(Kiosk 2) Utility of Ultrasound in the Electrodiagnostic Evaluation of Patients with History of Ulnar Nerve Transposition: A Case Series

Case Diagnosis: Ultrasound identified the presence of the ulnar nerve in the epicondylar groove in patients with reported history of ulnar nerve transposition, which influenced subsequent management.

Case Description or Program Description: Patient 1 is a 44-year-old female with history of right subcutaneous ulnar nerve transposition 2 years prior, who presented for electrodiagnostic evaluation of right hand pain, paresthesias, and weakness. The electrodiagnostic impression was a right ulnar mononeuropathy at the elbow, electrically severe, as well as a right median mononeuropathy at the wrist, electrically mild. Patient 2 is a 58-year-old female with history of right subcutaneous ulnar nerve transposition 8 years prior, who presented for electrodiagnostic evaluation of right hand pain and paresthesias. The electrodiagnostic impression was a normal study, with no evidence for a right ulnar mononeuropathy at the elbow, median mononeuropathy at the wrist, or cervical radiculopathy.

Setting: Tertiary Care Academic Medical Center

Assessment/Results: Ultrasound of the right ulnar nerve at the elbow was performed in both patients. In Patient 1, the ulnar nerve was located in the epicondylar groove, however there was ulnar nerve dislocation with 70 degrees of elbow flexion. Maximum cross-sectional area of the ulnar nerve across the elbow was 33 mm2. In Patient 2, the ulnar nerve was located in the epicondylar groove, however there was ulnar nerve dislocation with 90 degrees of elbow flexion. Maximum cross-sectional area of the ulnar nerve across the elbow was 8 mm2.

Discussion (relevance): This case series demonstrates the value of utilizing ultrasound during electrodiagnostic testing in this patient population. Without the use of ultrasound, it would have been presumed that the ulnar nerve remained transposed anteriorly. In addition, the presence of ulnar nerve dislocation would have been undiagnosed. These findings could influence subsequent management.

Conclusions: Using ultrasound in conjunction with electrodiagnostic testing in patients with history of ulnar nerve transposition can provide key information in the evaluation of the ulnar nerve.