Cerebral Vascular Accident or stroke – This is when a clot of some sort enters the circulatory system of the brain and gets stuck – thus causing a blockage and subsequent possible necrosis of the brain that is being blocked.  This is where the FAST test is useful.  Having an extremely high blood pressure can be a cause of this. Once the diagnosis is made it is best for the patient to be transferred to a Stroke Unit – and this can sometimes mean bypassing several hospitals en route to do so.