A prospective consecutive sample of possible stroke cases will be recruited within 12 hours of symptom onset. Final diagnoses may include: ischemic stroke (IS), TIA, aneurysmal subarachnoid hemorrhage (SAH), intracerebral hemorrhage (ICH) with or without intraventricular hemorrhage (IVH) (or primary IVH), and stroke mimic (all other patients presenting with acute onset stroke-like symptoms who do not have ischemic or hemorrhagic stroke).