[Annie S. Dubuisson, MD
Department of Neurosurgery, CHU Liege, Belgium
(Dr. Dubuisson was a peripheral nerve fellow at LSUMC)

Abstract:
Thoracic outlet syndrome (TOS) is due to compression/irritation of brachial plexus (BP) elements ("neurogenic TOS") and/or subclavian vessels ("vascular TOS") in their passage from the cervical area toward the axilla. The usual site of entrapment is the interscalenic triangle. TOS is a source of disagreement among clinicians regarding its incidence, diagnostic criteria and optimal treatment. Constitutional factors, like a cervical rib, predispose to the development of TOS. The syndrome often develops during the 3rd or 4th decade, following external factors such as trauma, weight excess, incorrect shoulder posture.

The clinical picture can be varied: pain in the cervical region and arm, paresthesias (medial side of arm predilected) aggravated by overhead positions of the arms, hand intrinsic muscle deficit/atrophy, easy fatiguability, paleness, coldness of hand.]

more-
http://www.medschool.lsuhsc.edu/Neur...enter/TOS.html