Clinical localization · Core
Localize median slowing at the wrist
Carpal tunnel syndrome
Use comparisons under the same hand conditions to identify focal median abnormalities.
01Initial studies
- Median sensory and APB motor studies are common starting points; assess at least one neighboring nerve.
- Add median–ulnar ring-finger, palmar mixed or median–radial thumb comparisons as indicated.
02Location and severity
- Comparative techniques require specified distance, cursors and laboratory limits.
- Absent responses or a low CMAP warrant assessment of axonal loss, technique and other neuropathies; sample APB when indicated.
03Report within the evidence
- EDX describes median neuropathy at the wrist; clinical carpal tunnel syndrome also requires symptoms and examination.
- Proximal median muscle abnormalities or thenar skin sensory loss prompt assessment beyond the tunnel.
Related nerves
Pause and explain
Explain in your own words: “Comparisons add information about focal localization.” Then think of a situation in which it could be misinterpreted.
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A negative Phalen sign or one normal NCS does not exclude every clinical possibility.
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References and further reading
- Median Mononeuropathies ↗AAPM&R KnowledgeNow · Society educational review · Link accessed 2026-09-08
- Upper and Lower Extremity Nerve Conduction Studies (2023) ↗AANEM · Technical course · 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.