Predicting the outcome of revision carpal tunnel release.

PURPOSE: To test the hypothesis that the result of steroid injection in the carpal tunnel in a patient with recurrent carpal tunnel symptoms would serve as a good predictor of the outcome of later carpal tunnel release (CTR).
METHODS: We conducted a retrospective review of all patients who underwent revision CTR for recurrent or persistent carpal tunnel syndrome over a 2-year period at our institution. A total of 28 wrists in 23 patients met inclusion criteria. We evaluated patients to determine whether preoperative factors or the result of injection predicted the outcome of revision CTR. We used a multivariate logistic regression analysis to predict surgical success when multiple preoperative findings were considered.
RESULTS: Of the 23 wrists that had relief from injection, 20 had symptom improvement with surgery. Although they did not reach statistical significance, the sensitivity and positive predictive value for injection alone predicted outcome of revision CTR in 87%. No patient characteristic or physical examination finding predicted successful revision CTR. Multivariate logistic regression analysis combining preoperative injection results with physical examination findings (numbness and/or motor weakness in median nerve distribution, positive Durkin test, and positive Phalen test) provided a sensitivity of 100% and a specificity of 80%.
CONCLUSIONS: In a small group of patients with recurrent carpal tunnel syndrome, cortisone injection into the carpal tunnel was not, by itself, a statistically significant predictor of successful revision surgery. However, relief from injection as a diagnostic test for predicting successful revision CTR was found to have both a high sensitivity and a positive predictive value. Coupled with the components of the physical examination, injection provides a good screening test to establish surgical success with revision CTR. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic III.