Helical CT Angiography of Thoracic Outlet Syndrome

714 Helical CT Angiography of Thoracic Outlet Syndrome We read with interest the study by RemyJardin et al. [1] describing findings of helical CT angiography with thoracic outlet syndrome. Their elegant study of 79 patients shows the usefulness of helical CT in portraying this complex anatomic region. Furthermore, their detailed morphometric analysis helps to objectively quantify the functional changes with arm movement in the region. However, we disagree with their claim that this is the first in vivo evaluation of functional anatomy. In fact, several groups of investigators have published findings using helical CT [2], conventional CT [3], duplex sonography [4], and venography with pressure measurements [5]. All of these studies found vascular compromise in patients when the arm was placed under a functional stress. The findings of the larger French study would be better appreciated if discussed in the context of the existing knowledge that it reinforces and builds on. Our group has also studied helical CT in healthy, asymptomatic volunteers. We found noteworthy compromise of the costoclavicular space, as well as marked venous compression. These findings have been seen in other studies of asymptomatic arms [5–7]. We are surprised that Remy-Jardin et al. have discovered a statistically significant difference between the maximum clavicle and first rib distance in their symptomatic patients with postural maneuver, which they did not observe in their healthy, asymptomatic volunteers [1, 8]. This discrepancy may be accounted for by the alternative interpretation: that it is only the minimum distance between the clavicle and first rib that is correlated with vascular compromise, and that symptoms related to overuse occur superimposed on a background of widespread anatomic compression. The lack of a difference in meaningful measurable parameters between healthy and symptomatic patients is important because it would suggest that these anatomic differences on helical CT scanning are not useful in differentiating patients with and without the thoracic outlet syndrome, and that the assessment of the entire clinical picture remains essential in the diagnosis of these patients. On this latter point, there seems to be consensus among many groups that objective testing and imaging are useful in portraying the anatomy. However, the clinical examination remains dominant because neurovascular compression is common in asymptomatic individuals whether it is measured by physical examination or by expensive diagnostic imaging. We appreciate the opportunity to comment on this important study. Jon S. Matsumura James S.T. Yao Albert A. Nemcek, Jr. Northwestern University Medical School Chicago, IL 60611