Adson's sign is no longer used as a positive diagnosis of TOS since many people without TOS will show a positive Adson's. There is minimal evidence of interexaminer reliability. Thoracic outlet obstruction may be caused by a number of abnormalities, including degenerative or bony disorders, trauma to the cervical spine, fibromuscular bands, vascular abnormalities, and spasm of the anterior scalene muscle. Symptoms are due to compression of the
brachial plexus and
subclavian vasculature, and consist of complaints ranging from diffuse arm pain to a sensation of arm fatigue, frequently aggravated by carrying anything in the
ipsilateral hand or doing overhead work such as window cleaning. ==Process==