Thromboangiitis obliterans is an inflammatory vasculopathy of small and medium sized vessels. Primary features include thrombosed and recanalized arteries and veins of the extremities, with no atherosclerotic degeneration.
The clinical picture of TAO encompasses symptoms originating from arterial occlusion and superficial thrombophlebitis. Initially the symptoms are observed in the extremities, both hands and feet, and include:
There is no specific test, invasive or not, to definitively diagnose TAO in a patient. Test are carried out primarily to eliminate the possibility of another disease that could produce symptomatology similar to TAO's.
A complete blood count, glucose tests, ESR and liver function tests are amongst the first to be performed. Additional laboratory examinations include a urinalysis, c-reactive protein, complement, scl-70, antinuclear and antiphospholipid antibodies and rheumatoid factor. These tests will help to exclude other conditions, such as systematic vasculitis. An echocardiographic evaluation or a computerized tomography angiography (CTA) will help to diagnose conditions that lead to the formation of emboli in the heart, which can cause an arterial blockage in smaller vessels if they are transferred .
Angiography can detect arterial occlusion in patients with TAO, that has no atherosclerotic components. Revascularization is also detected and is characteristic for the disease, since smaller vessels try to overcome the blockage and are a result of the vascular dilation in the site of occlusion. They are called corkscrew collaterals and contribute to the prevention of complete ischemia but have a typically increased resistance to blood flow. The aforementioned findings are typical of TAO but not exclusively: they can be observed in patients with a multitude of other conditions such as rheumatoid vasculitis, systemic scleroderma, systemic lupus erythematous, diabetes mellitus etc.
There is no definitive treatment for TAO except for the cessation of smoking. It has been proposed that the use of tobacco in any of its forms (cigarettes, chewed tobacco) can further deteriorate the clinical picture; therefore, patients are advised to refrain from the use of all tobacco products . Adaptations to a person's dietary habits are not required and have not proven to be successful in controlling the disease.
TAO patients do not usually need to be hospitalized for the condition, since adequate follow up and wound care suffice. The indications for hospitalization include inability to stop smoking independently, active infection that does not respond to per os medication treatments and the need for surgery.
Drug therapy has been applied with minimal response from the patients. It seems that IV administration of iloprost, which is an analogue of prostaglandin, ameliorates the symptomatology to an acceptable extent and leads to a decrease in the frequency of amputations. Thrombolysis and gene transfer of VEGF (vascular endothelial growth factor) have been performed but are not yet recommended therapeutic schemes .
Ischemic ulcers are treated with antimicrobial agents and patients may also be prescribed various painkillers and narcotic ones to alleviate the pain, although they are not expected to have very effective results.
Surgical therapy is usually not an option for TAO patients. Revascularization is a challenging procedure because the condition affects only small and medium sized vessels. It is, however attempted, if an appropriate distal site is found and a vein bypass can be performed. Hyperbaric oxygen therapy could be chosen for patients who cannot be operated on, although it is a rather experimental approach with scarce scientific data .
Thromboangiitis obliterans follows a deteriorating course, unless the patient strictly ceases the use of tobacco in any form. Individuals who smoked for more than 20 years exhibited a significantly higher risk of undergoing considerable amputation due to TAO . The most frequently diagnosed disease type is the remitting/relapsing type, followed by the primary and secondary relapsing and the benign type.
The causes of TAO still remain unclear but the disease is generally considered as requiring the implication of multiple factors in order to develop. Substances contained in tobacco, immunological defects, coagulation irregularities and genetic factors are believed to contribute to its etiology.
Smoking, in particular, is a confirmed etiologic factor. Statistically relevant increase in the frequency of the disease has been observed amongst known smokers of non-filtered tobacco products, such as Bangladeshi patients who smoke homemade unfiltered "bidis", a type of cigarette, and cannabis users  .
Genetic factors are also believed to play a role. Japanese patients are believed to be significantly immune to TAO because of their MyD88 gene, which is responsible for the production of the myeloid differentiation primary-response protein 88 . It has been also debated whether infection is a possible cause of TAO: patients often present with the vasculopathy accompanied by periodontal inflammation. Pseudomonas gingivalis is is thought to possibly contribute to the TAO disease, in the sense that thrombi containing the bacteria can be transferred from the oral cavity to non-adjacent vessels.
The condition is strongly associated with tobacco use, especially unprocessed tobacco that people in some regions of the world use to produce their own homemade cigarettes. Hence, TAO is frequently observed amongst populations in Asia, the Middle East and Mediterranean countries , while it has displayed a definite decrease in frequency in North America; this is thought to have occurred due to an alteration in smoking habits . Individuals start to experience symptoms at the age of 40-45 years old and there is a predilection for male patients, since approximately 80% of the individuals diagnosed with the disease are males. A steady increase has been observed in the female population affected by TAO in some areas, which is attributed to more women opting for smoking .
TAO is a pathophysiologically multi-factorial inflammatory vasculitis. Both arteries and veins are prone to occlusion and the most common sites of disturbance include small and medium sized vessels of the extremities, brain, kidneys, heart and genitalia. Late-stage disease may also encompass the axial artery and subclavian arteries.
It has been confirmed that all three vascular layers partake in the inflammatory process in its acute phase; when the condition lapses into a chronic type, inflammation is restricted within the adventitial and medial layers, accompanied by a revascularization process. The occlusion occurs as a result of thrombi formation, with the elastic lamina remaining normal.
The accurate pathogenesis of thrombus formation is still unconfirmed, although various observation-based suggestions have been made. It is believed that the vasodilatory process in patients with TAO is distorted as a result of a dysfunctional endothelium . Tobacco use is the only confirmed factor causing TAO, probably due to a certain hypersensitivity to substances contained within the product. Nicotine abuse has been found to increase the concentration of kallikreins and kininase II : patients who were not affected by the condition, regardless of their smoking habit, and TAO patients who ceased to smoke, exhibited significantly lower levels of these components when compared to TAO patients who continued to smoke .
Immunologic factors are also believed to partake in the pathogenesis of TAO. The HLA-DRA (histocompatibility leukocyte antigen) was more often detected in TAO patients compared to people who did not smoke and people who smoked but where not affected by TAO. The HLA-DRW6 component was respectively less often detected.
TAO can generally not be prevented, especially amongst smokers. Rapid deterioration, however, can be prevented with smoking cessation, early wound treatment, appropriate shoes that protect the feet from sustaining traumatization and avoiding medications that cause vasoconstriction.
Thromboangiitis obliterans affects the small and medium sized vessels of the extremities. It is characterized by profound inflammation and vascular occlusion due to the formation of localized thrombi. Its typical presentation includes significant claudication, which can follow a rapidly deteriorating course and lead to critically decreased perfusion of the affected areas and ischemic phenomena. Acute ischemia is an emergency condition and typically presents with pain in the affected body part, pallor, sensory impairment, temporary paralysis and localized low temperature  .
Thromboangiitis obliterans, abbreviated as TAO, is also known as Buerger's disease and is strongly linked to tobacco use. There has yet to be developed a successful therapeutic scheme involving the administration of medications, and smoking cessation is the only proven way to hinder the condition's progress.
Thromboangiitis obliterans (TAO) is a condition that affects small and medium sized vessels. Due to various causes, blood clots are formed in some parts of the arteries and veins and block the blood flow.
The only known cause of TAO is smoking. Cigarettes are believed to contain compounds to which some individuals are extremely sensitive. Dental infections have been proposed as a possible co-factor, while other researchers believe that the disease could also be autoimmune.
Symptoms of TAO include pain in the legs or feet during exercise or rest, cold and pale extremities, strange sensations such as numbness, tingling, or picking and ulcers. Raunaud's phenomenon can also be observed: the hands first become white, then blue and ultimately red when a person exposes them to a cold environment. This symptomatology is experienced almost exclusively in the hands and feet, as those are the sites where the vessels are most frequently affected by TAO.
TAO is diagnosed mainly after other diseases are excluded, which can cause similar symptomatology. Blood tests are performed in order to detect various antibodies or markers which would point to another condition. Angiography can reveal findings which are compatible with TAO, but they are not specific to this condition either.
Unfortunately, there is no particular treatment for TAO and it cannot be cured. The only known way to reduce symptoms and stop the rapid progression is to stop smoking. Painkillers are prescribed for the pain and wound care should be sought as well. Surgical procedures to improve the blood flow are possible, yet difficult to achieve, because of the small size of the affected vessels.