Validation of preoperative nerve conduction studies by intraoperative studies in patients with ulnar neuropathy at the elbow.

Abstract

To validate the findings of preoperative motor short-segment nerve conduction studies (SSNCSs) by intraoperative SSNCSs in patients with cubital tunnel syndrome. We prospectively recruited patients with ulnar neuropathy at the elbow (UNE) localized distal to the medial epicondyle (ME). Preoperatively, motor SSNCSs and ultrasonography (US) were performed. Immediately after surgical dissection of the humeroulnar aponeurotic arcade (HUA), intraoperative near-nerve motor SSNCSs were performed, and compared to preoperative findings. We studied 36 arms with UNE in the cubital tunnel. Preoperative US localized UNE distal to ME in all operated arms, and demonstrated ulnar nerve constriction in 19 of them. Visual inspection confirmed ulnar nerve swelling in all studied nerves, but was unreliable with regard to ulnar nerve constriction. In all 5 (14%) arms with inconclusive localization by SSNCSs, intraoperative SSNCSs confirmed the preoperative US diagnosis of cubital tunnel syndrome. Intraoperative SSNCSs confirmed the preoperative localization in 24 (67%) arms, and were non-contributive in 7 (19%) arms with intraoperatively non-recordable responses. Intraoperative near-nerve SSNCSs did not change the localization in any of 36 arms with UNE distal to ME. Therefore, our data indicate that a combination of preoperative SSNCSs and US reliably localizes UNE in the cubital tunnel. Our present study suggests that in arms with consistent preoperative SSNCSs and US studies, no intraoperative near-nerve SSNCSs are needed to confirm ulnar nerve entrapment under the HUA.