Neurogenic thoracic outlet syndrome (TOS) is one of the most controversial pain disorders of the upper extremity. Difficulty arises in the effective diagnosis and then classification of the true and subjective forms of TOS. The condition itself is a clinical manifestation resulting from compression of the neurovascular bundle in the thoracic outlet. Potential sites of compression within the outlet have been identified as: the interscalene triangle, costoclavicular space and the subpectoral tunnel. True neurogenic subtypes are rare (1 per 1 million) and present with clear clinical signs of nerve compression. In contrast, subjective subtypes of neurogenic TOS tend to be the vast majority and they present with non-specific clinical findings.