The Value of Median Nerve Sonography as a Predictor for Short- and Long-Term Clinical Outcomes in Patients with Carpal Tunnel Syndrome: A Prospective Long-Term Follow-Up Study

Abstract

Objectives: To investigate the prognostic value of B-mode and Power Doppler (PD) ultrasound of the median nerve for the short- and long-term clinical outcomes of patients with carpal tunnel syndrome (CTS).

Methods: Prospective study of 135 patients with suspected CTS seen 3 times: at baseline, then at short-term (3 months) and long-term (15-36 months) follow-up. At baseline, the cross-sectional area (CSA) of the median nerve was measured with ultrasound at 4 levels on the forearm and wrist. PD signals were graded semi-quantitatively (0-3). Clinical outcomes were evaluated at each visit with the Boston Questionnaire (BQ) and the DASH Questionnaire, as well as visual analogue scales for the patient's assessment of pain (painVAS) and physician's global assessment (physVAS). The predictive values of baseline CSA and PD for clinical outcomes were determined with multivariate logistic regression models.

Results: Short-term and long-term follow-up data were available for 111 (82.2%) and 105 (77.8%) patients, respectively. There was a final diagnosis of CTS in 84 patients (125 wrists). Regression analysis revealed that the CSA, measured at the carpal tunnel inlet, predicted short-term clinical improvement according to BQ in CTS patients undergoing carpal tunnel surgery (OR 1.8, p = 0.05), but not in patients treated conservatively. Neither CSA nor PD assessments predicted short-term improvement of painVAS, physVAS or DASH, nor was any of the ultrasound parameters useful for the prediction of long-term clinical outcomes.

Conclusions: Ultrasound assessment of the median nerve at the carpal tunnel inlet may predict short-term clinical improvement in CTS patients undergoing carpal tunnel release, but long-term outcomes are unrelated to ultrasound findings.

Fig 1. Study flow chart.

n, number of wrists; parenthesis: the number of patients in each group (the sum of the numbers in parenthesis might exceed the number of patients under study because patients contributing a wrist to more than 1 group were counted separately); *111 Patients completed short-term follow-up, with 65 of 80 CTS cases included in the regression models; 15 (18.8%) patients had missing or invalid data. **105 Patients completed long-term follow-up, with 74 of 84 CTS cases included in the regression models; 10 (11.9%) patients had missing or invalid data.