Morbidity and Mortality Rounds Subarachnoid Hemorrhage Diagnostic Challenges in the ED Neil Collins

47 y.o. male Day 8 of headache PLC ED

Mr. K.T. ED VISIT SAH state of wellnessRehabilitation Headache May 1915

History

Features of headache at onset

History Features of headache at onset – Sudden – Severe – Ongoing pain

History Associated features – No neck pain, photophobia, neuro symptoms

Physical Exam BP 138/98, afebrile Neuro “normal” Neck supple GCS 15/15

Lab CBC, lytes, Cr., Gluc all normal

Lumbar Puncture 2000 hrs – RBC 1045 X106/L – WBC 1.7 X106/L – Xanthochromia negative – Protein 0.60 (0.15 – 0.45) – Glucose normal

NEXT STEPS?

Repeat LP 2300 hrs RBC # RBC # hrs RBC #1 954 RBC #4 1045

NEXT STEPS?

Objectives Explore the significance of SAH in the context of headache presentations to the ED Understand the principles of the diagnosis of SAH – role of advanced imaging and lumbar puncture

Epidemiology 100 per year in Calgary 50% mortality

Pathophysiology Aneurysmal 85% Perimesencephalic bleeding 10%

(a) Preoperative digital subtraction angiographic (DSA) three-dimensional reformation of wide-necked basilar tip aneurysm. Tähtinen O I et al. Radiology 2009;253: ©2009 by Radiological Society of North America

Scope of the Problem HA comprises 1% of ED visits Benign HA is 50 times more common than SAH 1% of all headaches = SAH 10% of all “thunderclap headaches” = SAH

“Cannot Miss” Headaches SAH Cervico-cranial Artery Dissections Temporal Arteritis Acute narrow Angle Closure Glaucoma Hypertensive Emergencies CO poisoning Meningitis encephalitis Dural Sinus Thrombosis Hemorrhagic Stroke ?Mass Lesions

Cognitive Errors Diagnostic Momentum/Anchoring Outcome Bias Feedback Sanction Overconfidence Bias Frequency Bias

Diagnosis of SAH

Physicians Consistently Misdiagnose SAH

Patients with the greatest likelihood of benefitting from surgery are the ones who most often receive an incorrect diagnosis

Reasons For Misdiagnosis Failure to know the spectrum of presentations of SAH Failure to understand the limitations of CT Failure to perform an LP Failure to interpret CSF results correctly

Reasons For Misdiagnosis Failure to know the spectrum of presentations of SAH Failure to understand the limitations of CT Failure to perform an LP Failure to interpret CSF results correctly

Classic Presentation Abrupt onset of severe unique exertional headache/neck pain with meningismus and altered LOC Neurologic abnormalities – Third nerve palsy – Seizure – Motor deficit

Other Clinical Presentations Less obvious scenarios – Acute confusional state – New seizure – Trauma with subarachnoid blood – Altered LOC and ECG changes

Neurologically Intact Patient With Sentinel Bleed 20 – 50 % of patients report a distinct unusually severe headache in the days or weeks preceding the index episode of SAH

Clinical Features Sudden Onset (Thunderclap)

Differential Diagnosis of TCH SAH Benign Cough Headache Intracerebral Hemorrhage Dissection Sinus Thrombosis Reversible vasospasm Sexual Activity Headache

Prospective study of TCH Results for the SAH cohort Timing of Onset Almost instantaneous50% 2 – 60 seconds24% 1- 5 minutes19%

Prospective Study of TCH 23 patients (11%) had SAH Unable to distinguish on clinical grounds – Activity at onset – Location – Intensity – Hx of migraine – Pain relief with analgesia

Prospective Study of TCH SymptomSAH (%)Non-SAH (%) Nausea9161 Neck Stiffness6110 Altered LOC179 Occipital location5738 Scintillating Scotomata07 Exploding pain6147

Clinical Features Summary Most describe abrupt onset Unique Severe Nausea/vomiting, syncope, seizure, diplopia

Reasons For Misdiagnosis Failure to know the spectrum of presentations of SAH Failure to understand the limitations of CT Failure to perform an LP Failure to interpret CSF results correctly

Sensitivity of CT Problems with interpretation of the literature – Predominance of retrospective studies – Heterogeneity of post headache “time to CT” – Different CT scanners – Neuroradiologist reads

Sensitivity of CT for SAH inside 12 hours Best case is 100% – Perry, J et al (100% sensitivity inside 6 hrs) – Boseger et al (100% sensitivity inside 6 hrs)

Sensitivity of 100% Cortnum et al, (Neurosurgery 2010) Retrospective chart review of patients referred to a neurosurgical center with confirmed SAH or suspicion of SAH (60% had SAH) 99.7% sensitive, only miss was at day 5

Studies with < 100% van der Wee N, et al 1995 – 117/119 (98%) in 12 hours – 14/15 (93%) in 24 hours

Studies with <100% Byyny et al 2008 – Retrospective – Overall sensitivity 93% – Neurologically intact 91%

CT negative, SAH with aneurysm AgeHeadacheGCSHeadache duration CSF supernate RBCVascular anomaly 42SS, LOC15<12 hNa70,000aneurysm 22SS15<12 hXantho370,000aneurysm 21SS15<12hnaposaneurysm 79SS1524 hClear93,500aneurysm 55SS153 daysClear2770aneurysm

Sensitivity of CT for SAH SensitivityDays after bleed ?93%< Near zero14

Reasons For Misdiagnosis Failure to know the spectrum of presentations of SAH Failure to understand the limitations of CT Failure to perform an LP Failure to interpret CSF results correctly

WHY LP in SAH? Unruptured aneurysms of <7mm have a very low risk of bleeding 3-5% incidence of aneurysms in general populations 10% morbidity/mortality in surgery Technology creep

“Cannot Miss” Headaches SAH Cervico-cranial Artery Dissections Temporal Arteritis Acute narrow Angle Closure Glaucoma Hypertensive Emergencies CO poisoning Meningitis encephalitis Dural Sinus Thrombosis/(benign IC Hypertension) Hemorrhagic Stroke ?Mass Lesions

Frequency of LP after negative CT 2010 study on those who listed R/O SAH as reason for CT – 59% before educational program – 64% after educational program

Reasons For Misdiagnosis Failure to know the spectrum of presentations of SAH Failure to understand the limitations of CT Failure to perform an LP Failure to interpret CSF results correctly

Positive LP Persistently bloody CSF Xanthochromia

RBC’s Immediately present, persist for ?2 weeks <5 (X 106) is “negative” SAH with RBC’s in the low 100’s rare

Traumatic Tap Can a decline in RBC between tubes 1 and 4 be used to distinguish between SAH and traumatic tap?

Swadron 2007 Retrospective look at SAH dx by CT and LP 65% of patients with confirmed SAH had a decline in RBC, most by >25%

Traumatic Tap D-Dimer Increased opening pressure Repeat LP

xanthochromia Not reliably present until 12 hours Persists for ? 2 weeks

Xanthochromia Specificity reduced by invitro production – centrifuge delay – Hemolysis from pneumatic tube system

Xanthochromia Spectrophotometry vs visual inspection

TCH Diagnostics Vascular imaging posVascular imaging neg CSF PosSentinel bleedLow risk CSF NegLow RiskN/A

CT Scan Thunderclap Headache negative positive CTA and consult < 6 hrs > 6 hrs or high pretest probability Benign TCH LP negative Xanthochromia Persistent RBC Consider CTA or NSX Consult if ambiguous LP, > 10 days, or very high risk

Mr KT Normal CT head 9 days from headache onset Persistently bloody (minor) CSF without xanthochromia

Mr. KT Events Two Aneurysms on CTA – 5 X 5 X 8 mm Anterior Communicating Artery – 4 X 4 X 4 left M1 bifurcation

MR KT Events FMC admit

Digital Subtraction Angiography

Mr. KT Events Discharge May 13 with diagnosis of headache NYD and ?incidental intracranial aneurysms

May 14, large SAH May 15 Craniotomy – ACA culprit – ACA and MCA clipped – Post op course complicated by edema

Major Points LP after CT (?within 6 hours) Caution with ambiguous LP results Caution with delayed presentations