Daily neurological checks and collection of all routine clinical and radiographic data as per standard of care will be gathered as the gold standard data for statistical comparison. Neurocognitive tests will be performed routinely every 8 hours by attending physicians to assess for neuro-deterioration and radiological (Computed tomographic angiography (CTA) and Digital subtraction angiography (DSA) components. Data collected from patients will be stripped of all personal health identifiers. Each subject will receive a unique identifying patient number linking the individual to their deidentified clinical data set. Only the medical staff attending to the patient's standard care will be knowledgeable to the identity of the subject.