Axonal channelopathies: an evolving concept in the pathogenesis of peripheral nerve disorders.

Abnormalities of peripheral nerve Na+ and K+ channels result in clinical manifestations unrelated to axonal degeneration or demyelination. Na+ channel blockade causes weakness and sensory loss associated with slowed conduction and decreased motor and sensory action potential amplitudes. K+ channel abnormalities result in high frequency repetitive action potentials (e.g., myokymia). Ion channel abnormalities may also play an important role in electrophysiologic changes seen in demyelinating disorders.