Thoracic outlet syndromeis a condition resulting from the compression of nerves, blood vessels or bothdue to inadequate thoracic outlet or way out between the base of the neck andthorax to pass to the axilla (armpit). The muscles named as scalene muscles, first rib and clavicle surround the thoracic outlet. It is observed that any movement or enlargement of tissues of or near the thoracic outlet can cause the syndrome. This can include activities like muscle enlargement due to weightlifting, congenital extra rib, increase in the weight, tumors or aftersustaining injuries. Many a times no specific cause for this condition is found.
Some believe that evolutionary changes that led to the upright stature of human beings are responsible for this thoracic outlet syndrome. It led to flattening of chestand shoulder joint was shifted backwards as compared to the four-legged position of the primates. This caused reduction in the thoracic outlet.
Causes & Risk factors
Causes of the thoracicoutlet syndrome can be clubbed in two groups. Soft tissue causes and bonycauses. Bony factors include conditions like congenital rib anomalies,exostoses (formation of new bone on the surface of the bone) of first rib andclavicle. Soft tissue causes can be enlarged muscle mass in athletes,development of the muscular or fibrous band near brachial plexus or developmentof space occupying lesions like tumors. Trauma is also a major cause of thethoracic outlet syndrome so also as post trauma conditions like formation ofthe scar can also lead to the formation of the thoracic outlet syndrome.
Symptoms & Signs
The signs and symptoms ofthe thoracic outlet syndrome depend upon whether the compression is vascular(involving blood vessels) or neurogenic (involving nerves) or is thecombination of both.
Vascular compression canlead to swelling in the upper extremity, pain in the hand or diffuse arm if thevascular compression is venous primarily. Arterial compression can leadto change in the color of the upper limbs, pain in the hand, diffuse arm orintermittent claudication. Gangrene, absence of the pulse in thehand or ulcers is also a possibility. This kind of vascular compression is moredue to vigorous muscular activities especially overhead activities in youngpersons.
Neurogenic compression iscaused mainly due to the compression of the brachial plexus. Patients complainof tingling sensation, numbness, pain in the hand, painless atrophy of themuscles of the hand. Many patients also experience weakness in the hand.
Mostly thoracic outletsyndrome also results from trauma sustained after motor vehicle accident. Purevascular or neurogenic compression is rare. Combination of both is much common.Large group of the patient feel pain in the arm, shoulder, cervical region ofunknown origin.
Slumped posture (posturein which our own muscles literally drag us down) of shoulder and ‘porkedforward’ position of the head and neck can be seen. Edema (swelling) andcyanosis (bluish color) is seen in vascular compression. Swollen blood vessels,cold extremities, decreased power of the upper limbs, ulcers on the limbs andsometime decreased blood pressure is observed.
Tests & Diagnosis
Complete blood count witherythrocyte sedimentation rate (ESR)
X-Ray of the cervicalspine and upper thorax.
X-Ray of the shoulder,Chest and clavicle.
Computed Tomography (CT)scan and Magnetic Resonance Imaging (MRI).
Magnetic ResonanceAngiography (MRA)
Venography and duplexscanning
Physical therapy includesstrengthen the shoulder muscles, improves the range of movements. It alsopromotes better posture. The results are better with better compliance from thepatient. Other modalities of treatment like ultrasound, transcutaneous nervestimulation and biofeedback is helpful.
Thrombolysis withurokinase (drug that make blood thinner) is commonly practiced. Anticoagulantsare started to the patients. Warfarin (Coumadin) and heparin aregenerally used. Nonsteroidal anti-inflammatory medications(NSAIDs) are also prescribed.
Surgical care is needed if the physical therapyand medical management is not able to improve the symptoms. In surgery below mentionedthings can be done:
1.Extra rib in case is present then it can beremoved surgically.
2.Sometimes pressure due to section of a ribcan be relieved due surgically cutting it.
3. Bypass surgery is also done in some casesto reroute the blood vessels around the compression.
Complications Of Disease
Some of the complicationsof the disease can be gangrene, pulmonary embolism, nerve injury and ulcers.
Complications of medicalmanagement:
Sometimes the symptoms canbe refractory to the medical management.
Complications of surgicalcare:
Potential complications ofsurgical care can be pneumothorax, injury to the brachial plexus, subclavianblood vessels, hematoma and injury to the thoracic duct or thoracic nerve.
It is estimated thatthoracic outlet syndrome can be present in about 3 to 80 persons per 1000population. The exact number is not known.
It is more common infemales as compared to the males. Poor muscular development, poor posture orcombination of both factors is considered the reason for greater incidences infemales.
Prognosis in general isgood with treatment. Surgical removal of the first rib or the fibrous bandcausing the symptoms gives excellent results. Surgery has given successfulresult in about 50% to 80% of the cases. However, in about 5% of the cases thesymptoms reoccurred even after surgery.