6533b7dcfe1ef96bd1271d17

RESEARCH PRODUCT

Electrophysiology of sensory neuropathies

subject

description

In sensory neuropathy maximal conduction velocity is a crude measure. Variations up to 10 m/s have to be considered normal. The relation to clinical impairment is poor in either axonal/neuronal lesions or demyelination as indicated by a small normal latency and a delayed broad polyphasic nerve action potential (NAP), respectively. Conduction block evaluated on NAP changes has not yet been established. Mild disorder of impulse conduction may be disclosed by evaluating a) conduction along long nerve segments studying the H-reflex or SSEP, b) late components of the averaged NAP which make > 10% of the main deflection, c) velocities of slow conducting fibers utilizing the collision technique or single motor unit excitation, or d) the relative refractory period following a test stimulus. Conduction studies of small fibers mediating slow pain, sudomotor or vasomotor activity need intrafascicular microelectrode recordings and are not yet applied as a routine diagnostic test.