compound motor action potential
Also written as: CMAP — compound motor action potential
The summated electrical response of muscle fibers to stimulation of their motor nerve, recorded in nerve conduction studies.
Full Definition
The compound motor action potential (CMAP) represents the algebraic summation of individual muscle fiber action potentials following electrical stimulation of the motor nerve. This biphasic or triphasic waveform is routinely recorded during nerve conduction studies and provides crucial information about the integrity of motor axons and their target muscle fibers. CMAP parameters include amplitude (reflecting the number of functioning motor units), latency (indicating nerve conduction velocity), and duration (suggesting temporal dispersion). Reduced amplitude may indicate axonal loss, while prolonged latency suggests demyelination. The CMAP is fundamental to electrodiagnostic assessment of neuromuscular disorders.
Usage
Usage note: CMAP is the preferred acronym in clinical documentation.
In Context
- "The reduced CMAP amplitude indicated significant motor axonal loss." — Electromyography report
- "Compound motor action potentials were recorded from multiple muscles to assess nerve function." — Electrodiagnostic study protocol