Carpal Tunnel Syndrome Diagnosis with Ultrasound Despite Negative Electromyography

Case Diagnosis: A patient underwent EMG and ultrasound for diagnostic purposes for carpal tunnel syndrome, where EMG was negative and ultrasound found CTS in her bilateral wrists.

Case Description or Program Description: A 45-year-old female patient with suspected CTS underwent both EMG and ultrasound for diagnostic purposes. The EMG results were negative for any evidence of CTS in the bilateral wrists, but the ultrasound results showed that the right median nerve was enlarged at the carpal tunnel cross-sectional area at 12mm². The left ultrasound also showed enlargement just shy of 10mm². The patient was then treated with carpal tunnel steroid injections, which resulted in improved symptoms.

Setting: Outpatient Clinic

Assessment/Results: The case presented challenges in the accurate diagnosis of CTS, despite negative EMG results. However, ultrasound was able to provide a more definitive diagnosis, which ultimately led to successful treatment of the patient's symptoms.

Discussion (relevance): The diagnostic accuracy between ultrasound and EMG may be influenced by several factors, including the severity and duration of the CTS, the skill and experience of the clinician performing the test, and the individual patient's clinical presentation.
Ultrasound may be more sensitive to structural changes in the wrist especially early in CTS, while EMG may be more sensitive to subtle changes in nerve conduction, especially in advanced cases of CTS

Conclusions: Overall, accurate diagnosis of CTS is crucial for appropriate treatment and management of the condition. Both EMG and ultrasound have a place in the accurate diagnosis of this condition.