Prognostic value of clinical and electrodiagnostic factors after corticosteroid injection in carpal tunnel syndrome

BACKGROUND: Electrodiagnostic (EDX) studies are used to confirm the diagnosis of carpal tunnel syndrome (CTS), quantitatively assess disease severity, and distinguish CTS from other conditions. The purpose of this study was to evaluate whether the EDX study findings can predict the success or failure of corticosteroid injection (CI) in patients with CTS. METHODS: A retrospective review was conducted of 79 patients who received first-time CI for CTS without image-guidance between April 2019 and November 2022 and were followed for more than 1 year. Demographic information, disease characteristics, initial physical examination findings, pre-treatment EDX findings and Boston Carpal Tunnel Questionnaire (BCTQ) scores before and after CI were collected. RESULTS: Of the 79 patients, 41 (51.9%) required no additional procedures (treatment success group), whereas 38 (48.1%) underwent additional CI or surgery within 1 year (treatment failure group). Multivariable logistic regression analysis showed that a positive Phalen test (odds ratio [OR] 7.053; 95% confidence interval, 1.349-36.882, p = 0.021), larger static two-point discrimination (OR 1.491; 95% confidence interval, 1.049-2.118, p = 0.026), and higher initial BCTQ-symptom scores (OR 1.978; 95% confidence interval, 1.027-3.810, p = 0.041) were significant risk factors for treatment failure after CI. Pre-treatment EDX parameters were not significantly associated with predicting CI failure. CONCLUSIONS: Although EDX studies are useful for diagnosing CTS and assessing severity, their value in predicting CI outcomes appears limited. In contrast, provocative tests, sensorimotor assessment of the median nerve, and severe baseline symptoms were significant indicators of CI failure. LEVEL OF EVIDENCE: Prognostic, level IV.