Diseases of the Brain and its Meninges: Embolism.
Definition.—The obstruction of the cerebral arteries or capillaries by material (embolus) floated, by the blood-stream, from some distant part.
Etiology.—Nearly ninety per cent of all cases of embolism occur as the result of valvular disease of the left heart. It may be a vegetation of an acute endocarditis, though more frequently the result of chronic inflammation of the valves or the ulceration of their segments. In rarer cases it occurs from a portion of a clot from the auricle, from aneurism or atheroma of the aorta, or from the great vessels of the neck or of the lungs.
In certain infectious diseases, as pneumonia, diphtheria, puerperal fever, septicemia, and kindred affections, heart-clots may form and portions be washed into the cerebral vessels, giving rise to embolism. Since the embolus more frequently enters the left carotid, the left middle cerebral artery is most often the seat of the disease.
The lesion occurs more frequently among young adults, and in females, than in males.