Anomalies at the thoracic outlet are frequent in the general population

: Abnormal anatomy at the thoracic outlet is frequent in patients operated on for thoracic outlet syndrome (TOS). The present study was designed to find out the rate of thoracic outlet anomalies in the general population. : Fifty cadavers representing a general population were subjected to a total of 98 meticulously performed cervical dissections to ascertain the frequency of congenital anomalies in the thoracocervicoaxillary region. : During the 98 cervical dissections, 62 instances of abnormal anatomy of the thoracic outlet were found, and fully normal anatomy was found in 36 cases. Of the total 69 abnormalies, 66 could be classified according to Roos: 37 were type 3 abnormalities, 15 were type 5, 9 were type 11, and there was 1 each of type 4, type 6, type 7, type 9, and type 10 abnormalities. The remaining 3 abnormalities did not fit into Roosʹ classification. Only 10% (5/50) of the cadavers had a bilaterally normal anatomy. : The results demonstrate that abnormal structures, such as congenital bands in the thoracic outlet, are more common in the general population than had previously been described. We suggest that fibrous bands confer a predisposition for TOS following a certain degree of stress or injury.