"NTOS" redirects here. For the Windows NT microkernel used in computing, see Windows NT kernel . Thoracic outlet syndrome The right brachial plexus , viewed from in front. Specialty Vascular surgery , thoracic surgery Symptoms Pain, weakness, loss of muscle at the base of the thumb , swelling, paleness, bluish coloration   Usual onset 20 to 50 years of age  Types Neurogenic , venous , arterial  Causes Compression of the nerves, arteries, or veins in the passageway from the lower neck to the armpit  Risk factors Trauma , repetitive arm movements , tumors , pregnancy , cervical rib  Diagnostic method Nerve conduction studies , medical imaging  Differential diagnosis Rotator cuff tear , cervical disc disorders, fibromyalgia , multiple sclerosis , complex regional pain syndrome  Treatment Pain medication, surgery   Frequency ~1%  Thoracic outlet syndrome ( TOS ) is a condition in which there is compression of the nerves, arteries, or veins in the passageway from the lower neck to the armpit .  There are three main types: neurogenic , venous , and arterial .  The neurogenic type is the most common and presents with pain, weakness, and occasionally loss of muscle at the base of the thumb .   The venous type results in swelling , pain, and possibly a bluish coloration of the arm.  The arterial type results in pain, coldness, and paleness of the arm.  TOS may result from trauma , repetitive arm movements , tumors , pregnancy , or anatomical variations such as a cervical rib .  The diagnosis may be supported by nerve conduction studies and medical imaging .  Other conditions that can produce similar symptoms include rotator cuff tear , cervical disc disorders, fibromyalgia , multiple sclerosis , and complex regional pain syndrome .  Initial treatment for the neurogenic type is with exercises to strengthen the chest muscles and improve posture.  NSAIDs such as naproxen may be used for pain.  Surgery is typically done for the arterial and venous types and for the neurogenic type if it does not improve with other treatments.   Blood thinners may be used to treat or prevent blood clots .  The condition affects about 1% of the population.  It is more common in women than men and it occurs most commonly between 20 and 50 years of age.  The condition was first described in 1818 and the current term "thoracic outlet syndrome" first used in 1956.   Contents 1 Signs and symptoms 2 Causes 3 Diagnosis 3.1 Classification 3.1.1 By structures affected and symptomatology 3.1.2 By event 3.1.3 By structure causing constriction 4 Treatment 4.1 Physical measures 4.2 Medications 4.3 Surgery 5 Notable cases 6 See also 7 References 8 External links Signs and symptoms [ edit ] TOS affects mainly the upper limbs, with signs and symptoms manifesting in the shoulders, neck, arms and hands. Pain can be present on an intermittent or permanent basis. It can be sharp/stabbing, burning, or aching. TOS can involve only part of the hand (as in the pinky and adjacent half of the ring finger), all of the hand, or the inner aspect of the forearm and upper arm.