The diagnosis of thoracic outlet syndrome (TOS) is sometimes confused by its nonspecific symptoms and various etiologies. Moreover, the paths of involving nerves and arteries are highly diverse. We report a 35 year-old man who had numbness and coldness in his left upper extremity with no improvement to medical therapy. The electrophysiologic studies were normal. Radial artery pulse was absent and the thermography revealed markedly reduced temperature below the left mid-forearm. The arteriography showed compression of the left subclavian artery between the clavicle and the 1st rib with aneurysmal change proximal to the compression. Occlusion of the left brachial artery and collateral arteries were also observed. Under the diagnosis of vascular TOS, 1st rib resection was performed and his symptoms were relieved. Vascular TOS may be considered in cases of upper limb paresthesia. (J Korean Acad Rehab Med 2007; 31: 257-260)
