eMedicine Specialties > Emergency Medicine > Neurology

Subarachnoid Hemorrhage: Differential Diagnoses & Workup

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

Differential Diagnoses

Encephalitis
Stroke, Hemorrhagic
Headache, Cluster
Stroke, Ischemic
Headache, Migraine
Temporal Arteritis
Headache, Tension
Transient Ischemic Attack
Hypertensive Emergencies
Meningitis

Workup

Laboratory Studies

  • Complete blood count
  • Prothrombin time, activated partial thromboplastin time
  • Blood typing and screening
    • Blood bank typing is indicated when subarachnoid hemorrhage is identified or a severe bleed is suspected.
    • Intraoperative transfusions may be required.
  • Troponin I (cTnI): cTnI measurement is a powerful predictor for the occurrence of pulmonary and cardiac complications, but it does not carry additional prognostic value for clinical outcome in patients with aneurysmal subarachnoid hemorrhage.2

Imaging Studies

  • The initial study of choice is an urgent CT scan without contrast (see Media file 1).
Brain CT scan showing subtle finding of blood at ...

Brain CT scan showing subtle finding of blood at the area of the circle of Willis consistent with acute subarachnoid hemorrhage. Image courtesy of Dana Stearns, MD, Massachusetts General Hospital.

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Brain CT scan showing subtle finding of blood at ...

Brain CT scan showing subtle finding of blood at the area of the circle of Willis consistent with acute subarachnoid hemorrhage. Image courtesy of Dana Stearns, MD, Massachusetts General Hospital.


    • Sensitivity decreases with time from onset and with older resolution scanners.
    • In one study published by the New England Journal of Medicine, good quality CT scanning revealed subarachnoid hemorrhage in 100% of cases within 12 hours of onset and 93% within 24 hours of onset.3 Other studies traditionally report 90-95% sensitivity within 24 hours of onset of bleeding, 80% at 3 days, and 50% at 1 week.
    • CT also can detect intracerebral hemorrhage, mass effect, and hydrocephalus.
    • A falsely negative CT scan can result from severe anemia or small-volume subarachnoid hemorrhage.
  • Distribution of subarachnoid hemorrhage can provide information about the location of an aneurysm and prognosis.
    • Intraparenchymal hemorrhage may occur with middle communicating artery and posterior communicating artery aneurysms. Interhemispheric and intraventricular hemorrhages may occur with anterior communicating artery aneurysms.
    • Outcome is worse for patients with extensive clots in basal cisterns than for those with a thin, diffuse hemorrhage.
  • Cerebral angiography is performed once the subarachnoid hemorrhage diagnosis is made.
    • This study assesses the following:
      • Vascular anatomy
      • Current bleeding site
      • Presence of other aneurysms
    • This study helps plan operative options.
    • Angiography findings are negative in 10-20% of patients with subarachnoid hemorrhage.
    • If negative, some advocate repeating angiography a few weeks later.
  • Magnetic resonance imaging (MRI) is performed if no lesion is found on angiography.
    • Its sensitivity in detecting blood is considered equal or inferior to that of CT scan.
    • The higher cost, lower availability, and longer study time make it less optimal for detecting SAH.
    • MRI mostly is used to identify possible AVMs that are not visible on angiography.
    • MRI may miss small symptomatic lesions that have not yet ruptured.
  • Magnetic resonance angiography (MRA) is less sensitive than angiography in detecting vascular lesions; however, many believe CT angiography and/or MRA one day will play a more central role.
  • Multidetector computed tomography angiography (MD-CTA) of the intracranial vessels is now a routine examination, and it is becoming fully integrated into the imaging and treatment algorithm of patients presenting with acute subarachnoid hemorrhage in many centers in the United Kingdom and Europe.4 Digital-subtraction cerebral angiography has been the criterion standard for the detection of cerebral aneurysm, but CT angiography has gained more popularity and is frequently used owing to its noninvasiveness and a sensitivity and specificity comparable to that of cerebral angiography.5

Other Tests

  • Electrocardiogram
    • About 20% of subarachnoid hemorrhage cases have myocardial ischemia from the increased circulation of catecholamines.
    • Typical results are nonspecific ST-and T-wave changes, prolonged QRS segments, U waves, and increased QT intervals.
    • ECG changes reflect myocardial ischemia or infarction and should be treated in the usual manner. Suspicion of subarachnoid hemorrhage is a contraindication to thrombolytic and anticoagulant therapy.

Procedures

  • Lumbar puncture
    • Lumbar puncture (LP) is indicated if the patient has possible subarachnoid hemorrhage and negative CT scan findings.
    • Perform CT scan prior to LP to exclude any significant intracranial mass effect or obvious intracranial bleed.
    • LP may be negative less than 2 hours after the bleed; LP is most sensitive at 12 hours after symptom onset.
    • Red blood cells (RBCs) in the cerebrospinal fluid (CSF) remain consistently elevated in 2 sequential tubes or punctures in SAH, whereas the number of RBCs in technically traumatic punctures decrease over time.
    • Xanthochromia (yellow-to-pink CSF supernatant) usually is seen by 12 hours after the onset of bleeding; ideally this is measured spectrographically, although many laboratories rely on visual inspection.
    • LP findings were thought to be positive in 5-15% of all subarachnoid hemorrhage presentations that are not evident on the CT scan. This number may be no longer valid with the advent of newer generations of CT scans. A recent small retrospective chart review about patients presenting to the emergency department undergoing fifth generation CT scans and LP showed no patients with positive LP and negative CT scan.6

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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  2. Schuiling WJ, Dennesen PJ, Tans JT. Troponin I in predicting cardiac or pulmonary complications and outcome in subarachnoid haemorrhage. J Neurol Neurosurg Psychiatry. Nov 2005;76(11):1565-9. [Medline].

  3. Suarez JI, Tarr RW, Selman WR. Aneurysmal subarachnoid hemorrhage. N Engl J Med. Jan 26 2006;354(4):387-96. [Medline].

  4. Goddard AJ, Tan G, Becker J. Computed tomography angiography for the detection and characterization of intra-cranial aneurysms: current status. Clin Radiol. Dec 2005;60(12):1221-36. [Medline].

  5. Jayaraman MV, Mayo-Smith WW, Tung GA. Detection of intracranial aneurysms: multi-detector row CT angiography compared with DSA. Radiology. Feb 2004;230(2):510-8. [Medline].

  6. Boesiger BM, Shiber JR. Subarachnoid hemorrhage diagnosis by computed tomography and lumbar puncture: are fifth generation CT scanners better at identifying subarachnoid hemorrhage?. J Emerg Med. Jul 2005;29(1):23-7. [Medline].

  7. [Best Evidence] Tseng MY, Czosnyka M, Richards H. Effects of acute treatment with pravastatin on cerebral vasospasm, autoregulation, and delayed ischemic deficits after aneurysmal subarachnoid hemorrhage: a phase II randomized placebo-controlled trial. Stroke. Aug 2005;36(8):1627-32. [Medline].

  8. Lynch JR, Wang H, McGirt MJ. Simvastatin reduces vasospasm after aneurysmal subarachnoid hemorrhage: results of a pilot randomized clinical trial. Stroke. Sep 2005;36(9):2024-6. [Medline].

  9. Dorhout Mees SM; MASH-II study group. Magnesium in aneurysmal subarachnoid hemorrhage (MASH II) phase III clinical trial MASH-II study group. Int J Stroke [serial online]. Feb 2008;3:63-5. Available at http://www3.interscience.wiley.com/cgi-bin/fulltext/119422961/HTMLSTART.

  10. Koivisto T, Vanninen R, Hurskainen H, Saari T, Hernesniemi J, Vapalahti M. Outcomes of early endovascular versus surgical treatment of ruptured cerebral aneurysms. A prospective randomized study. Stroke. Oct 2000;31(10):2369-77. [Medline].

  11. Molyneux A, Kerr R, Stratton I, Sandercock P, Clarke M, Shrimpton J, et al. International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised trial. Lancet. Oct 26 2002;360(9342):1267-74. [Medline].

  12. van der Schaaf I, Algra A, Wermer M, Molyneux A, Clarke M, van Gijn J, et al. Endovascular coiling versus neurosurgical clipping for patients with aneurysmal subarachnoid haemorrhage. Cochrane Database Syst Rev. Oct 19 2005;CD003085. [Medline].

  13. Whitfield PC, Kirkpatrick PJ. Timing of surgery for aneurysmal subarachnoid haemorrhage. Cochrane Database Syst Rev. 2001;CD001697. [Medline].

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  16. Bederson JB, Awad IA, Wiebers DO, Piepgras D, Haley EC Jr, Brott T, et al. Recommendations for the management of patients with unruptured intracranial aneurysms: A statement for healthcare professionals from the Stroke Council of the American Heart Association. Circulation. Oct 31 2000;102(18):2300-8. [Medline]. [Full Text].

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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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