The heart represents a major source of cerebral emboli. Valvular heart disease: rheumatic heart disease e.g. mitral stenosis with atrial fibrillation or mitral value prolapse. ,-Ischaemic heart disease: myocardial infarction with mural thrombus formation.
> ^___ Arrhythmias: Non-rheumatic (non-valvular) atrial
• fibrillation is the most common cause of cardioembolic stroke Bacterial endocarditis may give rise to septic cerebral embolisation with ischaemia -» infection -» abscess
Neurological signs will occur in 30% of all cases of bacterial endocarditis, 5. aureus and streptococci being the offending organisms in the majority.
Non-bacterial endocarditis (marantic endocarditis): associated with malignant disease due to fibrin and platelet deposition on heart valves.
Atrial myxoma is a rare cause of recurrent cerebral embolisation. Bihemisphere episodes with a persistently elevated ESR should arouse suspicion which may be confirmed by cardiac ultrasound.
Patent foramen ovale may result in paradoxical embolisation; suspect in patient with deep venous thrombosis who develops cerebral infarction.
New cardiac imaging techniques especially Transoesophageal Echocardiography (TOE) allow a more accurate detection of potential embolic source. Transcranial Doppler (TCD) may characterise emboli by analysing their signals and help quantify risk of recurrence.
Fat emboli: following fracture, especially of long bones and pelvis, fat appears in the bloodstream and may pass into the cerebral circulation, usually 3-6 days after trauma. Emboli are usually multiple and signs are diffuse.
Air emboli follow injury to neck/chest, or follow surgery. Rarely, air emboli complicate therapeutic abortion. Again the picture is diffuse neurologically. Onset is acute; if the patient survives the first 30 minutes, prognosis is excellent.
Nitrogen embolisation or decompression sickness (the 'bends') produces a similar picture, but if the patient survives, neurological disability may be profound.
Tumour emboli result in metastatic lesions; the onset is usually slow and progressive. Acute stroke-like presentation may occur, followed weeks or months later by the mass effects.
Lung Melanoma Testicular tumours
Lymphoblastic leukaemia commonly metastasise to brain. Prostate Breast Renal
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