I read your question carefully and I understand your concern. I don t think that your mother is without treatment currently. I am sure your doctors have her under some type of blood thinner such as Aspirin and Clopidogrel which offers protection. As for the decision for surgery it is not always that straightforward. Actually for a completely occluded artery (100% stenosis) usually no surgery is done as that artery does not release any more emboli and surgery would only risk another stroke. As for the 50% side the decision should also be carefully weighed. Surgery carries its own risks, even stroke initially, usually surgery is done when there is a stenosis over 70% and causing symptoms, 50-70% is more debatable. So the characteristics of the atherosclerotic plaque are considered through ultrasound to evaluate its potential to release emboli. Also it is important to know whether that stenosis is causing any symptoms. If it is a stable plaque and is not causing symptoms (the origin of the stroke was the other side) continuing blood thinners might be more appropriate. Another issue to evaluate might be her heart vessels condition as many of these patients may have silent narrowings of their heart vessels and might risk a heart attack. I imagine I might be confusing you. More than you assimilating all this information what I am trying to do is make you understand that there are medication approaches available and in choosing between surgery and medication there are many variables at play which your doctors should consider to decide which choice carries the best prognosis. Each choice has its pros and cons, it s a matter of percentages. I hope things work out for the best.