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Case Reports in Orthopedics
Volume 2015 (2015), Article ID 378627, 4 pages
Case Report

Ultrasound-Guided Quadrilateral Space Block for the Diagnosis of Quadrilateral Syndrome

University of California, Riverside School of Medicine, Riverside, CA 92507, USA

Received 2 December 2014; Accepted 4 January 2015

Academic Editor: Kiyohisa Ogawa

Copyright © 2015 Hamilton Chen and Vincent Reginald Narvaez. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Quadrilateral space syndrome (QSS) is a rare nerve entrapment disorder that occurs when the axillary nerve and posterior circumflex humeral artery (PCHA) become compressed in the quadrilateral space. QSS presents as vague posterolateral shoulder pain that is exacerbated upon the abduction and external rotation of the shoulder. Diagnosis of QSS is difficult because of the vague presentation of QSS. In addition, even though MRI and MR angiography can be used in QSS diagnosis, there is currently no “gold standard” diagnostic imaging studies for QSS. In this case report, we describe a novel ultrasound-guided technique for a diagnostic quadrilateral space block and present a case where the diagnostic block was used to diagnose QSS. We believe that a diagnostic block of the quadrilateral space is a useful adjunct in the evaluation of patients with suspected QSS, especially in cases where examination findings and other diagnostic modalities are indeterminate.