ADSON TEST FOR THORACIC OUTLET SYNDROME (TOS) - SCALENE TRIANGLE The Adson test seems to be the most accurate test for TOS with a sensitivity of 79% and a specificity of 79% according to a review done by Gillet et al. (2001): This test asseses the posterior scalene post, where the brachial plexus and subclavian artery are passing through. Often patients with COPD or with an impairment of the diaphragm are using the scalenes more than usual to assist with breathing.This can lead to scalene hypert