Thoracic Outlet Syndrome (TOS) is a condition causing numbness, tingling and weakness in patient's upper limbs. Symptoms are due to compression and restriction of the nerves and blood vessels (neurovascular bundle) that extend from the neck into the upper limb exerted by a patient's various anatomical structures. Neurovascular bundle compression can result in decreased nerve conduction and blood flow through the arteries supplying structures downstream from the restricted site. These anatomical restrictions include tight scalene muscles in the neck, tightened pectorialis minor muscle in the chest and extra ribs growing from the C7 vertebra. TOS can be diagnosed by using special tests designed to re-elicit neurovascular bundle compression. Upon obtaining a positive test, the patient can undergo osteopathic manipulative treatments (OMT) to change the anatomical restrictions allowing for a decrease of symptoms and even eradication of the syndrome altogether. Although diagnosis and treatment of TOS is common in osteopathic medicine, the effectiveness of the diagnostic special tests and treatment has not been thoroughly investigated. This study aims to examine the effectiveness of the special tests (Adson's, Wright's hyperabduction and Halstead maneuver) in diagnosing a change in blood flow through the arteries of the upper arm compared to evaluation with Doppler ultrasound to measure blood flow while the tests are performed. Patients with positive tests will be treated with OMT including myofascial release, soft tissue, and articulation to relieve restricting structures. Upon completion of treatment, the special tests will be performed again along with the Doppler ultrasound to measure blood flow through blood vessels. Results then are analyzed statistically for significance of the ability correctly diagnose and treat TOS symptoms. Results from this study will contribute towards the validity of teaching special tests in osteopathic medical schools and allow for a noninvasive treatment protocol for patients with TOS.