Exam

Ottawa Subarachnoid Hemorrhage Rule

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Ottawa Subarachnoid Hemorrhage Rule

  • See Also
  1. Subarachnoid Hemorrhage
  • Indications
  1. New, severe non-Traumatic Headache reaching maximal intensity within one hour
  2. Age >15 years
  • Contraindications
  1. New associated neurologic deficits
  2. Cerebral Aneurysm history (or prior Subarachnoid Hemorrhage)
  3. Brain neoplasm history
  4. Chronic Recurrent Headache (3 or more Headaches in >=6 months)
  • Criteria
  1. Age over 40 years old
  2. Witnessed loss of consciousness (+LR: 3.77)
  3. Neck Pain or stiffness (more suggestive of severe SAH, +LR 2.29)
  4. Limited neck flexion on exam
  5. Thunderclap headadache (severity peaks rapidly, within 15-60 minutes)
  6. Onset during exertion (Exertional Headache, +LR 2.16)
  • Interpretation
  1. All criteria absent excludes nearly 100% of Subarachnoid Hemorrhage cases
    1. Test Sensitivity: 99.5 to 100%
    2. Test Specificity: 8 to 24%
  • References
  1. Perry (2013) JAMA 310(12): 1248-55 [PubMed]
  2. Bellolio (2015) Am J Emerg Med 33(2): 244-9 [PubMed]