Type A ganglion cysts of the radiocapitellar joint may involve compression of the superficial radial nerve.

INTRODUCTION: Two types of ganglion cysts at the elbow have been described depending on their anatomic location. Type A ganglion cyst is located proximal to the arcade of Frohse, and type B distal to it. Compressive neuropathies of the radial nerve at the level of the radial tunnel may lead to two different clinical entities with different clinical manifestations. These different conditions depend on which branch is involved. Although compression of the deep motor branch due to a ganglion cyst has been previously described, affection of the superficial sensory branch is considered much rarer. The aim of this study was to describe a series of patients in which painful and dysesthetic symptoms arose from superficial radial nerve compression due to type A ganglion cysts coming from the radiocapitellar joint.

METHODS: A review of currently available literature about the disease was carried out. The clinical, histological and radiological records of a series of eight cases (seven patients) with compression of the superficial radial nerve diagnosed and treated between 2008 and 2011 were retrospectively reviewed. All patients complained of pain and dysesthesia at the lateral aspect of the elbow. All patients were initially diagnosed and managed as lateral epicondylitis. Persistence of the symptoms was evidenced in all patients after a course of six months of non-operative management. Magnetic resonance imaging was performed and revealed the presence of a mass compatible with a ganglion cyst coming from the radiocapitellar joint, pushing up the superficial sensory branch of the radial nerve and compressing it against the extensor carpi radialis brevis. Surgical excision was performed in all cases.

RESULTS: Histology confirmed the diagnosis of ganglion cysts. Histological findings consisted of dense fibrous tissue, with no synovial or epithelial lining and mucoid material with foamy macrophages. The mean follow-up after surgical excision was 28months (range 24-30). The symptoms subsided in all cases. No complications were registered during the follow-up.

CONCLUSION: Type A ganglion cysts of the radiocapitellar joint may involve compression of the superficial radial nerve. Our series of eight cases may suggest that this pathology might not be as rare as it was thought before. This evidence may be useful for the orthopaedic population, who may have another differential diagnosis when managing cases of painful symptoms located in the lateral aspect of the elbow.

TYPE OF STUDY: Therapeutic study.

LEVEL OF EVIDENCE: IV.