Subarachnoid hemorrhage (SAH) represents bleeding into the subarachnoid space, most commonly from a ruptured cerebral aneurysm. This chapter presents a case study of a 52-year-old right-handed female with a medical history of smoking and hypertension who developed an abrupt onset of a severe bifrontal headache. The development of the operative microscope and interventional procedures has allowed for the early treatment of cerebral aneurysms to prevent rebleeding. Rebleeding occurs within the first few weeks of the initial hemorrhage in one-third of patients with SAH and acutely worsens outcomes. Treatment of patients with SAH, once an aneurysm is secured, includes generous use of intravenous isotonic fluids. Clinical studies have suggested that a majority of neurologic deficits can be reversed with the application of the hemodynamic techniques. The application of interventions for vasospasm may be guided by noninvasive measures of vessel narrowing and cerebral blood flow.