Cervical Ribs and Thoracic Outlet Syndrome

Prevalence

Because of a lack of a gold standard for diagnosis it is difficult to obtain meaningful epidemiological figures. Irrespective of the overall incidence, it is estimated that over 90% of all TOS cases are neurogenic, whereas 3-5% are venous. Less than 1% is arterial. The true neurological type probably affects no more than 1 person in 1 million. The overall incidence is given as between 3 and 80 per 1,000. Onset is from the 2nd to the 8th decade with a peak in the 4th decade. It is more common in women than in men, with an excess of between 3- and 9-fold.

History

Symptoms will depend on the type of TOS.

In the neurogenic type, there may be painless wasting of the muscles of the hand, resulting in weakness (eg, difficulty in grasping a racket). Numbness or tingling of the upper limb may be reported. Symptoms are often vague and general and may affect the whole arm. There may also be a painful neck and headache. If there is compression of autonomic nerves, cold hands, swelling or blanching can occur. Stellate ganglion involvement may be possible.

Vascular TOS is seen less frequently than the neurogenic type. If the subclavian vein is compressed, there may be swelling of the arm, distension of the veins or a diffuse pain in the arm or hand.

If the subclavian artery is compressed, patients may notice colour changes, claudication or a vague pain in the arm or hand. Early symptoms may be ignored and patients may not seek medical advice until the condition gets worse, with the development of ulceration or gangrene.

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Pure types are rare and patients often present with symptoms indicative of more than one type. There is often a history of trauma. This may be whiplash from a road traffic accident. It occurs in sportsmen, especially swimmers and throwers.

The interval between trauma and symptoms may be hours to weeks

Foundation of the condition

Cervical ribs or fibrous bands are just one feature that predisposes to narrowing and compression at the outlet.

Poor posture can produce mechanical problems. Sometimes people who are depressed or just have a bad habit with regard to posture let the head drop forward, shoulders droop and this allows the thoracic outlet to narrow and compress the neurovascular structures.

Large breasts can pull the chest wall forward and cause symptoms. Reduction mammoplasty may have a beneficial effect.

Trauma can move structures in the shoulder and chest wall. Fracture of the clavicle can cause compression by bone fragments, excessive callus, haematoma or pseudoaneurysm.

Some of the typical precursors of myofascial pain can cause this syndrome too: sleep disorder, oestrogen or thyroid deficiency, inflammatory disease including rheumatoid arthritis, fibromyalgia and disorders of posture such as kyphosis and scoliosis.

It is necessary to exclude thrombosis, embolism and nerve entrapment in other places. This includes Pancoast’s syndrome, where lung cancer infiltrates the brachial plexus. Paget-Schrötter syndrome is thrombosis of the subclavian vein following heavy exercise of the upper limb.

Distinguished identification

Acromioclavicular joint injury

Brachial plexus injury

Cervical disc injuries

Cervical discogenic pain syndrome

Cervical radiculopathy

Clavicular injuries

Elbow and forearm overuse injuries

Shoulder impingement syndrome

Thoracic disc injuries

Thoracic discogenic pain syndrome

Tests

CXR (CHEST X RAY) with apical lordotic views and cervical spine should be obtained. An X-ray may show cervical ribs, which may be the cause, or have fibrous bands with them. It may also show elevated first ribs, caused by tight anterior or middle scalene muscles. Displaced fractures of clavicle, non-union and excessive callus may be apparent. Cervical spine degenerative changes may be causing neck or shoulder pain or impingement of the spinal nerve roots. Exclude a malignant lesion in the chest.

MRI scan of the cervical spine and supraclavicular or brachial plexus area is useful to find other causes.

A CT scan of the area of the brachial plexus and apex of lung may be indicated.

MRI and CT can distinguish cervical root injury from degenerative spurs, herniated discs or other causes.

Adjunctive tests such as CT angiography can be helpful in difficult cases.

Doppler and plethysmography studies can show impediment of blood flow. A near-complete cut-off of flow during the stress manoeuvre with reproduction of the symptoms would be most impressive. Occlusion can occur in normal subjects but is unusual and is not related to age.

Angiography and venography can show blockage of the vessels from thrombi or emboli. Angiography can demonstrate aneurysms that may be compressing the plexus and causing neurological features. Asymmetry of temperature suggests interference with blood flow from obstruction of autonomic dysfunction. It should improve with successful treatment..

Therapy

• Conservative management is generally considered first-line.
• In cases where postural deviations contribute substantially to compression of the thoracic outlet, rehabilitation helps to decompress the outlet.
• Graded restoration of scapular control at rest and through movement. Humeral head control
• Isolated strengthening of weak shoulder muscles
• Taping and other manual therapy techniques are other adjunctive approaches.
• Occupational therapy may help with back protection techniques and better working practices.

Injection of trigger points and associated muscles may be necessary. An injection of deep muscular structures, as in a scalene block, is dangerously close to the brachial plexus.

Non-steroidal anti-inflammatory drugs (NSAIDs) have a good analgesic as well as anti-inflammatory action and it may be the former that is rather more important.

Some people recommend muscle relaxants such as methocarbamol but they cause sedation.

Calcium-channel blocking agents may possibly be of value where there is vascular instability.

Early surgical intervention leads to better functional outcome than late surgery. This is because early intervention prevents degeneration of the brachial plexus and increases the effectiveness of postoperative physiotherapy.

Surgical intervention may help where there is an obvious physical lesion but, in many cases where this is not the case, it not only fails to improve matters but may lead to deterioration.

Damage to the long thoracic nerve or the brachial plexus is a possibility.

Patients need careful appraisal before neurosurgery.

Paget-Schrötter syndrome requires thrombolysis followed by surgical decompression of the subclavian vein. This gives rather better results than more conservative practices such as anticoagulation.

Some surgeons resect the first rib through a transaxillary approach and others remove the scalene muscles too.

Cervical ribs and fibrous bands should be removed if they are tethering the plexus.

Another option is decompression with neurolysis of the involved regions of the brachial plexus, especially the C7, C8 and T1 nerve roots, through a supraclavicular approach (supraclavicular ‘neuroplasty’).

There is some evidence that transaxillary rib resection is more effective than supraclavicular neuroplasty in relieving pain.

Where the clavicle has been fractured, the removal of excessive callus may be required. Fixation of a fracture that has failed to unite may be required.

As mentioned earlier, reduction of very large breasts may be beneficial. Botulinum toxin may help with symptom relief.

Complications and prognosis

Generally prognosis is good, unless the condition is severe enough to merit surgery and spontaneous recovery will occur. However, sometimes complications occur :

Neurological complications.

Thrombosis,

ischaemia

pseudoaneurysm.

Post-thrombotic syndrome of the lower limb following deep vein thrombosis is well recognised but problems may also follow thrombosis of the upper limb.

CONCLUSION

Cervical ribs are anomalies that arise from the lowest cervical vertebrae but their relationship to thoracic outlet syndrome (TOS) is not so constant that the two conditions should be seen as synonymous. Perhaps no more than 10% of people who have cervical ribs develop Thoracic Outlet Syndrome (TOS) and the syndrome may well occur in the absence of ribs.

Diagnosis of TOS may be difficult and depends upon a thorough history and examination together with supportive tests.

Two main types have been identified – vascular and neurogenic. The vascular type can be further categorised into arterial or venous. Neurogenic TOS can be subcategorised into true or disputed. The true form is accompanied by objective findings whereas the disputed form (which is in fact far more common) is not.