http://www.hf.hio.no/mensend/student...menter/TOS.pdf

The first page - see the rest of 76 page pdf article at the above link -

Thoracic Outlet Syndrome

Introduction
There are few topics more controversial in the field of surgery than
thoracic outlet syndrome (TOS). The term TOS is used to describe
patients with compression of the subclavian vein, subclavian artery, and
the brachial plexus in the region of the thoracic outlet. The name itself is
confusing and misrepresentative because anatomically the area of compression
between the scalene muscles and the first rib is termed correctly
the thoracic inlet. The wide variability of patient symptoms that include
vascular and/or neural signs, diffuse symptoms, and the lack of a valid
reliable test to confirm the diagnosis of TOS makes it difficult to identify
correctly those patients with TOS.
Compression of the vascular structures is relatively easy to identify with
objective vascular studies such as venograms and arteriograms. With such
objective evidence, many physicians are confident in making the diagnosis
of TOS. In cases of severe compression and compromise of the
subclavian vein or artery, surgical treatment is often recommended.
However, in less severe cases, surgical intervention is performed less
frequently and is more controversial.
The neurologic signs and symptoms can range from mild paresthesias
and numbness to intrinsic hand muscle atrophy. Patients with intrinsic
hand muscle atrophy that localizes to the level of the brachial plexus with
no distal sites of nerve compression likely have a cervical rib and/or
anomalous ligamentous bands that are compressing the nerve. There is
little controversy regarding the treatment of these patients; although in
most cases surgical decompression of this region is suggested, recovery of
intrinsic muscle function is not always forthcoming.
The main controversy in patients with TOS relates to the patient with
the neurologic-type complaints of paresthesias, numbness, and pain but
with no positive objective test to identify the cause. This neurogenic TOS
is thought to be over-diagnosed by some health care professionals
(including physicians, nurses, physical therapists, and occupational therapists)
and under-diagnosed by other health care professionals.