Disclosures: Giuseppe Amore, MD, MPH: Nothing to disclose

Case Description: A 43-year-old male auto mechanic presented with complaints of severe, progressively worsening left shoulder and axillary pain associated with numbness of his palm and first 3 digits. He denied any trauma to his left shoulder, axilla, neck, or wrist. Magnetic resonance imaging of his cervical spine was positive for chronic degenerative changes with no acute process. He reported that he had been diagnosed with carpal tunnel syndrome of his left wrist in the past and was treated with corticosteroid injections which provided minimal relief. On physical exam, his shoulders and upper extremities were symmetrical with no signs of trauma, normal range of motion bilaterally in all major joints, and no tenderness to palpation to the neck, shoulders, or wrists. Interestingly, special tests such as Tinel’s sign and Phalen’s maneuver were negative. He exhibited decreased sensation to light touch on the palmar aspect of digits 1-3 on the left hand. Reflexes were intact throughout.

Setting: Acute Inpatient Hospital

Patient: 43-year-old male with carpal tunnel syndrome refractory to treatment.

Assessment/Results: Ultrasound examination of the patient’s left upper extremity proximal to the wrist was unremarkable. Sonographic visualization of the patient’s left carpal tunnel revealed a bifid median nerve with increased cross-sectional area measuring 12.3mm² with unaffected surrounding tendons and ligaments.

Discussion: A bifid median nerve is a rare variation that may make the nerve more susceptible to compression in the carpal tunnel due to its increased cross-sectional area. This anatomical variation may present with normal electrophysiological or clinical findings.

Conclusion: Although quite rare, a bifid median nerve in the carpal tunnel may help the clinician explain the persistence of carpal tunnel syndrome in a patient that is refractory to corticosteroid treatment. Sonographic evidence may also help in targeting treatment options for this uncommon anatomical structure.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/a-rare-sonographic-finding-of-a-bifid-median-nerve-in-a-patient-with-carpal-tunnel-syndrome-refractory-to-treatment-a-case-report/