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When is it safe to rule out subarachnoid hemorrhage without CT and lumbar puncture?

Three Part Question

In [an adult presenting with acute headache to the emergency department], [how effective are patient histories and physical findings] in [ruling out subarachnoid hemorrhage]?

Clinical Scenario

A 26 year old man attends the emergency department with a first-time headache of moderate to severe intensity, with no clinical course of vomiting. It is however of a sudden onset. Neurological examination was unremarkable. He has no history of trauma and has no relevant previous medical history. You wonder if it would be safe to rule out sub-arachnoid hemorrhage without an emergent CT scan.

Search Strategy

Medline 1950 to 10/12 via PubMed
headache[Title/Abstract] AND subarachnoid[Title/Abstract] AND (\\\"humans\\\"[MeSH Terms] AND English[lang])

Search Outcome

883 Results

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Gilbert JW, Johnson KM, Larkin GL, Moore CL.
15,062 atraumatic headache-related ED visits identified using preassigned reason-for-visit codes. Retrospective study to (1) estimate recent trends in CT/MRI utilisation among patients seeking emergency care for atraumatic headache in the USA. (2) to identify factors associated with a diagnosis of significant intracranial pathology (ICP) in these patients.Factors significantly associated with ICP diagnosis (odds ratio)>50 years (7.26), arrival by ambulance (3.66), triage immediacy <15 min (6.04), systolic blood pressure > 160 mm Hg (2.34) or diastolic blood pressure more than 100 mm Hg (1.98) / disturbance in sensation (6.04), vision (3.02), speech (10.54) or motor function (11.67) including neurological weakness (8.46)Dataset reliant on accuracy of patient record. Missing diagnoses, coding bias. Lack of follow-up to track diagnoses or investigations after initial ED evaluation.
Factors not significantly associated (odds ratio)dizziness (1.85), heart rate <60 or >100 (1.70), convulsions/seizures (1.12), nausea (0.95), neck stiffness (0.44), vomiting (1.42), male gender (1.56), non-Hispanic white (1.49)
Adkins K, Crago E, Kuo CW, Horowitz M, Sherwood P.
193 adult aSAH patientsRetrospective review of the (1) presenting historical features in patients with aneurysmal subarachnoid hemorrhage to the emergency department, (2) whether presentation predicts length of stay or deathSAH Presentationheadache 160 (82.9%), nausea 83 (43%), stiff neck 53 (27.5%). No significant neurological deficits ost patients in this analysis arrived at the emergency department without significant neurologic deficits: GCS 15 (55%) and HH score<3 36 (39%)Bias in severity of injury due to inclusion criteria. Subjective symptom reporting from variety of sources.
Perry JJ, Stiell IG, Sivilotti ML, Bullard MJ, Lee JS, Eisenhauer M, Symington C, Mortensen M, Suthe
1999 alert patients aged ≥16 who presented to an emergency department with a chief complaint of non-traumatic headache peaking within an hour or of syncope associated with a headache were included. 130 were eventually diagnosed with subarachnoid hemorrhage. Prospective multicentre cohort study at university affiliated tertiary care teaching hospitals. Univariate analyses of 26 potential predicting variables. Subsequently multivariate models via recursive partitioning to predict for subarachnoid hemorrhage.Rule 1 Age>40, complaint of neck pain or stiffness, onset with exertion, witnessed LOC. Sensitivity 100%, Specificity 28.4%, Negative Predictive Value 100%, Investigation Rate 73.5%Potentially missing a third of patients in enrollment.
Rule 2 Age>45, arrived by ambulance, vomiting at least once, diastolic BP at least 100 mmHg. Sensitivity 100%, Specificity 36.5%, Negative Predictive Value 100%, Investigation Rate 65.8%
Rule 3: Age 45-55, arrived by ambulance, complaint of neck pain or stiffness, diastolic BP at least 160 mmHg. Sensitivity 100%, Specificity 38.8%, Negative Predictive Value 100%, Investigation Rate 63.7%
Grimaldi D, Nonino F, Cevoli S, Vandelli A, D Amico R, Cortelli P.
256 patients presenting to ED for non-traumatic headaches. Prospective study: patient assigned to 1 out 4 scenarios. Scenario 1 aims to include headache associated with SAH or other causes of thunderclap headache with the following features: acute onset (thunderclap headache), OR with neurological signs, OR with vomiting OR syncope at the onset of headache.SAH DiagnosisAll assigned to Scenario 1 accuratelyLimited sample size with high drop-out rate (18%) Reproducibility of diagnostic algorithm untested
Gambhir S, O Grady G, Koelmeyer T.
New Zealand
403 autopsied cases of fatal subarachnoid haemorrhage.Retrospective review to (i) compare the fatal case population to local unselected data; (ii) examine the aetiology and risk factors that contribute to fatality from SAH in our community; and (iii) determine the clinical factors that might help reduce misdiagnosis.SAH Presentation>females (67%), sedentary at onset (39% asleep), involved in significant physical exertion (6%), found dead or collapsed (69%), complaint of headache (27%), atypical primary symptoms (4%), warning headaches (38%), posterior circulation aneurysms 25%, left ventricular hypertrophy (45%), prominent fatty metamorphosis of liver (16%)Lack of multivariate analysis to establish significance.
Togha M, Sahraian MA, Khorram M, Khashayar P.
28 cases of spontaneous SAH.Prospective analysis. History obtained from patient when possible, or if necessary, by family member or associate. Evaluation of the quality and frequency of warning symptoms in patients admitted with spontaneous SAH. SAH Presentationsudden pulsatile severe onset (64.3%), transient loss of consciousness (42.8%), difficulty in walking (21.4%), hemiparesis (14.2%), ocular signs (14.2%) and seizure (3.6%)Multivariate analysis was not performed. Small sample size, descriptive in character Severity of SAH outcomes not calculated.
Breakdown of Symptomsbilateral headache (63%), nausea (41%), not relieved by analgesia (10.7%), headache as sole warning symptom (11%), headache in association with other neurologic signs and symptoms (53.6%), various neurological signs and symptoms but no headache (35.7%)
SAH Risk Factorshypertension (39.3%), smoking (32.1%)
Bø SH, Davidsen EM, Gulbrandsen P, Dietrichs E.
433 ED adult patients seen in Norway 1998–2002 72 (16%) with SAH. Parameters: sex, age, state at ictus, maximum pain intensity, nausea, vomiting, photophobiaSAH PresentationHigher mean age; otherwise considerable overlap between diagnostic groups regarding headache characteristics
Perry JJ, Stiell IG, Wells GA, Mortensen M, Lesiuk H, Sivilotti M, Kapur A.
747 patients, including 50 (6.7%) with SAHsProspective cohort assessing emergency physicians in: 1) pretest accuracy for predicting SAH, 2) comfort with not ordering either CT or LP in patients with acute headache, and 3) comfort with not ordering head CT before performing LP in patients with acute headache. Clinical suspicion of SAH (pretest probability) Sensitivity 93%, specificity 49%Inclusion criteria allowed less severe headaches to be enrolled by including headaches with slower onset (up to 1 hour)
Physician confidence in clinical judgementUncomfortable or very uncomfortable with not ordering any tests for 75.4% of patients when in reality 6.7% had SAH
Kowalski RG, Claassen J, Kreiter KT, Bates JE, Ostapkovich ND, Connolly ES, Mayer SA.
Inception cohort of 482 SAH patients admitted to a tertiary care urban hospital between August 1996 and August 2001. Of which, 12% were misdiagnosed. Prospective analysis. Identifying independent predictors of misdiagnosis with forward stepwise logistic regression. Factors associated with misdiagnosislower education (less than 12 years), smaller hemorrhages, nonfluency in English, being unmarriedHospital-based study: may not fully capture all SAH misdiagnosis, no data on misdiagnosed patients with good outcomes
Seet CM.
61 patients with diagnosis of SAH confirmed by CT, LP or cerebral angiogram. Retrospective studySAH Risk FactorsHistory of hypertension: 30 (49%) Uncaptured or unrecorded physical findings or historical features
SAH Presentationheadache (70%), vomiting (61%), giddiness (30%), unconsciousness (28%), syncope (26%), fits (20%)
SAH Physical Findingselevated blood pressure (34%), neck stiffness (21%), focal weakness (13%), fever (8%), preretinal haemorrhages (2%)
Linn FH, Rinkel GJ, Algra A, van Gijn J.
The Netherlands
102 adult patients referred by GP for acute severe headeache suggestive of aneurysmal subarachnoid hemorrhage (ASAH). ASAH was diagnosed in 42 patients (41%), perimesencephalic hemorrhages (PMH) 23 (23%), and benign thunderclap headache 37 (36%).Prospective study. Comparison was made between groups by means of relative risks (RRs), or mean differences, at 95% CI. Headache characteristics were also compared. Headache onset (RR: ASAH vs BTH)Almost instantaneous 50% (RR 0.7), 1-5 minutes 19% (1.0), exertion 50% (2.3)Deliberate exclusions of patients with acute severe headache not caused by ASAH, BTH or PMH.
SAH presentationTransient loss or clouding of consciousness 26% (RR 1.6), transient focal symptoms 33% (RR 1.5), female sex 57% (1.6), nausea 76% (1.0), vomiting 69% (1.6)
Lledo A, Calandre L, Martinez-Menendez B, Perez-Sempere A, Portera-Sanchez A.
27 patients with acute severe headache of recent onset in EDProspective cohort. SAH presentationbilateral, very intense and involving the occipital region.
Bassi P, Bandera R, Loiero M, Tognoni G, Mangoni A.
364 patients with intracranial aneurysms confirmed by angiography and reliable clinical history.Retrospective survey of subarachnoid hemorrhage cases, with comparison of clinical features. Correct First Diagnosis of SAH (Group A - 78)headache (97.4%), nausea or vomiting (70.5%), dizziness (14.1%), loss of consciousness (33.3%), transient motor deficit (7.7%), headache only (14.1%), Potential selection bias Loss of data due to lack of records
Diagnosed only at a second episode of SAH (Group B: 74)headache (98.6%), nausea or vomiting (51.3%), dizziness (20.3%), loss of consciousness (12.2%)*, transient motor deficit (2.7%), headache only (32.4%),
Fontanarosa PB.
109 patients presenting to ED with proven nontraumatic, spontaneous subarachnoid hemorrhage (SAH),Retrospective review of clinical presentation, diagnostic modalities used, and accuracy of diagnosis.SAH PresentationHeadache (74%), nausea or vomiting (77%), loss of consciousness (53%), nonexertional activities (57%) vs exertional activites (21%), neurologic findings (64%: mainly altered LOC), nuchal rigidity (35%).Absent or inadequate documentation of useful data due to retrospective nature design.
Delayed diagnosisDelayed diagnosis in 16 patients (15%), majority of whom had headaches and normal neurologic examinations
Adams HP Jr, Jergenson DD, Kassell NF, Sahs AL.
182 patients admitted for treatment of SAH reviewed. Focus was on 41 patients with delayed diagnosis of SAH. Retrospective review of the 41 patients misdiagnosed initially. SAH Presentation (in the misdiagnosed 41 cases)headache (85%), nausea (44%), vomiting (34%), brief loss of consciousness (32%), neck stiffness (15%), confusion (12%)Inherent flaws of retrospective study: missing data
Misdiagnoses (in the 41 cases)systemic infection (24%), migraine headache (20%0, hypertensive crisis (7%), neck trouble (10%), brain tumor (7%), aseptic meningitis (7%), sinusitis (7%)


In patients presenting with an acute history of headache, the emergency physician is often wary of missing a diagnosis of subarachnoid hemorrhage (SAH). Such associated morbidity and legal consequences may engender the fear of discharging these patients without further investigative studies – despite additional costs and complications associated with computed tomography (CT) and lumbar puncture (LP). Use of CT/LP in the emergent setting has thus increased significantly despite the incidence of SAH having remained relatively constant. Publications till date have suggested a potential role of evidence-based clinical criteria that recommend high-risk patients for further investigations. Such criteria should be based on account of patient history and physical findings, with faultless sensitivity in picking up SAH. Only one of the studies has developed clinical rules based on multivariate models that predict for SAH. The other studies review cohort of patients to consider the clinical features of SAH – age, neck stiffness, vomiting, arrival by ambulance, etc – while attempting to qualify them. Another study prospectively assigns patients with non-traumatic headaches into 1 of 4 scenarios for further management, but this was limited by a small sample size.

Clinical Bottom Line

History-taking and physical examination will reveal clinical features that are significantly associated with subarachnoid hemorrhage. Each feature by itself does not predict for SAH, but when used in combination, can yield clinical rules with 100% sensitivity and 100% negative predictive value for SAH.


  1. Gilbert JW, Johnson KM, Larkin GL, Moore CL. Atraumatic headache in US emergency departments: recent trends in CT/MRI utilisation and factors associated with severe intracranial pathology Emerg Med J. 2012 Jul;29(7):576-81. Epub 2011 Aug 19.
  2. Adkins K, Crago E, Kuo CW, Horowitz M, Sherwood P. Correlation between ED symptoms and clinical outcomes in the patient with aneurysmal subarachnoid hemorrhage. J Emerg Nurs 2012 May;38(3):226-33. Epub 2011 Jan 22.
  3. 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.
  4. Grimaldi D, Nonino F, Cevoli S, Vandelli A, D Amico R, Cortelli P. Risk stratification of non-traumatic headache in the emergency department. J Neurol. 2009 Jan;256(1):51-7. Epub 2009 Feb 9.
  5. Gambhir S, O Grady G, Koelmeyer T. Clinical lessons and risk factors from 403 fatal cases of subarachnoid haemorrhage. J Clin Neurosci. 2009 Jul;16(7):921-4. Epub 2009 Apr 18.
  6. Togha M, Sahraian MA, Khorram M, Khashayar P. Warning signs and symptoms of subarachnoid hemorrhage. South Med J. 2009 Jan;102(1):21-4.
  7. Bø SH, Davidsen EM, Gulbrandsen P, Dietrichs E. Acute headache: a prospective diagnostic work-up of patients admitted to a general hospital. Eur J Neurol. 2008 Dec;15(12):1293-9. Epub 2008 Sep 13.
  8. Perry JJ, Stiell IG, Wells GA, Mortensen M, Lesiuk H, Sivilotti M, Kapur A. Attitudes and judgment of emergency physicians in the management of patients with acute headache. Acad Emerg Med. 2005 Jan;12(1):33-7.
  9. Kowalski RG, Claassen J, Kreiter KT, Bates JE, Ostapkovich ND, Connolly ES, Mayer SA. Initial misdiagnosis and outcome after subarachnoid hemorrhage. JAMA. 2004 Feb 18;291(7):866-9.
  10. Seet CM. Clinical presentation of patients with subarachnoid haemorrhage at a local emergency department. Singapore Med J. 1999 Jun;40(6):383-5.
  11. Linn FH, Rinkel GJ, Algra A, van Gijn J. Headache characteristics in subarachnoid haemorrhage and benign thunderclap headache. J Neurol Neurosurg Psychiatry. 1998 Nov;65(5):791-3.
  12. Lledo A, Calandre L, Martinez-Menendez B, Perez-Sempere A, Portera-Sanchez A. Acute headache of recent onset and subarachnoid hemorrhage: a prospective study. Headache. 1994 Mar;34(3):172-4.
  13. Bassi P, Bandera R, Loiero M, Tognoni G, Mangoni A. Warning signs in subarachnoid hemorrhage: a cooperative study. Acta Neurol Scand. 1991 Oct;84(4):277-81.
  14. Fontanarosa PB. Recognition of subarachnoid hemorrhage. Ann Emerg Med. 1989 Nov;18(11):1199-205.
  15. Adams HP Jr, Jergenson DD, Kassell NF, Sahs AL. Pitfalls in the recognition of subarachnoid hemorrhage. JAMA. 1980 Aug 22-29;244(8):794-6.