
  • Ephaptic transmission
  • Potassium channels
  • Sodium channels

ASJC Scopus subject areas

  • General Neuroscience
  • Clinical Neurology


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