A cerebral thrombosis is a blood clot that forms within one of the cerebral vessels, diminishing the blood, oxygen, and nutrient supplies to the brain parenchyma. The two types of thrombosis are arterial thrombosis and venous thrombosis. Cerebral thrombosis most often refers to thrombus formation within cerebral arteries, and the cerebral venous thrombosis refers to clot formation within cerebral veins and sinuses. It is also a synonym for brain attack and brain infarct, and is responsible for approximately 50% of all stroke cases.
The classic triad, or Virchow’s triad, of thrombosis are endothelial cell injury, blood stasis, and hypercoagulability. Hypercoagulability, or thrombophilia, refers to the increased tendency to form clots, and is usually secondary to deficiencies of anticoagulation factors and autoimmune disorders. Endothelial cell injury refers to injury to blood vessel walls, and this may occur due to trauma, infection, or surgery. Stasis may be due to long periods of lack of physical activity, which often occurs among people on long plane flights, bedridden patients, or the elderly. These factors that make up the Virchow’s triad also contribute to clot formation and obstruction of the cerebral vessels.
Most cases of arterial thrombosis result from the rupture of an atheroma, a lesion of accumulated lipids, macrophages, and connective tissue on the walls of blood vessels, characteristic of atherosclerosis. The two types of cerebral thrombosis include small-vessel thrombosis and large-vessel thrombosis. Small-vessel thrombosis is used for thrombosis of smaller and deeper arteries, such as lacunar arteries. Large-vessel thrombosis is used for thrombosis of bigger arteries, such as the middle cerebral and carotid artery.
The symptoms of cerebral thrombosis are also the symptoms of stroke. Depending on which blood vessel is involved, an affected person may experience weakness or paralysis on one side of the body or face, speech difficulty, and have difficulty swallowing. Loss of muscle coordination, loss of balance, severe headache, sudden loss of vision, and confusion may also occur.
To diagnose this condition, computed tomography (CT) or magnetic resonance imaging (MRI) may be requested. MRI is the more specific test because it allows the visualization of the thrombosed vessel even if there is no accompanying hemorrhage. To detect large-vessel thrombosis, a carotid ultrasound or transcranial Doppler imaging may be performed. Magnetic resonance angiography or computed tomography angiography may also be performed.
Treating cerebral thrombosis involves dissolving the thrombus through thrombolytic therapy, such as alteplase, tenecteplase, streptokinase, and anistreplase. These drugs are most effective when administered within 60 minutes of symptom onset. Anticoagulant drugs, such as heparin, may be given to prevent the formation of other thrombi.
Preventing cerebral thrombosis involves the modification of its risk factors, which include hypertension, diabetes, smoking, and alcohol consumption. People with high blood pressure should take antihypertensive medications, decrease their consumption of salt, exercise regularly, and aim for a blood pressure of less than 120/80 millimeters of mercury (mmHg). Diabetic patients should target a hemoglobin A1c (HbA1c) level of less than or equal to 7%. Those who have elevated cholesterol, triglycerides, and low-density lipoproteins (LDL) should also control their lipid levels, preferably through diet modification, physical activity, and statin intake. People who smoke are advised to quit, while those who drink alcohol excessively are advised to eliminate or reduce their alcohol consumption.