Abstract
BACKGROUND: Quadrangular space syndrome (QSS) is a rare condition involving compression of the axillary nerve and/or posterior circumflex humeral artery within the quadrangular space. Neurogenic QSS is caused by entrapment of the axillary nerve due to fibrotic bands, paralabral cysts, trauma, or space-occupying lesions, leading to shoulder pain, weakness, and deltoid atrophy, which is frequently observed in athletes performing overhead activities. INDICATIONS: A 21-year-old female competitive volleyball player presented with a 5-year history of progressive right arm weakness and shoulder pain, worsened by shoulder activity. The patient's symptoms persisted despite conservative treatments. On examination, she had visible right anterolateral deltoid atrophy and 4/5 weakness with right shoulder forward flexion. Electromyography showed denervation of all 3 deltoid heads with severely decreased motor units, while magnetic resonance imaging demonstrated compression of the right axillary nerve within the quadrangular space and denervation changes of the deltoid muscle. Given the failure of nonsurgical interventions, ongoing symptom progression, and examination findings, axillary nerve decompression was recommended. TECHNIQUE DESCRIPTION: A posterior surgical approach was used for axillary nerve decompression using microsurgical techniques. The patient was positioned supine; a posterior arm incision was made, and the deltoid muscle and the long head of the triceps brachii were exposed and retracted to access the quadrangular space. The teres major fascia was opened to visualize and divide a compressive fibrotic band, completing the nerve decompression. RESULTS: The surgery was successful, with significant postoperative improvements. The patient began rehabilitation at 4 weeks postoperatively and experienced restored deltoid muscle mass and strength by the 6-month follow-up, and durable relief at 2 years postoperatively. She achieved a full return to sports. DISCUSSION/CONCLUSION: Axillary nerve decompression proved effective for treating neurogenic quadrangular space syndrome in this case, especially after conservative management had failed. The procedure preserved shoulder function without the need for additional surgical interventions. Return to sports was achievable without complications by 6 months postoperatively. At 2 years postoperatively, the patient continued to have durable relief. The treatment and outcome in this case were consistent with existing literature on this topic, which is Level 4 evidence in the form of case reports and case series. PATIENT CONSENT DISCLOSURE STATEMENT: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.