Thoracic Outlet Syndrome
Thoracic outlet syndrome (TOS) is a condition wherein the surrounding neurovascular tissues or the tissues itself of the thoracic outlet are injured, compressed, or irritated (Chang & Bohan, 2009). The surrounding structures may involve the base of the neck, in between the clavicle and the first rib, and the muscles under the shoulder and upper part of the chest. Specifically, the thoracic outlet is located within the borders of the first rib, spine, clavicles, and manubrium. Hence, any insult to the anatomical structures that directly line or lie within these neurovascular tissues may result to thoracic outlet syndrome. Patients usually develop TOS due to frequent poor positioning of the neck muscles for an extended period of time and innate anatomical abnormalities such as malformed ribs. TOS is common among people who work as secretaries and cashiers or occupations that involve major lifting of heavy equipments hence the need for routine referral (Chang & Bohan, 2009). Women ages 30 to 55 years are commonly found to have thoracic outlet syndrome (Lohr, 2001).
There are three types of TOS namely the true neurogenic TOS, arterial or venous (vascular) TOS, and disputed TOS (Lohr, 2001; Chang & Bohan, 2009). When the nerves in the brachial plexus become compressed, this results to true neurogenic TOS. On the other hand, when the major artery that leads to the arm becomes compressed, this results to arterial or vascular TOS. Meanwhile, the last type of TOS is not actually considered TOS but it is used only to describe the experienced chronic pain in related anatomical locations for TOS. These patients do not have any other diseases or explained cause for the experienced pain (Lohr, 2001).
Thoracic outlet syndrome is not an emergency case and patients are usually treated and referred only when symptoms appear. First, vascular TOS prompts more urgent interventions than neurogenic TOS hence urgent referral is needed. Second, neurogenic TOS involving compression of the brachial plexus requires outpatient referral and treatment most commonly physiotherapy. Third, vascular TOS in severe cases that lead to complications such as lack of oxygenation in the limb resulting to loss of limb may require immediate referral for surgical intervention (Chang & Bohan, 2010).
Diagnostics and Protocols for TOS
Thoracic outlet syndrome symptoms usually manifested in patients are pain in the neck and shoulder region that radiates to the extremities (arm and hand). Patients may also experience a tingling sensation or numbness in the affected area. Weakness of the affected area may also be present (Lohr, 2001). It is important to note that there are no specific diagnostic tests for TOS. Diagnosis is usually made based on the combination of clinical manifestations, physical examination findings, and results of different diagnostic and laboratory tests.
Non-specific tests for TOS include the Adson’s and Allen’s test. First, Adson’s test is performed by asking the client to breathe deeply while hyperextending his neck then turning his head from side to side. If the physician observes that the strength of the pulse on the wrist contralateral to the head turn is decreased, this suggests presence of TOS. Second, Allen’s test is performed by asking the client to raise and rotate the affected arm while positioning his head on the opposite side of the arm being rotated. If the physician also notes that the pulse strength on the opposite side is decreased, this suggests TOS also. On both occasions, TOS is potentially caused by subclavian artery compression (Lohr, 2001). These two tests are considered unreliable tests for thoracic outlet syndrome because more than 90 percent of patients who do not present symptoms have pulse strength variations from changes in positioning (Chang & Bohan, 2009).
Some of the diagnostic and laboratory tests used to support the diagnosis of thoracic outlet syndrome are cervical and chest radiography, color flow duplex scanning, arteriography, and venography (Chang & Bohan, 2009). These diagnostic tests are not specific or definitive of TOS but these are used to rule out other diseases that may have caused the experienced pain in the affected area of the patient. Chest radiography is ordered if the pain location is in the chest or first rib. This is commonly related to arterial TOS but can also be a predisposing factor to the neurogenic type probably as a consequence of neck injury. Even the result of this radiography is also not reliable because it is commonly a false-positive result. Cervical angiography is also ordered for suspected TOS and will usually reveal skeletal deformities. Arteriography is indicated if there is an emboli in the arms and hands, a pulse pressure of 20 mmHg or more, and a positive elevated arm stress test (EAST). EAST is performed by asking the client to form a right angle with his affected arm at the level of the shoulders, forming an L-like figure. Then, the patient is asked to open and close his hands for 3 minutes. Failure to continue doing this for 3 minutes suggests presence of TOS. This stress test is also not reliable because even other patients who do not have the disease or have other diseases may not be able to complete the exercise. Venography is indicated for patients who manifest with edema of the arms or hands, cyanosis on one side of the extremities, venous lines prominently seen over the skin of the upper extremity and chest (Chang & Bohan, 2010).
Another diagnostic test used for TOS is the color-flow duplex testing for patients with suspected TOS of vascular origins. Duplex examination is used to see the movement of blood in the arteries and veins through the emission of sound waves creating both picture of blood vessels (traditional) and determining speed of blood flow (Doppler ultrasonography) in these blood vessels. Duplex examination is performed in the radiology department using the traditional and Doppler ultrasounds. The patient may be asked to wear a patient gown and lie down on the examination table. A gel will be spread over the affected area to be examined and a transducer, which sends the sound waves, will be moved around it. The patient is primarily required to lay still during the whole exam though at some point, the patient will be instructed to change position, take a deep breath, and other instructions will be given. Results showing normal flow of blood, without any signs of blood flow impedance, and normal blood pressure ranges indicate a normal result. However, any deviations from these are abnormal and indicate that the blood vessel is occluded by a blood clot or a plaque (Dugdale, 2008).
From the discussion in the two previous paragraphs, authors are correct in emphasizing that the diagnostic tests used for diagnosing TOS are not accurate or at the level of gold standard. To reiterate how diagnosis is made for TOS, careful analysis of presenting clinical manifestations, assessment findings, and diagnostic tests results are used to rule out other diseases and make the diagnosis of TOS (Lohr, 2001). Due to this, the prevalence of thoracic outlet syndrome is also inaccurate because TOS is oftentimes misdiagnosed or undiagnosed. It is reported that TOS is diagnosed among 3-80 people per 1000 population (Chang & Bohan, 2010). However, there has been no reported mortality directly associated with TOS. There are consequent disabilities from TOS such as loss of the functionality of upper extremities. In line with this, patients may also lose their jobs especially if their jobs involve activities requiring overhead movements of the arms and hands. Furthermore, neurogenic TOS results in neurologic and sensory deficits. Adverse complications may also arise from surgery for TOS treatment (Chang & Bohan, 2010). Even though the diagnostic tests are not gold standard and accurate in diagnosing the condition, health professionals are still able to help patients in identifying the underlying cause of disease and provide appropriate treatment for these hence, prevention of long-term and debilitating complications.
There are specific guidelines or protocols to guide professionals in diagnosing thoracic outlet syndrome. The Society for Vascular Ultrasound (SVU) emphasizes seven specific guidelines to consider in the physiologic evaluation of TOS (2007). First, patient communication is very important in giving information to the patient regarding the TOS condition and specific referral to doctors. It is also important to inform the patient regarding risk factors of TOS and lifestyle change required if diagnosed with TOS so that the patient becomes educated and aware about his or her possible condition. Second, patient assessment allows health professionals to obtain pertinent health history and physical examination findings from the patient that may potentially explain the history of the present disease. Third, the client is subject to appropriate and required diagnostic procedures to evaluate the patient’s condition and underlying causes of disease. Fourth, the results of the diagnostic tests are documented, reviewed and interpreted based on guidelines; results are collaborated with the appropriate health team members. Fifth, the physical and diagnostic findings are presented to the physician for final diagnosis. Sixth, there is a recommended time allotment for each procedure or step in the diagnostic process to allow optimum best results from both indirect (patient communication) and direct examinations (diagnostic procedures). Last, vascular technologists are recommended to be continually updated and educated regarding advancements in vascular technology and diagnosis to remain competent in the field (SVU, 2007).
References
Chang, A. K. and Bohan, J. S. (2010). ‘Thoracic Outlet Syndrome.’ Retrieved June 3, 2010, from http://emedicine.medscape.com/article/760477-overview
Dugdale, D. C. (2008). ‘Duplex ultrasound.’ Retrieved June 3, 2010, from http://www.healthline.com/adamcontent/duplex-ultrasound
Lohr, J. T. (2001). ‘Thoracic Outlet Syndrome.’ Encyclopedia of Medicine. Retrieved June 3, 2010, from http://findarticles.com/p/articles/mi_g2601/is_0013/ai_2601001345/
Society for Vascular Ultrasound (SVU). (2007). ‘Physiologic evaluation for thoracic outlet compression syndrome.’ Retrieved June 3, 2010, from http://www.svunet.org/i4a/pages/index.cfm?pageid=3286