Nontraumatic Subarachnoid Hemorrhage and Ruptured Intracranial Aneurysm: Recognition and Evaluation.

Subarachnoid hemorrhage caused by a ruptured intracranial aneurysm is a neurosurgical emergency with a mortality rate of approximately 50%. Prompt identification and treatment of aneurysmal subarachnoid hemorrhage are paramount to reduce mortality, long-term morbidity, and health care burden for survivors. The prevalence of intracranial aneurysms is 2% to 6% of the global population, many of which are found incidentally during workup for an unrelated condition. Screening is not recommended for the general population and should be reserved for patients who have at least one family member with a history of intracranial aneurysm or subarachnoid hemorrhage or when there is a high index of suspicion for those with certain medical conditions associated with an increased incidence of intracranial aneurysms. Physicians who treat patients with headache should be aware of the spectrum of clinical presentation of aneurysmal subarachnoid hemorrhage because not all patients present with the classic thunderclap headache. The Ottawa Subarachnoid Hemorrhage Rule is a validated clinical decision tool to help determine which patients with a sudden, acute headache require imaging with noncontrast computed tomography. Based on the results of initial computed tomography and duration of symptoms, the patient may require a lumbar puncture or additional imaging to confirm the diagnosis. Prompt diagnosis of an aneurysmal subarachnoid hemorrhage is essential to patients receiving definitive treatment.