Neuromuscular ultrasound in patients with carpal tunnel syndrome and normal nerve conduction studies.

Introduction: Nerve conduction studies (NCS) are sensitive for carpal tunnel syndrome (CTS), but a small proportion of patients with clinical CTS have normal NCS. This retrospective study was designed to assess the neuromuscular ultrasound findings in a group of CTS patients.

Methods: The electronic medical record was reviewed by a neurologist to identify patients who had a diagnosis of CTS with normal NCS, including either mixed median-ulnar comparison or transcarpal sensory studies, and complete neuromuscular ultrasound evaluation for CTS.

Results: Fourteen individuals (22 wrists) met all criteria. A total of 92.3% had median nerve cross-sectional area enlargement at the wrist (mean 16.3 mm ), 100% had increased wrist-to-forearm median nerve area ratio (mean 2.4), 82.4% had decreased median nerve echogenicity, 75.0% had decreased median nerve mobility, and 7.1% had increased median nerve vascularity.

Conclusion: A large proportion of patients with clinical CTS but normal NCS have abnormal neuromuscular ultrasound findings. Muscle Nerve 55: 913-915, 2017.