Treatment of transient ischemic attack (TIA) in common carotid artery basin

Platelet antiaggregation therapy

The action of antiplatelet therapy for a transient ischemic attack (TIA) and small strokes has been criticized for the same reasons that the action of anticoagulants. The most studied drug used to prevent stroke is acetylsalicylic acid (aspirin). In the course of eight randomized trials have tested aspirin alone and aspirin in combination with other antiplatelet agents. Studies have shown that aspirin alone has a beneficial effect by preventing the development of recurrent transient ischemic attacks (TIA) and stroke in patients with clinical neurologic symptoms.

In another study in which patients underwent routine angiography arteries of the neck and brain, suggested that aspirin is effective in those patients with transient ischemic attack (TIA) combined with a lesion of the internal carotid artery, but not in patients who have had only a TIA with no signs of carotid artery lesions, ie, possibly due to embolism from the heart. According to these studies, the greatest effect of aspirin is to reduce the risk of stroke within 3 years from about 19% to 12%. The latter risk score was significantly higher than those in operation endarterectomy.

Most experts believe that aspirin could help, but it is not an alternative means of treatment for transient ischemic attack (TIA) arising on the background of atherosclerosis with thrombosis of the internal carotid artery. Aspirin is often used in cases where symptoms of transient cerebral ischemia occur in patients with severe narrowing of the lumen (stenosis) of carotid siphon or a small degree of narrowing of the lumen (stenosis) in the initial part of the internal carotid artery, carotid siphon or middle cerebral artery trunk.

There are also theoretical background and in order to avoid excessive use of aspirin, patients with transient ischemic attack (TIA). It is paradoxical that aspirin:

• low (inhibit) the formation of platelet thromboxane Ag, coil association (aggregation) of platelets
• vasoconstrictor prostaglandin
• inhibits the synthesis of prostacyclin and prostaglandin originating from endothelial cells and possesses antiaggregatory and vasodilating action

At low doses, aspirin inhibits the production of thromboxane mainly Ag, so many doctors recommend it in small doses, is 300 mg or less per day.

The drug dipyridamole acts by inhibiting platelet phosphodiesterase, which is responsible for cleavage of cyclic adenosine monophosphate. The resulting increase in cyclic AMP in platelets leads to inhibition of the association (aggregation) of platelets. However, there is no conclusive evidence that dipyridamole prevents recurrence of transient ischemic attack (TIA) and stroke in patients with symptomatic atherosclerosis with thrombosis of the arteries of the neck and brain.

The drug sulfinpyrazone inhibits the reaction activation in platelets and effect on adhesion (adhesion) of platelets to the subendothelial tissue of the arterial wall. It prolongs the survival of platelets in patients with prosthetic heart valves. There is no evidence a higher efficacy in the prevention of transient ischemic attack (TIA) and stroke in sulfinpyrazone and other antiplatelet agents such as clofibrate and ibuprofen compared with aspirin, taken in isolation.

 

Surgical therapy

Carotid endarterectomy

The operation of carotid endarterectomy - a common method of treatment for transient ischemic attacks (TIA) due to narrowing (stenosis) of the lumen of the carotid artery. First proposed in 1954, this operation gives complications in 1-20% of cases, and this figure depends on the experience of patients and surgical team and doctors. Although many studies have shown the effectiveness of this operation in the prevention of recurrent transient ischemic attacks (TIA) and stroke, its clinical significance is still required to confirm through a clearly defined, controlled, randomized clinical trial. Despite the fact that the combined rate of complications of angiography and surgery is less than 3 %, it appears that surgery is more dangerous than no treatment.

Patients with severe narrowing of the lumen (stenosis) of one carotid artery, as well as a full constriction (occlusion), the opposite carotid artery, or a functional deficiency circle of Willis exposed to a slightly higher risk of stroke during endarterectomy surgery. It should be noted that EEG monitoring during surgery allows us to establish cerebral ischemia during surgery, and the operating surgeon to warn about the need to take certain steps to improve the blood supply to the brain.

The majority of patients undergoing endarterectomy operations have hypertension arteriosclerotic lesion of cardiovascular and peripheral vascular disease. Active coronary disease, such as unstable angina, recent myocardial infarction (within 6 months) and congestive heart failure, are contraindications for this operation. High hypertension can usually be corrected before surgery, but lumen in patients with severe narrowing (stenosis) carotid artery should not be excessively lower blood pressure, as it contributes to the progression of lesions to the full narrowing of the lumen of the affected vessel (occlusions) with ischemic stroke.

Narrowing of the carotid arteries (stenosis) might re-emerge after the operation, although this is rare. This is due to lack of surgical technique, excessive formation of scar tissue and active arteriosclerotic disease. In the first year of primary disease is manifested mainly the growth of scar (fibrous) tissue and adhesions, after the first year - further growth of fibrous tissue and atherosclerosis. When it begins to manifest clinically re- narrowing of arteries (restenosis), and although surgery is feasible, but it becomes more difficult technically because of the scarring and adhesions after the first operation.

When combined lesions of the internal carotid artery - for example, one of the carotid bifurcation, and another - the siphon internal carotid artery, a more careful approach. If the narrowing of the arterial lumen (stenosis) of the siphon the remaining lumen diameter of more than 2 mm, and the underlying plot of the internal carotid artery - less than 2 mm, it is possible to recommend endarterectomy. In cases of more pronounced narrowing of the siphon significance endarterectomy is less convincing and preferred destination of anticoagulants and antiplatelet agents. But the common opinion on the effectiveness of any treatment in these situations do not exist.

 

Endovascular therapy (stenting and balloon angioplasty)

Method intravascular balloon angioplasty with stenting are increasingly used by neurosurgeons in the treatment of patients with episodes of transient ischemic attack or asymptomatic stenosis of the lumen of a particular artery of the brain. Intravascular balloon angioplasty with stenting of the carotid artery enlarges and maintains the vessel lumen disclosed that contributes to the restoration of arterial blood supply to the brain. Intravascular balloon angioplasty of the carotid artery is applicable:

• in the area of its bifurcation (division into outer and inner carotid artery)
• in segments of the internal carotid artery prior to entering the base of the skull
• in intracranial internal carotid artery segments

Atherectomy device for intravascular treatments of patients with peripheral artery disease (cerebrovascular atherosclerotic thrombosis).

In patients at high risk of embolism (heart disease and lung blockage opposite carotid restenosis after endarterectomy, pharyngeal nerve dysfunction on the opposite side ported radical surgery or radiation therapy to the neck tissue, age >80) with a special set stenitirovaniem emboloprotektor (captures clots in the blood) or produce endarterectomy surgery. The risk of death, stroke (on the side of the manipulation), or myocardial infarction within the first month and the first year after the stent is 12%. After surgery endarterectomy the same risk is 20%.

 

Extracranial-to-intracranial bypass surgery

Creating a branch of the anastomosis the superficial temporal artery and external carotid branch of the cortical surface of the middle cerebral artery bypass may provide blood flow to the basin of the middle cerebral artery. This operation was offered to patients with obstruction (occlusion) carotid artery and narrowing of the lumen rude (stenosis) in the trunk of the middle cerebral artery, which are observed in the attending physician on repeated transient ischemic attack (TIA) or small strokes. Results of a randomized trial of the World did not confirm the higher efficacy of surgery in these states compared with treatment with anticoagulants and antiplatelet agents.

Choice of treatment of ischemic stroke in the pool of internal carotid artery (carotid system) depends on the severity of recently developed stroke. When complete paralysis of half of the body (hemiplegia), the patient, aphasia, or anosognosia rough, indicating involvement of the vast areas in the basin of the middle cerebral artery blood flow, prevention of recurrent ischemic strokes in the same blood pool becomes less urgent. Instead, it is essential to maintain an adequate level blood pressure and prevent brain swelling.

There is limited evidence to support the use of anticoagulants after "completed" or an ischemic stroke in the presence of a stable defect in the case of stroke, with an extensive lesion. But if the first few hours after the onset of clinical improvement or slight neurological deficits, there are indications of the effectiveness of a short course of administration of anticoagulants (heparin ) to prevent the growth of lesions, ie "development stroke". At present, many authors recommend heparin for fluctuating or progressive course of acute disorders of cerebral circulation.

Based on the pathophysiological mechanisms of stroke in the pool carotid artery (carotid system), many doctors perform a short course of anticoagulation in patients with mild stroke on the background of recently developed occlusion or stenosis of sharp internal carotid artery, hoping thereby to prevent a second, possibly more severe, episode of. In such cases, there is the likelihood of hemorrhagic impregnation of small ischemic infarcts, but this is rare. Therefore, issues of time use and usefulness of early use of heparin remains controversial.

Although the relevant controlled studies had been conducted, the operation of endarterectomy is recommended in patients with severe stenosing lesions of the internal carotid artery, suffered a small stroke in the pool, which is located distal to the lesion. Indicator of risk operations for experienced surgeons is less than 2 % if the patient has no medical contraindications. If the opposite carotid artery narrowed sharply in the lumen (stenotic) or occluded, planned in such a case, the carotid artery endarterectomy surgery carries a higher risk. Comparison between the course of the disease in patients with symptomatic severe carotid stenosis and results of surgical intervention was carried out. Practice has shown that repeated strokes are developed, more than 3% of patients who received nonsurgical treatment.

Bleeding into the area of ??cerebral infarction occurs only rarely after the operation, the internal carotid artery endarterectomy and, apparently, no more frequently than those without surgical intervention in the postoperative period if the patient can avoid hypertension. But be that as it may, after an ischemic stroke is recommended to postpone surgery carotid endarterectomy for 2-6 weeks to the patient's condition has stabilized. But at the same time, undue delay in surgical treatment can result in severe consequences for the patient. The earlier operation is preferable to endarterectomy if neurological deficit is small or has a transitory nature, although opinions on this subject are contradictory.

Endarterectomy surgery is carried out in some cases of acute obstruction of the lumen (occlusion) carotid artery, usually in the first 8 hours after its occurrence, but with a deep neurological deficits, it usually gives unsatisfactory clinical results. Therefore, the operation endarterectomy for patients with severe neurological deficit slightly.

Alternative methods of treatment for most patients with ischemic stroke or mild to moderate severity and confirmed by the blockage (occlusion) of the lumen of the internal carotid artery include the use of anticoagulants, antiplatelet agents, or the application does not provide neither the one nor the other drugs. Some physicians prescribe anticoagulants for 6 months, hoping to prevent embolism from a thrombus propagating. Sometimes, depending on the results of angiography and the nature of recurrence of clinical symptoms of possible operation the external carotid artery endarterectomy or the other stenotic internal carotid artery. Probably need therapy for such patients determine a possible cause of ischemia. Embolism of the occluded carotid artery are the reason for the appointment of anticoagulants, whereas recurrent symptoms suggestive of reduced blood flow in the hemisphere of the brain is isolated from sources of collateral blood flow and therefore serve as the basis for the operation endarterectomy.

When choosing a treatment of a patient with narrowing of the lumen (stenosis) of carotid siphon or middle cerebral artery trunk, coupled with recurrent stroke or transient ischemic attacks (TIA), you should take into account both conditions. Due to the fact that the extracranial - intracranial bypass surgery does not reduce the risk of ischemic stroke, in most cases, treatment is recommended antiplatelet (aspirin) or anticoagulant (warfarin sodium). If there is evidence of more effective treatments for patients with luminal narrowing (stenosis) of carotid siphon first recommend antiplatelet therapy, and then, with repetition (recurrence) of symptoms - anti-coagulants.

Due to the potentially devastating effects of blockage (occlusion) of the middle cerebral artery narrowing (stenosis) of its trunk, which is accompanied by neurological symptoms, we recommend anticoagulant therapy with warfarin sodium. If, in spite of treatment, relapses of symptoms, may be effective in reducing blood viscosity. But over time, often there is a weakening of neurological symptoms in patients regardless of method of treatment.

Unusual localization of atherosclerosis with thrombosis causes narrowing of the lumen (stenosis) or blockage (occlusion) artery may cause the transient symptoms involving the opposite leg. In this case, antiplatelet agents and anticoagulants. Studies to support the development of atherosclerosis with thrombosis of a given location, there is, as surgical procedures to prevent ischemia in the distal territory of anterior cerebral artery blood flow due to its proximal stenosis.

Much attention given to the study effectiveness of opiate substance naloxone in acute ischemic cerebral infarction (stroke), but its effectiveness still needs to be confirmed. One of the promising new directions for treatment in ischemic stroke - a decrease in total blood viscosity. If blood pressure is stable, the overall decrease in blood viscosity by lowering hematocrit and / or serum fibrinogen leads to an increase in blood flow through narrowed (stenosis) section of the vessel. It is believed that this method of treatment should increase blood flow to the ischemic zone ("penumbra"), located between the heart attack and subjected to normal brain tissue. However, the size of the "penumbra" are unknown in each case of ischemic stroke. Treatment reduced total blood viscosity is associated with little risk to the patient.