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An Unusual Case of Median Neuropathy

Application of Short Segmental Sensory Nerve Stimulation

Luetmer, Marianne T.*; Laughlin, Ruple S.

Journal of Clinical Neurophysiology: November 2019 - Volume 36 - Issue 6 - p 468–470
doi: 10.1097/WNP.0000000000000616
Case Report

Summary: A 55-year-old woman presented with an 18-month history of intermittent left-hand paresthesias affecting her first, second, and third digits. A small, immobile, nontender midline mass on the volar aspect of the left wrist was also present. Evaluation included normal routine nerve conduction studies and needle electromyography. An ultrasound was performed in the electromyography laboratory, verifying median nerve involvement of the mass within the proximal carpal tunnel. This finding guided the electromyographer to perform the unconventional technique of sensory nerve short segmental stimulation across the carpal tunnel, which confirmed focal slowing across the lesion, achieving electrodiagnostic confirmation of median nerve impairment. This case of atypical carpal tunnel syndrome due to a median nerve schwannoma demonstrates both the utility and specificity of short segmental sensory stimulation in some cases of median neuropathy at the wrist and the value of sonography in the electromyography laboratory.

Departments of *Physical Medicine and Rehabilitation and

Neurology, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, U.S.A.

Address correspondence and reprint requests to Ruple S. Laughlin, MD, Department of Neurology, Clinic College of Medicine and Science, 200 1st St SW, Rochester, MN 55905, U.S.A.; e-mail:

The authors have no funding or conflicts of interest to disclose.

© 2019 by the American Clinical Neurophysiology Society