the brain so this is what we're fighting against this progression of atherosclerosis so causes a stroke atherosclerosis and the large vessels meaning the ones we talked about in the neck about 25% atherosclerosis and the small vessels vessels in the brain about 20% of stroke 20% are clots that form in the heart from atrial fibrillation or other heart problems 15% we talked about bleeding bleeding in the brain or bleeding in the subarachnoid space and look at this even now when we do a very detailed evaluation we take