Vasospasm is a major problem when treating subjects with aneurismal subarachnoid hemorrhage. Up to 75% of subjects with aneurismal subarachnoid hemorrhage will develop vasospasm, and 30% of subarachnoid hemorrhage subjects will become clinically symptomatic, with muscle weakness as the primary symptom. (Dorsch) Even with intervention, 12% of patents with symptomatic vasospasm will develop permanent clinical deficits (after a ruptured aneurysm) including hemiplegia, aphasias, and visual loss. Less severe strokes may lead to modest loss of strength and sensation on one side of the body, and/or deterioration in higher brain functions, such as memory, speech comprehension, and planning.