I read your question and I understand your concern. The main cause for ischemic disease are factors like high blood pressure, diabetes, smoking, high cholesterol, factors which predispose to injury to blood vessels wall and narrowing which if marked could obstruct blood flow causing ischemia. In your case this narrowing involves mainly small vessels. What you could do to lower the risk of advancement and stroke is address those factors I mentioned as well as a blood thinner such as aspirin. Those factors are more often the cause, but at times there might be also genetic factors involved, metabolic factors like amyloid deposition in blood vessels. Also if you are young should investigate for connective tissue disease or other inflammatory conditions, prothrombotic conditions. I hope to have been of help.