Usefulness of Ultrasonography to Predict Response to Injection Therapy in Carpal Tunnel Syndrome

OBJECTIVE: To verify the feasibility of initial parameters of ultrasonography or electromyography for the prediction of effect after steroid injection therapy in a carpal tunnel syndrome (CTS) patient. METHOD: We recruited individuals with clinical and electrodiagnostic evidence of CTS. Results from the Boston self-assessment questionnaire, median motor and sensory nerve conduction studies, and median nerve ultrasonography were evaluated at baseline, 1 month, and 6 months after injection. Evaluation of median nerve ultrasonography parameters included measurements taken at the maximal swelling point (MS), 2 cm proximal from MS (2MS), and 12 cm proximal from MS (12MS), and its ratio (MS/12MS, 2MS/12MS) was calculated. The correlation between improvement of the symptom score after treatment and baseline parameters was estimated. RESULTS: Fourteen individuals (14 women, mean age 53.8 years) with 22 affected wrists were enrolled. After steroid injection therapy, clinical and electromyographic parameters showed significant improvements at 1 month or 6 months after injection, and ultrasonographic parameters showed significant changes in maximal area and area ratio (MS/12MS) of the median nerve. Symptom score improvement showed a positive correlation in the initial 2MS and ratio of 2MS/12MS after 6 months (p<0.05). CONCLUSION: Most of the improvements occurred during the first month after injection and lasted up to 6 months. The initial median nerve swelling and its ratio may be a useful predictor of response after steroid injection.

Feasibility of Ultrasonographic Area Ratio of Median Nerve in the Diagnosis of Carpal Tunnel Syndrome in Korea

OBJECTIVE: To examine the usefulness of ratio of maximal swelling to normal cross sectional area (CSA) of median nerve with ultrasound in patients with carpal tunnel syndrome (CTS) and healthy controls. METHOD: Patients with electrodiagnostically proven CTS underwent ultrasonography of the median nerve. The median nerve area was measured at three points (maximal swelling site, 2 cm proximal to maximal swelling site, 12 cm proximal to maximal swelling site) and compared to values from asymptomatic volunteers. RESULTS: The ratio of maximal swelling site to 12 cm proximal was 1.34+/-0.14 in asymptomatic volunteers and 2.31+/-0.43 in patients presenting with CTS. The ratio of maximal swelling site to 12 cm proximal gave 73.7% sensitivity and 90.0% specificity. While using only median nerve area at the wrist resulted in 81.6% sensitivity and 70.0% specificity, depending on the cutoff value used. CONCLUSION: The ratio of maximal swelling site to proximal in patients with CTS is elevated as compared to asymptomatic controls. The ratio of maximal swelling site to 12 cm proximal has higher specificity to diagnose CTS, and may be superior to measuring median nerve area at the wrist alone.