The Thoracic Outlet Syndrome 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.
The clinical examination may be entirely normal or show cervical muscle spasm, tenderness of BP in the supraclavicular area, radial pulse attenuation and occurence of symptoms upon positional maneuvers, sensory or motor deficit. The diagnosis is based upon clinical evaluation and absence of other relevant pathology. Therefore, the cervical spine and distal peripheral nerves are studied by radiological and electrophysiological studies. There is no laboratory test confirming TOS: most of the time, there is no anatomic variation seen radiologically and electrophysiological testing is normal. The scalene muscle block appears a helpful diagnostic tool if used with the other clinical data.