Introduction: Traditional diagnosis of nerve entrapment syndromes is confirmed by clinical and electrodiagnostic evaluations. High-resolution imaging techniques, such as magnetic resonance and ultrasound imaging, have made it possible to visualize focal abnormalities in nerve anatomy. Previous studies have demonstrated that magnetic resonance neurography has higher sensitivity than nerve conduction studies in diagnosing ulnar nerve entrapment at the elbow, and evidence is emerging of a similar benefit of high-resolution ultrasound of the ulnar nerve. We present a case showing concordance of ultrasound and magnetic resonance neurography findings with clinical, electrodiagnostic, and intraoperative findings.
Methods: 56-year old man presented with right hand weakness, numbness, and paresthesia. Electrodiagnostic studies were consistent with ulnar nerve entrapment at the elbow with an enlarged ulnar nerve confirmed by magnetic resonance neurography. We compared cross-sectional areas of the enlarged ulnar nerve by ultrasound and magnetic resonance imaging to assess how well these two imaging techniques correlate.
Results: Our case study shows for the first time that cross-sectional area measured using ultrasound and magnetic resonance neurography correlate well. Moreover, the nerve swelling may have direct functional consequences as conduction block and marked slowing of motor nerve conduction identified on electrodiagnostic studies corresponded with the segment demonstrating maximal nerve enlargement.
Conclusions: Ultrasound can be a quick and non-invasive alternative to magnetic resonance neurography in patients with multiple compression syndromes or inconclusive electrodiagnostic results. This report demonstrates agreement between electrodiagnostic, magnetic resonance, and ultrasound imaging results in confirming the diagnosis of ulnar nerve entrapment at the elbow made initially on the basis of clinical history, symptoms, and physical exam findings. These findings imply that one or more of these tests can help confirm the clinical diagnosis of ulnar neuropathy at the elbow, especially in ambiguous cases.
Patient Care: This research will allow clinicians to understand the use of ultrasound and/or magnetic resonance imaging to help diagnose ulnar neuropathy, especially in difficult cases with ambiguous electrodiagnostic findings.
Learning Objectives: Imaging of the ulnar nerve may prove to be a useful technique to confirm the diagnosis of ulnar neuropathy at the elbow, particularly when standard electrodiagnostic studies are unable to localize the site of ulnar nerve injury. By the conclusion of this session, participants should be able to: 1) understand that the use of ultrasound and/or magnetic resonance imaging techniques are available for diagnosing difficult ulnar neuropathy cases and 2) that the cross-sectional areas of the enlarged ulnar nerve correlate well by ultrasound and magnetic resonance imaging.