Measurement of subclavicular pressure on the subclavian artery and brachial plexus in the costoclavicular space during provocative positioning for thoracic outlet syndrome

Thoracic outlet syndrome is thought to be caused by compression of the brachial plexus or subclavian artery in the interscalene, costoclavicular, or subcoracoid space. Some provocative tests are widely used for diagnosing thoracic outlet syndrome. However, whether provocative positions actually compress the neurovascular bundle in these spaces remains unclear. The purpose of this study was to investigate the possibility of neurovascular bundle compression in the costoclavicular space by measuring the pressure applied to the brachial plexus and subclavian artery in provocative positions. Bilateral shoulders of eight fresh-frozen transthoracic human cadavers with no obvious anatomical abnormalities were used in this study. There were three female and five male cadavers with a mean age of 81.7 years (range 72-90 years). The pressure on the brachial plexus and subclavian artery between the clavicle and first rib were measured using a 0.13-mm thin pressure sensor in each of four provocative positions (depressed position, alternative Eden position, throwing position, Wright position). Nerve contact pressure was increased in seven shoulders in the Wright position (2.87 +/- 3.13 N/cm(2); range 0.81-9.76 N/cm(2)). The frequency of nerve compression in the Wright position was significantly higher when compared to that in the other three limb positions (P = 0.018). Artery contact pressure was increased in three shoulders in the Wright position (mean 0.59 +/- 0.13 N/cm(2); range 0.45-0.7 N/cm(2)). As was the case with nerve compression, the frequency of compression tended to be higher for the Wright position, but no significant difference was seen. In four of eight specimens with no obvious anatomical abnormalities, the brachial plexus was compressed in the costoclavicular space in the Wright position. The Wright position thus may be a useful position for inducing nerve compression in the costoclavicular space.