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ORIGINAL RESEARCH article

Front. Neurol.
Sec. Neuromuscular Disorders and Peripheral Neuropathies
Volume 15 - 2024 | doi: 10.3389/fneur.2024.1468813

Proximal Median Nerve Neuropathy: Electrodiagnostic and Ultrasound Findings in 62 Patients

Provisionally accepted
Lisa B.E. Shields Lisa B.E. Shields 1*Vasudeva Iyer Vasudeva Iyer 2Yi Ping Zhang Yi Ping Zhang 1Christopher B. Shields Christopher B. Shields 3
  • 1 Norton Healthcare, Louisville, Kentucky, United States
  • 2 Neurodiagnostic Center of Louisville, Louisville, Colorado, United States
  • 3 Other

The final, formatted version of the article will be published soon.

    Objectives: Proximal median nerve neuropathies (PMN) are due to lesions proximal to the carpal tunnel which include the forearm, elbow, upper arm, and brachial plexus. Differentiating between carpal tunnel syndrome and PMN is important to guide management and is based on clinical, electrodiagnostic (EDX), and ultrasound (US) findings. This study describes the clinical, EDX, and US features in 62 patients with PMN. Methods: All patients underwent EDX studies, and 52 (83.9%) had an US study. The patients were assigned to one of four localization zones of PMN based on clinical and EDX criteria: Zone 1: Extends from the fascicles in the brachial plexus contributing to the median nerve to the innervation of the pronator teres (PT). Zone 2: Distal to the branch to the PT and proximal to the origin of the anterior interosseous nerve (AIN). Zone 3: Involves the origin of the AIN. Zone 4: Distal to the origin of the AIN and proximal to the carpal tunnel. The localization was based on the pattern of muscle weakness, topography of EMG abnormalities, and US study findings.The anatomical location of the PMN based on clinical, EDX, and US findings was: Zone 1 in 38 patients (61.3%]), Zone 2 in 6 patients (9.7%), Zone 3 in 7 patients (11.3%), and Zone 4 in 11 patients (17.7%). The most common etiologies among all 62 patients was iatrogenic injury (30 [48.4%]), followed by non-iatrogenic trauma (20 [32.2%]). The following EDX findings were noted: prolonged distal motor latency (29 [46.8%]), decreased motor nerve conduction velocity in the forearm (22 [35.5%]), low amplitude or absent compound muscle action potentials (50 [80.6%]), and abnormal or absent sensory nerve action potentials (50 [80.6%)]). Of the 52 (83.9%) patients who underwent US studies, a total of 22 (42.3%) patients showed an increased cross-sectional area of the median nerve. A neuroma was seen in 9 (17.4%) patients. Conclusions: It is often possible to localize the site of median nerve involvement and gain insight into the underlying cause based upon clinical and EMG findings, but in certain cases an US study may be necessary to confirm the diagnosis.

    Keywords: Neurology, proximal median nerve neuropathy, Iatrogenic nerve injury, Electrodiagnostic studies, ultrasound study of nerve

    Received: 22 Jul 2024; Accepted: 11 Nov 2024.

    Copyright: © 2024 Shields, Iyer, Zhang and Shields. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Lisa B.E. Shields, Norton Healthcare, Louisville, Kentucky, United States

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.