MRN findings of lateral antebrachial cutaneous nerve impingement in a collegiate athlete

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MRN findings of lateral antebrachial cutaneous nerve impingement in a collegiate athlete My-Linh Nguyen 1 & Jeffrey Rosenthal 1 & Monica Umpierrez 1 & Gary M. Lourie 2,3 & Adam D. Singer 1 Received: 9 October 2019 / Revised: 28 October 2019 / Accepted: 10 November 2019 # ISS 2019

Abstract Dynamic compression of the lateral antebrachial cutaneous nerve (LABCN) occurs with forearm pronation when the LABCN becomes compressed by the lateral margin of the biceps tendon. LABCN compression is a rare occurrence and is often overlooked as an etiology for forearm pain. While this entity has been described in several case reports in the orthopedic literature, it has not yet been described in radiology literature. We present a case of LABCN compression by the biceps tendon which was suggested by high-resolution magnetic resonance neurography in combination with the clinical findings and was subsequently confirmed and corrected surgically. Keywords Lateral antebrachial cutaneous nerve . LABC . LABCN . Dynamic . MRI . MRN . Elbow

Introduction Chronic compressive neuropathy is common; dynamic nerve compression is uncommon. In particular, dynamic compression of the lateral antebrachial cutaneous nerve (LABCN) by the biceps tendon is a rare occurrence and is often overlooked as an etiology for elbow and forearm pain [1–3]. This compressive syndrome has been sparsely described in orthopedic case reports and small case series [1, 4–10]. To the best of our knowledge, this syndrome has not been reported in the radiology literature. In this report, the anatomy of the LABCN is reviewed, the mechanism of dynamic impingement is discussed, and imaging findings are correlated with physical

Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00256-019-03345-3) contains supplementary material, which is available to authorized users. * Adam D. Singer [email protected] 1

Department of Radiology and Imaging Sciences Section of Musculoskeletal Imaging, Emory University Hospital, 59 Executive Park South, 4th Floor Suite 4009, Atlanta, GA 30329, USA

2

Department of Orthopaedic Surgery, Emory University Hospital, Atlanta, GA, USA

3

The Hand and Upper Extremity Center of Georgia, Atlanta, GA, USA

exam and surgical findings. Surgical management is briefly discussed.

Anatomy The musculocutaneous nerve arises from the lateral cord of the brachial plexus, with contributions from the C5, C6, and C7 nerve roots through the anterior divisions of the upper and middle trunks. The muscular branch innervates the biceps brachii, coracobrachialis, and brachialis muscles. The terminal branch of the musculocutaneous nerve is the LABCN and consists of pure sensory fibers with contributions from C5 and C6 [11, 12]. It is officially labeled the LABCN as it penetrates superficially through the deep brachial fascia lateral to the biceps tendon, 2–5 cm above the crease of the elbow. The nerve then divides into an anterior division, innervating the radial half of the volar forearm, and a posterior divis