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Subarachnoid hemorrhage

Last updated: September 17, 2020

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Subarachnoid hemorrhage (SAH) refers to traumatic as well as nontraumatic bleeding into the subarachnoid space. SAH most often results from head trauma. Nontraumatic SAH is responsible for 5–10% of all strokes and is most commonly caused by the rupture of an aneurysm involving the circle of Willis. SAH typically presents with severe headache, nausea, vomiting, and/or acute loss of consciousness. Acute bleeding in the subarachnoid space appears hyperdense on noncontrast CT scan, which is the initial recommended test in diagnosis. CT angiography and lumbar puncture may be necessary for further evaluation if the initial noncontrast head CT is unremarkable. Treatment consists of carefully lowering blood pressure and preventing cerebral vasospasm. Definitive management typically consists of clipping or coiling the bleeding aneurysm to prevent potentially fatal rebleeding. SAH has a high mortality rate as a result of complications such as rebleeding and secondary ischemic strokes due to vasospasm.

See also overview of stroke, ischemic stroke, and intracerebral hemorrhage for more information.

References:[2][4]

Epidemiological data refers to the US, unless otherwise specified.

References:[2][4][11]

Initial evaluation

  • Immediate noncontrast head CT
    • Best initial test
    • Sensitivity is almost 100% within the first 6 hours of hemorrhage [10]
    • Findings: shows blood in subarachnoid space (hyperdense)
  • Lumbar puncture (LP)
    • Best test if head CT is negative but suspicion for SAH remains high
    • Findings
      • ↑↑ RBC count: red discoloration
      • ↑ Protein (gamma globulin)
      • ↑ Or normal opening pressure
      • Xanthochromia: the yellowish discoloration of CSF is due to the presence of xanthematin, a yellow pigment derived from hematin that is released when RBCs break down
      • WBCs
      • Normal glucose

Subsequent evaluation

References: [10][12]

Medical therapy [13]

Surgical therapy [13]

  • Should be performed as early as possible to prevent rebleeding
  • Definitive treatment options for aneurysmal SAH
    • Surgical clipping
      • Following a craniotomy, the neck of an aneurysm is surgically occluded with the help of metal clips.
      • Treatment of choice but more invasive than coiling
    • Endovascular coiling
    • The decision on which procedure to perform should be made on an individualized basis.
  • If the patient has hydrocephalus: ventricular drain, serial LPs, or permanent ventriculoperitoneal shunt may become necessary.

Use of nitrates should be avoided, since they may raise ICP!

References:[13][14][15][16][17][18][19]

References:[10][12][13]

We list the most important complications. The selection is not exhaustive.

  • Approx. 30% mortality rate in the U.S. within the first 30 days [13]
  • Survivors: increased rates of neurologic impairment (e.g., cognitive, mood changes, functional, epilepsy) and increased risk of recurrent SAH

References:[15]

  1. Frontera JA, Lewin III JJ, Rabinstein AA, et al. Guideline for Reversal of Antithrombotics in Intracranial Hemorrhage. Neurocrit Care. 2015; 24 (1): p.6-46. doi: 10.1007/s12028-015-0222-x . | Open in Read by QxMD
  2. Velat GJ, Kimball MM, Mocco JD, Hoh BL. Vasospasm After Aneurysmal Subarachnoid Hemorrhage: Review of Randomized Controlled Trials and Meta-Analyses in the Literature. World Neurosurgery. 2011; 76 (5): p.446-454. doi: 10.1016/j.wneu.2011.02.030 . | Open in Read by QxMD
  3. Tichter AM, Malhi J. Does Magnesium Therapy in Aneurysmal Subarachnoid Hemorrhage Affect Clinical Outcome?. Ann Emerg Med. 2017; 69 (2): p.208-209. doi: 10.1016/j.annemergmed.2016.05.027 . | Open in Read by QxMD
  4. Zazulia A, Diringer M. Aneurysmal Subarachnoid Hemorrhage: Strategies for Preventing Vasospasm in the Intensive Care Unit. Semin Respir Crit Care Med. 2017; 38 (06): p.760-767. doi: 10.1055/s-0037-1607990 . | Open in Read by QxMD
  5. Kirkpatrick PJ, Turner CL, Smith C, Hutchinson PJ, Murray GD. Simvastatin in aneurysmal subarachnoid haemorrhage (STASH): a multicentre randomised phase 3 trial. The Lancet Neurology. 2014; 13 (7): p.666-675. doi: 10.1016/s1474-4422(14)70084-5 . | Open in Read by QxMD
  6. Ortega-Gutierrez S, et al. Effectiveness and Safety of Nicardipine and Labetalol Infusion for Blood Pressure Management in Patients with Intracerebral and Subarachnoid Hemorrhage. Neurocrit Care. 2012; 18 (1): p.13-19. doi: 10.1007/s12028-012-9782-1 . | Open in Read by QxMD
  7. Diringer MN, Bleck TP, Claude Hemphill J, et al. Critical Care Management of Patients Following Aneurysmal Subarachnoid Hemorrhage: Recommendations from the Neurocritical Care Society’s Multidisciplinary Consensus Conference. Neurocrit Care. 2011; 15 (2): p.211-240. doi: 10.1007/s12028-011-9605-9 . | Open in Read by QxMD
  8. Li H, Pan R, Wang H, et al. Clipping Versus Coiling for Ruptured Intracranial Aneurysms. Stroke. 2013; 44 (1): p.29-37. doi: 10.1161/strokeaha.112.663559 . | Open in Read by QxMD
  9. Bederson JB, Connolly ES, Batjer HH, et al. Guidelines for the Management of Aneurysmal Subarachnoid Hemorrhage. Stroke. 2009; 40 (3): p.994-1025. doi: 10.1161/strokeaha.108.191395 . | Open in Read by QxMD
  10. Gigante P, Hwang BY, Appelboom G, Kellner CP, Kellner MA, Connolly ES. External ventricular drainage following aneurysmal subarachnoid haemorrhage. Br J Neurosurg. 2010; 24 (6): p.625-632. doi: 10.3109/02688697.2010.505989 . | Open in Read by QxMD
  11. Connolly ES, Rabinstein AA, Carhuapoma JR, et al. Guidelines for the management of aneurysmal subarachnoid hemorrhage: a guideline for healthcare professionals from the American Heart Association/american Stroke Association. Stroke. 2012; 43 (6): p.1711-1737. doi: 10.1161/STR.0b013e3182587839 . | Open in Read by QxMD
  12. Muralidharan R. External ventricular drains: Management and complications. Surgical Neurology International. 2015; 6 (7): p.271. doi: 10.4103/2152-7806.157620 . | Open in Read by QxMD
  13. Bisnaire D, Robinson L. Accuracy of levelling intraventricular collection drainage systems.. J Neurosci Nurs. 1997; 29 (4): p.261-8. doi: 10.1097/01376517-199708000-00008 . | Open in Read by QxMD
  14. Lee et al.. Comprehensive Assessment of Isolated Traumatic Subarachnoid Hemorrhage. JOURNAL OF NEUROTRAUMA. 2014 : p.595-609. doi: 10.1089/neu.2013.3152 . | Open in Read by QxMD
  15. Daroff RB, et al.. Bradley's Neurology in Clinical Practice. Elsevier
  16. Feigin VL, Lawes CM, Bennett DA, Barker-Collo SL, Parag V. Worldwide stroke incidence and early case fatality reported in 56 population-based studies: a systematic review. The Lancet Neurology. 2009; 8 (4): p.355-369. doi: 10.1016/s1474-4422(09)70025-0 . | Open in Read by QxMD
  17. Louis et al.. Merritt's Neurology. Wolter Kluwers ; 2015
  18. Behari S, Bhaisora K, Godbole C, Phadke R. Traumatic aneurysms of the intracranial and cervical vessels: A review. Neurol India. 2016; 64 (7): p.14. doi: 10.4103/0028-3886.178032 . | Open in Read by QxMD
  19. Keedy A. An overview of intracranial aneurysms.. McGill Journal of Medicine. 2006; 9 (2): p.141-6.
  20. Macdonald RL, Schweizer TA. Spontaneous subarachnoid haemorrhage. The Lancet. 2017; 389 (10069): p.655-666. doi: 10.1016/s0140-6736(16)30668-7 . | Open in Read by QxMD
  21. Chalouhi N, Hoh BL, Hasan D. Review of Cerebral Aneurysm Formation, Growth, and Rupture. Stroke. 2013; 44 (12): p.3613-3622. doi: 10.1161/strokeaha.113.002390 . | Open in Read by QxMD
  22. Etminan N, Rinkel GJ. Unruptured intracranial aneurysms: development, rupture and preventive management. Nature Reviews Neurology. 2016; 12 (12): p.699-713. doi: 10.1038/nrneurol.2016.150 . | Open in Read by QxMD
  23. Singer RJ, Ogilvy CS, Rordorf G. Clinical manifestations and diagnosis of aneurysmal subarachnoid hemorrhage. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-aneurysmal-subarachnoid-hemorrhage.Last updated: September 26, 2013. Accessed: March 1, 2017.
  24. Muehlschlegel S. Subarachnoid Hemorrhage. CONTINUUM. 2018; 24 (6): p.1623-1657. doi: 10.1212/con.0000000000000679 . | Open in Read by QxMD
  25. Becske T. Subarachnoid Hemorrhage. Subarachnoid Hemorrhage. New York, NY: WebMD. http://emedicine.medscape.com/article/1164341-overview#showall. Updated: August 12, 2016. Accessed: February 14, 2017.
  26. Brunicardi F, Andersen D, Billiar T, et al.. Schwartz's Principles of Surgery. McGraw-Hill Education ; 2014
  27. Singer RJ, Ogilvy CS, Rordorf G. Treatment of aneurysmal subarachnoid hemorrhage. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/treatment-of-aneurysmal-subarachnoid-hemorrhage?source=search_result&search=sah&selectedTitle=2~150#H9.Last updated: October 7, 2014. Accessed: February 14, 2017.
  28. Liebeskind DS. Intracranial Hemorrhage. Intracranial Hemorrhage. New York, NY: WebMD. http://emedicine.medscape.com/article/1163977-overview. Updated: May 10, 2016. Accessed: March 1, 2017.
  29. Singer RJ, Ogilvy CS, Rordorf G. Treatment of cerebral aneurysms. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/treatment-of-cerebral-aneurysms.Last updated: October 18, 2013. Accessed: March 1, 2017.
  30. Hemphill JC, Greenberg SM, Anderson CS et al. Guidelines for the Management of Spontaneous Intracerebral Hemorrhage. Stroke. 2015; 46 (7). doi: 10.1161/STR.0000000000000069 . | Open in Read by QxMD
  31. Rordorf G, McDonald C, Kasner SE, Wilterdink JL. Spontaneous Intracerebral Hemorrhage: Treatment and Prognosis. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/spontaneous-intracerebral-hemorrhage-treatment-and-prognosis.Last updated: May 21, 2014. Accessed: March 29, 2017.
  32. Singer RJ, Ogilvy CS, Rordorf G. Unruptured intracranial aneurysms. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/unruptured-intracranial-aneurysms.Last updated: September 26, 2013. Accessed: February 7, 2017.
  33. Singer RJ, Ogilvy CS, Rordorf G. Aneurysmal subarachnoid hemorrhage: Epidemiology, risk factors, and pathogenesis. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/aneurysmal-subarachnoid-hemorrhage-epidemiology-risk-factors-and-pathogenesis.Last updated: September 26, 2013. Accessed: March 1, 2017.
  34. [No authors listed]. Report of World Federation of Neurological Surgeons Committee on a Universal Subarachnoid Hemorrhage Grading Scale. J Neurosurg. 1988; 68 (6). doi: 10.3171/jns.1988.68.6.0985 . | Open in Read by QxMD
  35. Hunt WE, Hess RM. Surgical Risk as Related to Time of Intervention in the Repair of Intracranial Aneurysms. J Neurosurg. 1968; 28 (1): p.14-20. doi: 10.3171/jns.1968.28.1.0014 . | Open in Read by QxMD
  36. Lawton MT, Vates GE. Subarachnoid Hemorrhage. N Engl J Med. 2017; 377 (3): p.257-266. doi: 10.1056/nejmcp1605827 . | Open in Read by QxMD
  37. Westerlaan HE, van Dijk JM, Jansen-van der Weide MC, et al. Intracranial aneurysms in patients with subarachnoid hemorrhage: CT angiography as a primary examination tool for diagnosis--systematic review and meta-analysis.. Radiology. 2011; 258 (1): p.134-45. doi: 10.1148/radiol.10092373 . | Open in Read by QxMD
  38. Meurer WJ, Walsh B, Vilke GM, Coyne CJ. Clinical Guidelines for the Emergency Department Evaluation of Subarachnoid Hemorrhage. J Emerg Med. 2016; 50 (4): p.696-701. doi: 10.1016/j.jemermed.2015.07.048 . | Open in Read by QxMD
  39. Mensing LA, Vergouwen MDI, Laban KG, et al. Perimesencephalic Hemorrhage. Stroke. 2018; 49 (6): p.1363-1370. doi: 10.1161/strokeaha.117.019843 . | Open in Read by QxMD
  40. Marcolini E, Hine J. Approach to the Diagnosis and Management of Subarachnoid Hemorrhage. Western Journal of Emergency Medicine. 2019; 20 (2): p.203-211. doi: 10.5811/westjem.2019.1.37352 . | Open in Read by QxMD
  41. Perry JJ, Alyahya B, Sivilotti MLA, et al. Differentiation between traumatic tap and aneurysmal subarachnoid hemorrhage: prospective cohort study. BMJ. 2015; 350 (feb18 8): p.h568-h568. doi: 10.1136/bmj.h568 . | Open in Read by QxMD