1529 - Superimposed Carpal Tunnel Syndrome in a Patient with Charcot-Marie-Tooth Disease Type 1A: A Diagnostic Challenge

Thursday, February 19, 2026

5:00 PM - 6:30 PM AST

Presenting Author(s)

KS

Kacie M. Shannon, BS

Medical Student
University of Texas Southwestern Medical School
Dallas, Texas, United States

Corresponding Author(s)

HC

Haibi Cai, MD

Assistant Professor
University of Texas Southwestern Medical Center
Dallas, Texas, United States

Submitter(s)

KS

Kacie M. Shannon, BS

University of Texas Southwestern Medical School
Dallas, Texas, United States

Case Diagnosis: A 54-year-old woman with genetically confirmed Charcot-Marie-Tooth disease type 1A (CMT1A) presented with new-onset median nerve paresthesias, raising concern for superimposed carpal tunnel syndrome (CTS).

Case Description: The patient reported bilateral intermittent burning, numbness, and tingling in digits 1–3, worse at night and with hand use. Physical exam revealed positive Tinel’s and Phalen’s signs bilaterally, with preserved motor strength and no thenar atrophy. Electrodiagnostic studies showed diffuse demyelinating polyneuropathy, consistent with CMT1A, with slowed conduction velocities in all nerves tested and prolonged sensory peak latencies in both median and ulnar nerves. Neuromuscular ultrasound revealed diffuse nerve enlargement consistent with hereditary neuropathy. However, focal enlargement of the median nerves at the carpal tunnel—13 mm² on the right and 12 mm² on the left—yielded elevated wrist-to-forearm ratios of 1.44 and 1.75, respectively, suggestive of superimposed CTS. The patient underwent diagnostic and therapeutic ultrasound-guided corticosteroid injections with 70% symptom relief, followed by successful bilateral carpal tunnel release, which resulted in complete resolution of symptoms.

Discussions: CTS and CMT1A share overlapping clinical and diagnostic features, complicating the recognition of superimposed compressive neuropathy. In CMT1A, electrodiagnostic studies may be confounded by baseline demyelination, while ultrasound may show diffuse nerve hypertrophy. However, disproportionate enlargement of the median nerve at the wrist and a wrist-to-forearm cross-sectional area ratio >1.4 can support the diagnosis of CTS. In this case, a multimodal diagnostic approach, including electrodiagnostics, ultrasound, and therapeutic response to corticosteroid injection, enabled accurate identification and effective treatment.

Conclusions: In patients with hereditary neuropathies such as CMT1A, new focal symptoms should prompt consideration of superimposed entrapment neuropathies. Ultrasound-guided corticosteroid injection served as both a diagnostic and therapeutic tool, facilitating definitive surgical treatment and an excellent clinical outcome.