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Updated: Jun 21, 2026

Screening of Axonal Degeneration in Carpal Tunnel Syndrome Using Ultrasonography and Nerve Conduction Studies
Published on: January 11, 2019
Relation of wrist angles to median nerve conduction studies
Ramon L Cuevas-Trisan1, Aileen G Ojeda-Rodriguez
1Physical Medicine & Rehabilitation Service, Veterans Affairs Medical and Regional Office Center Program, San Juan, Puerto Rico. ramon.cuevas-trisan@med.va.gov
Objectives:
To measure the changes in median nerve conduction parameters at various angles of wrist flexion and extension.
Design:
We studied 8 patients with carpal tunnel syndrome (CTS) and 4 subjects (5 hands) without the condition (controls). Conduction parameters were measured with the wrist in neutral position and at different wrist angles.
Results:
Onset motor latency increased in both groups with wrist extension and decreased with wrist flexion. Sensory onset latency decreased in both groups with wrist flexion. Compound Muscle Action Potential (CMAP) amplitude increased with wrist flexion for both groups. Wrist extension resulted in reduction of the CMAP amplitude in controls; however, for the CTS group it increased for the first 30 degrees and then decreased. Sensory Nerve Action Potential (SNAP) amplitude increased with wrist flexion and decreased with wrist extension in both groups.
Conclusion:
Median nerve conduction parameters improve with wrist flexion and generally worsen with extension.
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