Historical perspectives and anatomic considerations. Thoracic outlet syndrome.

The major developments in the evolution of understanding the thoracic outlet syndromes is presented in a chronologically historical record beginning with the first mention of a cervical rib by Galen in the second century A.D. Appreciation of the vascular and neurologic types of TOS progressed slowly through the centuries until detailed clinical studies were presented in the early 1900s. Interest in these syndromes increased steadily since then with description of the effectiveness of first rib resection by Murphy in 1910, and scalenotomy without cervical rib resection favored by Adson in 1927. The term "thoracic outlet syndrome" was coined by Peete et al in 1956 to encompass all the forms and causes of neurovascular compression in the base of the neck. Although rib resection may be considered the oldest operation on mankind, its application to treatment for TOS became popular only after Clagett's description of the posterior periscapular approach in 1962 and the transaxillary approach in 1966. The techniques of arteriography and venography were introduced in the 1960s and remain the hallmark for evaluation of the arterial and venous types of TOS. The neuroelectric studies introduced by Jebsen in 1968 have become popular, but offer little definitive diagnostic information for the neurogenic form of this syndrome. Recent histochemical studies of scalene muscles have shown important changes at the cellular level of the scalene muscles with trauma leading to TOS. The basic cause of the various neurovascular symptoms relates to anatomic abnormalities, either congenital or developmental, that cause abnormal compression and irritation of the major nerves and vessels in the thoracic outlet, causing certain people to have anatomic susceptibility to develop symptoms under certain conditions. These anomalies are described in some detail to facilitate the understanding, diagnosis, and surgical treatment of these special patients.