Neurogenic Thoracic Outlet Syndrome (TOS)
The primary purpose of the Washington University Center for Thoracic Outlet Syndrome at Barnes-Jewish Hospital is to better treat patients.
We have tried to provide information that we hope will be helpful to our patients in order to better understand the diagnosis, nonsurgical management, and surgical treatment of all types of TOS, including:
We have also provided information here that may help in navigating work-related and legal issues surrounding TOS. This section also includes some basic information on our approach to caring for patients with TOS, what you can expect in the course of evaluation and treatment, and details that may be useful in planning a visit to our Center.
Important characteristics of neurogenic TOS include:
- From 85-95% of all patients with TOS are affected by neurogenic TOS
- Most frequent in individuals between 20 and 40 years of age
- Can occur in adolescents as well as in middle age
- More than 50% of patients are women
- Often occurs in individuals engaged in occupational or recreational activities that involve repetitive overhead use of the arms and/or heavy lifting
- Frequently develops following various types of injury to the head, neck or upper extremity (e.g., a motor vehicle collision or a fall upon the outstretched arm)
- May also develop in patients with no apparent predisposition because of congenital anatomical variations or a history of trauma
Neurogenic TOS is characterized by compression of the brachial plexus nerve roots (C5 to T1) within the scalene triangle and/or subpectoralis space (see anatomy of TOS).
Patients with neurogenic TOS often exhibit normal or nonspecific findings on conventional electrophysiological testing and/or imaging studies, and are thereby identified on the basis of positive clinical findings and the exclusion of other conditions through a process known as differential diagnosis.
(For stories of patients treated for neurogenic TOS by Robert Thompson, MD, at The Washington University Center for Thoracic Outlet Syndrome at Barnes-Jewish Hospital, see “Patient Features” in top menu bar.)
An important part of the initial assessment is concerned with evaluating the extent of the patient’s disability and expectations for continuing or returning to work. It is particularly helpful to obtain from the patient a detailed description of activities that exacerbate symptoms, as well as those activities normally required in the workplace.
Most individuals with neurogenic TOS have only positional upper extremity complaints and are affected to a mild and tolerable degree. These symptoms are usually due to transient irritation of the brachial plexus in certain positions or activities of the arm. There is little risk of progressive injury in these situations, and most patients will improve with conservative management, not requiring more specific intervention.
A smaller subset of patients with neurogenic TOS exhibit progressively disabling symptoms, which effectively prevent them from working or carrying out simple daily activities. These patients often describe progressive disability, a long history of specialist physician consultations, and multiple partial or ineffective treatments. Such patients may have been prevented from working for long periods of time before consultation, or may have attempted to persist in work-related activities despite ongoing neurogenic symptoms. Assessment and documentation of the level of disability is often required if relief from work is necessary in initial management, and in guiding later decisions about treatment.
History and Symptoms of Neurogenic TOS
The symptoms of neurogenic TOS are typically present throughout the affected arm or hand, and often involve different areas of the entire upper extremity.
Most patients with neurogenic TOS have symptoms affecting just one upper extremity, but bilateral symptoms are not uncommon. When both sides are affected, the dominant extremity is often more symptomatic at first presentation. The opposite extremity can become involved over time, perhaps as a result of compensatory overuse in protecting the extremity initially affected.
Actual muscle weakness or visible muscle atrophy is rare. Since hand or arm pain with use of the affected extremity may lead to the perception of weakness in patients with neurogenic TOS, these symptoms should be clearly distinguished from objective muscle weakness or detectable atrophy to help identify other neuromuscular conditions that may be present.
Symptoms consist of one or more of the following:
- Pain, numbness or tingling in the shoulder, arm or hand
- Tingling (paresthesias) in the arm or hand
- Perception of arm or hand weakness, particularly in elevated positions of the arm
- Substantial symptoms of pain and tension in the neck and/or upper back (often perceived to be the most functionally disabling)
- Headaches in the back of the head
- Difficulty or exacerbation of symptoms while lying on the back with the face up
- Cold sensations, swelling or intermittent discoloration in the hands and fingers
Almost all patients with neurogenic TOS describe reproducible exacerbation of symptoms with arm elevation or sustained overhead use of the arms or hands. Activities that can trigger symptoms include:
- Reaching for objects or lifting with the outstretched arm
- Throwing or catching
- Prolonged typing or work at computer consoles
- Driving a motor vehicle
- Holding a phone
- Combing, brushing or drying the hair
Many patients experience discomfort when their bodies are in specific positions. Symptoms may be brought on while lying supine, especially when the arms are positioned overhead, resulting in pain, numbness, tingling and difficulty sleeping. Patients also frequently describe being awakened by symptoms at night, or awakening with symptoms in the morning, with improvement only after a period of moving or shaking the arm and hand.
Headaches are a common but often overlooked symptom of neurogenic TOS. Headaches associated with neurogenic TOS are typically in the back of the head (occipital), whereas frontal headaches are not specifically associated with brachial plexus compression. Many patients with neurogenic TOS also have migraine headaches, but there is no clear link between these two conditions.
Many patients with neurogenic TOS describe substantial symptoms of pain and tension in the neck and/or upper back, and these symptoms are often perceived to be the most functionally disabling. These symptoms are considered to be caused by excessive stretch and muscle spasm in the neck, shoulder and back (particularly the sternocleidomastoid, trapezius, rhomboid and other periscapular muscles). This most likely occurs as a result of inadvertent alterations in posture and carry of the shoulder girdle that patients may subconsciously make, in order to minimize positions that worsen their symptoms.
The presence of complex regional pain syndrome (CRPS, formerly known as causalgia or reflex sympathetic dystrophy) may also exist in patients with neurogenic TOS. The intensity of CRPS symptoms often leads to avoidance and withdrawal from even light touch of the affected extremity. The identification of co-existing CRPS is important in patients with neurogenic TOS, because it may substantially alter the diagnostic and treatment options to be considered.
Symptoms of neurogenic TOS often can be:
- Variable throughout the day
- Differing day-to-day, depending on levels of activity
- Typically dynamic, with marked positional exacerbation during arm abduction, elevation and other maneuvers
- Accompanied by localized tenderness in the base of the neck
- Known to include pain and muscle spasm frequently extending to the upper arm, neck and back
There are no known disease conditions that specifically predispose an individual to neurogenic TOS, and most patients have been otherwise healthy and physically active before the onset of symptoms.
The presence of a cervical rib is often cited as a predisposing factor in the development of neurogenic TOS. However, few patients with neurogenic TOS actually exhibit a definable cervical rib or first rib anomaly. The development of neurogenic TOS is also rare, even in patients with known cervical ribs, in the absence of additional injury.
Physical examination is initially directed towards identifying particular factors that exacerbate painful hand and arm complaints and determining the degree of neurogenic disability.
- The physician will assess the patient’s resting posture while he/she is sitting comfortably. This examination often reveals the “slumped-forward” position of the head and neck that commonly accompanies neurogenic TOS. The patient is initially asked to describe any symptoms present at rest and to clarify their distribution.
- The physician will check for the presence of any swelling, edema, discoloration or distention of subcutaneous veins in the upper extremities.
- The patient’s hands are evaluated for evidence of muscle atrophy and weakness of hand-grip strength.
- The range of motion of the upper extremities is then assessed under both passive and active conditions, with the patient asked to identify any exacerbation of pain, numbness or tingling along with their specific distribution.
- The effects of arm elevation on the strength of the radial pulse, or visible changes in perfusion of the hand, are evaluated during the Adson maneuver. It is notable that many patients with neurogenic TOS exhibit a pale color in the affected hand during elevation, sometimes referred to as the “white hand sign.” Many physicians with experience in the management of neurogenic TOS find the Adson test to be of little diagnostic value.
- Range of motion of the neck is evaluated with respect to both lateral turning and flexion toward the shoulder (head-tilt), with the symptoms of neurogenic TOS elicited on the opposite side.
- The clavicle and sternoclavicular joint are examined to identify any focal tenderness or palpable deformity that might be associated with a previous fracture or dislocation.
- Pain and tenderness over the shoulder joint is evaluated as potentially related to rotator cuff tears, biceps tendonitis, or degenerative conditions of the acromioclavicular joint.
- Palpation over the sternocleidomastoid, trapezius, parascapular and paraspinous muscles is used to localize specific areas that reproduce symptoms of pain. The presence of multiple muscular “trigger points” is a characteristic feature of fibromyalgia, another condition that can overlap with neurogenic TOS.
- A critical aspect of the physical examination is palpation of the supraclavicular space to determine the presence of scalene muscle spasm, localized tenderness, and reproduction of upper-extremity symptoms. Almost all patients with neurogenic TOS exhibit both tenderness over the scalene triangle and exacerbation of pain, numbness and tingling in the arm and/or hand upon supraclavicular palpation, whereas these findings are infrequent in patients with other cervico-brachial syndromes. Palpable spasm in the anterior scalene muscle is not uncommon in neurogenic TOS. A firm supraclavicular mass may also be palpable in patients with a cervical rib or first rib anomaly.
- Palpation over the infraclavicular space is used to help identify symptoms related to brachial plexus compression at the level of the pectoralis minor muscle, which in our experience occurs in 30-50% of patients with neurogenic TOS.
- The physician will ask the patient to perform positional maneuvers of the upper extremity.
The Upper Limb Tension Test (ULTT)
One of the most important components of the physical examination for neurogenic TOS is the Upper Limb Tension Test (ULTT). The symptoms of brachial plexus compression are usually exacerbated by elevated arm positioning, so the ULTT is performed with the patient placing both arms at 90 degrees of abduction from the trunk, with the elbows extended and the palms flat. Reproduction of arm or hand symptoms during wrist extension, with some degree of relief during wrist flexion, is a frequent finding in those with neurogenic TOS.
- The Elevated Arm Stress Test (EAST)
Perhaps the most widely used and informative provocative maneuver is the Elevated Arm Stress Test (EAST), in which the patient is positioned with the arms elevated in a 90/90 degree “surrender” position and asked to repetitively open and close the hands for up to 3 minutes. Patients are asked to describe all changes in the nature and distribution of symptoms in the neck and upper extremity and are instructed to lower the arms if unable to continue because of pain. Most patients with neurogenic TOS report the rapid onset of typical upper extremity symptoms within 20 to 30 seconds of initiating the EAST, and are often unable to continue the exercise beyond 60 seconds.
Vascular Laboratory Tests
There are no clear indications for vascular laboratory (Doppler) tests in patients suspected of having neurogenic TOS. There are also vascular laboratory testing procedures that may be used in evaluating vasoconstriction in the fingers (e.g., cold-pressor testing), when Raynaud’s phenomemon or complex regional pain syndrome are suspected, but these tests are rarely performed in current practice.
Electromyography and nerve conduction (EMG/NC) studies are usually performed at some point during evaluation of patients with upper-extremity neural symptoms, most often before a diagnosis of neurogenic TOS is considered.
These electrophysiologic tests are accurate and particularly useful in the diagnosis of
- Cervical radiculopathy (due to degenerative spine disorders)
- Peripheral nerve compression syndromes (carpal tunnel and cubital canal syndromes)
- Specific forms of nerve injury
- Generalized neuromuscular diseases
EMG/NC studies with positive results for one of these conditions can thereby direct attention toward specific treatment. Unfortunately, the results of conventional EMG/NC studies are usually negative or nonspecific in patients with neurogenic TOS. This is probably due, at least in part, to the extremely proximal location of brachial plexus nerve root compression, where it may be technically difficult to obtain accurate NC readings. Secondly, nerve compression in neurogenic TOS is typically intermittent, only rarely causing the type of permanent changes in motor nerve function that are most easily detected by EMG/NC studies.
When conventional EMG/NC studies do indicate brachial plexus nerve dysfunction thought to be attributable to neurogenic TOS, this may be considered a sign of relatively advanced and longstanding neural injury. It is not yet clear to what extent this indicates a poor prognosis, but such patients are probably unlikely to improve satisfactorily with prolonged nonsurgical approaches to treatment.
Despite much study in the past, peripheral sensory NC studies have not been shown to carry sufficient sensitivity, specificity, or reproducibility to be widely useful in the diagnosis of neurogenic TOS. In contrast, over the past decade there has been increasing attention drawn to the use of NC studies of the medial antebrachial cutaneous (MAC) nerve.
Plain radiographs of the chest or neck are helpful in determining whether an osseous cervical rib, an anomalous first rib, or an abnormally wide C7 transverse process is present. Although each of these findings may solidify a diagnostic impression of neurogenic TOS, none of them are essential and in most patients the results are negative.
Plain X-rays of the neck are also useful in potentially revealing evidence of degenerative cervical spine disease, and films of the chest may be used to detect any previous injuries to the clavicle or first rib.
Computed tomography (CT) and magnetic resonance imaging (MRI), are important to exclude other conditions that could be responsible for upper-extremity symptoms, including degenerative cervical spine or disc disease, shoulder joint pathology, and various forms of intracranial pathology. Such studies have often been performed before referral for evaluation of neurogenic TOS, but should be considered if clinical findings suggest one of these other conditions.
The results of CT and MRI of the brachial plexus are usually negative in patients with neurogenic TOS, in part because they provide only static images that do not account for changes that occur when the body is in different positions.
Scalene/Pectoralis Muscle Blocks
Injection of a local anesthetic into the anterior scalene muscle (ASM) and/or pectoralis minor muscle (PM) was introduced more than 10 years ago by Dr. Sheldon Jordan (UCLA), as a means to improve the diagnosis of neurogenic TOS and to help predict outcomes of treatment. This approach was based on the recognition that muscle relaxation induced by an ASM/PM anesthetic block can temporarily “decompress” the brachial plexus nerve roots passing through the thoracic outlet. This probably occurs through relief of nerve compression exerted directly by ASM or PM spasm, as well as through indirect effects to decrease narrowing of the costoclavicular space.
Successful ASM/PM blocks are characterized by prompt improvement in symptoms of numbness, tingling, pain and fatigability of the affected limb in patients with neurogenic TOS, with little effect in patients who have an alternative condition, thereby providing strong confirmation of the diagnosis otherwise based on clinical criteria. Strong correlations between the relief of symptoms following an ASM/PM block and the success of surgical thoracic outlet decompression in neurogenic TOS have been reported.
The specific technique used for ASM/PM blocks is an important consideration in interpreting the results. After the block is administered, the intensity of upper-extremity pain is monitored as the patient maneuvers through different body positions. The patient maintains a pain diary over the next 24 hours to further assess the extent and duration of symptom improvement. Data show that most patients with treatment-responsive neurogenic TOS will exhibit improvement after this testing procedure. Specialists with the Thoracic Outlet Syndrome Center recommend the use of ASM/PM blocks in the majority of patients thought to have a diagnosis of neurogenic TOS.
Differential Diagnosis of Neurogenic TOS
Various conditions can mimic or overlap with neurogenic TOS. Because of the difficulties in diagnosis and the controversies regarding treatment, it is likely that neurogenic TOS is still widely under-recognized and undertreated in current practice.
Estimates suggest that there are fewer than 2,000 operations performed for this condition each year in the United States. Surgical treatment is generally thought to be necessary in less than 10% of patients with neurogenic TOS.
The actual prevalence of neurogenic TOS is probably substantially higher than these rough estimates indicate, as patients are often symptomatic for long periods of time before definitive diagnosis and are frequently treated for years by nonspecific approaches.
A short summary of the various conditions that can mimic or overlap with neurogenic TOS is shown in the following table:
Condition:Carpal Tunnel Syndrome
Differentiating Features: Hand pain and paresthesia in median nerve distribution; positive findings on nerve conduction studies; treatment with physical/occupational therapy or surgical decompression.
Condition: Cubital Canal Syndrome
Differentiating Features: Hand pain and paresthesia in ulnar nerve distribution; positive findings on nerve conduction studies; treatment with physical/occupational therapy or surgical mobilization.
Condition: Rotator Cuff Tendinitis
Differentiating Features: Localized pain and tenderness over biceps tendon and shoulder pain on abduction; positive findings on MRI; relief from NSAIDs, local steroid injections or arthroscopic surgery.
Condition: Cervical Spine Strain
Differentiating Features: Post-traumatic neck pain and stiffness localized posteriorly along cervical spine; paraspinal tenderness; relief with conservative measures over weeks to months.
Condition: Cervical Disc Disease
Differentiating Features: Neck pain and stiffness, arm weakness and paresthesia involving thumb and index finger (C5-6 disc); symptom improvement with arm elevation; positive findings on CT or MRI.
Condition: Cervical Arthritis
Differentiating Features: Neck pain and stiffness; arm or hand paresthesia infrequent; degenerative rather than post-traumatic; positive findings on spine radiographs.
Differentiating Features: Post-traumatic inflammation of trapezius and parascapular muscles; tenderness, spasm and palpable nodules over affected muscles; may coexist with TOS and persist after surgery.
Condition: Brachial Plexus Injury
Differentiating Features: Caused by direct injury or stretch; arm pain and weakness, hand paresthesias; symptoms constant not intermittent or positional; positive findings on neurophysiological studies.
Condition: Acromioclavicular Joint
Differentiating Features: Localized pain and tenderness over AC joint; arthritis/bursitis on MRI; responds to NSAIDs, local steroid injections, or distal claviculectomy.
Differentiating Features: Pain and tenderness in multiple (>10) muscle sites; responds to trigger point injections.
Differentiating Features: Digital ischemia with localized fixed skin changes/mottling in the presence of radial/ulnar pulses, proximal atherosclerotic arterial source detected by CT/MR/contrast arteriography, often follows intravascular catheterization, surgical manipulation, or Coumadin treatment; treatment by removal of proximal source, oral vasodilators, or intra-arterial vasodilator infusion; consider sympathetic blocks/sympathectomy; digital amputation when necessary.
Condition: Raynaud’s Syndrome
Differentiating Features: Episodic digital vasospasm, often cold- or activity-induced; absence of serological/rheumatological findings; treatment with oral vasodilators and avoidance of cold exposure; cervical sympathetic blocks or sympathectomy only for nonhealing lesions with threatened tissue loss.
Differentiating Features: Sustained digital vasospasm with ischemic ulceration; systemic manifestations, elevated ESR and serological tests; conservative management of digital lesions with oral vasodilators; consider sympathetic blocks/sympathectomy; digital amputation when necessary.
Differentiating Features: Chronic pain syndrome with digital vasospasm and allodynia in extremity/neck, usually following relatively minor trauma; diagnosis by response to sympathetic blockade; comprehensive pain management with serial cervical sympathetic blocks or cervical sympathectomy.
Condition: Cervical Dystonia
Differentiating Features: Severe, spontaneous, repetitive neck muscle spasm; responds to Botox injections.
Condition: Psychogenic Syndrome
Differentiating Features: Debilitating symptoms, often chronic pain, with no definable pathophysiological abnormality; counseling, psychiatric consultation, and comprehensive pain management required.
Condition: Psychogenic Syndrome
Differentiating Features: Debilitating symptoms, often chronic pain, with no definable pathophysiological abnormality; counseling, psychiatric consultation, and comprehensive pain management required.
Condition: Parsonage-Turner Syndrome
Differentiating Features: Spontaneous brachial neuritis resolving within 3 weeks; no specific treatment.
Condition: Nerve Sheath Neoplasm
Differentiating Features: Neck or axillary mass and neurological deficit; well detected by MRI; treatment by resection.
Condition: Pancoast Tumor
Differentiating Features: Apical lung neoplasm; brachial plexus, sympathetic chain, or subclavian vessel involvement; detected by CT/MRI; treatment by resection with/without radiation/chemotherapy.
Condition: Catheter-Induced Thrombosis
Differentiating Features: Central venous access or pacemaker; initial treatment by catheter removal; anticoagulation.
Condition: Primary Thrombosis
Differentiating Features: Hypercoagulable disorder with spontaneous thrombosis at multiple sites or times; defined by laboratory coagulation studies; treatment with anticoagulant and/or antiplatelet medications.
Condition: Arterial Embolism
Differentiating Features: Digital ischemia with a defined proximal source of thromboembolism, possibly with acute ischemia and/or tissue loss; detected by CT/MR/contrast angiography; treatment by exclusion of proximal artery source, anticoagulation, oral vasodilators; consider arterial vasodilator infusion or cervical sympathectomy.
Neurogenic TOS is initially treated with physical therapy approaches to:
- Relieve scalene/pectoralis muscle spasm
- Improve relevant postural disturbances
- Enhance functional limb mobility
- Strengthen associated shoulder girdle musculature
- Diminish repetitive strain exposure in the workplace
It is important that the patient be referred to a therapist with experience, expertise and interest in TOS, since the management of this condition is different from that of other disorders affecting the neck, shoulder, spine and upper extremity. Many physical therapists do not have great depth of experience with neurogenic TOS, and incorrect approaches to therapy can result in worsening of symptoms and premature failure of conservative management.
The physical therapist treating the patient with neurogenic TOS outlines a specific plan for initial treatment over a 4-6 week period, to be followed by physician reassessment.
Initial patient assessment should include evaluation of 1) posture, 2) alignment, and 3) movement patterns.
Specific focus on areas of impairment that may contribute to compression of the brachial plexus should be given. These areas include:
- Slope of the shoulder girdle
- Angle of the clavicle
- Position of the scapula on the thorax
- Alignment of the cervical and upper thoracic spine
- Position of the humerus in the glenoid fossa (located in the shoulder)
- Posturing of the head and neck
The therapist also examines dynamic patterns, such as scapular mechanics and timing during upper-extremity movements, as well as any changes in muscle length, strength and/or recruitment that may put stress on the brachial plexus.
The therapist utilizes the results of individual-based assessment to focus patient treatment on correcting the postural and movement faults that may be contributing to his or her symptoms.
The treatment may include any one or more of the following:
- Patient education on the specific biomechanical faults associated with movement
- Instruction in an exercise program
- Possible use of external devices, such as bracing or taping
- Correction of daily postures
- Review and instruction on approach to work duties and hobbies that may be contributing to the poor posture and disordered movement patterns
After the initial course of physical therapy, the physician will reassess the progress made and outline plans for future treatment. Most patients with mild symptoms of neurogenic TOS, or those in whom therapy has been started early after the onset of symptoms, will exhibit significant improvement. Therapy is then continued with the expectation that continued benefits will preclude the need to consider surgical treatment.
Because neurogenic TOS is considered by many to be a chronic condition subject to occasional “flare-ups” of more acute symptoms (often related to overuse activities or new injury), it remains important for the patient to continue regular physical therapy exercises and occasional therapist visits as needed during long-term follow-up.
If progress with the initial course of conservative management has been unsatisfactory, the basis for the diagnosis of neurogenic TOS is reviewed and any further testing thought to be appropriate is carried out.
When the patient has symptoms that substantially interfere with daily activities and/or work and has not responded sufficiently to conservative management, surgical treatment is considered. Even with surgical interventions, physical therapy remains an important part of subsequent patient care.
Pharmacologic management of neurogenic TOS typically includes use of the following as needed:
- Nonsteroidal anti-inflammatory agents (NSAIDs)
- Muscle relaxants
- Analgesics and nerve pain medications
The use of opiate (narcotic) analgesics is not generally recommended for neurogenic TOS, as it is a condition of chronic neuropathic pain for which opiates do not have long-term or definitive efficacy yet carry risks of side effects, dependency and dose-escalation. These medications may nonetheless be appropriate for short-term use during temporary “flares” of symptoms or in management of pain after specific interventions (e.g., during recovery from surgical treatment).
Many of our patients with neurogenic TOS have previously had chronic pain management with opiate narcotics, before referral, from which abrupt withdrawal is not advised.
Additional medications that may be used for treatment of pain in neurogenic TOS include antidepressants, such as serotonin norepinephrine reuptake inhibitors (SNRIs) or tricyclic antidepressants (TCAs), antiepileptic or anticonvulsant drugs, and topical agents, such as capsaicin ointment or lidocaine patches. The following table provides a brief list of medications sometimes used in neurogenic TOS:
Non-Opiate Pain Medications and NSAIDs
acetylsalicylic acid (Aspirin)
ibuprofen (Advil, Motrin)
naproxen (Aleve, Naprosyn)
Weak Opiate Pain Medications
propoxyphene + acetaminophen (Darvocet-N)
hydrocodone + acetaminophen (Vicodin, Lortab)
hydrocodone + ibuprofen (Vicoprofen)
oxycodone + acetaminophen (Percocet, Tylox, Roxicet)
oxycodone + aspirin (Percodan)
oxycodone + ibuprofen (Combunox)
Strong Opiate Pain Medications
morphine (Kadian, MS Contin, Avinza)
fentanyl (Duragesic patches)
oxymorphone (Opana, Numorphan)
capsaicin cream (Capzasin-P, Zostrix)
lidocaine patches (Lidoderm)
In some cases of neurogenic TOS, localized injection of botulinum toxin is used to reduce spasm in muscles thought to be responsible for brachial plexus nerve root compression, particularly the anterior and middle scalene and/or pectoralis minor muscles.
Botulinum toxin is a bacterial protein that interferes with the transmission of nerve signals to muscle fibers (“chemodenervation”), thereby reducing prolonged muscle contraction. It is FDA-approved for chemodenervation in cervical dystonia, a disease of excessive neck muscle spasm.
Promising results have been reported with the use of botulinum toxin in neurogenic TOS, producing significant improvement in symptoms similar to that observed after a scalene/pectoralis anesthetic muscle block.
Side effects of botulinum toxin can include dysphagia (diificulty swallowing) and choking sensations, which are usually dose-related. Allergic reactions can also occur.
Because neurogenic TOS is outside the approved indications for use of botulinum toxin, it is often not covered by insurance and is therefore quite expensive for patients. For these reasons, we only use botulinum toxin injections on an occasional basis, when we are specifically seeking a temporary effect, for the treatment of neurogenic TOS.
Neurogenic TOS Surgery
Surgery for neurogenic TOS is based on removing one or more of the structures considered responsible for brachial plexus nerve root compression at the level of the scalene triangle, including:
- The anterior and middle scalene muscles
- Any additional scalene muscle or fascial band anomalies that may be encountered
- The first rib (and cervical rib if present)
- Fibrous scar tissue that may have accumulated around the brachial plexus nerve roots
In patients with a significant component of symptoms attributable to brachial plexus compression at the level of the pectoralis minor muscle, division of the pectoralis minor muscle tendon (a tenotomy) may also be performed, either as an isolated procedure or in combination with decompression at the scalene triangle.
There are several different approaches that have been described for thoracic outlet decompression surgery. The two principal operations in current use are:
- Transaxillary first rib resection, performed through an upper chest incision just under the arm
- Supraclavicular decompression, performed through an anterior neck incision just above the clavicle
Although surgical approach for treatment of neurogenic TOS is not viewed as “one size fits all,” based on long experience the specialists with the Thoracic Outlet Syndrome Center have come to prefer the supraclavicular approach for almost all situations encountered with this condition.
Indications for Surgery
Surgical treatment is considered in patients with neurogenic TOS who have exhibited substantial disability and in whom conservative measures have failed to produce sufficient clinical improvement.
Preoperative evaluation is designed to ensure that the patient meets these criteria and does not have additional underlying medical conditions that might unduly elevate the risks of anesthesia or surgery. Because most patients with neurogenic TOS are relatively young and otherwise healthy, few patients are found to be unsuitable candidates for surgical treatment.
Supraclavicular thoracic outlet decompression is performed through an incision in the front of the neck, parallel to and just above the clavicle. After entering the tissues immediately underneath the skin, the surgeon detaches the scalene fat pad from adjacent tissues and removes a portion of the omohyoid muscle. The scalene fat pad is then mobilized and reflected to the side of the incision. This allows exposure of the anterior scalene muscle, the phrenic nerve along its surface, the underlying subclavian artery, and the brachial plexus nerve roots.
The anterior scalene muscle is traced to its attachment on the top of the first rib, and divided from the bone. The anterior scalene muscle is then lifted and dissected away from any underlying attachments. After tracing the muscle to its origin on the transverse process of the cervical spine, the surgeon divides the upper part of the anterior scalene and removes the muscle.
The brachial plexus nerve roots are dissected free of adjacent tissues and gently retracted toward the front, and the middle scalene muscle is exposed. The long thoracic nerve is identified as it passes from the middle scalene muscle, and it is gently retracted posteriorly. The attachment of the middle scalene muscle to the top of the first rib is divided from the bone, from the side of the rib to its posterior portion. The upper part of the middle scalene muscle is then divided, and the muscle is removed. In patients found to have a scalene minimus muscle anomaly (a small extra muscle that may pass between the brachial plexus nerve roots), this muscle is also removed at this stage of the procedure.
Brachial Plexus Neurolysis
Each of the five nerve roots of the brachial plexus is individually identified. In most patients, there is a variable amount of scar tissue around the brachial plexus that has accumulated as a result of previous injury, inflammation and repair. This scar tissue is meticulously removed from each nerve root to the level of the posterior first rib, along with any additional fibrofascial bands that may be encountered, until full mobility of the brachial plexus is ensured. Direct visualization of all nerve roots is important to protect them from injury and to ensure complete decompression. At the end of the operation, the brachial plexus nerve roots will be wrapped with an absorbable polymer film to help prevent adhesions, an important factor in limiting long-term recurrence of neurogenic TOS.
First Rib Resection
The posterior part of the first rib is exposed near its junction with the transverse process of the spine. This portion of the bone is then divided while the C8 and T1 nerve roots are protected under direct visualization. The remaining cut end of the first rib is trimmed to its attachment with the transverse process of the spine and is then made smooth with a bone rongeur instrument and sealed with bone wax. The small intercostal muscles that attach to the outside surface of the first rib are divided, and the pleural membrane is separated from its underside. The first rib is exposed in the anterior direction to a level just central to the scalene tubercle (a small bony prominence at the previous site of attachment of the anterior scalene muscle). The bone is divided at this location, and the first rib specimen is removed. The remaining anterior end of the first rib is then made smooth with a bone rongeur instrument and sealed with bone wax.
It is notable that from either the transaxillary or supraclavicular approaches to the thoracic outlet, it is not feasible to remove the entire anterior portion of the first rib all the way to its attachment with the sternum. However, since this anterior portion of the first rib does not contribute to nerve (or arterial) compression, it is not necessary to remove this part of the first rib in operations for neurogenic (or arterial) TOS. In contrast, the anterior portion of the first rib is removed in operations for venous TOS, in which an additional infraclavicular incision is used (see venous TOS).
Cervical Rib Resection
In patients with a cervical rib anomaly, this structure is readily identified during the dissection of the anterior and middle scalene muscles, where it is found behind the brachial plexus displacing the nerve roots forward. In these cases, the cervical rib is exposed in a manner similar to that described for the first rib, and the posterior end of the cervical rib is divided before resection of the first rib. When the cervical rib attaches to the first rib by forming a true joint, the junction is maintained while the first rib is resected, and the two are removed together as a single specimen. When the cervical rib ends in a ligamentous band attaching to the first rib, this connection is divided and the cervical rib is removed as a separate specimen before removing the first rib.
Pectoralis Minor Tenotomy
Pectoralis minor tenotomy is approached through a short vertical incision near the shoulder, placed between the deltoid and pectoralis major muscles and just below the coracoid process. After entering the skin, the surgeon separates the tissues between the deltoid and pectoralis major muscles to identify the cephalic vein, and the dissection is carried deep to this level along the edge of the pectoralis major. The lateral portion of the pectoralis major muscle is lifted and the underlying connective tissue is entered to identify the pectoralis minor muscle. The pectoralis minor muscle tendon is encircled approximately one inch below its attachment to the coracoid process and then divided. The end of the muscle is allowed to retract away from the underlying neurovascular bundle.
Alternative Surgical Approaches
One variation of supraclavicular decompression that was performed in the past is one in which the scalene muscles are divided from the top of the first rib, but not fully removed (known as “scalenotomy”). Although this procedure can produce significant initial improvement in patients with neurogenic TOS, it was found to have a substantial recurrence rate, primarily because of reattachment of the scalene muscles around the brachial plexus nerves, and is not widely performed in current practice. Another variation of supraclavicular decompression may be performed without resection of the first rib, consisting of scalenectomy and brachial plexus neurolysis alone. Our experience indicates that there is no clear advantage to retaining the first rib in these operations (i.e., no reduction in risk of operative injury, post-operative pain, rate of recovery after surgery, or subsequent limitations). The retained first rib may also serve as a site for attachment of fibrous scar tissue adjacent to the brachial plexus, leading to recurrent nerve compression. To ensure the most thorough decompression and durable treatment, we generally recommend that surgical treatment include first rib resection.
The principal alternative to supraclavicular decompression in current practice is transaxillary first rib resection. In this operation, the first rib is approached from the side of the upper chest with the arm elevated overhead. The anterior and middle scalene muscles are divided at their attachments to the top of the first rib, after identifying and protecting the lower nerve roots of the brachial plexus (C8 and T1), as well as the subclavian artery and vein. The posterior part of the first rib is divided with protection of the lower nerve roots, and the anterior part of the first rib is divided in a location similar to that described for the supraclavicular approach. Through the transaxillary approach there is not sufficient exposure of the relevant anatomy to perform a complete scalenectomy or brachial plexus neurolysis. Although excellent results have been reported by individual surgeons with vast experience with this operation, there is evidence that these intrinsic limitations are linked to a higher rate of recurrent neurogenic TOS than that occurring after supraclavicular decompression. For surgeons who might perform this operation only on an occasional basis, the risk of nerve injury may also be considerable because of the potential for stretch-induced injury of the brachial plexus during elevated-arm positioning by mechanical retraction devices or assistants unfamiliar with the procedure.
Potential Complications of TOS Surgery
Operations for TOS carry some of the same general risks of any type of surgery, such as bleeding and/or wound hematoma, wound infections, and anesthesia-related complications. These risks are exceptionally low with either supraclavicular decompression or transaxillary first rib resection, occurring in less than 1% of patients. Patients undergoing surgery for TOS may also experience difficulties in the early postoperative period related to incomplete pain control, nausea and loss of appetite, fatigue with activity, listlessness and depression, and various potential side effects of medications. In addition, there are several potential complications that are unique to thoracic outlet decompression. These include:
- Nerve injury to the brachial plexus or its branches. This is an inherent risk of any operation undertaken so closely around major nerves, and includes both sharp injury in which a nerve is cut and postoperative nerve dysfunction (neuropathy) secondary to retraction of the intact nerve. Sharp nerve injury to the brachial plexus should be exceedingly rare and would usually occur in the setting of associated pathological abnormalities that have markedly distorted the anatomy. When recognized, such nerve injuries may warrant direct nerve repair, either at the same time or in a later operation. Retraction neuropathy of the brachial plexus can occur after any operation for neurogenic TOS and is characterized by weakness in lifting the arm or squeezing the hand, as well as sensory symptoms. This type of injury will heal with time and usually resolves within several weeks to months after operation. The overall incidence of retraction neuropathy of the brachial plexus is approximately 5% in operations for neurogenic TOS.
- Nerve injury to the phrenic nerve. The phrenic nerve runs directly within the field of exposure during operations for TOS and is thereby susceptible to potential injury. As the phrenic nerve supplies the diaphragm, injury of the nerve results in paralysis of the diaphragm on the side of operation. This is usually well compensated by increased use of the diaphragm on the other side of the chest and other muscles of respiration, and may result in no symptoms or in relatively mild shortness of breath with exertion, taking a deep breath, or with lying flat. Patients with underlying lung disease may experience significant shortness of breath, at times even at rest, which may require use of supplemental oxygen. Sharp injury to the phrenic nerve is exceptionally rare and postoperative phrenic nerve palsy is usually the result of retraction neuropathy, which can occur even in the hands of surgeons experienced with TOS, with an overall incidence of approximately 10%. Phrenic nerve retraction injury typically resolves within several weeks to months after operation, but in some cases recovery of the phrenic nerve and diaphragm function may take more than 9 to 10 months. Because of the possibility of significant respiratory difficulties that might occur with bilateral phrenic nerve dysfunction, patients with a phrenic nerve palsy on one side should not undergo thoracic outlet decompression on the other side until there is a demonstrated return of phrenic nerve function on the side of the initial operation.
- Nerve injury to the long thoracic nerve. Like the phrenic nerve, the long thoracic nerve runs directly within the field of exposure during operations for TOS and is thereby susceptible to potential injury. Although sharp injury is exceptionally rare, postoperative retraction neuropathy of the long thoracic nerve can occur after any operation for TOS. This results in dysfunction of the serratus anterior muscle underneath the scapula, producing a “winged scapula” in which the edge of the scapula protrudes somewhat during arm elevation and other motions of the upper extremity. Long thoracic nerve palsy typically resolves within several weeks to months after operation, but in some cases recovery of serratus anterior function may take more than 6 to 8 months.
- Pneumothorax. Pneumothorax is caused by entry of air into the chest cavity with partial collapse of the lung, and is readily detected by chest X-ray. This occurs as a result of an opening that has been created in the pleura, the thin membrane that lines the inner surface of the chest cavity. Pneumothorax is relatively common during the course of operations for TOS and may not even be considered a complication, as it can be readily managed by placement of a closed-suction drain within the area of surgery at the completion of the operation (indeed, in order to prevent accumulation of blood or fluid around the brachial plexus, which may be a factor contributing to postoperative perineural fibrosis, it is our preference to open the pleura in all operations for TOS). Development of a pneumothorax in the postoperative period may require placement of a temporary chest tube.
- Pleural effusion. Pleural effusion represents an accumulation of fluid within the chest cavity, consisting of either blood or serous fluid, which can be readily detected by chest X-rays. Placement of a closed-suction drain at the time of surgery helps to minimize the development of fluid collections in the neck and chest, but temporary pleural effusions are observed relatively frequently after operations for TOS (as noted above, we prefer to have blood or fluid drain into the chest after operation, rather than accumulate around the area of the brachial plexus). These pleural effusions typically resolve completely, with reabsorption of the fluid back into the circulation, within several weeks of surgery. Most patients with pleural effusion have minimal difficulty with breathing or chest discomfort, but some may experience shortness of breath with exertion or pain in the lower part of he chest. In rare situations, a temporary chest tube may be needed to help remove the fluid and to improve breathing.
- Blood vessel injury to the subclavian artery or subclavian vein. The subclavian vessels are directly within the operative field during surgical procedures for TOS. Direct blood vessel injury with significant blood loss is rare but a relatively obvious potential problem, and requires immediate suture repair of the artery or vein. Blood vessel injury can also occur through retraction and pulling on one of the small branches that arise from the subclavian vessels, creating an injury to the main subclavian artery or vein that requires suture repair. Major vascular injuries that might require subclavian artery or subclavian vein reconstruction, such as a bypass graft, are exceptionally rare in operations for neurogenic TOS.
- Lymph fluid leak. Lymph fluid draining from the abdomen and chest passes through lymphatic channels that pass through the area of the thoracic outlet, with the largest being the thoracic duct on the left side. The thoracic duct and other lymphatic channels empty fluid into the subclavian and jugular veins, which lie within the operative field during surgery for TOS. Although the thoracic duct can be ligated when necessary, disruption of smaller lymphatic channels during surgery can lead to localized collections of lymph fluid within the neck or chest. These types of lymph fluid leak are usually apparent by the collection of cloudy milky fluid within the closed-suction drain that is left after surgery, and they typically subside within several days after the operation as the underlying tissues heal and scar tissue forms around the lymphatic channels. Persistent leaks can be treated by administration of a low-fat diet and medication to reduce the flow of lymph fluid, as well as maintaining the closed-suction drain, until sufficient healing has occurred to obliterate the small channels. Rarely, in the case of a particularly persistent leak unresponsive to conservative measures, a short reoperation in the neck may be needed to ligate the leaking lymph channel.
- Horner’s syndrome due to sympathetic nerve injury. The sympathetic chain is a set of autonomic nerves that runs vertically along the side of the spine, with branches that pass to supply the entire upper extremity and parts of the face and head. Although the sympathetic chain is not usually directly within the surgical field during operations for TOS, there are special situations in which a cervical sympathectomy (removal of a part of the sympathetic chain) may be included as part of the operative procedure. In these cases, interruption of sympathetic nerve branches that supply the face may occur, resulting in Horner’s syndrome (a condition characterized by partial drooping of the eyelid and excessive constriction of the pupil). This may be a temporary finding that resolves within several weeks to months after surgery or a more permanent change, and it can range widely in severity from barely detectable to pronounced drooping of the eyelid. The occurrence of Horner’s syndrome does not affect visual acuity but may be bothersome, especially when the patient is fatigued. Use of artificial tears and other eyedrops (e.g., Visine) may help alleviate symptoms.
- Complex regional pain syndrome (CRPS) or reflex sympathetic dystrophy (RSD). Some patients with neurogenic TOS may have developed coexisting CRPS/RSD, a severe chronic pain syndrome characterized by extreme skin hypersensitivity, allodynia, and vasoconstriction in the hands and fingers. Because the symptoms of CRPS/RSD can be aggravated by any surgical procedure, this can complicate surgical decision-making as well as postoperative management. Rarely, patients undergoing operations for neurogenic TOS can develop the onset of CRPS/RSD after surgery; this may occur within the first few days to weeks after operation or its onset may be delayed by several months. The cause of CRPS/RSD is not known, but it is recognized to involve abnormalities in transmission of pain signals and sympathetic nerve function. CRPS/RSD can be identified by a temporary improvement in symptoms following a cervical sympathetic (stellate ganglion) anesthetic block, and it may be managed with medications and serial sympathetic blocks until symptoms improve.
- Incomplete decompression. Persistence of symptoms despite operation, or the later development of recurrent neurogenic TOS, can be considered complications of surgical treatment.
This list of potential complications of surgery for TOS is not meant to be exhaustive, but reflects the types of complications of greatest concern to patients and physicians and those that tend to occur with the greatest frequency. In aggregate, all of these potential complications are quite infrequent in patients undergoing operations by surgeons with experience in operations for TOS, yet any of these adverse outcomes can occur even in experienced hands. The overall risk of complications may be considerably higher for those only occasionally performing operations for TOS (e.g., fewer than one to two operations a year), reinforcing the importance of specialist referral for surgical treatment.
Expected Outcomes of Surgery
In properly selected patients with neurogenic TOS who undergo supraclavicular decompression using the approach described here, we expect approximately
- 85% to have substantial improvement in symptoms within 3 months of the operation or earlier (it is relatively rare for patients with neurogenic TOS to describe a complete absence of symptoms and no restrictions in activity, but this type of exceptionally favorable outcome can occur in approximately 5% of patients after surgery).
- Approximately 10% of patients will have less improvement or no substantial change in symptoms after surgery
- Approximately 5% will describe symptoms that have worsened in the first several months
Although most patients with neurogenic TOS exhibit substantial improvement in symptoms within the first several months of operation, some will continue to have more steady improvement over a period as long as 1 to 2 years after surgery.
Patients with neurogenic TOS are generally kept from returning to work or school for approximately 4 to 6 weeks after surgery, to allow sufficient time for recovery from the operation and to make satisfactory progress with physical therapy. Some patients may require a longer period of recovery before returning to work, depending on their preoperative levels of symptoms, pre-existing limitations and restrictions, and the nature of their work activities.
Some may return to limited activities earlier, particularly if their work or school activities are relatively sedentary.
Most patients are able to drive within 2 to 3 weeks of operation, but in some this can aggravate neck muscle spasm.
Excessive activity in patients who return to work or other activities too early can lead to flares of neck and back muscle spasm, recurrent neurogenic symptoms, and even more prolonged recovery.
Reoperations for Neurogenic TOS
Patients with neurogenic TOS who have not had improvement in symptoms following surgical treatment, in the absence of an alternative diagnosis, are considered to have “persistent” neurogenic TOS.
If, upon evaluation, your physician finds that inadequate surgical decompression was achieved at the initial operation, a reoperation may be considered. The decision for such action is dependent in part on what type of procedure was originally performed.
Patients who have had an improvement in symptoms for at least 3 months after an operation for neurogenic TOS, followed by a return in the same or similar symptoms at a later time, are considered to have “recurrent” neurogenic TOS. This appears to occur in approximately 5% of patients and primarily within the first 2 years after operation, after which recurrence is far less likely.
The most frequent cause of recurrence following transaxillary first rib resection is reattachment of the previously divided anterior scalene muscle, along with formation of fibrous scar tissue, around the brachial plexus nerve roots. Formation of fibrous scar tissue around the brachial plexus is also the principal cause of recurrence after supraclavicular decompression operations, but reattachment of the anterior scalene muscle may also occur in this situation if it was not resected at the original operation. In patients in whom the first rib was not resected at the initial operation, or with a substantial remnant of the first rib (incomplete resection), the retained first rib may also be contributing to nerve compression. Reoperation may be considered in all of these situations, to include resection of any residual scalene muscle, fibrous scar tissue around the brachial plexus, and any first rib remnant.
Because there is considerable risk of nerve and blood vessel injury in any reoperation for neurogenic TOS, these types of procedures should be considered only when the symptoms are clearly disabling and unresponsive to conservative treatment measures, and should be