Sonographic Changes in the Median Nerve Predict Conversion to Surgery after Corticosteroid Injection of the Carpal Tunnel.
Academic Article
Overview
abstract
BACKGROUND: Risk factors for conversion to surgical management of moderate severity carpal tunnel syndrome (CTS) are poorly understood. We hypothesized that sonographic findings along the carpal tunnel could predict failure of conservative management for CTS. METHODS: We report on 96 wrists with moderate clinical signs and symptoms of CTS. Sonographic evaluation with measurement of median nerve cross-sectional area (CSA) was performed at 3 consistent anatomic locations. We recorded median nerve morphology, inlet/outlet dimensions of the carpal tunnel, and maximal thickness of the transverse carpal ligament. Subsequently, steroid injection was performed. Patients were followed for a minimum of one year after injection and progression to surgical management was recorded. RESULTS: 54% (n = 52) patients converted to surgical management within 1 year following injection. Median nerve CSA decreased over the course of the carpal tunnel from proximal to distal in 81 of 96 wrists. A greater decrease in CSA of the median nerve between the pisiform and the hamate was associated with conversion to operative intervention for CTS with the average decrease in median nerve CSA among those who failed conservative treatment being 5.01 mm2 compared to 2.97 mm2 among those who did not progress to surgical treatment. CONCLUSIONS: Our study demonstrates that ultrasound may be one additional tool used by clinicians in order to better counsel patients about the severity and progression of their disease. Patients who demonstrate a decrease in cross-sectional area of the median nerve along the carpal tunnel demonstrate a higher likelihood of progression to operative management.
