Ottawa_Subarachnoid_Hemorrhage_Rule_for_Headache_Evaluation v.1

The Ottawa Subarachnoid Hemorrhage (SAH) Rule for Headache Evaluation rules out SAH in patients with headache. The rule is that if all of the following criteria is false for the patient, SAH can be ruled out, otherwise, SAH cannot be ruled out. The criteria are: Age ≥40 years. Neck pain or stiffness. Witnessed loss of consciousness. Onset during exertion. Thunderclap headache (instantly peaking pain). Limited neck flexion on examination.

Jack Msonkho

models@cambiocds.com

@Cambio CDS

The Ottawa Subarachnoid Hemorrhage (SAH) Rule helps to rule out SAH in patients with headache.

Use to rule out SAH for patients with headache who are neurologically intact. Only apply in: Alert patients ≥15 years old, new severe atraumatic headache, maximum intensity within 1 hour. Should only be used in patients who are alert and oriented, presenting within 14 days of headache, without history of head trauma or fall in the past 7 days. SAH is rare and accounts for only ~1% of ED patients presenting with headache (Vermeulen 1990), and missed diagnoses have potentially devastating results. Conversely, a tool that reliably rules out SAH is useful to avoid unnecessary workup (more tests do not always clarify the diagnosis). Lumbar puncture (LP) is often performed as the confirmatory test if noncontrast CT is negative but clinical suspicion still high. LP is painful and carries risk of bleeding and headache worse than the original presenting headache. Inclusion criteria for this rule: Alert patients >15 years with a non‐traumatic acute headache: “Alert” is a GCS=15, “Non‐traumatic” is no direct head trauma in previous 7 days, “Acute” is maximal pain in <1 hour and presents within 14 days.

Do not apply if patient is not alert (Glasgow Coma Scale < 15), or less than 15 years old. It can NOT be used in patients with new neurologic deficits, prior aneurysm, prior SAH, known brain tumors, previous history of headache syndrome, intracranial lesions, or chronic recurrent headaches (≥3 headaches of the same character and intensity for >6 months). Do not use as a diagnostic tool. The Ottawa SAH Rule was developed for use in an emergency department setting in patients presenting with acute headache. The rule is 100% sensitive for SAH (i.e., a rule-out tool), but only 15% specific. Given the low specificity it should not be used to diagnose SAH, even in patients in whom all criteria are positive. As with other rule-out decision aids, just because a patient fails the rule does not require that all patients are then evaluated for SAH, given its very low specificity.

Perry JJ, Stiell IG, Sivilotti ML, Bullard MJ, Lee JS, Eisenhauer M, Symington C, Mortensen M, Sutherland J, Lesiuk H, Wells GA. High risk clinical characteristics for subarachnoid haemorrhage in patients with acute headache: prospective cohort study. BMJ. 2010 Oct 28;341:c5204. doi: 10.1136/bmj.c5204. Validation Perry JJ, Stiell IG, Sivilotti ML, Bullard MJ, Hohl CM, Sutherland J, Émond M, Worster A, Lee JS, Mackey D, Pauls M, Lesiuk H, Symington C, Wells GA. Clinical decision rules to rule out subarachnoid hemorrhage for acute headache. JAMA. 2013 Sep 25;310(12):1248-55. doi: 10.1001/jama.2013.278018. Bellolio MF, Hess EP, Gilani WI, VanDyck TJ, Ostby SA, Schwarz JA, Lohse CM, Rabinstein AA. External validation of the Ottawa subarachnoid hemorrhage clinical decision rule in patients with acute headache. Am J Emerg Med. 2015 Feb;33(2):244-9. doi: 10.1016/j.ajem.2014.11.049. Epub 2014 Dec 3.

OBSERVATION.ottawa_subarachnoid_hemorrhage_rule_for_headache_evaluation.v0, EVALUATION.ottawa_subarachnoid_hemorrhage_rule_for_headache_evaluation.v0