Sonoanatomy of the ulnar nerve in the cubital tunnel: a multicentre study by the GEL.

Abstract

The objective is to determine the normal appearance of the ulnar nerve on a posterior axial sonogram section of the elbow through the medial epicondyle and the humeroulnar joint space. Ultrasound evaluation was carried out on 400 elbows with measurement of the ulnar nerve cross-sectional area and ulnar nerve-cortex distance, as well as recording of apparent ulnar nerve division. Factors that significantly influenced the study variables were sought by statistical analysis. Mean cross-sectional area of the ulnar nerve at the elbow was 7.9 +/- 3.1 mm2 overall. Values were lower in females than in males and increased between 40 and 60 years of age. The ulnar nerve-cortex distance was 0.8 +/- 0.4 mm and varied widely across individuals. Apparent ulnar nerve division at the elbow was noted in about one-fifth of individuals, with no difference between females and males or between the right and left elbows. When present, apparent division was often bilateral and was not associated with changes in cross-sectional area or in distance from the medial epicondyle cortex. This study provides normative data on ulnar nerve sonoanatomy at the elbow and establishes that apparent ulnar nerve division at the elbow is a normal variant.