Subarachnoid Hemorrhage

Overall, about 20% of strokes are hemorrhagic, with SAH and Intracerebral hemorrhage (ICH) each accounting for 10%. Subarachnoid space is described as a space between the arachnoid membrane and the pia mater. It consists of the cerebrospinal fluid and the blood vessels that supply different areas of the brain. A subarachnoid hemorrhage (SAH) is defined as the accumulation of blood in the space between the arachnoid membrane and the pia mater around the brain referred to as the subarachnoid space.  The etiology of SAH can be either nontraumatic (about 85% are secondary to aneurysm rupture) or traumatic in nature. In this review, we shall discuss the various aspects of nontraumatic SAH. Most nontraumatic causes of SAH (~ 85%) are caused by the rupture of an intracranial aneurysm. The remaining 15-20% of patients presenting with SAH do not have a vascular lesion on the initial digital subtraction angiography. Regardless of the cause, a SAH is often a devastating clinical event with substantial mortality and high morbidity among survivors. Prehospital care is critical and involves triaging the patient with attention to the airway, breathing, and circulation to a hospital with neurocritical/neurosurgical expertise. The classic presentation is often a sudden-onset, severe headache typically described as the "worst headache of my life". Treatments are based on randomized controlled studies and prospective cohort studies. A SAH has a prolonged course of illness and is complicated by various factors not limited to seizures, vasospasm, hydrocephalus, and delayed cerebral ischemia (DCI).