Paralabral Cysts with Associated Infraspinatus and Teres Minor Denervation: A Case Report.

Introduction: The shoulder is one of the most intricate articulation complexes in the human body. Any insult to its equilibrium can cause joint instability, pain, and dysfunction. The complex bony projections of the scapula, lengthy nature of the nerves, and extensive mobility of the joint places nerves at risk for impingement; this can, especially, be seen when examining the axillary and suprascapular nerves. Another rare cause of nerve impingement is a paralabral cyst secondary to labral tearing. If a paralabral cyst expands into the limited space occupied by the nerves, this can result in neuropraxia, muscle wasting, and loss of function. This phenomenon presents an interesting anatomic and clinical correlation.

Case Report: A 41-year-old male with no past medical history presented with left shoulder pain for 3 months. Physical examination showed a great range of motion but diffusely decreased strength. Magnetic resonance imaging of the left shoulder demonstrated posterosuperior labral tearing with an associated paralabral cyst extending into the spinoglenoid notch. An additional anteroinferior labral tear with an associated paralabral cyst was also found. Extensive infraspinatus and teres minor muscle atrophy suggesting active denervation was present. The patient failed conservative management and underwent arthroscopic labral repair with posterosuperior and anteroinferior paralabral cysts excision. The patient had an unremarkable recovery and by 1 year had full motion and 5/5 strength in all planes.

Conclusion: While paralabral cysts are well documented, there have been limited reports of cysts causing neural impingement of the axillary or the distal suprascapular nerve, let alone both occurring within the same individual. This case provides an interesting clinical scenario which very clearly depicts the neural innervation of the shoulder and pathologies that can impact function. This cystic impingement is a very interesting and rare finding that provides tremendous insight into both shoulder pathology and anatomy. This case is also useful to predict patient recovery after long-term nerve impingement and muscle denervation. This patient presented with significant loss of strength, motion, and shoulder dysfunction, but after surgical intervention, he regained complete motion and strength. This information can be used to help educate and guide patients in practice.