The diagnostic role of ultrasound in cubital tunnel syndrome for patients with a previous cubital tunnel surgery

Ultrasound is widely used in the diagnosis of peripheral nerve compressions. Nevertheless, the role of ultrasound, and in particular the cross-sectional area (CSA) measurements, in the diagnosis of cubital tunnel syndrome (CuTS) is debatable, especially in patients who have had previous surgeries. We evaluated the diagnostic value of ultrasound and CSA measurements in a heterogenous group of CuTS patients suffering from persisting or recurrent CuTS after a previous surgical intervention. All patients with persisting or recurrent CuTS after previous surgery, who received a nerve ultrasound with or without CSA measurements in a tertiary referral center between 2015 and 2022, were included. Median CSA was calculated at five locations from the upper arm to the wrist. The sensitivity of ultrasound and electrodiagnostic studies and the correlation between both diagnostic tools were calculated. Thirty-seven nerves from 35 patients who received nerve ultrasound, of which 21 nerves from 19 patients who received additional CSA measurements, were included. Ultrasound indicated signs of persisting or recurrent compression in 73.0% of patients, and ulnar swelling based on CSA measurements was found in 71.4% of patients. Electrodiagnostic testing was positive in 40.7% of patients. CuTS diagnosis was supported by both electrodiagnostic studies and CSA in only 34.6% of patients. CSA and electrodiagnostic testing in patients with persistent or recurrent symptoms after previous surgery did not correlate well, and the sensitivity of both tests was lower than in diagnostic accuracy studies. Ultrasound was found to be useful in evaluating ulnar nerves after previous surgery.