四角腔症候群：診断と臨床管理

Quadrilateral space syndrome (QSS) is a rare disorder characterized by axillary nerve and posterior humeral circumflex artery (PHCA) compression within the quadrilateral space. The quadrilateral space is bounded superiorly by the teres minor, inferiorly by the teres major, medially by the long head of the triceps, and laterally by the humerus. QSS most commonly presents in overhead athletes with posterolateral shoulder pain, paresthesias, and point tenderness over the quadrilateral space. Diagnosis is confirmed by MRI demonstrating fatty infiltration of the teres minor and MRA showing PHCA stenosis or occlusion with arm abduction. Management ranges from conservative therapy to surgical decompression or endovascular intervention depending on the clinical presentation.