[The thoracic outlet: true syndromes, disputed syndrome (TOS, thoracic outlet syndrome). Current status 1991].

There are 5 syndromes involving the thoracic outlet. The first four, although not well known, especially the first two, are authentic; they are: 1) arterial, due to a well formed cervical rib or to an incompletely formed first rib; 2) neurological, related to the fibrous band associated with a rudimentary cervical rib or a giant transverse process of C7; 3) venous, namely "effort thrombosis"; 4) late post-traumatic, secondary to a fracture of the clavicle. The study of these four syndromes prepares the reader to that of the controversial fifth syndrome, which is entirely subjective, made only of symptoms. The fifth syndrome, by very far the most frequent in the literature, called "scalenus anticus syndrome" in the past, now called "thoracic outlet syndrome" or "TOS" by North-American authors, has two varieties, one where hypotonic shoulder muscles, mostly in women, respond well to specific and simple exercises, and one where there is an accident in the background, a whiplash type of injury in most cases. Despite the fact that TOS is made only of symptoms, "diagnosing" it has led to scores of operations, scalenotomy in the past, now mostly resection of the first rib, sometimes scalenectomy. Huge surgical statistics, that deal mostly with resection of the first rib, have not proven the authenticity of this second variety of the 5th syndrome. Surgeons report only early surgical results, and the results claimed are invariably impressive. Never is there a statistic about return to work after surgery. First rib resection can be dangerous and it can be complicated by tardy permanent brachial plexopathy. One very recent European study proves the discrepancy between the early appreciation of the results by the surgeon and the late appreciation by independent observers.