You're right, I don't have an exact answer. Yes, high BP can be a precursor to stroke, however there are other causes such as arteriosclerosis (formerly known as hardening of the arteries), which just means that the arteries become rigid over time and blood flow is decreased. That condition is usually, but not always associated with aging. If blood flow to the brain is decreased, no matter the cause it can cause stroke. So, yes you can have a stroke and still have normal BP.