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Neurological emergency secondary to the extravasation of blood into the spaces covering the CNS that are filled with cerebrospinal fluid.
One in every 20 strokes caused by SAH from an intracranial aneurysm.
Because this process occurs in fairly young individuals and is often fatal the loss of productive life years is similar for cerebral infarction or intracerebral hemorrhage.
About 80% of subdural hematomas are due to ruptured intracranial aneurysms.
20% of such hemorrhages are nonaneurysmal and carry a good prognosis with uncommon neurological complications.
Greater than 30,000 people per year have a SAH from a ruptured saccular aneurysm resulting in more than 18,000 deaths.
Non-traumatic subarachnoid hemorrhage are subcategorized is aneurysmal or non-aneurysmal.
Aneurysmal subarachnoid hemorrhage associated with higher rates of morbidity and mortality than non–aneurysmal hemorrhage.
In aneurysmal subarachnoid hemorrhage, patients who lives three months the risk of death is 8.7% within five years, and 17.9% within 10 years.
In non-aneurysmal subarachnoid hemorrhage outcomes are better and they are less likely to cause death.
Most nontraumatic subarachnoid hemorrhages involve rupture of an intracranial aneurysm or a cerebraj AV malformation.
Congenital AV anomalies are more likely to cause stroke in adolescents and young adults.
Accounts for 2-5% of all new strokes.
Incidence stable over the last 30 years.
Worldwide incidence about 10.5 cases per 100,00 person-years.
About 5% due to A-V malformations.
40-50% of patients die over the first few days after initial hemorrhage.
Patients usually present with a thunderclap headache or loss of consciousness.
Rarely present without headaches.
Often present without focal neurological deficits.
Neurologic deficits maybe acute or may manifest hours to days following onset of subarachnoid hemorrhage.
May present with nuchal rigidity or photophobia, nausea and vomiting.
17% of all patients with SAH die before reaching the hospital.
CT scan indicated if SAH suspected.
If suspected and a CT scan is negative, a lumbar puncture is indicated.
Combination of neck pain and headache considered a warning sign of and active aneurysm.
Approximately 46% of survivors suffer with cognitive impairment and functional impairment.
Associated with elevations of cardiac troponin levels in 17-28% of patients with left ventricular dysfunction, suggesting increased intracranial pressure leads to marked release of catecholamines, which can induce arrhythmias, vasospasm, vasoconstriction and direct myocardial toxicity.