Prognostic Value of Ultrasound Imaging of the Median Nerve in Carpal Tunnel Syndrome.

Background

Ultrasound has been well established as a diagnostic modality for carpal tunnel syndrome, but its prognostic utility has not been deeply investigated. Few studies, showing contradictory results, exist investigating ultrasound results as a predictor of patient outcomes.

Methods

Patients with ultrasound measurement of the cross-sectional area (CSA) of the median nerve who completed the Boston Carpal Tunnel Questionnaire (BCTQ) and followed up after surgery were included in the study. A total of 199 wrists from 172 patients met the inclusion criteria. Preoperative CSA of the median nerve at the wrist was compared with change in BCTQ at various follow-up times postoperatively.

Results

The BCTQ score was found on average to decrease for patients after surgery at all 3 follow-up times. There was a larger decrease in the preoperative BCTQ with each progressive follow-up time, with the largest change of 1.43 points coming at 6+ months. The average change in BCTQ at each follow-up time was found to be greater than the minimal clinically important difference. The greatest R2 for preoperative CSA compared with change in BCTQ was 0.0552 for the 6+ month visits. No specific CSA value or range above or below which patients have better postoperative outcomes was found.

Conclusions

Higher preoperative CSA, signifying worse carpal tunnel severity, showed almost no correlation with better outcomes after carpal tunnel release surgery as measured by improvement in patient-reported outcome scores.