Foundations · Core

Separate axonal and myelin features

Axonal loss vs demyelination

Interpret low amplitude and slowing within the complete pattern.

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

01Axonal features

  • Reduced SNAP or CMAP amplitude may support axonal loss after technique and other causes are considered.
  • Loss of the fastest fibers can also cause some slowing; slow conduction does not automatically mean demyelination.

02Demyelinating features

  • Disproportionate slowing, prolonged distal or late responses, or qualifying conduction block and dispersion may provide clues.
  • Assess multiple nerves and segments outside usual compression sites using disease-specific criteria.

03Mixed patterns and limitations

  • Chronic demyelination may cause secondary axonal loss.
  • Consider cold, very low CMAPs, focal compression and hereditary patterns of uniform slowing.

Pause and explain

Explain in your own words: “Describe the distribution and parameters before assigning a pathological pattern.” Then think of a situation in which it could be misinterpreted.

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Mild slowing in one nerve is not enough to diagnose CIDP.

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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.