Nerve conduction · Advanced
Repetitive stimulation and the NMJ
Repetitive nerve stimulation
A stable baseline CMAP is essential before interpreting decrement or increment.
01Low-frequency stimulation
- Low-frequency trains assess reproducible changes in CMAP amplitude or area.
- Specify which later response and which parameter are compared with the first response.
02Postsynaptic and presynaptic patterns
- MG may show decrement. LEMS often has a low baseline CMAP with marked facilitation after brief exercise.
- Sensitivity depends on muscle, phenotype and technique; normal RNS does not exclude NMJ disease.
03Quality control
- Stabilize the limb, electrodes and stimulation site; confirm supramaximal stimulation and adequate warming.
- Medication and exercise affect results. Any medication withholding must be directed by the clinical team.
Related nerves
Pause and explain
Explain in your own words: “A decrement must be reproducible and free from movement or stimulation artifact.” Then think of a situation in which it could be misinterpreted.
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One percentage does not automatically diagnose MG or LEMS.
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References and further reading
- Electrodiagnostic Studies in Neuromuscular Junction Disorders ↗AAPM&R KnowledgeNow · Society educational review · Link accessed 2026-09-08
Educational synthesis; independent neuromuscular specialist review is pending. Publication dates and compilation dates are distinct. This is an original teaching synthesis; consult the source for complete methods and criteria.