Ultrasound imaging of the median nerve as a prognostic factor for carpal tunnel decompression

Abstract

The diagnostic value of ultrasound imaging in carpal tunnel syndrome is established, but reports on its prognostic value have been contradictory. This investigation was an observational study of subjective surgical results, evaluated by symptom severity and functional status scales, and an ordinal scale for overall outcome, for 145 carpal tunnel decompressions in relation to preoperative measurement of median nerve cross-sectional area. The surgical success rate was 86%. In univariate analyses no significant correlation existed between outcome and preoperative cross-sectional area, nor with preoperative nerve conduction studies or patient variables, except for body mass index and gender. A multivariate model including electrophysiological, imaging, and patient variables was moderately predictive of success with an area under the receiver operating characteristic curve of 0.82. Cross-sectional area alone is unlikely to be a sufficiently reliable predictor of outcome for use in counseling individual patients, but imaging results may be useful in multivariate prognostic models.