Subarachnoid hemorrhage (SAH) presents as a sudden severe headache, often described as "the worst headache of life," with nausea, vomiting, and photophobia.
Examination can be normal or may reveal altered consciousness, meningismus, intraocular hemorrhages, or focal findings.
Computed tomography (CT) indicated if subarachnoid hemorrhage is clinically suspected. Lumbar puncture is indicated if CT is unrevealing. Cerebral angiography confirms the presence of aneurysms.
Initial stabilization followed by surgical clipping or endovascular coil embolization is standard therapy.
Complications are common and include rebleeding, acute hydrocephalus, and delayed cerebral ischemia.
SAH is bleeding into the subarachnoid space and is an emergency. The most common cause of nontraumatic SAH is rupture of an intracranial aneurysm. Aneurysmal SAH causes substantial morbidity and mortality. When a cerebral aneurysm ruptures, blood flows into the subarachnoid space, sometimes seeping into brain parenchyma and/or ventricles. The sudden increase in intracranial pressure, as well as the destructive and toxic effects of blood on brain parenchyma and cerebral vessels, accounts for most complications.
History and exam
Key diagnostic factors
- loss of consciousness
- third cranial nerve palsy
Other diagnostic factors
- age >50 years
- female sex
- black people
- altered mental status
- unilateral or bilateral sixth cranial nerve palsies
- intraocular hemorrhage
- focal neurologic deficits
- family history
- autosomal dominant polycystic kidney disease (ADPKD)
- alcohol use
- cocaine use
- Marfan syndrome
- Ehlers-Danlos syndrome
- pseudoxanthoma elasticum
- neurofibromatosis type I
1st investigations to order
- CT head
- clotting profile
- serum electrolytes
- troponin I
Investigations to consider
- lumbar puncture (LP)
- digital subtraction angiography (DSA)
- computed tomography angiography (CTA)
- magnetic resonance angiography (MRA)
Salah Keyrouz, MD, FAHA
Neurology and Neurosurgery
Washington University School of Medicine
SK is an author of a reference cited in this topic.
Dr Salah Keyrouz would like to gratefully acknowledge Dr Michael N. Diringer, a previous contributor to this topic.
MND is an author of a number of references cited in this topic.
Venkatesh Aiyagari, MD
Department of Neurology and Rehabilitation
University of Illinois at Chicago
VA declares that he has no competing interests.
Peter Martin, MA, BM BCh, MD, FRCP
PM declares that he has no competing interests.
Giovanni Grasso, M.D., PhD
Aggregate Professor of Neurosurgery
Department of Clinical Neuroscience
University of Palermo
GG declares that he has no competing interests.
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