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Are the Sensory Fibers of the Ulnar Nerve Affected in Carpal Tunnel Syndrome?

Selek, Özgür*; Alemdar, Murat

Journal of Clinical Neurophysiology: November 2017 - Volume 34 - Issue 6 - p 502–507
doi: 10.1097/WNP.0000000000000410
Original Research

Purpose: Distribution of paresthesia throughout the skin area without median nerve innervation is frequently seen in carpal tunnel syndrome (CTS). However, its pathophysiologic mechanisms are still unclear. We aimed to research whether a dysfunction in sensory fibers of the ulnar nerve (UN) was present or not in hands with CTS.

Methods: Totally, upper extremity nerve conduction study recordings of 508 patients were considered. After exclusions, 331 upper extremity recordings of 277 patients were included. We compared the results of sensory conduction studies of median nerve and UN between normal hands and hands with CTS.

Results: The mean distal sensory latency of the median nerve was longer, the mean conduction velocity was slower, and mean nerve action potential amplitude was higher in the hands with CTS than in normal hands (P < 0.001 for all comparisons). There was no statistically significant difference on any sensory conduction parameters of UN recorded on digit IV or digit V between the disease and control groups (P > 0.05 for all comparisons). The rates of conduction abnormalities of the UN sensory fibers were also similar in hands with CTS and in normal hands (P > 0.05 for all comparisons).

Conclusions: The hands with CTS do not have an increased rate of conduction abnormalities of UN sensory fibers compared with the normal hands in our study population. Therefore, our study did not confirm the distortion of UN sensory fibers as a mechanism underlying the spread of paresthesia throughout the skin area without median nerve innervation in CTS.

*Department of Orthopaedic Surgery, Faculty of Medicine, Kocaeli University, Kocaeli, Turkey; and

Sakarya University Education and Research Hospital, Neurology Clinic, Sakarya, Turkey.

Address correspondence and reprint requests to Murat Alemdar, MD, Sakarya University Education and Research Hospital, Adnan Menderes c., Saglik s., No: 195, Sakarya, Turkey; e-mail:

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

© 2017 by the American Clinical Neurophysiology Society