Neurologic Thoracic Outlet Syndrome

Thoracic outlet syndrome (TOS) is a complex clinical entity characterized by various neurovascular signs and symptoms of the upper limb.[1] TOS includes several different types of disorders, as follows:

• Neurologic TOS

  • Classic (true) neurologic TOS

  • Common (disputed) neurologic TOS

• Vascular TOS

  • Arterial TOS

  • Venous TOS

• Combined neurovascular TOS

TOS can involve various components of the brachial plexus, the blood vessels, or both at different sites between the base of the neck and the axilla.

The arterial form is caused by compression of the subclavian artery, the venous form is caused by compression of the subclavian vein, and the neurologic form is caused by brachial plexus compression. Combined neurovascular TOS is usually traumatic.

Most authors suggest that nonspecific neurologic TOS results from injury to the brachial plexus, by either traction or compression, at some point within the cervicoaxillary canal.

True (classic) neurologic TOS, which is rare, is caused by congenital anomalies. Usually these anomalies include a taut fibrous band or rudimentary cervical rib.[1]

Frequency

The exact prevalence of TOS is difficult to assess. True neurogenic or vascular TOS is considered rare, but common (nonspecific/disputed) neurogenic TOS is more prevalent.

Demographics

TOS is more common in women than in men. The sex ratio varies depending on the type of TOS.

The female-to-male ratio in neurologic-type TOS is approximately 3.5:1[2]

The vascular type has no sexual predilection

Because of complex etiology and absence of good diagnostic tests, patient history is important in TOS.

Pain

In common neurogenic TOS, pain is the most common and earliest complaint. Detailed history characterizing the patient's pain may lead to appropriate diagnostic and therapeutic plans.

Ask the patient to describe the pain location and type on a pain diagram (anterior/posterior and lateral view of human picture).

Pain, numbness, and/or tingling of the upper extremity are common presenting features of neurogenic TOS.

Sometimes the patient may report pain in the chest, neck, and/or face and even headache.[3]

Precipitating factors include repetitive or stressful activity, such as prolonged computer keyboard use or overhead work, which can provoke or intensify pain.

Most patients report a history of an automobile accident or work-related injury.

Alleviating factors may exist and may provide additional clues for possible etiologies.

Various terms can be used to describe quality of pain, but it is usually a dull aching type in neurogenic TOS.

Spreading or radiation of pain is also important in evaluation of neuropathic pain. If retrosternal pain (radiating pain from the intercostobrachial nerve, a branch of the T2 intercostal nerve) is noticed on the left side, it can be confused with pain of cardiac or pulmonary origin.[4, 5]

Use some type of rating system to evaluate pain severity or intensity with a degree of objectivity and reproducibility. Different types of pain scales may be used. Numerical scales are more useful and reliable. The Visual Analog Scale (VAS) is a commonly used numerical scale.

Arterial TOS often is associated with aching, fatigue, weakness, and pallor due to brachial ischemia.

Cold temperature always worsens symptoms.

Several physical exam findings can aid the diagnosis of thoracic outlet syndrome (TOS):

• Hyperabduction and depression of the shoulder may provoke symptoms in patients with TOS.

• Various stress tests or provocative maneuvers are used by the clinician to evaluate TOS. The sensitivity and specificity of these maneuvers have been reported to be low.

  • Wright maneuver: This maneuver requires the patient to hold the arms next to the ears. Paresthesias usually are noted down the medial scapular border and into lower trunk distribution.

  • Elevated-arm stress test: In this test, the patient keeps arms abducted with flexed elbows for 3 minutes while flexing and extending the fingers. Results are considered positive if the patient cannot do this for 3 minutes.

  • Hyperabduction test: The radial pulse is diminished after elevating the involved arm above the head.

  • Supraclavicular pressure test: With the patient seated, the examiner places their fingers on the upper trapezius and the thumb on the anterior scalene muscle and squeezes for 30 seconds. Results are positive if there is reproduction of pain or paresthesias.

  • Adson maneuvers: While the patient is in a sitting position, ask the patient to inspire deeply, hold his breath, and extend his neck. Then, turn the patient's head passively as far as possible toward one side and then the other. When the head is turned toward the unaffected side, or sometimes the affected side, obliteration of the radial pulse with a drop in blood pressure in the arm is considered a positive result. While turning the head in either direction, the pulse may disappear on both sides, but, on the affected side, a longer lag occurs in its return. During this maneuver, a bruit may develop that is best heard in the supraclavicular space.[6]

  • Military maneuver (ie, costoclavicular bracing): This maneuver provokes symptoms when the patient elevates the chin and pulls the shoulder joint behind in an extreme "attention" position.[7]

  • Cyriax release test: With the patient leaning back slightly, grasp the patient's arms below the elbows with the elbow held at 80 degrees of flexion and elevate the shoulder girdle for up to 3 minutes. Results are positive if there is paresthesia, numbess, or reproduction of symptoms.

• In common neurogenic TOS, physical examination usually does not reveal appreciable sensory loss or motor atrophy in the limb.

  • Upper trunk involvement results in deltoid, upper arm, and medial scapular border pain.

  • Lower trunk involvement can cause dull ache in the medial forearm and paresthesias in the fourth and fifth fingers.

  • Tenderness to palpation over the brachial plexus and paresthesia on percussion may be observed (Tinel sign). Most patients demonstrate hypersensitivity to mechanical compression over the supraclavicular and infraclavicular fossae.

  • The Spurling sign (ie, pain during direct compression of the foraminal exit areas of cervical nerve roots) may help in making the diagnosis of cervical radiculopathy.

  • Vasomotor involvement caused by TOS must be differentiated from coexistent or other causes of vasomotor instability (eg, complex regional pain syndrome [reflex sympathetic dystrophy or causalgia]).

• In classic neurologic TOS, wasting (especially intrinsic hand muscle atrophy) is a characteristic feature. Signs of decreased pain and temperature sensation may be present in the C8 through T1 distribution.

• In arterial TOS, usual findings include cool and pale extremity. This finding depends on the extent of compression and injury to the subclavian artery.

• In venous TOS, the affected limb may be swollen and tender. It may exhibit cyanosis (dusky coloration), venous distension, and ischemic changes in the upper extremity. Strenuous physical activities of extremity can evoke these symptoms and signs. Venous thrombosis can develop at the site of compression.

The etiology of TOS varies. Most authors suggest that nonspecific neurologic TOS results from injury to the brachial plexus, by either traction or compression, at some point within the cervicoaxillary canal.

True (classic) neurologic TOS is caused by congenital anomalies and usually includes a taut fibrous band or rudimentary cervical rib. Other anatomic anomalies include elongated transverse process of C7.

Trauma or repetitive activities may produce TOS (eg, motor vehicle accident hyperextension injury, effort vein thrombosis).

Certain postures of the body may exacerbate or provoke the symptoms of TOS (eg, hyperabduction with external rotation of arm, depression of shoulder).

A thorough history and physical examination are the most important components in establishing the diagnosis of TOS. Use of radiographic and laboratory tests may improve the diagnostic yield. Various screening tests may be appropriate to exclude other causes of upper extremity pain and paresthesia.

Radiographs may exhibit bony anomalies.

Chest radiograph may demonstrate cervical or first rib, Pancoast tumor, or other skeletal deformity.

Cervical spine radiograph may be helpful in showing a cervical rib, an elongated transverse process, or scoliosis.

Color flow duplex scanning can identify interruption of blood flow to the affected extremity.

CT angiography can identify stenosis, or blockage of the artery from thrombi or emboli. It also can detect aneurysms that may be compressing the plexus.

Venography (subclavian vein) is confirmatory and remains the criterion standard if intervention is planned. This study can demonstrate the site of obstruction or the presence of thrombus.

CT scan or MRI is useful to exclude cord lesions and radiculopathy, evaluate soft tissue structures and may exhibit plexus distortion.

Electromyography/nerve conduction study (EMG/NCS) may be useful to exclude coexistent abnormalities such as peripheral nerve entrapment or cervical radiculopathy and is more useful in the diagnosis of true neurogenic TOS. In true neurogenic TOS, EMG/NCS of patients will show reduced amplitude in the medial antebrachial and ulnar sensory responses and reduced amplitude in median and ulnar (median more so than ulnar) motor responses, with a normal median sensory response.[8, 9]

Sensory evoked potentials are of limited value in making the diagnosis of neurogenic-type TOS and have no established value in vascular-type TOS.

Most patients with TOS require only symptomatic treatment and appropriate consultation. Arterial, venous, and neurologic features may coexist; treatment should be directed toward the dominant component.

Common neurologic-type TOS

Common neurologic-type requires conservative management that commonly includes pharmacologic therapy and gentle physiotherapy.

Patients with common neurologic-type TOS may respond to physical therapy, which increases the range of motion of the neck and shoulders, strengthens the rhomboid and trapezius muscles, and induces a more erect posture.

For true neurologic TOS, sectioning of the congenital band is an appropriate option.

Consider surgical intervention when patients have true weakness, intrinsic muscle wasting, and/or fail conservative therapy with continued pain limiting activities of daily living and work.

Vascular (arterial and venous) TOS

Vascular (arterial and venous) TOS is less common and often requires surgical treatment.

Patients with vascular-type TOS need thrombolysis and vascular surgery consultation.

Analgesic drug therapy

Analgesic drug therapy for TOS can be divided into the following categories:

• Nonopioid analgesics (eg, nonsteroidal anti-inflammatory drugs [NSAIDs], acetaminophen): NSAIDs commonly are used in patients with mild to moderately severe pain. They inhibit inflammatory reactions and pain by decreasing prostaglandin synthesis. Acetaminophen is a safe choice for treatment of pain during pregnancy and breastfeeding.

• Opioid analgesics: Opioids are used commonly as an analgesic in the short term for symptom "flares" or postsurgery.

Antidepressants

Antidepressant medications play a major role in treatment of neuropathic pain.

• Tricyclic antidepressants - amitriptyline (Elavil), nortriptyline (Pamelor)

• Selective serotonin reuptake inhibitor (SSRI) antidepressants - paroxetine (Paxil), fluoxetine (Prozac), sertraline (Zoloft)

• Serotonin and norepinephrine reuptake inhibitors (SNRIs) - venlafaxine (Effexor), duloxetine (Cymbalta)

Anticonvulsants

Sodium channel antagonists have been used in the management of neuropathic pain for several years. These medications are started slowly and administered as needed. Monitor the patient carefully.

Gabapentin and pregabalin are effective in chronic neuropathic pain syndromes.[10, 11, 12]

Other adjunct analgesics

Muscle relaxants (eg, metaxalone [Skelaxin], cyclobenzaprine [Flexeril], benzodiazepines, tizanidine) may be helpful to decrease spasm and provide pain relief. Botulinum injection into the scalene muscles has been shown to provide pain relief and decrease spasm.[13]

Careful evaluation and selection of the patient is very important.

Surgical management of TOS commonly includes supraclavicular and transaxillary approaches for anatomic decompression.[14]

For classic neurologic TOS, sectioning of the congenital band with a supraclavicular approach is the appropriate option. If necessary, the tip of the rudimentary cervical rib can be removed.

Cherington et al reported on 5 patients who suffered serious injuries after surgery for TOS. These patients had few or no clinical abnormalities on examination prior to the surgery.[15]

Consultation may be needed depending on the type of TOS and pathology, as follows:

• Neurology

• Orthopedic surgery

• Vascular surgery

• Physical medicine and rehabilitation

The goals of pharmacotherapy are to reduce morbidity and prevent complications.

Class Summary

Pain control is essential to quality patient care. Analgesics ensure patient comfort, promote pulmonary toilet, and have sedating properties, which are beneficial for patients who have sustained trauma or injuries.

Acetaminophen (Tylenol, Cetafen, Feverall, Aspirin Free Anacin)

Useful for pain in patients with documented hypersensitivity to aspirin or NSAIDs, with upper GI disease, or who are taking oral anticoagulants.

Class Summary

These agents inhibit inflammatory reactions and pain by decreasing activity of cyclooxygenase, which is responsible for prostaglandin synthesis. NSAIDs may provide pain relief in the patient with TOS.

Naproxen (Aleve, Anaprox, Naprelan, Naprosyn)

For relief of mild to moderately severe pain; inhibits inflammatory reactions and pain by decreasing activity of cyclooxygenase, which results in decrease of prostaglandin synthesis.

Ibuprofen (Motrin, Advil, Caldolor, Ibu, Provil)

NSAIDs used commonly for patients with mild to moderately severe pain. Inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.

Nabumetone

As with all the NSAIDs, this agent decreases the formation of prostaglandin precursors, has analgesic, antipyretic, and anti-inflammatory properties.

Ketoprofen

Ketoprofen is used for relief of mild to moderate pain and inflammation. Small dosages are indicated initially in small patients, elderly patients, and patients with renal or liver disease. Doses higher than 75 mg do not increase the therapeutic effects. Administer high doses with caution, and closely observe the patient’s response.

Class Summary

Moderate-to-severe pain in the setting of a flare or postsurgery may require an opioid analgesic.

Oxycodone (OxyContin, Oxaydo, Xtampza ER, Roxicodone)

Long-acting form of opioid currently used commonly for severe pain. Start with small dose and increase gradually.

Morphine sulfate (MS Contin, Arymo ER, Infumorph, Kadian)

Effective analgesic with good safety profile and ease of reversibility with naloxone. Various IV and PO doses used; commonly titrated until desired effect obtained.

Fentanyl transdermal (Abstral, Actiq, Duragesic, Fentora, Lazanda, Subsys)

Potent narcotic analgesic with much shorter half-life than morphine sulfate. Excellent choice for pain management and sedation with short duration (30-60 min); easy to titrate. Easily and quickly reversed by naloxone. When using transdermal dosage form, most patients' pain controlled with 72-h dosing intervals; however, some patients may require dosing intervals of 48 h.

Class Summary

This complex group of drugs has central and peripheral anticholinergic effects, as well as sedative effects. They have central effects on pain transmission. They increase synaptic concentration of serotonin and/or norepinephrine in CNS by inhibiting their reuptake by the presynaptic neuronal membrane.

Nortriptyline (Pamelor)

Has demonstrated effectiveness in treatment of chronic and neuropathic pain.

Amitriptyline (Elavil)

Analgesic for certain chronic and neuropathic pain.

Class Summary

These agents may be considered as alternative to TCAs.

Fluoxetine (Prozac)

Antidepressant with potent specific 5-HT uptake inhibition with fewer anticholinergic and cardiovascular adverse effects than TCAs.

Sertraline (Zoloft)

Antidepressant with potent specific 5-HT uptake inhibition with fewer anticholinergic and cardiovascular adverse effects than TCAs.

Paroxetine (Paxil, Pexeva)

Antidepressant with potent specific 5-HT uptake inhibition with fewer anticholinergic and cardiovascular adverse effects than TCAs.

Duloxetine (Cymbalta)

Antidepressant with 5-HT uptake and norepinephrine uptake inhibition with fewer anticholinergic and cardiovascular adverse effects than TCAs.

Venlafaxine (Effexor XR)

Antidepressant with 5-HT uptake and norepinephrine uptake inhibition with fewer anticholinergic and cardiovascular adverse effects than TCAs.

Class Summary

Use of certain antiepileptic drugs, such as the GABA analogue gabapentin (Neurontin), has proven helpful in some patients with neuropathic pain.

Pregabalin (Lyrica) can be effective, tolerable, and easy to titrate compared to gabapentin.

 

Gabapentin (Neurontin, Neuraptine, Fanatrex FusePaq)

Has antineuralgic effects. Structurally related to GABA but does not interact with GABA receptors.

Pregabalin (Lyrica, Lyrica CR)

Structural derivative of GABA. Binds with high affinity to alpha2 -delta site (a calcium channel subunit). In vitro, reduces calcium-dependent release of several neurotransmitters, possibly by modulating calcium channel function. FDA approved for neuropathic pain associated with diabetic peripheral neuropathy or postherpetic neuralgia and as adjunctive therapy in partial-onset seizures.

Patients with TOS generally are treated on an outpatient basis and require a variety of health care professionals to manage their condition optimally. Please refer to the Treatment section for a discussion of proper rehabilitation methods and other treatment options.

Hospitalization usually is not required for patients with TOS, but this decision depends on the invasiveness of the treatment choice for pain control and the severity of the patient's condition. Sometimes, a short hospitalization is necessary for individuals who require a continuous nerve block. Patients with TOS may have associated conditions that may be amenable to surgery and require further inpatient care.

See the list below:

• Neurogenic TOS usually requires chronic pain management.

• Vascular-type TOS may have better outcome with appropriate management.

• Patients with profound intrinsic muscle atrophy do not regain their function. Appropriate surgery may arrest the progressive deterioration.

See the list below:

• Instruct the patient on the following:

  • Good posture

  • Job modification

  • Exercise programs