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Subarachnoid Hemorrhage

Author: Rami C Zebian, MD, Resident Physician, Department of Internal Medicine, University of Texas Medical School at Houston
Coauthor(s): A Antoine Kazzi, MD, Chair and Medical Director, Department of Emergency Medicine, American University of Beirut, Lebanon
Contributor Information and Disclosures

Updated: Feb 25, 2009

Introduction

Background

Subarachnoid hemorrhage (SAH) implies the presence of blood within the subarachnoid space from some pathologic process. The common medical use of the term SAH refers to the nontraumatic types of hemorrhages, usually from rupture of a berry aneurysm or arteriovenous malformation (AVM). The scope of this article is limited to these nontraumatic hemorrhages.

Frequency

United States

Annual incidence of nontraumatic aneurysmal subarachnoid hemorrhage is 6-25 cases per 100,000. More than 27,000 Americans suffer ruptured intracranial aneurysms each year. Annual incidence increases with age and probably is underestimated because death is attributed to other reasons that are not confirmed by autopsies.

International

Varying incidences of subarachnoid hemorrhage have been reported in other areas of the world (2-49 cases per 100,000).

Mortality/Morbidity

  • An estimated 10-15% of patients die before reaching the hospital. Mortality rate reaches as high as 40% within the first week. About half die in the first 6 months.
  • Mortality and morbidity rates increase with age and poorer overall health of the patient.
  • Advances in the management of subarachnoid hemorrhage have resulted in a relative reduction in mortality rate that exceeds 25%. However, more than one third of survivors have major neurologic deficits.

Race

Blacks have a higher risk for subarachnoid hemorrhage than whites (2.1:1).1

Sex

Incidence of aneurysmal subarachnoid hemorrhage is higher in women than in men.

Age

Mean age of those experiencing subarachnoid hemorrhage is 50 years.

Clinical

History

  • Headaches
    • Patient experiences sudden onset of a severe headache.
    • Prodromal (warning) headache(s) from minor blood leakage (referred to as sentinel headache) is reported in 30-50% of aneurysmal subarachnoid hemorrhages.
      • Sentinel headaches may occur a few hours to a few months before the rupture, with a reported median of 2 weeks prior to diagnosis of SAH.
      • Minor leaks commonly do not demonstrate signs of elevated intracranial pressure (ICP) or meningeal irritation.
      • Minor leaks are not a feature of AVM.
      • More than 25% of patients experience seizures close to the acute onset; the location of a seizure focus has no relationship to the location of the aneurysm.
  • Nausea and/or vomiting
  • Symptoms of meningeal irritation (eg, neck stiffness, low back pain, bilateral leg pain): These are seen in more than 75% of cases of subarachnoid hemorrhage, but many take several hours to develop.
  • Photophobia and visual changes
  • Loss of consciousness: About half of patients experience this at the time of bleeding onset.

Physical

Physical examination findings may be normal, or the clinician may find some of the following:

  • Global or focal neurologic abnormalities in more than 25% of patients
  • Syndromes of cranial nerve compression
    • Oculomotor nerve palsy (posterior communicating artery aneurysms) with or without ipsilateral mydriasis
    • Abducens nerve palsy
    • Monocular vision loss (ophthalmic artery aneurysm compressing the ipsilateral optic nerve)
  • Motor deficits from middle cerebral artery aneurysms in 15% of patients
  • No localizing signs in 40% of patients
  • Seizures
  • Ophthalmologic signs
    • Subhyaloid retinal hemorrhage (small round hemorrhage, perhaps with visible meniscus, near the optic nerve head); other retinal hemorrhage
    • Papilledema
  • Vital signs
    • About half of patients have mild-to-moderate blood pressure (BP) elevation.
    • BP may become labile as ICP increases.
    • Fever is unusual at presentation but becomes common after the fourth day from blood breakdown in the subarachnoid space.
    • Tachycardia may be present for several days after the occurrence of a hemorrhage.
  • Grade SAH according to the following scheme:
    • Grade I - Mild headache with or without meningeal irritation
    • Grade II - Severe headache and a nonfocal examination, with or without mydriasis
    • Grade III - Mild alteration in neurologic examination, including mental status
    • Grade IV - Obviously depressed level of consciousness or focal deficit
    • Grade V - Patient either posturing or comatose

Causes

  • Primary subarachnoid hemorrhage may result from rupture of the following types of pathologic entities (the first 2 are most common):
    • Saccular aneurysm
    • AVM
    • Mycotic aneurysmal rupture
    • Angioma
    • Neoplasm
    • Cortical thrombosis
  • Subarachnoid hemorrhage may reflect a secondary dissection of blood from an intraparenchymal hematoma (eg, bleeding from hypertension or neoplasm).
  • Two thirds of cases of nontraumatic subarachnoid hemorrhage are caused by rupture of saccular aneurysms.
  • Congenital causes also may be responsible for subarachnoid hemorrhage.
    • Occasional familiar occurrence
    • Frequency of multiple aneurysms
    • Association of aneurysms with specific systemic diseases, including Ehlers-Danlos syndrome, Marfan syndrome, coarctation of the aorta, and polycystic kidney disease
  • Environmental factors associated with acquired vessel wall defects include age, hypertension, smoking, and arthrosclerosis.

More on Subarachnoid Hemorrhage

Overview: Subarachnoid Hemorrhage
Differential Diagnoses & Workup: Subarachnoid Hemorrhage
Treatment & Medication: Subarachnoid Hemorrhage
Follow-up: Subarachnoid Hemorrhage
Multimedia: Subarachnoid Hemorrhage
References
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References

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Further Reading

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Contributor Information and Disclosures

Author

Rami C Zebian, MD, Resident Physician, Department of Internal Medicine, University of Texas Medical School at Houston
Rami C Zebian, MD is a member of the following medical societies: American College of Physicians
Disclosure: Nothing to disclose.

Coauthor(s)

A Antoine Kazzi, MD, Chair and Medical Director, Department of Emergency Medicine, American University of Beirut, Lebanon
A Antoine Kazzi, MD is a member of the following medical societies: American Academy of Emergency Medicine
Disclosure: Nothing to disclose.

Medical Editor

Richard S Krause, MD, Senior Faculty, Department of Emergency Medicine, State University of New York at Buffalo School of Medicine
Richard S Krause, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

J Stephen Huff, MD, Associate Professor, Emergency Medicine and Neurology, Department of Emergency Medicine, University of Virginia Health Sciences Center
J Stephen Huff, MD is a member of the following medical societies: American Academy of Emergency Medicine, American Academy of Neurology, American College of Emergency Physicians, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Rick Kulkarni, MD, Medical Director, Assistant Professor of Surgery, Section of Emergency Medicine, Yale-New Haven Hospital
Rick Kulkarni, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: WebMD Salary Employment

 
 
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