Diagnosis and Treatment of Thoracic Outlet Syndrome

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DIAGNOSIS AND TREATMENT OF THORACIC OUTLET SYNDROME

Rishi N. Sheth, MD, and Allan J. Belzberg, MD, FRCSC

Thoracic outlet syndrome (TOS) is one of the for diagnosis, and defining the treatment proto- most controversial subjects in entrapment neu- col has never been undertaken. Future endeav- ropathies. Views differ regarding the patho- ors should include multicentric, randomized, genesis, diagnosis, and management of TOS. prospective clinical trials so as to ansrver these Some authorities even question its existence. questions. In spite of lack of understanding of the dis- Until the first half of the nineteenth cen- ease, clinicians often encounter patients whose tury, several terms were assigned to describe pain or neurologic deficits in the upper limb the symptom complex caused by neurovas- cannot be explained after ruling out cervical cular compression in the upper thoracic re- spine diseases and other common causes of pe- gion based on the physiologic mechanism ripheral neuropathies. The goals of this article and structure that caused the compression arc to provide a comprehensive understanding (Table 1).Such rigid classification was the basis of the syndrome by reviewing the anatomy of for explaining the pathogenesis, diagnosis, and the region and the pathomecl~anismof the dis- treatment.224"5 80 In 1956, Peet et al-' coined a ease. Diagnosis can be established confidently common term, thomcic outlet syfdr.o:w,to en- in cases where the neurologic deficits are ob- compass these various entities. It is now re- vious and tests sho~t-positive findings. Issues alized that strict classification is not practical. surrounding cases TI-here the objective find- Patients tend to have multiple abnormalities, ings are minimal are discussed. The duration of which may be responsible for the compression conservative treatment, indications for surgery, of the neurovascular bundle, and the clinical surgical approach, and patient selection for presentation is not unique to one ~yndrome.~" surgery are not standardized, and experiences vary across institutions. A number of studies in the past have shown conflicting results on the ANATOMY outcome of various surgical approaches, which has only added to the confusion. A systematic It has to be noted that TOS is a misnomer. scientific approach aimed at understanding the Anatomically speaking, the true thoracic out- pathogenesis of TOS, elucidating the criteria let is at the level of the diaphragn~.~'Early

From the Department of Seurosurger!; Iohns Hopkins University School of Medicine, Baltimore, Maryland

NEUROSURGERY CLINICS OF NORTH A-MERICA

VOLUME 17. NUMBER 7 APRIL 2001 295 296 SHETH & BELZBERG

Table 1. SYNDROMES INCLUDED UNDER THE DESIGNATION "THORACIC OUTLET SYNDROME" Cervical rib syndrome Bracllial pIe\us syndroine Costoclavicular syndroine Adson's syndrome First thoracic rib s!-ndrome Paget-Scliroetter syndrome Scalenus anticus s!-n~lromr Shoulder-girdle syn~ircmw Hyperabduction s!.~-drorne Fractured cla\.icle syndrome Cervicobracliial neuro\-ascular compression spdrome Cervical brachial compression syndrome Shoulder-arm syndrome Pectoralis ininor syndrome Effort vein t11rombor;is syndrome IHumeral head syndrome Pi~eumatichammer 51.ndrome Rucksack paralysis

authors described the syndrome of neurovas- the coracoid process of the scapula. The bundle cular compression at the superior aperture of is closely related to the fibrous clavipectoral the thorax as TOS, and this incorrect term has fascia and the dense costocoracoid ligament since remained in the medical vocab~lary.~~~anteriorly. As the flat tendon of pectoralis The anatomy of this region is . complex, minor muscle ascends laterally to insert on the and understanding the relation between the upper border of the coracoid process, it crosses neurovascular structures and the surro~~nding the subcoracoid space."' The ligament and muscles and bony structures is critical in un- tendon becoine taut during hyperabduction to derstanding the cause of compression. significantly compress the space. The neurovascular complex traverses through three narroI\- straits within the tho- PATHOMECHANISM racic outlet before entering the arm (Fig. The first passage, the so-called "scalene trian- Compression of the neurovascular structures gle," is mainly formed by muscles. The thoracic as they course through the narrow passages of rib forms the base, and the anterior and middle the upper thoracic aperture before entering the scalene muscles form the anterior and poste- arm causes TOS. Any factor that compromises rior borders, respecti\.el!: The scalene muscles this narrow passage, which eventually leads to arise from the tubercles of the transverse pro- compression of neurovascular structures, can cesses of the cervical \-ertebrae and insert on be included as a possible cause of TOS. These the dorsal surface of the first rib. Although the factors can be classified as: hiatus transmits all the trunks of the brachial plexus, only the subcla1-ian artery and lower Anatomic or structural abnormalities: congenital (cerl-ical ribs and fibromuscular trunk are closely related to the first rib. The bands) and acquired causes subclavian vein passes in front of the anterior Pl~ysiologicor dynamic factors: develop- scalene muscle." After passage through the in- mental and postural factors terscalene triangle, the neurovascular bundle Traumatic factors passes through the costoclavicular triangle. Idiopathic factors Bordered by the first rib below, the clavicle and the subclavius muscle superiorly, and the A number of hypotheses have been proposed upper border of the scapula and subscapularis to explain the mode of compression in cases muscle posteriorly, this hiatus transmits all where structural abnormalities are not obvious. the nerve trunks, the subclavian artery, and the vein. It has to be noted that the first rib is Structural Anomalies a structure common to both passages, and one of the surgical options is to resect the normal Congenital Anomalies rib so as to pave the Ivay to a wider passage. Finally, the neurovascular bundle traverses the Although congenital anomalies of all struc- subcoracoid space, a short tunnel just beneath tures that form the borders and contents of the DIAGNOSIS AND TREAT\IENT OF THORACIC OUTLET 5\?23OME 297 - C, Vertebra

Figure 1. The anatomic relation of the neurovascular bundle with adjacent structures. As the brachial plexus and the axillary artery emerge between the scalenes, they loop above the first rib then pass behind the clavicle. Note that the subclavian vein lies outside the scalene triangle. The spinal nerves are numbered on the left and the vertebrae on the right. (Adapted from Travel1 JG, Simons DG (eds): Myofascial pain and dysfunction, vol 1. Baltimore, William and Wilkins, 1983: with permission.) thoracic outlet have been known to compro- to reach into the arm, which can result in mi- mise the space through which the neurovascu- crotrauma to the nerves from stre~chingand lar structures course, the common anomalies compression." are described here. Cervical ribs are supernu- Fibrous bands are the most common con- merary ribs and can be fully or partially de- genital anomaly encountered thar cause the veloped. If a cervical rib is formed partially, sy~nptomsof TOS. Various kinds of fibrous it is associated with a ligamentous extension bands have been encountered, SF?, attempts that inserts on the manubrium or the rib be- lm\-e been made to classify tbsm accord- low. Incidence varies from 0.0004% to 1.5% ing to their origin, insertion, ani associated according to various studies.' '' 31 4y Fifty per- struct~res.'~'' As these anomalous structures cent of cervical ribs occur bilaterally, and, cu- tr'I\-erse through the thoracic outl?: they tend riously, there is a female predominance. The to elevate, kink, and compress the Rtlurovascu- mere presence of this anomaly does not con- lar bundle against the surrounding anatomic fer the diagnosis of TOS because only 5% to borders of the thoracic outlet. Anonlalous mus- 10% of individuals with cervical ribs actually cular insertion and muscle hyperrrophy have develop the symptoms of TOS.4XThe presence been described to cause TOS, as :bey tend to of this anomaly creates a barrier over which trap the loxver trunk of the plexus ayd the sub- the neurovascular bundle has to acutely ascend cla\.ian artery.'j 298 SHETH & BELZBERG

Acquired Anomalies and age all tend to sag the scapula, which puts These anomalies are space-0ccup.i-ing le- extra tension on the plexus." - sions and can arise from the struct&-es that Certain postures of the body tend to exac- form the borders or the thoracic outlet or from erbate or provoke the symptoms of TOS. Any structures outside the outlet. Such lesions limit position of tlie arm that stretches or compresses the neurovascular bundle into a narrow con- the plexus against the bones may consistently finement. Fractures of the clavicle leading to reproduce symptoms. Hyperabduction with external rotation of the arm is the most common malunion or formation of a large callus have position with ~\~hicllpatients associate their been reported to cause TOS by reducing the symptoms. At arm abduction above 90°, the costoclavicular space. Although uncommon, costoclavicular triangle closes, thereby com- benign or malignant tumors of the first rib or the clavicle ha\-e been described as caus- pressing the cords between the bones.71 Pa- tients usually complain that symptoms are ing TOS.-" Among the Iesions arising outside aggravated at lrork when they use their arm the outlet, a Pancoast tumor can compress the overhead such as when a teacher writes on the neurovascular structure. Rarely, malignant or blackboard or a painter paints the ceiling. Cer- inflammatory regional lyinpl~adenopathyand tain daily activities or l~ousel~oldchores that tumors of tlie spinal cord or bracl~ialplexus involve using a repetitive motion of the upper may present as TOS. extremity can x\,orsen the symptoms. ~imila&,arm positions tliat depress the Dynamic Factors shoulder girdle (e.g.,carrying heavy luggage, wearing a heavy bag over the shoulder) place Developmental Factors pressure over tlie neurovascular structure by drawing the clavicle against the first rib.Is It has been postulated that certain changes Hyperabduction and depression of the taking place during development can predis- shoulder are maneuvers used by the clinician pose to compression of the nerves and ves- to provoke symptoms in patients wit11 the di- sels. Tlie position of the scapula dictates tlie agnosis of TOS. inclination of the clavicle at the acromioclavic- ular joint, which, in turn, determines the width of the costoc1a.i-iiular space. In infants, the Traumatic Factors scapula is liigl~in the thorax, and the costoclavicular space is wider. As growth proceeds, The role of trauma is least understood of all, the scapula descends as a result of the weight yet it has to be realized that it plays an impor- of the bearing limb. This, in turn, brings the tant role. Most patients complain of the onset clavicle closer to tlie first rib, therebv narrow- of TOS symptoms after an automobile accident ing the costoc1a.i-icular space. ~escintof the or work-related injury that involves a strain scapula is more pronounced in women, and of the ipsilateral neck or shoulder regi~n.'~,~~,~' this may explain the predominance of TOS in Not all patients who have trauma to the neck wome11.'~ or shoulder region develop symptoms of TOS. Conversely, trauma in itself may be insuffi- cient to caise TOS. It is most likel; that trauma Body Position and Habitat may be a precipitating factor in developing Any factor thar lengthens the descent of the the symptoms in patients who have a predis- neurovascular bundle so that the nerves and position because of congenital anomalies of vessels become tensed as they tral-erse more the region. It has to be noted that there are obliquely against the first rib can cause TOS. few patients in whom the onset of symptoms Patients with ten-icodorsal scoliosis often de- occurs without any recognizable precipitating velop TOS symptoms on the side t\,here the event." j6 Whatever the cause, the final path- plexus has to travel a greater length. Poor way in the pathogenesis of symptoms is the physique of the shoulder girdle, debilitation, compression of the neurovascular bundle. DIAGSOSIS AKD TREAThlENT OF THORACIC OLTLET SYNDRCXIE 299

CLINICAL PRESENTATION sion or poststenotic dilatation resulting in tur- bulent blood flow is a rare complication. The Clinical features of the syndrome depend on severity of symptoms depends on :he extent the anatomic structures compressed. Accord- of collateral circulation in the arn1 In acute ingly, three distinct syndromes are recognized. cases, the presentation is typical of complete These syndromes also help to delineate the pre- blood loss to the arm. Patients complain of se- senting clinical signs and symptoms. They in- vere pain and numbness. The limb is cool, pale, clude (1) the arterial form caused by compres- and pulseless and may become para!yzed and sion of the subclavian artery, (2) the venous gangrenous. Formation of an aneun-sm of the form caused by compression of the subclavian subclavian artery secondary to com~ressionis vein, and (3) the neurogenic form caused by rare.37,58 brachial plexus compre~sion.'~The last form Diagnosis is mainly based on ?resenting is by far the most common one encountered,'* signs and symptoms. Se1-era1manecl-ers have and these syndromes rarely overlap. been described to aid in the diagnosis of arterial TOS. The following are the tests xost commonly used: Arterial Syndrome Adson test: with the patient in a sitting po- The severity of symptoms depends on the sition, arms by the side, neck in extension, extent of compression and injury to the subcla- and facing either aT\-ay or toward the af- vian artery. The symptoms and signs are sec- fected side. The examiner feels the obliter- ondary to the loss of blood supply to the arm. ation of the radial pulse of the aiiected arm Mild ischemic syn~ptomsmay be the result when the patient is asked to inspire deeply. of intermittent arterial compression at the tho- 90' abduction external rotation test: the ex- racic outlet. Symptoms caused by compres- aminer feels the radial pulse \\-hen the af- sion may appear during certain postures of the fected arm is abducted to 90' and externally arm (hyperabduction) or during exertion of the rotated with the forearm in the 9i' position. arm when the demand for blood supply in- When the patient is asked to look in the op- creases. Patients are usually symptom-free be- posite direction, the pulse may obliterate. tween the attacks or during the summer season. Hyperabduction test: this sirn~letest is Cold temperature always worsens the symp- positive when the radial pulse is dimin- toms. During an acute episode, patients com- ished after elevating the arm above the plain of pain followed by parestl~esias;the pain head. is poorly localized and may involve the whole Shoulder brace: many variants of this test hand. Signs include a cool and pale extremity have been described, but the test consists of and the feeling of a stiff hand. Patients recover bracing the shoulder backward 2nd feeling from the symptoms between the attacks. Such for obliteration of the pulse. seasonal variation in the severity of symptoms is not seen with neurogenic or subclavian vein Although these tests are emp1o~-?ato diag- syndron~es.~~4h " nose TOS, the specificity of these t;.sts needs Sustained compression is a form of trauma to be questioned. Studies have shox..-nthat po- to the arterial wall that can result in the for- sitional obliteration of the radial pc:se is seen mation of a mural thrombus leading to partial in normal asymptomatic subjects. rositive re- occlusion. Small emboli can dislodge from the sults can be interpreted confidently only if they thrombus and cause tissue necrosis, ulcers, and simulate the symptoms of the patient." '' gangrene of the digits. These ischemic insults Arteriography of the subclaviar system is are more localized in the radial aspect of the the gold standard. This can aid i:- delineat- hand, affecting mainly the index finger and the ing the site of obstruction, demonsrrate intra- thumb.;'" mural lesions, and shoil- dilatatior . Accord- Complete obstruction caused by a thrombus ing to Sadler et al,h"ositional arreriograms at the site of the injury secondary to compres- are of limited value, because positional arterial 300 iHETH & BELZBERG coinpressloll occurs in normal asympton~atic arm. Anticoagulation is advocated to recai~al- subjects Radiographs may reveal an associ- ize the thrombus. Arm elevation aids in re- ated cen ical rib."" There seeins to be a general ducing the edema. Venous throinbectolny has agreement about the indications for surgical in- been suggested when a gangrenous or post- terventlon in cases of thromboeinbolic compli- phlebitic complication of thrombosis is an im- cation, poststenotic dilatation, and aneurysm minent danger. Along with thrombectomy, the format~nn.Transaxillary resection of the first first rib should be removed to relie\-e the ob- rib is ad~.ocatedalong with resection of bony struction of the venous system.i6 anomahes like a cervical rib or bony exostosis, if present, to decompress the passageway. Vas- Neurogenic Syndrome cular repair may be necessary in certain cases. Compression of the brachial ple\us is the Venous Syndrome most common form of TOS." Neurologic symptoms relate to the distribution of the lo~ver Venous compression at the thoracic outlet trunk and the C8 through TI roots, the eleinents may be intermittent (positional), or venous ob- of the brachial plexus that are closely related struction may be associated with thrombosis. to the first rib and are prone to compression Veno~~sthrombosis can develop at the site of against it. Because the lower elements of the con~pression.~~Acute symptoms develop af- brachial plexus carry motor, sensor!-, and sym- ter stre~wousphysical activity of the arm and pathetic fibers to the arm, synlptoms relate to are referred to as effort tl~rombosisor Paget- the fibers that are compressed. Schroetter syndrome. The affected limb feels Sensory Symptoms heavy and becomes weak, tender, swollen, and cyanoti~.'~Excruciating deep pain is felt in the Pain is the most common and earliest coin- chest, shoulder, and arm. Tingling paresthesias plaint. Pain is usually located in the supra- in the arm are common. Certain positions of tlie clavicular region, axilla, back of tlie neck, and arm or strenuous physical activities can evoke shoulder region going down into the arm. intermittent compression. Synlptoins are simi- Some patients may have atypical pain in the lar to the ones described previously. retrosternal or parascapular region. If the ret- In addition to compression, other causes of rosternal pain is felt on the left side, it can be thron~bosishave to be considered in the differ- confused with anginal paii~.~Vainis usually ential diagnosis, which includes iatrogenic (as described as a dull constant ache that is difficult a result of venous catheterization) or hyperco- to localize. On most occasions, it does not re- agulable states (malignancy, glomerulonephri- spect the C8 through T1 dermatomes. tis, cr!-~globulinemia),vessel wall webs, and Paresthesias are frequently more localized to idiopathic factors.2947 the C8 through T1 dermatomes. Patients may Diagnosis depends on clinical suspicion. complain of a "pins and needles" sensation and Venography is confirmatory and can show the numbness on the medial side of the arm, fore- site of obstruction or the presence of thrombus. arm, hand, and fourth and fifth digit^.'^ 69 '' Intermittent compression of the subclavian The sensory symptoms can be 01: a sudden vein may be demonstrated during provoca- or insidious onset. In most cases, patients are tive maneuvers. The use and interpretation of able to relate a major accident, fall, or any injury Doppler flow measurement are difficult and involving the shoulder region. In cases, where of limited ~alue.~~,"Venous pressure measure- the onset is subtle, symptoms are recognized ment has been used to support the diagnosis. either during work (a barber may complain of Venous pressure higher than 10 mm Hg may pain and numbness in the hand after keeping be demonstrated in the affected limb compared the arm in a prolonged abducted position) or with the contralateral limb. during routine household chores. The treatment in the intermittent type is to Although pain and paresthesias may be felt avoid provocative arm positions and to rest the constantly, symptoms are aggravated by any DIAGNOSIS AND TREATMENT OF THORACIC OUTLET SYNDROME 301 activities (e.g., carrying heavy loads on the Sympathetic lnvolvemenl shoulder or in the dependent arm) or position (e.g., combing hair, reaching toward a shelf) of The C8 through T1 spinal roots carry sym- the arm that put traction or pressure on theneu- pathetic fibers, which supply most of the up- ral structures. These ma!- be related to occupa- per limb.66 Vasomotor disturbances accom- tion, sports, or daily activities. Symptoms are pany sensory and motor symptoms. Isolated usually worse at the end of a tiring day. Pain cases of sympathetic involvement are rare but may be seI7ere enough to disrupt a patient's have been reported in the past." Symptoms of sleep during the night. In many instances, pa- vasomotor instability include bluish red discol- tients are forced to quit or change jobs to a less oration of the dependent arm and blanching of the hand affecting the .n,hole hand. Intermit- demanding one. In a fen- patients, cold weather seems to \\-orsen symptoms. tent attacks of cyanosis or pallor of the hand Relief is bought about by discontinuing ag- are usually precipitated by emotional distur- gravating activities. Patients learn to relieve bances or by exposure to cold, and the severity of symptoms is independent of arm posi- pressure over the brachial plexus by elevating tion. Trophic changes of the hand have been the shoulder or resting the elbow on the table described in long-standlng cases, including or on the arm of a chair. thinning of skin, loss of hair, and thickening Objective signs of sensory loss are usually of nails.-14h7 a late finding. The percentage of patients with Vasomotor involvement caused by TOS has sensory s)-mytoms tvho demonstrate sensory to be differentiated from other causes of va- loss is ~unknol\.n.Hypesthesia to pinprick and somotor instability. Disturbances iike reflex touch sensation is distributed in theC8 through sympathetic dystrophy, causalgia, Raynaud's TI dermatomes. This 11)-pesthesia eventually disease, secondary causes of Raynaud's phe- spreads to cover the u-hole hand. Vibratory nomenon (e.g., connective tissue disorder, sense, proprioception, and two-point discrim- obstructive arterial diseases, neurogenic le- ination may be affected variably. sions elsewhere, drug intoxication, dyspro- teinemias), acrocyanosis, and erythromelal- Motor Symptoms gia should be kept in mind. Patients with Complaints of subjective motor weakness Raynaud's disease usually present with bilat- may be elicited on questioning. Activities in- eral involvement for longer than 2 years with- \-olved include hand grip, and fine hand move- out much progression of the disease. At times, ments are clumsy. Most notably, the intrinsic a careful history and physical examination can l~andmuscles innervated by the ulnar and me- elicit the secondary causes as a result of un- dian nerl-es are affected, which, in turn, have derlying disease. Acrocyanosis usually occurs contributions from the C8 through TI spinal in women and presents tvith bilateral cyanosis nerves. Objective signs of muscle wasting are of the hands and, occasionally, the feet. Ery- uncommon and seen in long-standing cases thromelalgia is rare and in1,olves sudden burn- only. Muscle bulk and signs of paresis of the ing pain along with redness and increased tem- small intrinsic hand muscles should be as- perature of the feet and 11ands.~' sessed. There is a predilection for the first dorsal interosseous muscle (innervated by the ulnar nerve) and thenar n~uscles(abductor pol- DIFFERENTIAL DIAGNOSIS licis brevis and opponens pollicis innervated b~,the median nerve). The pattern of thenar The symptoms of neurogenic TOS overlap muscle atrophy gives a characteristic guttering with the clinical presentation of commonly en- ~mthe lateral aspect of the hand. There are sev- countered entities. Clinicians are faced xvith the eral unsettled explanations as to the highly se- challenge of first excluding these causes before lective nature of muscle atrophy. The muscles giving a diagnosis of TOS. ot the medial forearm may also be affected, but Cervical degenerative diseases are common this is usually not conspicuous.2sh7 and important in the differential diagnosis. The 302 SHETH & BELZBERG following signs are helpful: The supraclavicular and akillary regions are Patients 1vit11 cervical disk disease have rich in lymph nodes. Enlargement of these tenderness over the spinous processes and nodes as a result of metastasis or inflamma- paraspinal muscles, whereas TOS patients tion can compress the braclual plexus. Palpat- tend to have tenderness over the supraclav- ing the supraclavicular and adlary regions can icular fossa. reveal adenopathy. Metastasis to the brachial Valsalva maneuvers and neck hyperexten- plexus from breast carcinoma can result in TOS. sion usually provoke radiating pain go- Trauma to the upper thoracic reg1011can lead ing down the sympton~aticarm in patients to compression. Malunited clavicular fractures with degenerative disk disease. can result in callus overgro~t-t11,\vhicll can im- Downward pressure on the top of the head pinge on the plexus.'" "'Atasov7 reported a case with the neck hyperextended and flexed of scl~wannomaof the C7 root causing coin- toward the symptomatic side worsens the pression of the tlloracic outlet. symptoms in patients with cervical herni- ated disks. DIAGNOSIS Signs of upper motor neuron involvement might be elicited on examination in cases Suspicion for TOS should be raised in where the osteophytes compress the spinal women with a long neck and sloping shoulders cord. who present with a history of some trauma to Entrapment of peripheral nerves distal to the shoulder region and symptoms referred to thoracic outlet present with a confusing pic- the C8 through T1 dermatomes. TOS remains a ture. The clinical picture caused by ulnar nerve diagnosis of exclusion; thus, a detailed history neuropathy closely mimics the presentation and physical exainination should aim at ruIing caused by TOS. Examinations oriented specif- out other common entities that present with an ically toward distinguisl~ingulnar entrapment overlapping or similar clinical picture.12 5"y from TOS are as follows: The authors like to distinguish two forins of neurogenic TOS. Most patients rvith brachial Tinel's sign at the medial epicondyle elic- plexus con~pressionpresent with the main its radiating paresthesias along the ulnar complaint of pain. There are no objective signs nerve distribution. of neurologic deficits present. Physical exami- Nerve conduction velocity studies show nation usually rex~ealsno a~preclablesensory slo~vingof conduction of the ulnar nerve loss or motor atrophy in the hand. Radio- at the level of the elbow. logic studies, nerve conduction tests, and elec- Normal pinprick and light touch sensa- tromyograpl~icrecordings show no abnormal- tion are demonstrated on the radial aspect ities. Wilbourne and Porter-" 11al.e called the of the fourth finger in the case of ulnar entity a disputed form of TOS. MLK~contro- neuropathy. versy exists as to its existence, because the di- Certain lion-neurologic diseases that can agnosis of thrs entity is based purely 011 clin- mimic the symptoms of TOS include muscu- ical judgment. Physical signs specific to TOS loskeletal (arthritis, bursitis, tendinitis of the that should help a clinician to support the di- shoulder or elbow region) and visceral (angina agnosis of TOS include (1)palpating the supra- pectoris, esophageal diseases, gastric ulcer, clavicuIar fossa to elicit tenderness and (2) tap- pul~nonarydiseases) causes. ping the supraclavicular fossa to elicit tingling It is in~portantto recognize secondary causes paresthesias radiating dow-n the arm. A posi- of brachial plexus compression. Pancoast tive Tinel's sign at the supraclavicular regioi~ tumors can invade the thoracic outlet and com- can be considered specific for TOS. press the plexus. The diagnosis is made on elic- Stress tests are maneuvers that provoke the iting a history of smoking, and a plain chest symptoms of pain and paresthesias on the radiograph reveals an apical mass. The pres- medial side of the hand and forearm. Such ence of Horner's syndrome is an indication for provoative tests further compress the neu- brachial plexus involvement." rovascular structures as they pass through DIAGNOSIS AND TREATLIEKT OF THORACIC OUTLET SYNDROME 303 the narrowed Commo:; tests are as causes of neuropathies at sites other than the follows: plexus such as ulnar neuropathy at the elbow and median neuropathy in the carpal tunnel. Hyperabduction test: the arnof the patient Abnormal patterns of neuroelectric distur- is raised above the level of t?.e bances have been described in TOS patients. Costoclavicular test: press-lre over the Electromyography may reveal denervation of shoulder region may provoh? symptoms. Intrinsic hand muscles innervated by the me- Military maneuver: eliciting rlxe symptoms dian and ulnar nerves.27 Prolongation of F- by elevation of the chin ar.d pulling the \\we latency has been described in patients shoulder joint behind in an eltreme "atten- with atrophy of the hand muscles.2081 Abnor- tion" position.34 malities in the somatosensory evoked poten- tlals obtained after stimulating the ulnar nerve Because of the lack of syste:natic clinical study, the reliability and specificity of these have been noted in a few patients." Urschel et al-' and Caldwell et a19 described the slow- tests in diagnosing TOS are unknown. Ing of ulnar nerve motor conduction velocity In the true neurogenic type of TOS, there may across the thoracic outlet with enthusiastic re- be signs of intrinsic hand muscl? atrophy and sults. They stimulated the plexus at the supra- reduced pinprick and touch sens3tion in the C8 clavicular fossa and found abnormal conduc- through T1 distribution. Radiologic and elec- tion in tlxe ulnar nerve in almost all their cases. trodiagnostic studies may indicate some ab- This test is controversial, because many investi- normality. Unfortunately, there is no test that gators have not been able to replicate the same is pathognomonic of TOS. Positive findings in res~~lts.'~I7 " The significance of electrodiagno- the ancillary tests are associated witlx the true sis in TOS is limited because most patients do form of TOS. The main purposs for ordering not sho\v any kind of abnormality. Numerous these tests is to exclude other dizgnoses. studies show a high variability in the outcome Radiologic studies are helpfu: in excluding of these tests. Until a systematic clinical trial re- the secondary causes of comprssion caused solves the question, caution must be exercised by structural anomalies. Plain r3diographs of when interpreting the data. the cervical spine are helpful in showing a cervical rib, an elongated transx.-erseprocess, or scoliosis of tlxe region. Mal~ritedfractures TREATMENT and malignant lesions arising trorn tlxe bony wall of the thoracic outlet can be demon- Patients witlx TOS have often been misdi- strated. The cervicotl~oracicju:lction should agnosed or passed off as histrionic. They are be carefully inspected for mal:-;nant lesions comforted to know that their symptoms are such as a Pancoast tumor. Cervical degenera- consistent with a diagnosis and that treatment tive diseases can be ruled out sing plain ra- can be instituted. As in most medical con- diographs. Discograms, my elogranxs, or MR ditions, treatment can be divided into non- imaging of the spine may be needed to fur- operative and operative categories. The pa- ther delineate the level of disk disease. CT is tient should avoid postures that exacerbate helpful in excluding intraspilx?.: (e.g., tumor, symptoms. A change in work habits, including syringomyelia) causes of senscry and motor attention to the work place can help those pa- symptoms.WR imaging of the csrvicothoracic tients ~\.ithrepetitive stress disorder. Physical region has been shown to be useful by demon- therapy likely plays a role, but the literature strating distortion of the plexus. In addition to is lacking in outcome data.77The general ap- demonstrating bony anomalies sf the region, proach involves measures to strengthen the MR imaging has the advantage of disclosing shoulder girdle and improve posture. Cervi- lxypertrophy of muscles and radiologically in- cal traction can be added. Nonoperative care visible bands that can compress the neurovas- can help many patients to avoid surgery."he cular bundle." " surgical approach to TOS varies depending on Electrodiagnostic studies can help to support the philosophy and training of the surgeon. the diagnosis of TOS by exc1udir.g the common If the pathology is thought to be caused by 304 SHETH & BELZBERG compression of the 10~1-ertrunk from fibrous tion of the brachial plexus. The patient is po- bands or a cervical rib, a supraclavicular ap- sitioned supine wit11 the arms adducted at proach is taken.@If, however, the pathologic the side, and a general anesthetic is delivered. findings are thought to be more distal, resec; Muscle paralysis is avoided to allow electric tion of the first rib is performed. Within the stimulation. The incision is made just above vascular literature, treatment of vascular coin- and parallel to the clavicle. The platysina is pression is approached most often with first rib sl~arplydivided, and the lateral one third of resection. the sternocleidomastoid muscle is divided. The Access to the first nb can be gained from a omohyoid muscle can either be retracted or di- supra- or infraclavicular approach. Murphyi' vided, and the fat pad of the posterior trian- described the supraclavicular approach to the gle is elevated. The phrenic nerve is located, first rib in 1910, but tlm approach was aban- often aided by electric stimulation, on the an- doned as being too dangerous. It was redis- terior scalene muscle and is protected for the covered in 1962, when Clagett16introduced the duration of the case (Fig. 2). The anterior sca- posterior thoracotomy rib resection. Roos" re- lene ~nuscleis then divided, and the bulk of ported the transaxillar? approach, which has the muscle is removed. The upper trunk of the become the most popular surgical approach brachial plexus is located along the lateral bor- for first rib removal. For some, a combined ap- der of the anterior scalene muscle. The middle proach affords the best surgical outcon~e.~" and lower trunk lies inferior and slightly posterior to the upper trunk. A branch of the thyro- cervical trunk may have to be divided to allow Supraclavicular Approach exposure of the lower trunk. A neurolysis is performed encompassing For most neurosurgeons, this approach is the upper, middle, and lower trunk of the the most familiar, prmiding direct visualiza- brachial plexus. Moving proximal along the

Spina~ccessory n

Levator scapulae m

Sternocleidomastoid m /

Trans cerv~cal3 & V

Scalenus ant m

Brachtal plexus

Figure 2. Structures encountered during supraclavicular approach to neurolysis of the brachial plexus. Often :he anterior scalene muscle is removed before the neurolysis of the plexus is performed. Note the close relation of the phrenic nerve with the anterior scalene muscle. Ext = external; Int = internal; Trans = transverse; v = vein; m = muscle; ant =anterior; n = nerve; a = artery. (AdaptedfromWeinshel SS: Surgical exposure of the brachial plexus. In Benzel EC (ed): Practical Approaches to Peripheral Nerve Surgery. Illinois, AANS publications; with permission.) DIAGNOSIS AND TREATMENT OF THORACIC OUTLET SYSDROME 305

lo~vertrunk, Sibson's fascia over the dome of the nerves and 1-essels between the surgeon the lung is released, and, separated by the first and the rib. As such, most surgeons prefer the rib, the C8 and T1 roots are identified. In this transaxillarv approach if the first rib is to be area, several anomalous structures can be en- resected. countered, including (1) fibrous bands arising from the C7 transverse process, first rib, or api- Transaxillary Approach cal lung pleura; (2) arterial vessels or a high arching subclavian artery; and (3) a cervical rib After delivery of general anesthesia, the pa- with fibrous bands arising from the end of the tient is positioned prone, with the arm ab- rib and inserting on the first rib. A cervical rib ducted, external11-rotated, and suspended (3-lb can be readily resected using this approach. weight). A11 inciiion is placed at the caudal ex- The first rib can be exposed by retracting tent of the axilla, [vhere the skin breaks away the elements of the plexus. The rib can be re- from the chest \$-all(Fig. 3). Dissection is taken moved through this exposure; however, this is to the chest ~valland up toward the axilla (see a technically challenging procedure that places Fig. 3'4). The interiostobrachial nerve, a branch

Figure 3. A. Structures seen from the transaxillary surgical approach. B F~brousband presses the neurovascular bundle as it extends from the transverse process to attach onto the first rib. C. View of the cervical rib from the transaxillary approach. The bundle can be seen to lcop above the cervical rib in an abnormal fashion. m = muscle; Lat. = laternal; n = nerve. (Adapted from PAacHleder HI (ed): Vascular disorders of the upper extremity. New York, Futura Publishing. 1998. pp 112-1 13; with permission.) of the T2 intercostai nerve, traverses the area a supraclavicular or transaxillary approac1.1.'~~72 on its way to the arm and needs to be identi- Patients ~vithprofound intrinsic muscle atro- fied and protected. The first rib is palpated as phy do not normally regain function; rather, a broad flat structure. A localizing radiograpli the surgery is performed to arrest the yrogres- can be obtained if there is any question as to sive deterioration. its identification. Deaver retractors are used to In one study, an orthopedic surgeon and elevate the soft tissr.es of the axilla, including a vascular surgeon jointly conducted 30 op- the vessels and nei-1-es.The intercostal muscles erations for TOS in 27 patients. Anterior are stripped from the rib using a combination scalenectomy was performed by the supra- of blunt dissection and cautery. The pleura is clavicular route, except in one case, where the gently stripped awTalr.Blunt dissection is used infraclavicular route was used. The further to identify the inserxion of the anterior scalene surgical procedure was tailored to the abnor- lnuscle on the rib, \\-hich is then di~.ided.Prox- malities identified (i.e., resection of a cervical imal on the rib, the middle scalene muscle is rib or band, medial scdenectomy). The first located and di17ided.Palpation is used to iden- rib lvas spared. At a median follow-up of 37 tify any anomalous bands inserting on the rib montl~s,results rvere judged excellent or good (see Fig. 3B). on 26 of 30 sides (87%);on the three occasions Reinm.al of the first rib can be accomplished when scalenectoiny alone was performed, the using a varietv of te;l-uniques. The authors pre- results 11-ere only fair or poor. There were no fer a rib cutter in cambination lvith rongeurs major complicatioi~s.The long-term outcome used to remove the rib piecemeal. Resection in this series suggests that good results can be proceeds to r

Donaghy et all\erformed 49 operations in ers still reported that thel- I\-ere"limited a lot" 40 patients (33 women, seven men; age range, in vigorous activities. Conlparec'i xt.ith a non- 22-62 years) with follow-up at 3 months to surgical sample of TOS patients, those receiv- 20 years after surgery. Cervical ribs were re- ing surgery had 50% greater medical costs and moved in 23 patients together with fibrous were three to four times more likely to be I\-ork- band excision in nine. In the 17 patients xvith- disabled. The nonspecific ~~eurogenicTOS di- out a cervical rib, the thoracic outlet xvas de- agnosis, complexity of ~vorkers'compensation compressed by resection of the first thoracic cases, and adverse event profiles are 1ikel~-sub- rib in nine and by supraclavicular operations stantial contributors to the I\-orseoutcomes re- in eight. After surgery, patients reported reported l~ere.~%offet al' compared surgery for duced pain (33 of 36 patients), and improved neurogenic TOS between laborers and nonla- sensory disturbance (30 of 35 patients), hand borers. Laborers with TO5 .itrere less likely to muscle strength (14 of 27 patients), and hand have a good result from surgical intervention function (23 of 24 patients). After surgery, TOS and were unlikely to return to thelr original recurred in two patients, and symptolns con- occ~~pation.~' tinued to progress in three patients in 1vhom other diagnoses eventually emerged. Surgical con~plicationswere recorded in 10 patients SUMMARY but were transient and did not result in per- manent symptomatic sequelae. These inves- TOS represents a spectrum of disorders tigators concluded that surgical treatment of encompassing four related syndromes: arterial suspected neurogenic TOS relieves pain and compression, venous comyression, neurogenic sensory disturbance (90%)but is less effective compression, and a pnor1~-defined pain syn- for muscle weakness (50%).Surgery relieved drome. Patients can present ~vithsigns of arte- sensory and motor abnormalities to a similar rial insufficiency, venous obstruction, painless degree in patients with and without a cervical wasting of intrinsic llar-td muscles, and pain. rib.'" History and physical examination are the most Franklin et aFstudied all injured workers in important diagnostic studies, and radiographs the Washington State Workers' Con~pensation of the chest and cervical spine and electromyo- system who received TOS surgery from 1986 grapl~y/nerveconduction studies are useful to 1991 (n = 158). The main outcome measure to identify other causes oi: pain and disability was work disability status 1 year after surgery. Surgical intervention is indicated for patients Additional functional status and quality of life failing nonoperative maneuvers and can usu- outcomes were determined by telephone sur- ally yield satisfactory results. TOS may also be vey an average of 4.8 years after surgery. A the most underrated, 01-erlooked, and misdi- sample of workers wit11 a TOS diagnosis who agnosed, and the most important and difficult did not receive surgery during the period from to manage peripheral nen-eiompression in the 1987 to 1989 were identified as a comparison upper e~tremity.~ group (n = 95). It cannot be stressed enough that this was not a randomized study, and as such, comparison of the surgical group lvith References the nonsurgical group is of limited value. Sixty percent of workers were still work-disabled I. Adson AW:Surgical treatnwr.: :.,rsyn~pto~ns prod~iced b!. cervical ribs and the scale:-.:i anticus rnusclt. Surg 1 year after surgery. The strongest predictors of Gyiiecol Obstet 85685-7011. :-1- remaining disability were the amount of work 2. Atasoy E: Thoracic outlet ;-,:npression sv~~iiromr. Orthop Clin North Am 27.2-7--313, 1996 disability before surgery, longer time bet~veen 3. Atamy E: Thoracic outiet ;.mpressioi~ synLirome injury and TOS diagnosis, and older age at in- caused by a schwaniwma 13: ::-e C7 nerx e rwt. 6r I jury. There was no relation between type of Hand Surg 22662-663,19CJ; surgery, presence of any provocative tests, ex- 4. Beers MH, Berkow R: Cari,:. ascular iilsor~lers.111 Berkow R, Beers MH (edsi: Ti.-Merck hlmual of Di- perience of the surgeon, and work disability agnosis and Treatinmt, ed 1- Selv Jerse!-. hlerik Re- outcome. In follow-up surveys, 72.5% of lvork- search I.aboratories, 1999, p~ :T-'0-1794 308 SHETH & BELZBERG

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Addws rcp:i:t r.~.q~ieststo Allan J. Belzberg, \ID, FRCSC Johns Hopkins Hospital 600 North Wolfe Street, \!eyer 5-109 Baltinlore, MD 21287-7509