temporal dispersion
Broadening and distortion of CMAP waveform due to differential slowing of individual nerve fibers.
Full Definition
Temporal dispersion refers to the abnormal broadening and morphologic distortion of the compound muscle action potential waveform that occurs when individual nerve fibers conduct at markedly different velocities. This phenomenon is typically seen in demyelinating conditions where some fibers are more severely affected than others. Unlike conduction block, temporal dispersion maintains total area under the curve while significantly increasing duration and creating a polyphasic, dispersed appearance. It indicates non-uniform slowing of conduction within the nerve.
Usage
Usage note: Quantify by measuring duration increase and describe morphologic changes.
In Context
- "Marked temporal dispersion of the CMAP suggested a demyelinating process affecting multiple fascicles." — Electrodiagnostic report
- "The presence of temporal dispersion without significant amplitude reduction favored demyelination over axonal loss." — NCS interpretation