Sonographic detection of ulnar nerve compression during elbow extension
Journal
American Journal of Physical Medicine and Rehabilitation
Journal Volume
93
Journal Issue
7
Pages
636-637
Date Issued
2014
Author(s)
Abstract
This feature is a unique combination of text (voice) and video that more clearly presents and explains procedures in musculoskeletal medicine. These videos will be available on the journal’s Website. We hope that this new feature will change and enhance the learning experience.Video: Gallery: To view the online video of these procedures, use your smartphone camera QR Reader App to scan and capture this QR Code or visit www.AJPMR.com to locate this digital video content.URL: http://wolterskluwer.http.internapcdn.net/wolterskluwer_vitalstream_com/MP4s/eJP/AJPMR/AJPMR_2014_Sonographic_detection_of_ulnar_nerve_compression_during_elbow_extension.mp4A 41-yr-old man in a traffic accident experienced right elbow pain, and radiographic examination revealed a capitellar fracture of the right elbow. He underwent surgery, and his pain improved. However, there was numbness along the ulnar side of the forearm, especially during elbow extension. Electrophysiologic studies revealed ulnar neuropathy at the elbow. Static ultrasonography did not reveal any nerve swelling or any space-occupying lesion compressing the nerve. Dynamic ultrasonography revealed flattening of the ulnar nerve near the medial epicondyle during elbow extension (Fig. 1). In contrast to the general recommendations of avoiding elbow flexion of more than 90 degrees, positioning with a brace in 70-degrees flexion at night and avoidance of full elbow extension were recommended. Follow-up disclosed improvement of numbness and nerve conduction velocity of the right ulnar nerve across the elbow.FIGURE 1: Morphologic changes in the ulnar nerve during elbow flexion and extension. Flattening of the ulnar nerve during elbow extension (left); oval shape of the ulnar nerve during elbow flexion (right).In the general population, the ulnar nerve travels in the retrocondylar groove of the elbow. The nerve leaves the groove and travels below the aponeurotic arch of the flexor carpi ulnaris muscle, also named as the humeroulnar arcade. With elbow flexion, the distance between the medial epicondyle and the olecranon increases up to 1 cm and results in tightening of the humeroulnar arcade of the flexor carpi ulnaris and narrowing of the cubital tunnel over the nerve.1 The medial elbow ligaments engorge and make the floor of the retrocondylar groove flat. The nerve shifted anteriorly in the cubital tunnel.2 Therefore, the nerve is stretched around the medial epicondyle in complete elbow flexion but has redundant length in full elbow extension. Ultrasonography may help diagnose ulnar nerve entrapment at the elbow. In a 50-yr-old woman diagnosed with left ulnar entrapment at the retrocondylar groove, dynamic ultrasonography differentiated concurrent dislocation of the triceps muscle and the ulnar nerve on the symptomatic side from isolated dislocation of the ulnar nerve on the asymptomatic side. The authors suggested that dynamic ultrasonography is complementary to electrodiagnosis in evaluating underlying anatomic structures of neuropathy.3 It is recommended that treatment of ulnar compression neuropathy should be initiated with splinting the elbow in extension at night.4 A review article revealed that avoidance of certain movements or positions may reduce discomfort.5 However, such positioning of the elbow might not be suitable for this patient because of his atypical presentation of ulnar nerve compression in elbow extension. After bracing the patient’s elbow in flexion, symptoms of ulnar nerve compression during elbow extension subsided. The etiology of this uncommon compression of the ulnar nerve during elbow extension is unknown, but it might be related to posttraumatic anatomic changes of the humeroulnar arcade, the olecranon, the medial epicondyle, and the surrounding soft tissues. In this patient, protruding synovial tissue from the medial elbow joint during elbow extension was noted, which might be the cause of the ulnar nerve flattening (Video; https://links.lww.com/PHM/A79). Dynamic ultrasonography may be useful in the detection of atypical ulnar nerve compression during elbow extension. With this video gallery, the authors suggest that clinicians should use dynamic ultrasonography in patients with atypical presentations for diagnosis and treatment guidance.
SDGs
Other Subjects
adult; article; case report; cubital tunnel syndrome; echography; elbow; human; humerus fracture; injury; male; methodology; movement (physiology); pathophysiology; physical examination; physiology; traffic accident; ulnar nerve; Accidents, Traffic; Adult; Elbow Joint; Humans; Humeral Fractures; Male; Movement; Physical Examination; Ulnar Nerve; Ulnar Nerve Compression Syndromes
Publisher
Lippincott Williams and Wilkins
Type
note