It would be useful if you told us your age as well. The older you are the more likely is small vessel ischemic disease rather than a demielinating focus. Demielinating diseases are a group of diseases of which the most famous is multiple sclerosis, highly unlikely if you are over 45, so since your doctor seems not to think that is the diagnosis I won t elaborate more. By sequel of small vessel ischemic disease, it means a small stroke, what we call a lacune. It means a small blood vessel is narrowed till it was closed and the small brain area it supplied was damaged due to lack of blood. In itself it may bring no major consequences if not in a critical area, but small vessel disease is almost always a more spread disease, meaning more blood vessels can be affected and cause accumulative damage over time. There are multiple causes of small vessel disease, but in most people the main culprit are factors like high blood pressure, diabetes, smoking, high cholesterol, obesity. So the best preventive treatment is addressing these issues and also take low dose aspirin daily. I don t know why you ve been sent to the cardiologist, perhaps to be evaluated for your blood pressure, or perhaps to check for a cardiac origin of your fainting, like abnormalities of heart rhythm or other heart structural abnormalities. I don t think the fainting was directly caused by that brain focus, it is an incidental finding.