conduction block
Focal failure of nerve impulse transmission along an axon segment, demonstrated by amplitude reduction between proximal and distal stimulation sites.
Full Definition
Conduction block is a focal impairment of nerve impulse propagation that occurs when the nerve remains structurally intact but loses its ability to conduct action potentials across a specific segment. It is diagnosed when the compound action potential amplitude recorded from proximal stimulation is significantly reduced compared to distal stimulation (>20% for motor nerves, >50% for sensory nerves). Conduction block is characteristic of demyelinating neuropathies and focal compression injuries. Unlike axonal degeneration, conduction block is potentially reversible with appropriate treatment.
Usage
Usage note: Must specify percentage of amplitude reduction and anatomical location.
In Context
- "Conduction block was demonstrated in the median nerve across the carpal tunnel with a 65% amplitude drop between wrist and palm stimulation." — Nerve conduction study interpretation