Subarachnoid hemorrhage

Last reviewed: 25 Aug 2022
Last updated: 19 Oct 2021



History and exam

Key diagnostic factors

  • headache
  • photophobia
  • loss of consciousness
  • third cranial nerve palsy
More key diagnostic factors

Other diagnostic factors

  • age >50 years
  • female sex
  • black people
  • nausea/vomiting
  • altered mental status
  • meningismus
  • unilateral or bilateral sixth cranial nerve palsies
  • intraocular hemorrhage
  • focal neurologic deficits
Other diagnostic factors

Risk factors

  • hypertension
  • smoking
  • family history
  • autosomal dominant polycystic kidney disease (ADPKD)
  • alcohol use
  • cocaine use
  • Marfan syndrome
  • Ehlers-Danlos syndrome
  • pseudoxanthoma elasticum
  • neurofibromatosis type I
More risk factors

Diagnostic investigations

1st investigations to order

  • CT head
  • CBC
  • clotting profile
  • serum electrolytes
  • troponin I
  • ECG
More 1st investigations to order

Investigations to consider

  • lumbar puncture (LP)
  • digital subtraction angiography (DSA)
  • computed tomography angiography (CTA)
  • magnetic resonance angiography (MRA)
More investigations to consider

Treatment algorithm


all patients



Salah Keyrouz, MD, FAHA

Associate Professor

Neurology and Neurosurgery

Washington University School of Medicine

St. Louis



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.

Peer reviewers

Venkatesh Aiyagari, MD

Associate Professor

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

Consultant Neurologist

Addenbrookes Hospital




PM declares that he has no competing interests.

Giovanni Grasso, M.D., PhD

Aggregate Professor of Neurosurgery

Neurosurgical Clinic

Department of Clinical Neuroscience

University of Palermo




GG declares that he has no competing interests.

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