A Novel Diagnostic and Prognostic Tool for Simple Decompression of Ulnar Nerve in Cubital Tunnel Syndrome

Abstract

Surgical decompression of the ulnar nerve (UN) is effective for treating cubital tunnel syndrome (CubTS). Nevertheless, the outcome is not always satisfying. Different surgical, clinical, and imaging findings have been claimed as outcome predictors, but there is no consensus in the literature. We analyzed the outcome-predicting role of ultrasonography (US) of the UN in patients with CubTS and its possible role for diagnosis and follow-up. Patients with CubTS treated by simple UN decompression underwent US and electrodiagnotic (ED) studies of the UN at the elbow before and after surgery. Outcome was evaluated through the Bishop scale. A correlation analysis between pre- and postoperative clinical, US, and ED findings was performed. Thirty-six patients were enrolled. Preoperatively, we observed a negative correlation between the motor conduction velocity (MCV) and the transverse (TD) and anteroposterior diameters and cross-sectional area (CSA) of the UN at the precubital (P= 0.001, P= 0.001, P= 0.005) and cubital level (P= 0.02, P= 0.002, P= 0.001). Preoperative precubital TD and CSA were associated with outcome (P= 0.01, P= 0.006) and postoperative MCV (P= 0.004, P= 0.008). The cut-off values TD >6 mm and CSA >23.91 mm2 were predictors of poor outcome. Finally, postoperative cubital TD and CSA values were inversely correlated with outcome (P= 0.0002, P= 0.0007) and postoperative MCV (P= 0.0002, P= 0.0004). The US examination of the UN is useful for the management of patients with CubTS as an adjunct to clinical and ED evaluations. US measurements are correlated with pre- and postoperative ED findings and thus are useful for diagnosis and follow-up. Interestingly, specific precubital US measurements are good predictors of outcome.