Cerebral embolism – Sudden occlusion of a cerebral vessel due to a thrombus arising from the carotid, artery or its branches or from a diseased heart constitutes the picture of cerebral embolism which develops suddenly with production of neurological signs. Common causes of cerebral embolism are:
1. Thrombosis arising from the right subclavian artery.
2. Clot arising from aortic aneurysm or atheromatous ulcer in the in-nominate artery.
3. Embolus arising from a dilated left ventricle following myocardial infarction.
4. Vegetation detached from mitral or aortic valve in cases of infective endocarditis.
5. Pulmonary vein thrombosis and an infected emboli passes from the lung to the brain.
6. Chronic atrial fibrillation in cases of rheumatic, heart disease or atherosclerotic heart disease where a clot may get detached and lodges in the brain.
The most common arteries involved are that of the left side of the brain as compared to that of the right. Left middle cerebral artery is the one which is most commonly effected. Following an embolus which lodges in one of the branches of the vessel, it may fragment and get inpacted in the smaller vessels. Thrombosis takes place at that site and produces cerebral infarction. Result is that blood supply to that part of the brain suffers. Infarct produced is generally haemorrhagic and if the embolus is infected, meningitis may develop later on.
Onset of the disease is sudden. A convulsion may occur at the beginning. Headache is variable and slight loss of consciousness may develop though it is never deep. Focal neurological disorder like monoplegia or aphasia may develop. Complete hemiplegia is not very common. Symptoms may be transient and become less in severity owing to the dislodgement of embolus.
Based on clinical history and sudden onset of neurological features which may be transient diagnosis is made. Confirmation is by CSF examination which shall exclude haemorrhage. CT scan helps in confirming the diagnosis.
Treatment of cerebral embolism is mainly preventive. Patients of infective endocarditis must be adequately treated with antibiotics.
In those with atrial fibrillation complicating myocardial infarction, cardiac valve prosthesis and rheumatic heart disease, attempt should be made to restore sinus rhythm and maintain the patient on long term anticoagulation. If cerebral embolism has developed and there is neurological deficit treatment is on the same lines as in cases of cerebral thrombosis. Prognosis in a case of cerebral embolism is good since in majority of cases neurological deficit is not extensive and is transient.