Helical CT angiography of thoracic outlet syndrome: Functional anatomy

OBJECTIVE. The objective of this study is to determine the anatomic charact eristics of the thoracic outlet in symptomatic patients before and after po stural maneuver. SUBJECTS AND METHODS, Seventy-nine symptomatic patients (61 female patients [group 1]; 18 male patients [group 2]; mean age, 38 years) underwent helic al CT angiography of the thoracic apexes in the neutral position and after a postural maneuver, enabling the evaluation of the functional anatomy of t he musculoskeletal and arterial structures of the ipsilateral thoracic outl et. RESULTS. A statistically significant difference was found between the distr ibution of the distances (maximum and costosubclavian) measured in the neut ral position and after postural maneuver in groups 1 and 2. The median valu e of these distances was smaller after postural maneuver in groups 1 and 2. A statistically significant difference was found between the distribution of the distances (maximum and costosubclavian) measured in patients of grou p 1 with arterial stenosis and in patients of group 1 without arterial sten osis. A slight indentation of the anterior wall of the subclavian artery wh en it arches around the anterior scalene muscle was observed in 39 patients (64%) in group 1 and in 11 patients (61%) in group 2 in the neutral positi on, in 19 patients (31%) in group 1 and in six patients (33%) in group 2 af ter the postural maneuver. The predominant positional changes of the vascul ar structures were the posteroanterior displacement of the subclavian vesse ls observed in groups 1 and 2, the arch made by the subclavian artery above the first rib in 40 patients (66%) in group 1 and nine patients (50%) in g roup 2, and the posterior displacement of the axillary artery observed in 3 6 patients (59%) in group 1 and in 12 patients (67%) in group 2. CONCLUSION. Helical CT shows significant narrowing of the costoclavicular s pace after postural maneuver in symptomatic patients.