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Congenital anomalies associated with thoracic outlet syndrome
Congenital Anomalies Associated with Thoracic Outlet Syndrome Anatomy, Symptoms, Diagnosis, and Treatment
David B. ROOS,MD, Denver, Colorado
Personal experience gained from evaluating more than 2,300 patients for possible thoracic outlet syndrome (TO@, and operating on 776 (204 bilaterally), has led to the firm conviction that patients who have TOS have an underlying anatomic abnormality not present in the general population that predisposes them to develop symptoms of TOS under particular circumstances. Careful anatomic evaluation during first rib resection to decompress the outlet, and cadaver studies in the anatomy laboratory, have disclosed several distinct congenital anomalies that contribute to compression or irritation of the brachial plexus and the subclavian vessels. These congenital anomalies may be correlated with the patient’s symptoms and the most appropriate clinical tests for diagnosis. From this combined anatomic and surgical experience, the most effective technics in the operative treatment of TOS have been elucidated. The knowledge and experience obtained from these studies comprise the present report. Anomalies
For decades, it has been general medical knowledge that the congenital anomaly of cervical rib could cause neurologic symptoms from irritation or compression of the brachial plexus, or vascular complications from similar involvement of the subclavian artery. Indeed, the first operation performed for apparent TOS was removal of a cervical rib in 1861 by Coote [I ] at St. Bartholomew’s Hospital in London. Other congenital anomalies also became associated with symptoms of TOS, such as hypoplastic first thoracic ribs and exostoses of the first rib or clavicle. Even developmental abnormalities of the thoracic outlet long have been recognized as potential contributors to development of TOS, such as a fractured clavicle (Figure 1) or first rib, a drooping FromtheDeperbnent of Surgery, University of Worado School of Medicine, Denver, Colorado. Reprint requests shod be dbssed to David B. Roes, MD. 2045 Franklin Street, Suite 700. Denver, Momdo 90205. Presented at the Twenty-Eighth Annual Meeting of the Southwestern Surgical Congress, Houston, Texas, May 3-6. 1976.
Volume 132. December 1976
shoulder from neurologic disease, injury or poor posture, or hypertrophic muscles seen in athletes and weight lifters. All these afflictions have been well defined and understood for decades because the bony abnormalities are obvious on roentgenograms, and the neurologic deficits, postural abnormalities, and muscle hypertrophy are evident on physical examination. However, all these conditions combined are present in only a small number of patients presenting with typical symptoms associated with TOS. What, then, can be the cause of the symptoms, often of unbearable or incapacitating severity, in all the other patients with TOS who do not have abnormalities detected by roentgenograms or physical observation? The answer is congenital fibrous or muscular band anomalies affecting the brachial plexus and the subclavian vessels. If the surgeon operating for this common syndrome carefully evaluates the anatomy of the thoracic outlet, he will almost invariably find an anomalous fibromuscular band associated with the major neurovascular structures in the patients who have failed to respond satisfactorily to conservative treatment for their outlet syndrome. These patients have a mechanical structural abnormality not found in the average person that causes neurovascular symptoms to develop under general activities, arm position, or trauma to the shoulder-neck area, which ordinarily would have no persistent effect in the average person. The long established structural abnormalities already mentioned will not be discussed further, as they are well known. Because little recognition [2] and no detailed anatomic studies have been devoted to the far more common, though less obvious, fibromuscular bands, the results of such studies in this series of patients and cadavers will be presented. (Tables I and II.) Seven distinct types of congenital fibrous or muscular band anomalies have been found at surgical exploration thus far. Type I is a tough fibrous ligament attached to the anterior tip of an incomplete cervical rib that stops short of a bony connection to the first thoracic rib. (Figure 2.) All incomplete or
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Flgure 1. Lateral cervical spine f//m shows nine vertebrae, seven cervkal and two thoraclc, above the level of the clavicle, indicating low-lying shoulder glrdle commonly seen in young women. Film on the right clearly shows a large left cervical rib and overlapping callous format/on from healed fractured clavicle. m/s patient exhlblts three remarkable anatomlc abnormallttes associated wlth developkg TOS, yet she was asymptomatk unttl she suffered a hyperextension-flex/on neck Injury In a rear end auto colllslon, which preclpltated typical symptoms of TOS. TABLE
I Anomalous Fibromuscular Bands Found in 241 Operations for TOS
Anomalies Found in 58 Thoracic Outlet Dissections in 29 Cadavers
Type of Band
No. of Cases
Incidence (%I
Type of Band
No. of Cases
Incidence (%I
None Type 1 Type 2 Type 3 Type 4 Type 5 Type 6 Type 7 Total
7 18 10 146 13 40 5 2 241
2 8 4 61 5 17 17 1 100
Normal Type 3 Type 4 Type 5
39 10 1 8
67 17 2 14 100
Figure 2. Neurovascular compresslon due to cervical rib. Large comptete left cervkal rib lmpkgkg on the subctavian artery, and a medium sked rtght cervkai rtb wtth the typkal rvpe 1 congen#al ligamenlous bandcompktlng the cervical rib anrage to the first rib. The brachialplexus k always elevated by the underlying Ilgament, thus predlsposkg the plexus to irrttatton and to compression from the clavicle above.
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TABLE II
short cervical ribs have this congenital ligamentous band completing the cervical rib anlage to the first rib, attaching just posterior to the scalene tubercle. The bands are not visible on roentgenograms, of course, because they contain no bone or calcium, but they will be found in every case of incomplete cervical rib that requires operation, if the surgeon specifically looks for them. Normally the transverse process of the seventh cervical vertebra is equal to or somewhat shorter than the process of the first thoracic vertebra just inferior to it, the transverse process that supports the first thoracic rib. If the process of the seventh cervical vertebra extends out beyond the process of the first thoracic vertebra (Figure 3, left), it represents an apparent abortive attempt to form a cervical rib. The cervical rib anlage then is represented by a taut fibrous ligament, again without bone or calcium so it is not visualized on roentgenograms, connecting the tip of the elongated transverse process of the seventh cervical vertebra to the first thoracic rib, also just posterior to the scalene tubercle. This anomalous fibrous band is type 2. (Figure 3, right.)
The American Journal ol Surgery
Thoracic Outlet Syndrome
Figure 3. Let?, roentgenogram showing large left cervical rib attaching to first thoracic rib pedestal forming a true arthrosis; the right skie shows a diiterent anomaly, an elongated seventh cervical vertebra transverse process spike (arrow) which typk%lly has a type 2 Wngenttal band pas&g under the brachial plexus and attaching to the fitst rib. Right, type 2 ligamentous band from tip of elongated seventh cervical vertebral transverse process showing how eighth cervical and first thoracic nerve roots, forming the inferior trunk of the brachialplexus, must curve over the band (arrow) as they cross the thoracic outlet.
Type 3 band is the smallest, deepest, and most difficult to visualize, yet it is by far the most common. It is a taut muscular band originating on the anterolateral surface of the neck of the first thoracic rib and passes straight across the thoracic outlet, inside the posterior curve of the rib, to attach again just behind the scalene tubercle. (Figure 4.) The first thoracic nerve root and the lower trunk of the brachial plexus, formed by the union of the first thoracic root with the eighth cervical nerve root, cross over this band, which may become the source of persistent
irritation of the lower trunk of the plexus. This partitular anomaly has been found in the majority of patients in this series who required operative relief for their TOS. Type 4 is an anomalous muscle connection between the anterior and middle scalene muscles either forming a muscle “sling” or “loop” under the inferior trunk of the brachial plexus and the subclavian artery or forming a common tendinous insertion of the two scalene muscles attached to the first rib. In the first case, the lower trunk of the plexus is elevated ab-
Figure 4. conrplete flmt rib removed from a cadaver w&h the tVplca/ type 3 band (arrow), the most commonanomatyiound in patients undergobg operatkm for TOS. tWetheor&#tdthebamlimvnbhsneckot thelk?trnPandbawr&nl~paste&rtotha scalene tube&e and hmp tithe ante&r scalene muscte. The tirst thorack nerve root and the infar& trunk of the brachlal ptexus C~OBB this typa of band, whtch may rasldthkWtat&ntithe--otthe ptexus, but tha sutxtavien artery Is unlnvotved with thfs anomaty,
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Figure 5. The four scaiene muscles and fhe relationship of the anomalousscaienus mlnimus originating on fhe sixth and seventh cervical vertebral transverse processes and Inserting on fhe first rib between fhe brachiai piexus and subciavian artery. Ris muscle fs Ihe type 5 congenital band.
normally by the sling, a condition that may be aggravated considerably by scalene muscle spasm. The plexus and subclavian artery are wedged into the V-shaped apex formed by the two scalene muscles joining together, another abnormality exaggerated by tension or spasm of the scalene muscles. Type 5 band is the small ribbon-shaped scalenus minimus muscle commonly found in the general population. It arises from the transverse processes of the lower cervical spine, particularly the sixth and seventh cervical vertebrae, and passes obliquely laterally to attach to the first rib between the subclavian artery and the brachial plexus, which is between the anterior and middle scalene muscles as well. (Figure 5.) Normally nothing at all lies between the artery and plexus, but the scalenus minimus will clearly separate these two structures, and the upper part of the plexus crosses over this muscle. Again, scalene muscle spasm obviously will tighten the minimus, causing pressure and irritation of the brachial plexus and its roots. Type 6 band also represents the same scalenus minimus muscle, but instead of inserting on the first rib between the anticus and medius, it clearly attaches to the cupula of the pleura beneath or medial to the first thoracic rib. This is of particular importance because if it is not specifically sought and excised at operation, it will be left intact after surgical removal of the first rib, and the plexus symptoms may persist postoperatively. Type 7 band is the least common of all, having been identified only in two of the patients operated on for TOS over the past two and a half years. It is a tight fibrous or muscular band originating on the
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anterior surface of the scalenus anticus, passes anteriorly in a swooping curve directly beneath the subclavian vein, and attaches to the costoclavicular junction of the first rib under the head of the clavicle, causing an abnormal kink in the vein. If such a variety of congenital anomaly bands exist in the thoracic outlet, of what practical significance are they? Clearly, they provide a mechanical anatomic explanation for the cause of the symptoms of neurovascular irritation or compression, explain the commonly observed failure of such symptoms to respond to conservative treatment, and suggest the most appropriate tests for diagnosis of the syndrome and the most effective form of relief. The bands are, therefore, the key to the whole problem of TOS. Symptoms
As the commonest bands found at operation on patients with TOS are intimately associated with the sensitive brachial plexus, it finally becomes clear on a mechanical basis why 99 per cent of the patients presenting with TOS complaints have primarily neurologic symptoms. These symptoms consist of pain, intermittent numbness, tingling, gradually progressive weakness, fatigue, and dysfunction of the hand. These are strictly neurologic symptoms and bear no relation to circulatory impairment. Arterial insufficiency of the upper extremities is far less frequent than in the lower extremities, though the resulting symptoms-pallor, coldness, and claudication (lameness with exercise&are similar. However, the coldness commonly felt by the patients with TOS is usually a reflection of peripheral neuropathy in the presence of strong,peripheral pulses. The symptoms of venous insufficiency-intermittent edema, venous engorgement, and cyanosis, all made worse by limb exercise-are more frequent than the symptoms of arterial insufficiency, which are the least common of all. For decades, however, the medical profession has focused on arterial compression in the thoracic outlet as the cause of the symptoms and on diagnostic tests that rely on positional radial pulse changes, bruits, plethysmograms, and arteriograms. The surgical procedure for intended relief was directed at decompressing the positional occlusion of the subclavian artery, merely by sectioning the anterior scalene muscle. This procedure had a failure rate of at least 40 per cent [2,3]. Diagnostic Tests
After personal evaluation of more than 2,300 patients for possible TOS, it has become obvious to me
Thoracic Outlet Syndrome
that compression of the subclavian artery has little to do with the cause of the symptoms in about 99 per cent of the patients with TOS, and therefore the physical tests for arterial compression have little bearing on the diagnosis of this common syndrome. Occlusion of the radial pulse when the arm is elevated or shoulder braced and the head turned to either side indicates one thing only: positional compression of the subclavian artery. This does not indicate that the patient has TOS, as several studies have shown positional radial pulse obliteration or subclavian bruits present in the majority of normal people examined. In Wright’s series [4] of 150 asymptomatic normal subjects, 92.6 per cent had obliteration of the radial pulse in at least one upper extremity tested in an elevated arm position. Raaf [2] found obliteration of the radial pulse in more than 60 per cent of asymptomatic subjects with the arm in the shoulder-braced position alone. Gilroy and Meyer [5] found radial pulse obliteration or subclavian bruit in 69 per cent of normal patients, and no symptoms were provoked in these subjects in the elevated arm tests. In the last 250 patients who required surgical relief in my own series, four (1.6 per cent) had a positive Adson test, performed with the arms down [6] on the symptomatic side, but three (1.2 per cent) had a false-positive result on the asymptomatic side. All these studies clearly indicate that pulse obliteration with the arms and head in various positions is a normaE finding in the majority of asymptomatic people and therefore has no relation to the etiology or presence of symptoms. Thus, positional pulse change cannot be used as a significant diagnostic test. Some other mechanism other than subclavian artery compression and pulse occlusion must produce the neurologic symptoms that predominate in 99 per cent of patients with TOS. If such test positions reproduce the patient’s usual symptoms and complaints, the response suggests only that the symptoms are arising from the thoracic outlet. Symptoms in such test positions, however, are usually neurologic complaints of pain, fatigue, heaviness, numbness, and tingling and are actually caused by compression of the brachial plexus in the outlet, since these symptoms may be reproducible irrespective of pulse changes. The long-standing emphasis on pulse evaluation, both clinically and arteriographically, for diagnosis of TOS merely reflects the convenience with which the pulse may be monitored by the examiner, and the recent popularity of angiography. Unfortunately, it is easier to feel pulses and to order elaborate laboratory exami-
Vohuna 132, December 1976
nations than it is to evaluate peripheral nerves and individual muscles thoroughly. Patients who had pulse changes with the head turned or the arm elevated and who underwent scalenotomy usually have a strong radial pulse in all test positions postoperatively but frequently have persistence of their original symptoms. These patients usually will respond well to decompression of the brachial plexus. It is not unusual to find patients with severe symptoms of TOS in one limb that has strong pulses in all test positions and pulse occlusion with arm elevation (Allen test) in the opposite limb that is symptom-free. On rare occasions (0.3 per cent in this series of 980 operative cases in 776 patients) scar tissue caused recurrence of the original symptoms to an unbearable degree and required reoperation for relief, yet the radial pulse and circulation were normal in each patient. This is further proof that the symptoms are almost always caused by irritation of the brachial plexus and have little to do with subclavian artery compression. Furthermore, it has been conclusively shown in recent studies by Rainer and Sadler [7] that positional selective arteriography has no bearing on the diagnosis of TOS or choice of patients for operative relief. In this present series, the same conclusion was derived from the much simpler, safer, and cheaper evaluation of subclavian artery compression, using positional plethysmography to monitor the pulse in several hundred patients. In fact, some patients have shown persistence of positional radial pulse occlusion after first rib resection for severe TOS symptoms, yet the patients were happy and symptom-free postoperatively because the brachial plexus irritation had been completely relieved. The physician evaluating a patient for possible TOS is committed to taking an elaborate history, including great detail of symptoms, onset, positional variation, kinds of relief or aggravation, and response to treatment. If positional evaluation of the radial pulses by palpation, subclavian bruits, plethysmography, or selective arteriography proves unreliable and inaccurate in diagnosis of TOS, what better clinical tests are available? Because the symptoms are neurologic from irritation or compression of the brachial plexus, physical examination must be directed to evaluation of the brachial plexus itself. The most valuable of these neurologic tests are listed in Table III. Reproduction of symptoms by shoulder bracing, which closes the costoclavicular scissor on the brachial plexus, with or without signs of arterial compression, and the 3 minute elevated arm stress test
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TABLE
III
Most Reliable
Tests to Establish
Diagnosis of Neurologic (1) Percussion pain. Supraclavicular over brachial Infraclavicular. lpsilateral side of neck.
TOS
plexus.
(2) Thumb pressure (30 seconds). Pain and tenderness over brachial plexus (supraclavicular). Gradual reproduction of usual symptoms down the arm. (3) Weak muscles. Grip Triceps (innervated by seventh cervical nerve). Interosseous hand muscles (innervated by eighth cervical and first thoracic nerve roots). (4) Hypesthesia to touch and pinprick. Inner forearm (eighth cervical, first thoracic dermatomes). Ulnar side of hand and fingers. Occasionally radial dermatome, dorsum first web. (5) Elevated arm exercise test (3 minutes). Early fatigue and heaviness of involved arm. Gradual onset of numbness and tingling in hand. Increasing vocal complaints. Crescendo of distress of entire upper extremity. Sudden dropping of limb into lap (“completely shot”). Involved limb slow to recover to normal. Total abnormal response commonly seen while radial pulses are strong.
(Figure 6), perhaps the most reliable test of all, will usually delineate TOS from the other problems with similar symptoms, such as cervical disc, carpal tunnel syndromes, or orthopedic shoulder problems. Tenderness elicited over the brachial plexus by light percussion and thumb pressure held in the supraclavicular fossa for 30 seconds indicate that the patient’s symptoms emanate from the plexus itself, not from the cervical spine. Weakness, frequently found in the triceps muscle (innervated from the seventh cervical nerve root) or in the interosseous muscles of the hands, especially between ring and small fingers (innervated from the eighth cervical nerve root) is commonly found, but only if specifically tested. The same is true of hypesthesia to light touch, and pinprick pain sensation in the eighth cervical and first thoracic dermatomes of the inner forearm and hand, because the congenital bands in the outlet usually involve the lower roots forming the brachial plexus. Thus, compression plexopathy most commonly affects the peripheral nerve distribution of the lower roots and inferior trunk of the plexus, that is, the ulnar nerve.
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Figure 6. Patient demonstrating fhe elevated am, stress tesf wifh brachium at right angies to the thorax ( 90“ AER po-
sition) and the toreatm fiexed 90’. The pafieni is instructed lo open and close his fist at moderatespeed for 3 minutes, with the elbows braced somewhat posteriorly. This has been found to be the most reliable tesi for TOS in the series presented herein, if if reproduces the pafienl’s usual symptoms within 3 minutes ( see Table iii).
If the fifth and sixth cervical nerve roots suffer the greatest pressure or irritation, then the peripheral distribution of these roots will be the location of the patient’s worst symptoms. This may be so specific and severe that the problem will closely mimic a fifth and sixth cervical disc lesion. This situation would be one of the few indications for cervical myelography. In such patients presenting with severe fifth and sixth cervical root-like pain, in whom the biceps and triceps muscle reflexes and cervical myelogram are normal, a type 5 scalenus minimus congenital muscle band will usually be found at operation for TOS. Removal of the anomaly and first rib will offer relief in most of these patients who were originally thought to have a ruptured disc. Appropriate tests must always be performed for clinical problems that may produce symptoms similar to TOS, such as carpal tunnel and cervical disc syndromes, cervical or shoulder sprain, and inflammatory conditions of the neck and shoulder. Cervical spine roentgenograms must be examined in every patient to determine the presence of congenital bone anomalies, trauma, degenerative arthritis, or superior sulcus tumors. Electromyography and nerve conduction velocities, advocated by Rainer and Sadler [ 71 and Urschel [8], usually have been of little benefit in the specific diagnosis of TOS and the selection of patients for
The American Journal 01 Surgery
Thoracic Outlet Syndrome
operative relief, according to studies by Daube [9] at the Mayo Clinic, and in the present series as well. There are good anatomic reasons why these neuroelectric studies are not reliable enough to be of help in diagnosis of TOS. First, the range of normal is wide, yet that some laboratories are relying on a specific nerve velocity to be “diagnostic” of TOS and predicting those patients who will benefit from operation, when the value lies well within the normal range of variation obtained in other laboratories. Second, the location of nerve compression or irritation in the thoracic outlet is so central on the plexus and roots (the congenital bands) that the stimulating electrode cannot be placed proximal to the compression site. Thus, the current measured will not cross the site of nerve abnormality. Third, the nerve compression and irritation are usually intermittent, as reflected by the symptoms, so the nerves involved do not undergo severe enough damage or changes to be detected by the relatively insensitive apparatus and technics used. Many physicians working in the field of TOS have abandoned neuroelectric studies as too inaccurate and nonspecific to warrant the considerable expense and patient discomfort involved in obtaining such tests. It must be emphasized that TOS is a clinical diagnosis based upon a detailed history and thorough physical examination using appropriate tests. Thus far, there are no short-cut laboratory or roentgenographic tests reliable enough to be used routinely for the diagnosis of this complex syndrome. Treatment
Once the diagnosis of TOS is well established by the history and appropriate physical and roentgenologic examination, decisions regarding treatment are not difficult and usually fall comfortably into place. Mildly symptomatic patients with paresthesias noted on prolonged arm elevation respond well simply by avoiding the activities or positions that precipitate the symptoms. Moderately symptomatic patients with brachial plexopathy, causing specific muscle weakness, positional paresthesias, and intermittent aching pain, may also respond to avoidance of aggravating activities but also may require pain medication. Physical therapy may be tried but usually offers only temporary relief. The same is true of specific exercises designed to improve posture and strengthen shoulder girdle muscles. An occasional patient with poor posture or muscle tone may respond to these measures, but most patients do not. Because these treatments are simple and without risks, it is usually worth trying them in an attempt to improve, or at least stabilize, the symptoms. The
Volume 132, December 1976
earlier the diagnosis can be established and these conservative measures instituted, the better chance the patient has of preventing mild symptoms from progressing to moderate symptoms (plexopathy) and then to more advanced symptoms (plexitis). Conservative treatment of severe cases of TOS plexitis are rarely effective. Physical therapy, especially cervical traction and TOS exercises, will usually aggravate the symptoms to such an extent that the patient cannot tolerate the treatments. The symptoms then have exceeded the effective range of therapy and safe medication. Injection of steroids or local anesthetics near the plexus, stellate ganglion, or scalene muscles may help localize the source of the symptoms but have no lasting benefits to offer. Many patients who have undergone months of physical therapy, transcutaneous nerve stimulation, osteopathy, chiropractic, and even acupuncture attest to the general ineffectiveness of these methods. The only type of treatment that has much chance of offering relief for this group of patients with severe symptoms is surgical alteration of the mechanical cause of irritation or compression of the neurovascular structures. Currently, the most effective means of accomplishing this is to resect the first thoracic rib, and cervical rib if it is present, plus completely excising all anomalous fibromuscular tissue. The easiest, safest, and most complete exposure to accomplish these ends is to use the transaxillary approach with the patient in the lateral position [10,11). At the time of the original description of the transaxillary technic, however, the frequency and importance of the congenital fibromuscular bands were not appreciated. Experience with many patients who required first rib resection after previous scalenotomy showed that the scalenus anticus had reattached itself onto the scalene tubercle of the first rib. This tendency for divided muscles to reattach to their original insertion is commonly seen elsewhere in the body, such as in avulsion sprains and divided heads of the gastrocnemius muscle. To obviate this phenomenon in the congenital fibromuscular bands frequently found in the thoracic outlet, it is essential to remove the site of the insertion, the first thoracic rib, and cervical rib if present, back to its attachment to the transverse process of the vertebra. It is equally essential to excise all anomalous and fibrous muscular tissue found near the first thoracic nerve root and the subclavian vessels. After the first rib is excised from the sternal cartilage to the transverse process, exposure around the first thoracic vertebra root and major vessels is excellent from the axillary approach, and complete removal of all abnormal tissue back to the neural foramina of the eighth cer-
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vital and first thoracic roots can be accomplished with relative ease and safety. The transverse scapular artery is a small vessel coming off the posterior aspect of the subclavian artery and frequently passes directly through the brachial plexus, usually between the eighth cervical and first thoracic nerve roots. It may be mistaken for a fibrous band and inadvertently divided. If this occurs, frantic clamping for hemostasis must be avoided close to the nerve roots. With “tonsil suction” to keep the field dry, the ends of the small bleeding artery may be carefully clamped with extra-long tonsil hemostats, then secured behind the hemostat with a steel clip. This technic is simple, rapid, and effective for control of bleeding in a hazardous area around the major nerve roots and vessels. It is preferable, of course, to recognize this small arterial branch, avoid it, or clip it before dividing it. With the present knowledge of the frequency and different types of congenital fibromuscular bands causing TOS and the known propensity for divided muscles, bands, and ligaments to reattach to their original site of insertion, resection of the first rib alone no longer should be considered adequate decompression of the brachial plexus and subclavian vessels. The congenital bands also must be totally excised for complete neurovascular decompression. Failure to do this in the past may explain a few of the disappointing results seen after first rib resection. It must be emphasized, however, that the most common cause of poor results of first rib resection is inaccurate diagnosis, resulting in misapplication of first rib resection, or lack of technical expertise in performing the correct procedure. Summary
Personal evaluation of more than 2,300 patients for possible thoracic outlet syndrome (TOS) and knowledge gained from 980 TOS operations in 766 patients (operative incidence of 33.7 per cent of the patients examined) have shown that most patients with TOS have anomalous fibrous muscular bands near the brachial plexus that predispose them to neurologic irritation or compression involving the plexus. Anatomic analysis during operations for TOS, plus cadaver dissections, have disclosed seven distinct types of fibromuscular bands in addition to the less frequent bony anomalies long associated with neurovascular compression. One third of fifty-eight cadaver thoracic outlets dissected showed at least one
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of the seven muscular anomalies recognized at operations. These anomalies can be accurately related to the patients’ symptoms, which are neurologic complaints in 99 per cent of the patients examined who ultimately have the diagnosis of TOS established. Neurologic symptoms are clearly explained by the anomalous bands irritating or compressing the brachial plexus and rarely have any effect on the subclavian vessels. These studies, and others before, have shown no correlation with impairment of circulation or positional radial pulse changes in almost all patients with true TOS. Also, arteriograms and nerve conduction studies generally have failed to be of value in establishing the accurate diagnosis. Reasons for these conclusions are explained, and the most reliable tests are described. The most effective means of relief of severe symptoms of TOS is to alter the mechanical irritation or compression of the brachial plexus by completely resecting the first thoracic rib and all anomalous fibromuscular tissue around the plexus and subclavian vessels. If patients are thoroughly evaluated with appropriate tests and highly selected for surgical treatment, gratifying relief will result in more than 90 per cent of patients, if the correct operation is performed with meticulous technic. References 1. Coote H: Exostosis of the left transverse process of the seventh cervical vertebra, surrounded by blood vessels and nerves; successful removal. Lancef 1: 360, 1861. 2. Raaf J: Surgery for cervical rib and scalenus anticus syndrome. JAMA 157: 219,1955. 3. Clagett OT: Presidential address: research and prosearch. J Thorac Cardiovasc Surg 44: 153, 1972. 4. Wright IS: The neurovascular syndrome produced by hyperabduction of the arms. Am Heart J 157: 1, 1945. 5. Gllroy J, Meyer JS: Compression of the subclavian artery as a cause of ischaemic brachial neuropathy. Brain 86: 733, 1963. 6. Adson W, Coffey RJ Jr: Cervical rib: a method of anterior approach for relief of symptoms by division of the scalenus anticus. Ann Surg 85: 839, 1927. 7. Rainer GW, Sadler TR: Thoracic outlet compression. Application of positional arteriographic and nerve conduction studies. Am J Surg 130: 704, 1975. 8. Urschel HC, Jr, Razyuk MA: Management of thoracic outlet syndrome-current concepts. N Engl J Med 286: 1140, 1972. 9. Daube JR: Nerve conduction studies in the thoracic outlet syndrome. Neurology 25: 347, 1975. 10. Roos DB: Transaxillary approach for first rib resection to relieve thoracic outlet syndrome. Ann Surg 163: 354, 1966. 11. Roos DB: Experience with first rib resection for thoracic outlet syndrome. Ann Surg 173: 429, 1971.
The Amrrlcan Jouma\ of Surgerv
David B. ROOS,MD, Denver, Colorado
Personal experience gained from evaluating more than 2,300 patients for possible thoracic outlet syndrome (TO@, and operating on 776 (204 bilaterally), has led to the firm conviction that patients who have TOS have an underlying anatomic abnormality not present in the general population that predisposes them to develop symptoms of TOS under particular circumstances. Careful anatomic evaluation during first rib resection to decompress the outlet, and cadaver studies in the anatomy laboratory, have disclosed several distinct congenital anomalies that contribute to compression or irritation of the brachial plexus and the subclavian vessels. These congenital anomalies may be correlated with the patient’s symptoms and the most appropriate clinical tests for diagnosis. From this combined anatomic and surgical experience, the most effective technics in the operative treatment of TOS have been elucidated. The knowledge and experience obtained from these studies comprise the present report. Anomalies
For decades, it has been general medical knowledge that the congenital anomaly of cervical rib could cause neurologic symptoms from irritation or compression of the brachial plexus, or vascular complications from similar involvement of the subclavian artery. Indeed, the first operation performed for apparent TOS was removal of a cervical rib in 1861 by Coote [I ] at St. Bartholomew’s Hospital in London. Other congenital anomalies also became associated with symptoms of TOS, such as hypoplastic first thoracic ribs and exostoses of the first rib or clavicle. Even developmental abnormalities of the thoracic outlet long have been recognized as potential contributors to development of TOS, such as a fractured clavicle (Figure 1) or first rib, a drooping FromtheDeperbnent of Surgery, University of Worado School of Medicine, Denver, Colorado. Reprint requests shod be dbssed to David B. Roes, MD. 2045 Franklin Street, Suite 700. Denver, Momdo 90205. Presented at the Twenty-Eighth Annual Meeting of the Southwestern Surgical Congress, Houston, Texas, May 3-6. 1976.
Volume 132. December 1976
shoulder from neurologic disease, injury or poor posture, or hypertrophic muscles seen in athletes and weight lifters. All these afflictions have been well defined and understood for decades because the bony abnormalities are obvious on roentgenograms, and the neurologic deficits, postural abnormalities, and muscle hypertrophy are evident on physical examination. However, all these conditions combined are present in only a small number of patients presenting with typical symptoms associated with TOS. What, then, can be the cause of the symptoms, often of unbearable or incapacitating severity, in all the other patients with TOS who do not have abnormalities detected by roentgenograms or physical observation? The answer is congenital fibrous or muscular band anomalies affecting the brachial plexus and the subclavian vessels. If the surgeon operating for this common syndrome carefully evaluates the anatomy of the thoracic outlet, he will almost invariably find an anomalous fibromuscular band associated with the major neurovascular structures in the patients who have failed to respond satisfactorily to conservative treatment for their outlet syndrome. These patients have a mechanical structural abnormality not found in the average person that causes neurovascular symptoms to develop under general activities, arm position, or trauma to the shoulder-neck area, which ordinarily would have no persistent effect in the average person. The long established structural abnormalities already mentioned will not be discussed further, as they are well known. Because little recognition [2] and no detailed anatomic studies have been devoted to the far more common, though less obvious, fibromuscular bands, the results of such studies in this series of patients and cadavers will be presented. (Tables I and II.) Seven distinct types of congenital fibrous or muscular band anomalies have been found at surgical exploration thus far. Type I is a tough fibrous ligament attached to the anterior tip of an incomplete cervical rib that stops short of a bony connection to the first thoracic rib. (Figure 2.) All incomplete or
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Flgure 1. Lateral cervical spine f//m shows nine vertebrae, seven cervkal and two thoraclc, above the level of the clavicle, indicating low-lying shoulder glrdle commonly seen in young women. Film on the right clearly shows a large left cervical rib and overlapping callous format/on from healed fractured clavicle. m/s patient exhlblts three remarkable anatomlc abnormallttes associated wlth developkg TOS, yet she was asymptomatk unttl she suffered a hyperextension-flex/on neck Injury In a rear end auto colllslon, which preclpltated typical symptoms of TOS. TABLE
I Anomalous Fibromuscular Bands Found in 241 Operations for TOS
Anomalies Found in 58 Thoracic Outlet Dissections in 29 Cadavers
Type of Band
No. of Cases
Incidence (%I
Type of Band
No. of Cases
Incidence (%I
None Type 1 Type 2 Type 3 Type 4 Type 5 Type 6 Type 7 Total
7 18 10 146 13 40 5 2 241
2 8 4 61 5 17 17 1 100
Normal Type 3 Type 4 Type 5
39 10 1 8
67 17 2 14 100
Figure 2. Neurovascular compresslon due to cervical rib. Large comptete left cervkal rib lmpkgkg on the subctavian artery, and a medium sked rtght cervkai rtb wtth the typkal rvpe 1 congen#al ligamenlous bandcompktlng the cervical rib anrage to the first rib. The brachialplexus k always elevated by the underlying Ilgament, thus predlsposkg the plexus to irrttatton and to compression from the clavicle above.
772
TABLE II
short cervical ribs have this congenital ligamentous band completing the cervical rib anlage to the first rib, attaching just posterior to the scalene tubercle. The bands are not visible on roentgenograms, of course, because they contain no bone or calcium, but they will be found in every case of incomplete cervical rib that requires operation, if the surgeon specifically looks for them. Normally the transverse process of the seventh cervical vertebra is equal to or somewhat shorter than the process of the first thoracic vertebra just inferior to it, the transverse process that supports the first thoracic rib. If the process of the seventh cervical vertebra extends out beyond the process of the first thoracic vertebra (Figure 3, left), it represents an apparent abortive attempt to form a cervical rib. The cervical rib anlage then is represented by a taut fibrous ligament, again without bone or calcium so it is not visualized on roentgenograms, connecting the tip of the elongated transverse process of the seventh cervical vertebra to the first thoracic rib, also just posterior to the scalene tubercle. This anomalous fibrous band is type 2. (Figure 3, right.)
The American Journal ol Surgery
Thoracic Outlet Syndrome
Figure 3. Let?, roentgenogram showing large left cervical rib attaching to first thoracic rib pedestal forming a true arthrosis; the right skie shows a diiterent anomaly, an elongated seventh cervical vertebra transverse process spike (arrow) which typk%lly has a type 2 Wngenttal band pas&g under the brachial plexus and attaching to the fitst rib. Right, type 2 ligamentous band from tip of elongated seventh cervical vertebral transverse process showing how eighth cervical and first thoracic nerve roots, forming the inferior trunk of the brachialplexus, must curve over the band (arrow) as they cross the thoracic outlet.
Type 3 band is the smallest, deepest, and most difficult to visualize, yet it is by far the most common. It is a taut muscular band originating on the anterolateral surface of the neck of the first thoracic rib and passes straight across the thoracic outlet, inside the posterior curve of the rib, to attach again just behind the scalene tubercle. (Figure 4.) The first thoracic nerve root and the lower trunk of the brachial plexus, formed by the union of the first thoracic root with the eighth cervical nerve root, cross over this band, which may become the source of persistent
irritation of the lower trunk of the plexus. This partitular anomaly has been found in the majority of patients in this series who required operative relief for their TOS. Type 4 is an anomalous muscle connection between the anterior and middle scalene muscles either forming a muscle “sling” or “loop” under the inferior trunk of the brachial plexus and the subclavian artery or forming a common tendinous insertion of the two scalene muscles attached to the first rib. In the first case, the lower trunk of the plexus is elevated ab-
Figure 4. conrplete flmt rib removed from a cadaver w&h the tVplca/ type 3 band (arrow), the most commonanomatyiound in patients undergobg operatkm for TOS. tWetheor&#tdthebamlimvnbhsneckot thelk?trnPandbawr&nl~paste&rtotha scalene tube&e and hmp tithe ante&r scalene muscte. The tirst thorack nerve root and the infar& trunk of the brachlal ptexus C~OBB this typa of band, whtch may rasldthkWtat&ntithe--otthe ptexus, but tha sutxtavien artery Is unlnvotved with thfs anomaty,
vutume 132. Dmsmk
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Figure 5. The four scaiene muscles and fhe relationship of the anomalousscaienus mlnimus originating on fhe sixth and seventh cervical vertebral transverse processes and Inserting on fhe first rib between fhe brachiai piexus and subciavian artery. Ris muscle fs Ihe type 5 congenital band.
normally by the sling, a condition that may be aggravated considerably by scalene muscle spasm. The plexus and subclavian artery are wedged into the V-shaped apex formed by the two scalene muscles joining together, another abnormality exaggerated by tension or spasm of the scalene muscles. Type 5 band is the small ribbon-shaped scalenus minimus muscle commonly found in the general population. It arises from the transverse processes of the lower cervical spine, particularly the sixth and seventh cervical vertebrae, and passes obliquely laterally to attach to the first rib between the subclavian artery and the brachial plexus, which is between the anterior and middle scalene muscles as well. (Figure 5.) Normally nothing at all lies between the artery and plexus, but the scalenus minimus will clearly separate these two structures, and the upper part of the plexus crosses over this muscle. Again, scalene muscle spasm obviously will tighten the minimus, causing pressure and irritation of the brachial plexus and its roots. Type 6 band also represents the same scalenus minimus muscle, but instead of inserting on the first rib between the anticus and medius, it clearly attaches to the cupula of the pleura beneath or medial to the first thoracic rib. This is of particular importance because if it is not specifically sought and excised at operation, it will be left intact after surgical removal of the first rib, and the plexus symptoms may persist postoperatively. Type 7 band is the least common of all, having been identified only in two of the patients operated on for TOS over the past two and a half years. It is a tight fibrous or muscular band originating on the
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anterior surface of the scalenus anticus, passes anteriorly in a swooping curve directly beneath the subclavian vein, and attaches to the costoclavicular junction of the first rib under the head of the clavicle, causing an abnormal kink in the vein. If such a variety of congenital anomaly bands exist in the thoracic outlet, of what practical significance are they? Clearly, they provide a mechanical anatomic explanation for the cause of the symptoms of neurovascular irritation or compression, explain the commonly observed failure of such symptoms to respond to conservative treatment, and suggest the most appropriate tests for diagnosis of the syndrome and the most effective form of relief. The bands are, therefore, the key to the whole problem of TOS. Symptoms
As the commonest bands found at operation on patients with TOS are intimately associated with the sensitive brachial plexus, it finally becomes clear on a mechanical basis why 99 per cent of the patients presenting with TOS complaints have primarily neurologic symptoms. These symptoms consist of pain, intermittent numbness, tingling, gradually progressive weakness, fatigue, and dysfunction of the hand. These are strictly neurologic symptoms and bear no relation to circulatory impairment. Arterial insufficiency of the upper extremities is far less frequent than in the lower extremities, though the resulting symptoms-pallor, coldness, and claudication (lameness with exercise&are similar. However, the coldness commonly felt by the patients with TOS is usually a reflection of peripheral neuropathy in the presence of strong,peripheral pulses. The symptoms of venous insufficiency-intermittent edema, venous engorgement, and cyanosis, all made worse by limb exercise-are more frequent than the symptoms of arterial insufficiency, which are the least common of all. For decades, however, the medical profession has focused on arterial compression in the thoracic outlet as the cause of the symptoms and on diagnostic tests that rely on positional radial pulse changes, bruits, plethysmograms, and arteriograms. The surgical procedure for intended relief was directed at decompressing the positional occlusion of the subclavian artery, merely by sectioning the anterior scalene muscle. This procedure had a failure rate of at least 40 per cent [2,3]. Diagnostic Tests
After personal evaluation of more than 2,300 patients for possible TOS, it has become obvious to me
Thoracic Outlet Syndrome
that compression of the subclavian artery has little to do with the cause of the symptoms in about 99 per cent of the patients with TOS, and therefore the physical tests for arterial compression have little bearing on the diagnosis of this common syndrome. Occlusion of the radial pulse when the arm is elevated or shoulder braced and the head turned to either side indicates one thing only: positional compression of the subclavian artery. This does not indicate that the patient has TOS, as several studies have shown positional radial pulse obliteration or subclavian bruits present in the majority of normal people examined. In Wright’s series [4] of 150 asymptomatic normal subjects, 92.6 per cent had obliteration of the radial pulse in at least one upper extremity tested in an elevated arm position. Raaf [2] found obliteration of the radial pulse in more than 60 per cent of asymptomatic subjects with the arm in the shoulder-braced position alone. Gilroy and Meyer [5] found radial pulse obliteration or subclavian bruit in 69 per cent of normal patients, and no symptoms were provoked in these subjects in the elevated arm tests. In the last 250 patients who required surgical relief in my own series, four (1.6 per cent) had a positive Adson test, performed with the arms down [6] on the symptomatic side, but three (1.2 per cent) had a false-positive result on the asymptomatic side. All these studies clearly indicate that pulse obliteration with the arms and head in various positions is a normaE finding in the majority of asymptomatic people and therefore has no relation to the etiology or presence of symptoms. Thus, positional pulse change cannot be used as a significant diagnostic test. Some other mechanism other than subclavian artery compression and pulse occlusion must produce the neurologic symptoms that predominate in 99 per cent of patients with TOS. If such test positions reproduce the patient’s usual symptoms and complaints, the response suggests only that the symptoms are arising from the thoracic outlet. Symptoms in such test positions, however, are usually neurologic complaints of pain, fatigue, heaviness, numbness, and tingling and are actually caused by compression of the brachial plexus in the outlet, since these symptoms may be reproducible irrespective of pulse changes. The long-standing emphasis on pulse evaluation, both clinically and arteriographically, for diagnosis of TOS merely reflects the convenience with which the pulse may be monitored by the examiner, and the recent popularity of angiography. Unfortunately, it is easier to feel pulses and to order elaborate laboratory exami-
Vohuna 132, December 1976
nations than it is to evaluate peripheral nerves and individual muscles thoroughly. Patients who had pulse changes with the head turned or the arm elevated and who underwent scalenotomy usually have a strong radial pulse in all test positions postoperatively but frequently have persistence of their original symptoms. These patients usually will respond well to decompression of the brachial plexus. It is not unusual to find patients with severe symptoms of TOS in one limb that has strong pulses in all test positions and pulse occlusion with arm elevation (Allen test) in the opposite limb that is symptom-free. On rare occasions (0.3 per cent in this series of 980 operative cases in 776 patients) scar tissue caused recurrence of the original symptoms to an unbearable degree and required reoperation for relief, yet the radial pulse and circulation were normal in each patient. This is further proof that the symptoms are almost always caused by irritation of the brachial plexus and have little to do with subclavian artery compression. Furthermore, it has been conclusively shown in recent studies by Rainer and Sadler [7] that positional selective arteriography has no bearing on the diagnosis of TOS or choice of patients for operative relief. In this present series, the same conclusion was derived from the much simpler, safer, and cheaper evaluation of subclavian artery compression, using positional plethysmography to monitor the pulse in several hundred patients. In fact, some patients have shown persistence of positional radial pulse occlusion after first rib resection for severe TOS symptoms, yet the patients were happy and symptom-free postoperatively because the brachial plexus irritation had been completely relieved. The physician evaluating a patient for possible TOS is committed to taking an elaborate history, including great detail of symptoms, onset, positional variation, kinds of relief or aggravation, and response to treatment. If positional evaluation of the radial pulses by palpation, subclavian bruits, plethysmography, or selective arteriography proves unreliable and inaccurate in diagnosis of TOS, what better clinical tests are available? Because the symptoms are neurologic from irritation or compression of the brachial plexus, physical examination must be directed to evaluation of the brachial plexus itself. The most valuable of these neurologic tests are listed in Table III. Reproduction of symptoms by shoulder bracing, which closes the costoclavicular scissor on the brachial plexus, with or without signs of arterial compression, and the 3 minute elevated arm stress test
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TABLE
III
Most Reliable
Tests to Establish
Diagnosis of Neurologic (1) Percussion pain. Supraclavicular over brachial Infraclavicular. lpsilateral side of neck.
TOS
plexus.
(2) Thumb pressure (30 seconds). Pain and tenderness over brachial plexus (supraclavicular). Gradual reproduction of usual symptoms down the arm. (3) Weak muscles. Grip Triceps (innervated by seventh cervical nerve). Interosseous hand muscles (innervated by eighth cervical and first thoracic nerve roots). (4) Hypesthesia to touch and pinprick. Inner forearm (eighth cervical, first thoracic dermatomes). Ulnar side of hand and fingers. Occasionally radial dermatome, dorsum first web. (5) Elevated arm exercise test (3 minutes). Early fatigue and heaviness of involved arm. Gradual onset of numbness and tingling in hand. Increasing vocal complaints. Crescendo of distress of entire upper extremity. Sudden dropping of limb into lap (“completely shot”). Involved limb slow to recover to normal. Total abnormal response commonly seen while radial pulses are strong.
(Figure 6), perhaps the most reliable test of all, will usually delineate TOS from the other problems with similar symptoms, such as cervical disc, carpal tunnel syndromes, or orthopedic shoulder problems. Tenderness elicited over the brachial plexus by light percussion and thumb pressure held in the supraclavicular fossa for 30 seconds indicate that the patient’s symptoms emanate from the plexus itself, not from the cervical spine. Weakness, frequently found in the triceps muscle (innervated from the seventh cervical nerve root) or in the interosseous muscles of the hands, especially between ring and small fingers (innervated from the eighth cervical nerve root) is commonly found, but only if specifically tested. The same is true of hypesthesia to light touch, and pinprick pain sensation in the eighth cervical and first thoracic dermatomes of the inner forearm and hand, because the congenital bands in the outlet usually involve the lower roots forming the brachial plexus. Thus, compression plexopathy most commonly affects the peripheral nerve distribution of the lower roots and inferior trunk of the plexus, that is, the ulnar nerve.
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Figure 6. Patient demonstrating fhe elevated am, stress tesf wifh brachium at right angies to the thorax ( 90“ AER po-
sition) and the toreatm fiexed 90’. The pafieni is instructed lo open and close his fist at moderatespeed for 3 minutes, with the elbows braced somewhat posteriorly. This has been found to be the most reliable tesi for TOS in the series presented herein, if if reproduces the pafienl’s usual symptoms within 3 minutes ( see Table iii).
If the fifth and sixth cervical nerve roots suffer the greatest pressure or irritation, then the peripheral distribution of these roots will be the location of the patient’s worst symptoms. This may be so specific and severe that the problem will closely mimic a fifth and sixth cervical disc lesion. This situation would be one of the few indications for cervical myelography. In such patients presenting with severe fifth and sixth cervical root-like pain, in whom the biceps and triceps muscle reflexes and cervical myelogram are normal, a type 5 scalenus minimus congenital muscle band will usually be found at operation for TOS. Removal of the anomaly and first rib will offer relief in most of these patients who were originally thought to have a ruptured disc. Appropriate tests must always be performed for clinical problems that may produce symptoms similar to TOS, such as carpal tunnel and cervical disc syndromes, cervical or shoulder sprain, and inflammatory conditions of the neck and shoulder. Cervical spine roentgenograms must be examined in every patient to determine the presence of congenital bone anomalies, trauma, degenerative arthritis, or superior sulcus tumors. Electromyography and nerve conduction velocities, advocated by Rainer and Sadler [ 71 and Urschel [8], usually have been of little benefit in the specific diagnosis of TOS and the selection of patients for
The American Journal 01 Surgery
Thoracic Outlet Syndrome
operative relief, according to studies by Daube [9] at the Mayo Clinic, and in the present series as well. There are good anatomic reasons why these neuroelectric studies are not reliable enough to be of help in diagnosis of TOS. First, the range of normal is wide, yet that some laboratories are relying on a specific nerve velocity to be “diagnostic” of TOS and predicting those patients who will benefit from operation, when the value lies well within the normal range of variation obtained in other laboratories. Second, the location of nerve compression or irritation in the thoracic outlet is so central on the plexus and roots (the congenital bands) that the stimulating electrode cannot be placed proximal to the compression site. Thus, the current measured will not cross the site of nerve abnormality. Third, the nerve compression and irritation are usually intermittent, as reflected by the symptoms, so the nerves involved do not undergo severe enough damage or changes to be detected by the relatively insensitive apparatus and technics used. Many physicians working in the field of TOS have abandoned neuroelectric studies as too inaccurate and nonspecific to warrant the considerable expense and patient discomfort involved in obtaining such tests. It must be emphasized that TOS is a clinical diagnosis based upon a detailed history and thorough physical examination using appropriate tests. Thus far, there are no short-cut laboratory or roentgenographic tests reliable enough to be used routinely for the diagnosis of this complex syndrome. Treatment
Once the diagnosis of TOS is well established by the history and appropriate physical and roentgenologic examination, decisions regarding treatment are not difficult and usually fall comfortably into place. Mildly symptomatic patients with paresthesias noted on prolonged arm elevation respond well simply by avoiding the activities or positions that precipitate the symptoms. Moderately symptomatic patients with brachial plexopathy, causing specific muscle weakness, positional paresthesias, and intermittent aching pain, may also respond to avoidance of aggravating activities but also may require pain medication. Physical therapy may be tried but usually offers only temporary relief. The same is true of specific exercises designed to improve posture and strengthen shoulder girdle muscles. An occasional patient with poor posture or muscle tone may respond to these measures, but most patients do not. Because these treatments are simple and without risks, it is usually worth trying them in an attempt to improve, or at least stabilize, the symptoms. The
Volume 132, December 1976
earlier the diagnosis can be established and these conservative measures instituted, the better chance the patient has of preventing mild symptoms from progressing to moderate symptoms (plexopathy) and then to more advanced symptoms (plexitis). Conservative treatment of severe cases of TOS plexitis are rarely effective. Physical therapy, especially cervical traction and TOS exercises, will usually aggravate the symptoms to such an extent that the patient cannot tolerate the treatments. The symptoms then have exceeded the effective range of therapy and safe medication. Injection of steroids or local anesthetics near the plexus, stellate ganglion, or scalene muscles may help localize the source of the symptoms but have no lasting benefits to offer. Many patients who have undergone months of physical therapy, transcutaneous nerve stimulation, osteopathy, chiropractic, and even acupuncture attest to the general ineffectiveness of these methods. The only type of treatment that has much chance of offering relief for this group of patients with severe symptoms is surgical alteration of the mechanical cause of irritation or compression of the neurovascular structures. Currently, the most effective means of accomplishing this is to resect the first thoracic rib, and cervical rib if it is present, plus completely excising all anomalous fibromuscular tissue. The easiest, safest, and most complete exposure to accomplish these ends is to use the transaxillary approach with the patient in the lateral position [10,11). At the time of the original description of the transaxillary technic, however, the frequency and importance of the congenital fibromuscular bands were not appreciated. Experience with many patients who required first rib resection after previous scalenotomy showed that the scalenus anticus had reattached itself onto the scalene tubercle of the first rib. This tendency for divided muscles to reattach to their original insertion is commonly seen elsewhere in the body, such as in avulsion sprains and divided heads of the gastrocnemius muscle. To obviate this phenomenon in the congenital fibromuscular bands frequently found in the thoracic outlet, it is essential to remove the site of the insertion, the first thoracic rib, and cervical rib if present, back to its attachment to the transverse process of the vertebra. It is equally essential to excise all anomalous and fibrous muscular tissue found near the first thoracic nerve root and the subclavian vessels. After the first rib is excised from the sternal cartilage to the transverse process, exposure around the first thoracic vertebra root and major vessels is excellent from the axillary approach, and complete removal of all abnormal tissue back to the neural foramina of the eighth cer-
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vital and first thoracic roots can be accomplished with relative ease and safety. The transverse scapular artery is a small vessel coming off the posterior aspect of the subclavian artery and frequently passes directly through the brachial plexus, usually between the eighth cervical and first thoracic nerve roots. It may be mistaken for a fibrous band and inadvertently divided. If this occurs, frantic clamping for hemostasis must be avoided close to the nerve roots. With “tonsil suction” to keep the field dry, the ends of the small bleeding artery may be carefully clamped with extra-long tonsil hemostats, then secured behind the hemostat with a steel clip. This technic is simple, rapid, and effective for control of bleeding in a hazardous area around the major nerve roots and vessels. It is preferable, of course, to recognize this small arterial branch, avoid it, or clip it before dividing it. With the present knowledge of the frequency and different types of congenital fibromuscular bands causing TOS and the known propensity for divided muscles, bands, and ligaments to reattach to their original site of insertion, resection of the first rib alone no longer should be considered adequate decompression of the brachial plexus and subclavian vessels. The congenital bands also must be totally excised for complete neurovascular decompression. Failure to do this in the past may explain a few of the disappointing results seen after first rib resection. It must be emphasized, however, that the most common cause of poor results of first rib resection is inaccurate diagnosis, resulting in misapplication of first rib resection, or lack of technical expertise in performing the correct procedure. Summary
Personal evaluation of more than 2,300 patients for possible thoracic outlet syndrome (TOS) and knowledge gained from 980 TOS operations in 766 patients (operative incidence of 33.7 per cent of the patients examined) have shown that most patients with TOS have anomalous fibrous muscular bands near the brachial plexus that predispose them to neurologic irritation or compression involving the plexus. Anatomic analysis during operations for TOS, plus cadaver dissections, have disclosed seven distinct types of fibromuscular bands in addition to the less frequent bony anomalies long associated with neurovascular compression. One third of fifty-eight cadaver thoracic outlets dissected showed at least one
778
of the seven muscular anomalies recognized at operations. These anomalies can be accurately related to the patients’ symptoms, which are neurologic complaints in 99 per cent of the patients examined who ultimately have the diagnosis of TOS established. Neurologic symptoms are clearly explained by the anomalous bands irritating or compressing the brachial plexus and rarely have any effect on the subclavian vessels. These studies, and others before, have shown no correlation with impairment of circulation or positional radial pulse changes in almost all patients with true TOS. Also, arteriograms and nerve conduction studies generally have failed to be of value in establishing the accurate diagnosis. Reasons for these conclusions are explained, and the most reliable tests are described. The most effective means of relief of severe symptoms of TOS is to alter the mechanical irritation or compression of the brachial plexus by completely resecting the first thoracic rib and all anomalous fibromuscular tissue around the plexus and subclavian vessels. If patients are thoroughly evaluated with appropriate tests and highly selected for surgical treatment, gratifying relief will result in more than 90 per cent of patients, if the correct operation is performed with meticulous technic. References 1. Coote H: Exostosis of the left transverse process of the seventh cervical vertebra, surrounded by blood vessels and nerves; successful removal. Lancef 1: 360, 1861. 2. Raaf J: Surgery for cervical rib and scalenus anticus syndrome. JAMA 157: 219,1955. 3. Clagett OT: Presidential address: research and prosearch. J Thorac Cardiovasc Surg 44: 153, 1972. 4. Wright IS: The neurovascular syndrome produced by hyperabduction of the arms. Am Heart J 157: 1, 1945. 5. Gllroy J, Meyer JS: Compression of the subclavian artery as a cause of ischaemic brachial neuropathy. Brain 86: 733, 1963. 6. Adson W, Coffey RJ Jr: Cervical rib: a method of anterior approach for relief of symptoms by division of the scalenus anticus. Ann Surg 85: 839, 1927. 7. Rainer GW, Sadler TR: Thoracic outlet compression. Application of positional arteriographic and nerve conduction studies. Am J Surg 130: 704, 1975. 8. Urschel HC, Jr, Razyuk MA: Management of thoracic outlet syndrome-current concepts. N Engl J Med 286: 1140, 1972. 9. Daube JR: Nerve conduction studies in the thoracic outlet syndrome. Neurology 25: 347, 1975. 10. Roos DB: Transaxillary approach for first rib resection to relieve thoracic outlet syndrome. Ann Surg 163: 354, 1966. 11. Roos DB: Experience with first rib resection for thoracic outlet syndrome. Ann Surg 173: 429, 1971.
The Amrrlcan Jouma\ of Surgerv