Association of Ultrasound and Electrodiagnostic Studies in Patients Evaluated for Ulnar Neuropathy

Purpose: Our goal was to determine the association between the severity of electrodiagnostic (EDX) studies with the cross-sectional area (CSA) of the ulnar nerve at the cubital tunnel using diagnostic ultrasound. Based on our clinical experience, we hypothesized there would not be a positive correlation between the severity of EDX and ulnar nerve CSA.

Methods: This was a retrospective analysis of patients 18 years or older evaluated from May 1, 2020, to June 31, 2021, referred for an upper limb EDX and neuromuscular ultrasound to evaluate for an upper limb neuropathy. History, physical examination, ultrasound imaging (ulnar nerve at elbow), and EDX were reviewed. Patients were excluded for age under 18 years or concomitant upper limb radiculopathy. Baseline sample characteristics were analyzed, including age, race, sex, ethnicity, body mass index (normal, overweight, obese, or morbid obesity), and smoking status.

Results: Of 1,043 patients, there were more females than males (634 vs 409) with an average age (SD) of 54.0 (15.5). Most of the patients were White (863) compared to Black (113) and other races (67). The average CSA of the ulnar nerve at the elbow increased with increased severity based on EDX results. There was a significant association between increasing severity on EDX and the increased nerve CSA at the elbow.

Conclusions: We found a positive association between the EDX severity and the CSA of the ulnar nerve on diagnostic ultrasound at the cubital tunnel. As the severity of ulnar neuropathy at the elbow increases, the CSA of the ulnar nerve correspondingly increases at the elbow.

Type of study/level of evidence: Prognostic II.