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