pathogenesis of peripheral nerve diseases

Last reviewed 12/2022

Two pathological processes predominate in diseases of peripheral nerves:

  • axonal degeneration:
    • severely damaged axons degenerate distally
    • within a week the nerve becomes electrically inert
    • muscle fibres supplied by damaged motor nerves atrophy
    • EMG records show fibrillation potentials
    • axons may regrow at about 1 mm/day
    • undamaged motor fibres sprout to supply more muscle fibres

  • demyelination:
    • demyelination of peripheral nerve fibres initially leaves the axon intact
    • the result is blockage or slowing of conduction
    • pressure or entrapment neuropathies are primarily caused by demyelination
    • inflammatory processes e.g. Guillan-Barre are caused by demyelination