Foundations · Core

Understand the time course of injury

Timing & reinnervation

EDX is a snapshot of an evolving process. Early preserved responses do not exclude injury.

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

01Early after injury

  • Distal responses may temporarily persist after an axonal lesion until distal degeneration develops.
  • Reduced recruitment may precede typical denervation activity.

02Weeks and beyond

  • The onset of spontaneous activity depends on lesion location, severity, distance and muscle.
  • Reinnervation changes MUAPs and recruitment, but an individual waveform is not an exact clock.

03Plan follow-up

  • If early findings conflict with the clinical picture, use the specific question and time course to decide on repeat testing.
  • Describe active denervation or chronic reinnervation evidence without overestimating the precision of injury dating.

Pause and explain

Explain in your own words: “Time since onset is part of the data you interpret.” Then think of a situation in which it could be misinterpreted.

Show a review prompt

The claim that every patient must wait three weeks for useful testing is an oversimplification.

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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.