CMAP
Also written as: CMAP — Compound Muscle Action Potential
The summed electrical response of multiple muscle fibers recorded during nerve conduction studies, representing motor nerve function.
Full Definition
CMAP (Compound Muscle Action Potential) is the electrical response recorded from a muscle when its motor nerve is stimulated during nerve conduction studies. The CMAP represents the summation of action potentials from multiple muscle fibers innervated by the stimulated nerve. Key parameters include amplitude (reflecting the number of functioning axons), latency (nerve conduction speed), and duration. Reduced CMAP amplitudes suggest axonal loss, while prolonged latencies indicate demyelination. Clinical editors should understand that CMAP measurements are fundamental to diagnosing peripheral neuropathies, myopathies, and neuromuscular junction disorders.
Usage
Usage note: Always capitalize as CMAP; distinguish from SNAP (sensory nerve action potential).
In Context
- "The median nerve CMAP showed reduced amplitude with normal latency." — Nerve conduction study report
- "Bilateral peroneal nerve CMAPs were absent, suggesting severe axonal loss." — Electrodiagnostic assessment