Intraneural cyst of the supraescapular nerve: Atypical cause of peripheral nerve entrapment syndrome. Case report and literature review.

OBJECTIVE: Intraneural cysts are benign lesions located within the epineurium of some peripheral nerves and their aetiopathogenesis is controversial. Most are located at the level of the lower limbs. In the upper limbs, the most frequently affected nerve is the ulnar nerve. Suprascapular nerve entrapment syndrome due to the formation of an intraneural cyst is rare. In this article, we show a new case and perform a literature review of intraneural cysts located in the suprascapular nerve.

METHODS: We present a 49-year-old woman with pain in the lateral shoulder region of several months' evolution. A brachial plexus MR showed a tumour of approximately 2×1.5cm, with a cystic appearance, in relation to the upper trunk of the right brachial plexus.

RESULTS: We used a supra-infraclavicular approach. The cystic tumour affected the suprascapular nerve. After locating a zone on the surface without nervous fascicles, we performed a partial resection of the capsule and emptying of the cyst, with a xanthochromic gelatinous content. The anatomopathological examination confirmed the diagnosis of intraneural cyst.

CONCLUSION: The suprascapular nerve is a mixed nerve, coming from the upper trunk. It provides the motor branches to the supraspinatus and infraspinatus muscle. Compression of the suprascapular nerve leads to atrophy of these muscles. This entity is one of the differential diagnoses in a patient with pain irradiating to the shoulder, and its correct treatment often results in complete remission of symptoms.