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Thoracic Outlet Syndrome


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Thoracic Outlet Syndrome

  1. 1. THORACIC OUTLET SYNDROME Dr.Anil Haripriya
  2. 2. Historically Sir Astley Cooper described the symptoms of Thoracic outlet syndrome in 1821. In 1861, Coote reported the excision of a cervical rib. In 1903, Bramwell suggested the relationship of possible brachial plexus Compression and a normal first rib. The phrase Thoracic out let syndrome was first used by Peet in 1956 and was popularized by Rob and Standeven in 1958.In late 1960s and 1970s, the dominant operative trend centered around the transaxillary resection of the first rib empirically to relieve the symptoms of thoracic outlet syndrome. In recent years however the trend is towards exact location of the compression. The syndrome should be considered in all patients with neurological and vascular complaints of the arm. Basic understanding of the anatomy is absolutely vital in all diagnostic and operative considerations in thoracic outlet syndrome1. SURGICAL ANATOMY At the superior aperture of the thorax, the subclavian vessels and the brachial plexus traverse the cervicoaxillary canal to reach the upper extremity. The cervicoaxillary canal is divided by the first rib into two parts, the proximal one, composed of costoclavicular
  3. 3. space and the distal one, composed of axilla. The proximal division is more critical for neurovascular compression. It is bounded superiorly by the clavicle and inferiorly by the first rib, anteromedially by the costoclavicular ligament and posterolaterrally by the scalenus medius muscle along with long thoracic nerve. The scalenus anticus muscle divides the costoclavicular space into two compartments, the anterior one containing subclavian vein and the posterior one contains the subclavian artery and brachial plexus. This compartment is bounded by scalene anticus anteriorly, scalene medius posteriorly and the first rib inferiorly, is called scalene triangle. In this area accessory cervical ribs, taut or anomalous scalene muscles and aberrant bands may individually or collectively be involved in compressive process. The structures not only encircle the artery but also contiguous brachial plexus constituting the neurovascular bundle which continues as a unit through axilla. The subclavian vein which lies anteriorly, also joins the nerve-artery combination for making a unit that proceeds together peripherally to pass between the clavicle and first rib into axilla. At this junction, the subclavius, costocoracoid ligament and possibly aberrant tissue
  4. 4. cross over the neurovascular bundle which proceeds over the pectoralis minor muscle and inferiorly beneath the pectoralis major muscle. All these structures become involved in the motion of the shoulder, the only human universal joint which is ordinarily maintained in motor balance by the attachment of twenty four muscles and eighteen ligaments1. FUNCTIONAL ANATOMY2 The cervicoaxillary canal, particularly its proximal portion, the costoclavicular space has ample room for passage of neurovascular bundle. Narrowing of this space occurs during functional maneuvers. It narrows during abduction of the arm because clavicle rotates backwards towards the first rib and the insertion of scalenus anticus muscle. In hyper abduction, the neuro vascular bundle is pulled around the pectoralis minor tendon, the coracoid process and the head of humerus. The coracoid process tilts downwards and exaggerates the tension on the bundle. The sternoclavicular joint which ordinarily forms an angle of 15-20 degrees forms a smaller angle when outer end of the clavicle descends as in drooping of the shoulders in poor
  5. 5. posture and narrowing of the costoclavicular space may occur. During normal inspiration the scalene anticus muscle raises the first rib and narrows the costoclavicular space .The subclavian artery and brachial plexus traverses the scalene triangle on the first rib. Anatomical variations may narrow the superior angle of the triangle and cause impingement on the upper components of the brachial plexus and produce upper type of scalene anticus syndrome that involves the trunk containing elements of C5-C6.If the base of the triangle is raised, compression of the subclavian artery and trunks containing components of C7-C8 and T1 results in the lower type of scalenus anticus syndrome. There are three major types of thoracic outlet syndrome : 1.Nerurogenic type 90-95%. 2.Arterial type. 3.Venous type. ETIOLOGY OF THORACIC OUTLET SYNDROME3 CONGENITAL ACQUIRED Osseous. Fractured clavicle. Cervical rib. Callous and pseudo arthritis, Long C7 process Fractured first rib, Abnormal or anomalous first rib Exostosis or tumors.
  6. 6. Soft tissue Anomalous ant. scalene insertion. Scalene muscle injury Middle scalene insertion Previous operation scar Scalene muscle hypertrophy . Reattachment of ant. Scalene minimus. Scalene muscle. Abnormal ligaments and fibrous bands Soft tissue tumors Prefixed or post fixed Brachial plexus tumors. Brachial plexus Direct brachial plexus injury. Posture. Sagging shoulders, Sagging breasts. CONTRIBUTING FACTORS:- Mechanical pressure- All the shoulder girdle compression syndromes have one common feature, namely compression of brachial plexus, subclavian artery and vein usually between the first rib and the clavicle. With elevation of upper limb, there is scissor like approximation of the clavicle superiorly and the first rib inferiorly. Trauma- The role of trauma to scalene muscles was first reported by Ocshner and colleagues. There can be direct trauma to brachial plexus due to Whiplash flexion extension injury to the neck after a rear end automobile accident. Indirect trauma can be
  7. 7. due to work related repetitive micro stress trauma in patients whose jobs demand repeated elevation of upper limb or heavy weight lifting. A neurochemical theory suggests that an initial injury whether gross or from micro stress produces a local perineural inflammation in the soft tissues. HISTOPATHOLOGY-Machleder and coworkers subjected frozen specimen of anterior scalenus muscle from patients of thoracic outlet syndrome to fibretyping. Normal human skeletal muscle has two main types of fibres with respect to histochemical staining. They are in equal percentage. Type 1 fibres are slow twitch, has high oxidative enzyme capacity and lower glycolytic activity. Type 11. fibres are fast twitch, quick reacting has low oxidative capacity . There is marked increase in type 1 fibres in cases of thoracic outlet syndrome (85%). Double crush hypothesis- was reported by Upton and Mc Comas in 1973.It states that a proximal source of nerve compression will render the distal nerve segment more susceptible to second site of compression. The authors hypothesized that one site alone would not cause a clinical disturbance but summation of two sites
  8. 8. would cause clinical disturbance. This hypothesis is directly applicable to brachial plexus compression in that several anatomical structures may compress the brachial plexus. The association between carpal and cubital tunnel syndromes and thoracic outlet syndrome is supported by double crush syndrome. With increase in jobs requiring repetitive activity like assembly lines and keyboarding, a cumulative trauma disorder or repetitive stress disorder is now recognized. This disorder relates to multiple level nerve compression4. ANOMALIES- In a study carried out by authors5 34% of 200 cases, no structural anomaly was discernible from the axillary approach.8.5% had a cervical rib articulating with first rib directly or by a fibrocartilaginous extension.10%had scalene minimus muscle inserted on first rib or sibsons fascia.19% had an anomaly of the subclavius tendon or its insertion.43% had an anomaly of scalene muscle development or insertion. In 30% cases there were other cartilaginous anomalies which could not be related to the specific development characteristics. More than one abnormality was recognized in 22.5% of cases. In 33 cases presenting with spontaneous axillo-subclavius thrombosis (Paget
  9. 9. Schrotter syndrome) 55% had hypertrophy of subclavius tendon associated with enlargement of insertion tubercle in males (70%). First rib and cervical rib anomalies- During development C7 rib forms and then regresses to C7 transverse process. Various stages in evolution range from a complete C7 rib to a rudimentary form associated with fibrocartilaginous band. A cervical rib is associated with prefixed type of brachial plexus in which there is major contribution from C4 and minor contribution from T1.Fibrocartilaginous bands extending from the end of incompletely formed cervical ribs are best thought of as an anomaly of the cervical rib formation. The anomalies have been classified as type 1and type 2 bands by Roos and coworkers. Scalene muscle ABNORMALITIES. The separation of muscle bundles interdigitating between neurovascular structures accounts for the muscular bridges seen between the middle and anterior scalene muscles that often penetrate the brachial plexus. They are not pathological but result in neurogenic symptoms as a consequence of abnormal growth.. Unique configuration of
  10. 10. scalene muscle insertion that leads to compression of neurovascular structures in the inter scalene triangle which accounted for 43% of the congenital variations. CLINICAL FEATURES Despite the congenital nature of the anomalies the onset of symptoms is in early to middle adult life has been recorded virtually by all the surgeons. The delay in onset is most often related to post natal development. The widening of the chest and the growth of the clavicle continues up to the age of 22-25 years after which the pectoral girdle begins to descend .Still later, with loss of strength and tone of the supporting musculature of the shoulder girdle, there is further traction on the neurovascular bundle at the thoracic outlet. The symptoms of thoracic out let syndrome depend upon whether brachial plexus, blood vessels or both are compressed. Neurogenic manifestations are more frequent than vascular symptoms. Neurogenic symptoms consist of pain and paraesthesias which are present in approximately 90% of the cases. Motor weakness and occasionally atrophy of the hypothenar and interosseous muscles occur which is ulnar
  11. 11. type of atrophy. The symptoms occur most commonly in areas supplied by the ulnar nerve including the medial aspect of the arm and hand, fifth finger and lateral aspect of the 4th.finger.The onset of pain is usually insidious and commonly involves the neck, shoulder, arm and hand. The pain and paraesthesias may be precipitated by strenuous exercise or sustained physical efforts with arm in abduction and the neck in hyperextension. Symptoms may be initiated by sleeping with arms abducted and hand clasped behind the neck. The symptoms related to upper plexus from C4-C7 is correlated with symptoms involving head, neck and upper back. The lower plexusC8-T1 is usually related anatomically to the medial aspect of the arm and hand. The patients with neurogenic thoracic outlet syndrome are usually women in their 3rd to 5th decade. Female to male ratio is 4:1.The onset is usually abrupt. Certain activities such as typing, painting and lifting weights may precipitate the problem. In vascular thoracic outlet syndrome, arterial symptoms vary from digital vasospasm to gangrene depending upon degree of compression and irritation. Irritation of the vessel wall by bony
  12. 12. prominence may lead to damage of intima, thrombosis and embolisation or to the media resulting in aneurysm formation. Arterial insufficiency, embolisation, atherosclerosis, vasospasm associated with Raynaud's disease and reflex vasomotor dystrophy must be considered in differential diagnosis. In the presence of complete cervical rib , the supraclavicular course of the subclavian artery is displaced. There is an upward extension of the thorax so that the subclavian artery passes high in the neck as it emerges from the lateral border of scalenus anticus muscle , it is elevated and readily palpable well above the clavicle. There is suparaclavicular mass represented by the cervical rib at its articulating site with the first rib6. Short described two variants of cervical rib. In type [a] subclavian artery crosses the first rib medial to its exostosis. In this type, he found all major vascular symptoms. In type [b],the subclavian artery crosses the first rib lateral to its exostosis. The symptoms are generally neurogenic than vascular. The prolonged compression of subclavian artery may lead to- 1 Structural changes of the arterial wall leading to the thickened
  13. 13. vessel wall adherent to the surrounding structures. 2 Stenosis at the site of compression. 3 Post stenotic dilatation due to turbulence of blood. 4 Subclavian aneurysm may lead to thromboembolic changes7. Small emboli may lodge into digital and palmer arteries producing picture like Raynaud’s phenomenon. Large emboli blocking the bifurcation of brachial artery may result in major ischemia or gangrene of the hand and fingers. Venous symptoms consists of tingling, aching ,tired and painful limb associated at times with cyanosis, swelling and distended distal veins are the result of obstruction of axillo-subclavian venous system. Other venous disorders including effort thrombosis, thrombophlebitis, heart failure, tumors and aneurysm of the mediastinum and thoracic outlet canal and A-V fistulas must be differentiated. While taking the patients history, it is important to elicit and closely evaluate the exact postural attitudes adopted during work or play that provoke the symptoms for example athletic practices such as
  14. 14. swimming, volley ball, hiking with back pack. Work habits involved in painting, carpentry, paper hanging, hair drying and routine household work like hanging clothes and washing windows. It is important to question sleeping habits especially when related to hyper abduction of the arms. It is necessary to carry out a thorough general physical examination with emphasis on posture, anatomical abnormality in the neck , localized swelling and tenderness, deficiency in brachial blood pressure or pulses of the arm, venous cyanosis or distension of the veins, bruit in the neck, skin temperature changes in hands and neurological evaluation of the brachial plexus. Finally three classical maneuvers must be carried out precisely since these maneuvers are often misinterpreted after being inaccurately performed. Adson Test-( Scalene test) In 1927 Adson and Coffey demonstrated the influence of the scalene anticus muscle by asking the patient to elevate the chin , extend the neck and rotate the head to the affected side while taking the deep breath. This
  15. 15. will produce paraesthesias over the distribution of the brachial plexus and frequently obliterate the pulse at the wrist of the affected side6. Costoclavicular manouver- (Military position) Falconer and Weddel demonstrated this test in 1943.Back ward and downward bracing of the shoulders as in military position will cause costoclavicular compression of the subclavian artery. This position may be simulated by carrying heavy weights or in services by marching with full back pack.. This manouvre is opposite of hyper abduction. Hyper abduction manouvre1 -It is also called Elevated Arm stress test It was introduced by Roos. Both arms are abducted at 90degree and externally rotated with shoulders braced posteriorly for three minutes. Most patients of neurogenic thoracic outlet syndrome will not be able to complete the test as there will be severe pain and numbness along the distribution of the brachial plexus if there is compression. Differential diagnosis of thoracic outlet nerve compression
  16. 16. Carpal tunnel syndrome Shoulder disorders Ulnar compression at the elbow. Rotor cuff tendinitis Cervical spine pathology Biceps tendinitis Cervical spine injury Myositis of the shoulder Cervical disc herniation muscles. Spinal stenosis Sympathetic disorders. Neurological disease of the spine Raynaud’s disease Spinal canal tumors. Reflex sympathetic Miscellaneous conditions dystrophy Angina Investigatios4 1. Cervical spine x-ray films for assessment of arthritic or degenerative changes and presence of cervical ribs. 2. Chest x-ray film to identify apical lung pathology and superior sulcus tumor. 3. Nerve conduction studies and electromyography to delineate the possible significance of neuroforaminal or cervical disc disease, as well as median nerve compression at the carpal
  17. 17. tunnel or ulnar nerve compression at the cubital tunnel. These studies are very helpful in patients who have double crush syndrome. 4. F-wave studies and somatosensory evoked responses to evaluate the brachial plexus. 5. Non Invasive vascular studies. Digital plethysmography and pulse volume recordings are of limited value in neurogenic thoracic outlet syndrome. They appear helpful in patients with ischcaemic symptoms .Duplex scanning of subclavian artery and vein may reveal an aneurysm or Venous thrombosis and may provide some anatomic information before angiography. Intermittent arterial stenosis can usually be localized by B-mode ultrasound and Doppler1. 6. Arteriography:- It is performed only when the patient is suspected of having arterial complication of thoracic outlet syndrome such as supraclavicular bruit, a pulsatile mass or vascular symptoms and signs of upper limb thromboembolism. Arteriography can be antegrade or retrograde arteriogram of the
  18. 18. subclavian artery and brachial artery. 7. Venography:- It can diagnose subclavian vein thrombosis or stenosis at the level of first rib and status of the collateral circulation. 8. Impedance plethysmography , venous Doppler survey and venous duplex scanning can help in diagnosing venous obstruction early. 9. C.T. Scan, myelography, M.R.I. are done to rule out cervical spinal cord tumors, spinal stenosis or a herniated disc. Saggital M.R.I. in the plane of brachial plexus is under investigation and in future may provide an accurate means of assessing the point of actual compression nerves. 10. Electrophysiological studies:- The tests are beset with technical problem because of the site of brachial plexus as compression is often deeply situated in the confines of the bony inlet and located proximally at the level of nerve roots near the intervertebral foramina. 11.Ulnar nerve conduction velocities in neurogenic thoracic outlet
  19. 19. syndrome was popularized by Urschel and Razzuk2.They reported decrease in ulnar nerve conduction velocities in these patients and the nerve conduction returns to normal after surgical decompression. TREATMENT:- 1. Conservative. 2. Surgical management. Conservative treatment1 Once diagnosis of neurogenic thoracic outlet compression is established, an initial period of supervised conservative treatment is instituted before operation is recommended for six weeks. It includes analgesics, muscle relaxants, occupational adjustment to improve posture or avoid elevating the arm during work and sleep. Physiotherapy in the form of simple heat and cold application, massages and ultrasonic wave application to supraclavicular area is carried out. Shoulder girdle strengthening exercises are taught to women with poor musculature. Brassieres with broad and padded shoulder strap is advised for women with heavy sagging
  20. 20. breast. SURGICAL MANAGEMENT It is indicated if there is (a) failure of conservative management (b) worsening of neurogenic symptoms leading to intractable pain (c) loss of job or interference in daily activity. (d) acute vascular symptoms. The decision to operate should be discussed with the patient explaining the possibility of neural or vascular complications, the possibility of achieving partial relief or recurrence of symptoms should be emphasized when symptoms are more than two and half years duration. OPERATIVE TREATMENT : The controversy surrounding Neurogenic thoracic outlet syndrome is best explained by diversity of surgical operations available .Various combination of operations like scalenotomy , scalenectomy, cervical rib resection, first rib resection and neurolysis of brachial plexus may be
  21. 21. carried out by four approaches1. A:- Supraclavicular B:- Transaxillary C:-Infraclavicular D:-Posterior approach Aim of operation 1- Relieving of brachial plexus symptoms 2- Any abnormal osseous structures such as cervical rib, exostosis, abnormal first rib or fracture callous should be removed in majority of patients . Supraclavicular approach3 : It provides the best route to reach all the structures . It allows direct visualization of the anatomic relationship between bony and myofascial structures and the brachial plexus through scalene space in the thoracic outlet and related congenital anomalies along with access to the first rib and clavicle. If the anterior scalene muscle requires decompression, it must be excised rather than simply divided because of possible
  22. 22. adhesions formation or perforation of the muscle with lower nerve roots of the brachial plexus. In such cases the original symptoms would be aggravated by the retraction of the divided muscle fibres against the imbedded nerves. Transaxillary approach1 : When the clinical picture suggests costoclavicular or hyper abduction symptoms, surgical exploration through a trans axillary incision described by Roos and Owens is usually preferred. Some of the advantages of the axillary approach include excellent cosmesis ,readily palpable and easily visible ligaments and bony structures which may be involved in the compression of neurovascular bundle. At the same time, it allows access for dorsal sympathectomy when indicated. Author believes that sufficient compression of the brachial plexus to produce symptoms simultaneously causes measurable compression of the subclavian vessels even in the absence of vascular symptoms. At operation, if the patient has been prepared so that axilla, shoulder and lower neck are exposed with the arm draped in a sterile field, it is possible to perform hyper abduction and costoclavicular manoeuvers under anaesthesia with the
  23. 23. thoracic outlet structures directly exposed. Under these circumstances, the physiology of the compressive process and the offending structures whether bony or soft tissue, can be identified and divided or excised. In a series of 194 patients,14 required bone excision and 180 required soft tissue excision to relieve symptoms with 96% success rate. Infraclavicular approach : It is used for bilateral neurovascular symptoms but cosmetic results are less favourable than other approaches. It can be used for subclavian venous thrombosis and first rib excision. Posterior approach : It is adopted only when there is history of previous Operation by other approach. This approach requires cutting of heavy muscles before reaching the thoracic outlet. Rationale for sparing the first rib : The first rib is seldom in actual contact with the brachial plexus except for T1. After neurolysis and scalenectomy, the brachial plexus runs an unobstructed course. Resection of first rib is unnecessary and adds to post operative pain and shoulder immobility with higher risk of pleural damage at
  24. 24. the time of surgery. Vascular Thoracic outlet syndrome : Three anatomic components of the disease process namely- arterial compression, subclavian axillary arterial lesion and distal emboli if present has to be dealt with simultaneously. Arterial reconstruction is necessary in the presence of arterial aneurysm or mural thrombus. Artery is mobilized after resecting the cervical and first rib. End to end anatomists is performed. Aneurysmorraphy can be performed along with internal stenting of the subclavian artery. Distal embolic occlusion causes major difficulties in surgical treatment of the patient as they are multiple in number. Thromboendarterectomy can be tried in these patients for distal emboli. Venous thrombosis of subclavian vein.: Thrombolytic agents like urokinase or streptokinase are delivered locally to dissolve the thrombosis. If there is external compression demonstrated on venography, it should be relieved by supraclavicular route.
  25. 25. Complications of operation for thoracic outlet syndrome7 Nerve Injury. Vascular Injury Brachial plexus Subclavian artery Long thoracic nerve Subclavian vein Phrenic nerve Thoracic duct injury. Intercostobrachial nerve Lymphatic fistula Recurrent laryngeal nerve Lymphoedema Pleural complications Chylothorax Pneumothorax Wound infection Pleural effusion Lymph collection Haemothorax REFRENCES 1. Stallworth JM. Thoracic outlet compression syndromes in: Text book of vascular surgery. Principles and Techniques. Ed. Haimovici H. W. B. Saunders Philladelphia-Tokyo 3rd edition 1993; pp 829-839. 2. Urschel HC. Thoracic outlet syndrome in: Glenns Text book of Thoracic and Cardiovascular surgery. Ed. Baue AE. Appleton and Lange. London-New Jersey, 1996; pp 567-580 . 3. Richard D, Rutolo C. Neurogenic thoracic outlet syndrome in : Text book of Vascular surgery . Ed. Rutherford RB. W. B. Saunders Philladelphia-Tokyo.2000; pp 1184-1199. 4. Machleder HI. Vascular diseases of the upper extremity And Thoracic outlet syndrome in : Text book of vascular surgery . A comprehensive review . Ed. Moore WS. W.B.Saunders Philladelphia-Tokyo.1993: pp 592-605. 5. Machleder HI. Thoracic outlet compression syndrome In:Text book on Vascular surgery.Theory and Practice. Eds. Callow AZD, Earnst CB. Appleton &Lange London-New Jersey.1995; pp235-265. 6. Haimovici H. Arterial thromboembolism due to thoracic outlet book of Vascular surgery. Principle and Technique. Ed.
  26. 26. Haimovici H. W.B. Saunders Philladelphia-Tokyo, 1993; pp 840-852. 7 Kieffer E. Arterial complications of thoracic outlet compression. In: Text book of Vascular surgery Ed . Rutherford RB. W. B. Saunders Philladelphia-Tokyo, 2000; pp 1200-1207.