Subarachnoid Hemorrhage

Abstract

Subarachnoid hemorrhage (SAH) represents a small portion of cerebrovascular disease but a disproportionally large percentage of the morbidity and mortality. The overall prognosis depends on the volume of the initial bleeding, rebleeding, and the degree of delayed cerebral ischemia. The presence of cardiac manifestations and neurogenic pulmonary edema at the initial presentation indicates a higher degree of severity and systemic complications. This review covers the pathophysiology, stabilization and assessment, diagnosis and treatment, and disposition and outcomes of SAH. Figures show common saccular aneurysm locations, a noncontrast head computed tomographic scan of an SAH, an angiogram and surgical clipping of a broad-based anterior communicating aneurysm, and a three-dimensional reconstruction angiogram of a complex anterior communicating aneurysm with additional imaging of endoscopic stent-assisted coiling of the same aneurysm. Tables list the natural history of unruptured aneurysms and the annual risk of rupture, common clinical features and syndromes related to aneurysm location, the World Federation of Neurologic Surgeons grading system, the Hunt and Hess grading systems, and the Fisher scale. This review contains 4 highly rendered figures, 5 tables, and 144 references. Key words: aneurysm rupture, cerebral aneurysm, cerebral vasospasm, Fisher scale, Glasgow Coma Scale assessment, Hunt and Hess grading criteria, subarachnoid hemorrhage, World Federation of Neurologic Surgeons grading scale Key Advances CT angiography is an emerging technology that has the diagnostic advantage of being non-invasive. The diagnostic accuracy of CTA varies widely and when compared to the standard digital subtraction angiography (DSA) the sensitivity and specificity range from 77% to 100% and 87%-100% respectively. The 2012 AHA guidelines and the 2011 Neurocritical care society (NCS) consensus guidelines recommend that from the time of symptom onset to securing of the aneurysm, the blood pressure be controlled with a titratable agent with a goal systolic blood pressure of less than 160mmHg or a MAP of less than 110mmHg. Cardiac abnormalities are common following acute SAH. Subendocardial ischemia may result from autonomic stimulation from the brain and circulating catecholamine surge, resulting in an abnormal ECG in 50% to 100% of patients with SAH in the acute phase depending on severity. The International Subarachnoid Aneurysm Trial ISAT was a landmark study that looked at aSAH repair comparing surgical clipping with endoscopic coiling and demonstrated a mortality benefit with coiling in the right patient population.