Diagnosis of ulnar nerve entrapment anterior to the medial epicondyle by ultrasound elastography and diffusion tensor imaging with fiber tractography: a case report

Guillaume Jaques,Sébastien Durand,Fabio Becce,Jean-Baptiste Ledoux

doi:10.1007/s00276-021-02881-9

Abstract

Ulnar/cubital tunnel syndrome is the second most common compressive neuropathy of the upper limb. Permanent location of the ulnar nerve anterior to the medial epicondyle is extremely rare, with only five cases reported in the literature. Using ultrasound elastography and diffusion tensor imaging with fiber tractography, we diagnosed a case in which ulnar nerve entrapment was associated with anterior nerve location. Surgical release confirmed the diagnosis and the patient was symptom free 3 months after surgery.

Highlights

Ulnar/cubital tunnel syndrome is the second most common compressive neuropathy of the upper limb with an estimated incidence of 25 cases per 100,000 individuals [12]
CSA Cross-sectional area DTI Diffusion tensor imaging MRI Magnetic resonance imaging SWE Shear-wave elastography SD Standard deviation permanent anterior location of the ulnar nerve is extremely rare, with only five cases reported in the literature since 1980 (Table 1) [12]
Electroneuromyography results showed a significant decrease in both ulnar nerve conduction velocity and amplitude of the nerve potential in the cubital tunnel

Summary

Introduction

Ulnar/cubital tunnel syndrome is the second most common compressive neuropathy of the upper limb with an estimated incidence of 25 cases per 100,000 individuals [12]. In B-mode, we observed a permanent anterior location of the ulnar nerve relative to the medial epicondyle at the left elbow (Fig. 1a). We observed a slight numerical difference in the fractional anisotropy values of the ulnar nerve at the level of the cubital tunnel between the left pathological elbow (mean 0.36; SD 0.07) and right normal side (mean 0.42; SD 0.06). Ulnar nerve tractography showed asymmetric fiber orientation of the left and right ulnar nerves (Fig. 1d, e; Supplementary Fig. 1), with an “S-shape” aberrant anterior pathway of the left ulnar nerve relative to the medial epicondyle (Fig. 1e; Supplementary Fig. 1). The ulnar nerve was located anterior to the medial epicondyle (Fig. 2) and complete release of all nerve compression points was performed: the aponeurosis of the flexor carpi ulnaris, the tunnel outlet between the two muscle heads of the flexor carpi ulnaris, the intermuscular septum, and

Discussion

Conclusion