Tuesday, August 19, 2008

Thoracic Outlet Syndromes

True TOS is a clear syndrome with weakness and sensory loss in the arm and hand usually caused by a fibrous band over which the lower trunk of the brachial plexus is stretched and angulated. It may coexist with a small rudimentary cervical rib.

Arterial TOS involves ischemia or even emboli in fingers and hands from a cervical rib causing stenosis and poststenotic dilatation of the subclavian artery. This type is more common in athletes.

Venous TOS is an acute or chronic syndrome with swelling of the arm due to stenosis or thrombotic occlusion of the subclavian vein.

Disputed (or nonspecific nonneurologic) TOS are chronic aching and pains or paresthesias in arms and shoulders with no findings. This is a large group, but neurologic signs are "either nonexistent or meager."

Posttraumatic TOS asociated with clavicular fracture and associated brachial plexopathy see separate article.

Clinical presentations
True TOS young to middle aged women develop paresthesias , pain and weakness on the ulnar border of the hand, rarely much pain, and no vascular symptoms. Per Thomas Swift they may have hand,arm, shoulder and neck pain. They have low set shoulders, long graceful "swan" necks and horizontal or downsloping clavicles. Muscle wasting resembles CTS with wasted APB but usually some ulnar innervated muscles waste as well. Sensory loss does not split the fourth digit. There is often weakness of the forearm flexors. The differential is median and ulnar neuropathy, lower trunk plexus lesion, radiculopathy. CT and MRI usually miss the fibrous band but may show other causes of plexus lesion. Plain films show characteristic bony abnormality most of the time. Treatment is supraclavicular exploration with division of the band.

Notes-- Adson;s test is valueless, because 11-80 % healthy controls obliterate radial pulse by holding hand above head. Other similarly useless tests are photoplethysmographic studies of blood flow in the fingers following Adson's test, the elevated arms stress test (east) with the arm abducted to 90 degrees, the elbow flexed and braced, the fist opened and closed for several minutes. Bruits are of no significance in the subclavian fossa. Arteriography and dopplers are useless. In contrast, there may be a Tinel's in the fourth and fifth fingers tapping the brachial plexus, and symptoms may be exacerbated pulling arm down to ground and relieved by pushing up (again from Swift). Patients are better when lying down (contrast to CTS) and by using armrests.

Plain films may show upper 3-4 thoracic vertebrae due to shoulders. OBLIQUE CERVICAL SPINE FILMS WILL SHOW CERVICAL RIBS IF THEY ARE PRESENT! Symptoms are usually unilateral but cervical rib may be bilateral, usually C 7 also occassionally C 6. The cervical rib has a one percent prevalence, again not all symptomatic. The fibrous band extending off the rib technically compresses the C8 and T1 roots.

The best treatment of nonspecific neurologic TOS may involve posture correction, stretching and strengthening exercises (of rhomboids, levator and trapezius, the shoulder elevators), and an orthosis designed to elevate the shoulder. Operate if a band is present it will help.

The association of TOS in musicians is debated by Stewart

Brachial plexitis causes and differential and foils

Avulsions occur with traction injuries and may be overlooked in patients with multi-trauma.

Clavicle fractures can injure the plexus through bone fragments or hematomas, scar tissue (in a healed fracture) or development of a subclavian pseudoaneurysm.

Stingers and burners (See separate post http://emgnotes.blogspot.com/2007/04/traunmatic-neuropathy-stingers.html ). Compression of the upper brachial plexus may occur between the shoulder pad and upper medial scapula and may be prevented with an orthosis (Markey et al, 1993, Am J Sports Med). Lesion can also be in the ventral rami, cord, roots or cervical cord but in professional players is more likely to be spinal stenosis .

Intraoperative plexopathy of brachial plexus can be due to hyperabduction of the relaxed arm, plexitis (autoimmune) following surgery, during median sternotomy such as CABG (5-7 % of time) which can mimic an ulnar neuropathy, with variable locale and severity. It can occur with traction on the plexus during wide sternotomy, during jugular cannulation, and is tenfold higher when the internal mammary artery is used for bypass grafting. Forceful traction can also fracture the first rib that then can cause plexopathy. Upper trunk damage can occur if the patient is held head down and the arm is abducted simultaneously.

Acute compression occurs with coma, or carrying heavy backpacks causing a bilateral syndrome especially affecting serratia anterior.

Hematomas during axillary angiograms can cause blood leak at edge of pectoralis muscle and recovery IF blood is removed rapidly. False aneurysms can occur years after trauma to plexus, median or radial nerve.

Newborns do not have a falling incidence of brachial plexus injury (0.05-0.3 % births) with Erb's being most common (weak shoulder abduction and elbow flexion), Klumpke's less common.

Malignant plexopathy is most often due to cancer of lung, breast, or lymphoma, rarely early except in the Pancoast tumor syndrome. It usually presents with shoulder pain radiating down the arm (medial most often) followed by paresthesias and weakness. The differential includes radiation plexopathy, intraoperative plexus trauma, and unrelated brachial plexitis.

Pancoast syndrome due to tumor at apex of the lung causes pain down inner arm with two thirds developing Horner's syndrome, and one third, weakness and sensory changes in lower trunk distribution.

Primary tumors of brachial plexus include neurofibromas (often/usually plexiform) with pain, supraclavicular mass, and mild neurologic deficit. Schwannomas with "dumbbell" lesions and sensory symptoms withouu deficit. Intraneural perineurioma (or localized hypertrophic neuropathy) presents with slowly progressive upper limb deficits. Malignant nerve tumors are rare.

Radiation plexitis can occur within 26 years of radiation of the plexus and presents with sensory and motor signs and swelling. Horner's occurs less frequently than in malignant plexitis but it can happen. Radiation is commonly, but not universally thought to be more likely to affect the upper trunk. It may be relentlessly progressive and lead to a useless arm. Occassionally it may stop or respond to PT or OT.

Radiation can also cause malignant nerve sheath tumors with painful enlarging mass and dysfunction. Ischemic plexitis can occur due to radiation induced segmental occlusion of the subclavian artery.

Thoracic outlet syndromes are discussed in another post.

Parsonage-Turner syndrome causes pain then weakness. It may mimic a shoulder joint lesion.

Hereditary neuropathy with liability to pressure palsies (HNPP) often affects the brachial plexus.

Patients with plexitis due to diabates have a subacute onset and good recovery. Plexitis in heroin addicted patients has less severe pain, and involvement of the lower part of the plexus.