Nerve conduction · Advanced

Jitter and single-fiber EMG

Jitter & single-fiber EMG

High sensitivity does not imply disease specificity.

3 learning sectionsCompiled 2026-09-08English edition · Traditional Chinese available

01What is measured

  • Jitter describes variation in timing between related muscle-fiber responses. Blocking indicates intermittent transmission failure.
  • Voluntary versus stimulated methods and single-fiber versus concentric-needle recordings have distinct quality and reference requirements.

02Clinical meaning

  • Increased jitter may support impaired transmission, but can also occur during reinnervation.
  • Select an appropriate muscle and technique while understanding the routine NCS/EMG background.

03Reporting

  • State the recording method, muscle, qualified signal count and method-matched limits.
  • Ordinary MUAP instability is not equivalent to a formal SFEMG result.

Pause and explain

Explain in your own words: “SFEMG sensitivity and specificity answer different questions.” Then think of a situation in which it could be misinterpreted.

Show a review prompt

Abnormal jitter does not identify a particular MG antibody subtype.

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References and further reading

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.