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Updated: Jun 18, 2026

Screening of Axonal Degeneration in Carpal Tunnel Syndrome Using Ultrasonography and Nerve Conduction Studies
Published on: January 11, 2019
Ultrasonographic and functional changes of the ulnar nerve at Guyon's canal after carpal tunnel release
F Ginanneschi1, G Filippou, F Reale
1Department of Neurological, Neurosurgical and Behavioural Sciences, Clinical Neurophysiology Unit, University of Siena, Italy.
Objective:
To describe morphologic and functional modifications of the ulnar nerve at the wrist in carpal tunnel syndrome (CTS) after carpal tunnel release (CTR).
Methods:
Ultrasonography was used to study the cross sectional area (CSA) of the ulnar nerve at Guyon's canal, before and 1 and 6 months after CTR, in 18 CTS patients. A parallel electrophysiological and clinical analysis was also conducted.
Results:
CSA of the ulnar nerve significantly increased 6 months after CTR. Ten (55%) cases showed abnormal CSA values compared to a control group before surgery and five (28%) at 6 month follow-up. In addition, there were improvements in the motor and sensory ulnar axon recruitment properties and the conduction values in sensory ulnar fibres. Patients with extra-median distribution of paresthesia (4 subjects) were free from symptoms.
Conclusions:
CTR has a significant effect not only on the anatomical geometry of Guyon's canal, but also on the morphology and function of the ulnar nerve.
Significance:
In CTS, high pressure in the carpal tunnel may result in anatomical changes of ulnar nerve, thus causing functional impairment to the ulnar fibres. CTR appears to reverse some of this damage.
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