Objectives:
Quadrilateral space syndrome (QSS) is described as compression neuropathy of the axillary neurovascular bundle in the quadrilateral space of the shoulder. This neurovascular bundle includes the posterior circumflex humeral artery (PCHA).
The rate of compression of the neurovascular bundle upon abduction and external rotation is unknown in the normal population.
The diagnosis of QSS is hence challenging and subject to some controversy.
The aim of our study was to assess if ultrasound can be used to characterize the heamodynamic properties of the PCHA.
Methods:
Asymptomatic patients were recruited.
All scans were performed on Seimens Sonoline Antares release 5.0 with linear VFX9-4MHz and VFX13-5MHz transducers. Hemodynamic characteristics of the PCHA in neutral position, and in abduction and external rotation were assessed. Outcome measurements included the PSV, EDV, RI and AT.
The teres minor muscle was also compared to the adjacent infraspinatus muscle in order to determine presence of fatty infiltration.
Results:
26 patients were recruited (mean age 40 ± 12 years). Ultrasound was able to visualize and characterize the PCHA in all cases.
Three patients (5.8%) presented with occlusions upon abduction and external rotation. The average PSV was 29.6 (± 9) cm/sec in neutral position, and 27.7 (± 19.8) cm/sec during abduction.
None of the patients showed signs of fatty infiltration of the teres minor.
Conclusion:
Ultrasound is capable of assessing occlusion/stenosis of the PCHA on abduction and external rotation in asymptomatic patients.
This modality can be used as the preferred first-line imaging tool for the diagnosis of QSS.