Diagnosis of Subarachnoid Hemorrhage in the Emergency Department Nathan Maust MS IV Emergency Medicine Sub-Internship May 2006

Overview Case – JM Epidemiology How to Diagnose –History & Physical –ED Diagnostic Testing – CT and LP Misdiagnosis –Reasons & Consequences Summary

Case: JM HPI –37 yo female with h/o ectopic pregnancy and GERD p/w acute onset nausea & vomiting, followed by severe HA –HA described as “12/10” and “like I was having a baby in my head” –Onset at rest –Severe sharp pain on the L side of the head –Denies visual disturbance, any focal neurologic deficit, or neck pain or stiffness –No h/o migraine or other chronic HA and has never before had a HA nearly this severe –After 5-10 minutes, pain began to gradually and modestly improve w/o treatment; pain 5/10 at time of interview

Case: JM ROS otherwise negative PMH: h/o ectopic pregnancy 2001 –Denies HTN, connective tissue disorder Meds: Allegra D, occasional Benadryl NKDA Social: Denies tobacco, alcohol, and illicits Family: Denies h/o SAH or any CTD

Case: JM Physical Exam –VS: T: 96.2 BP: 112/80 P: 89 RR: 14 –Well-appearing 37 yo female in NAD, A&O x 3 –PERRLA –CN II-XII intact –No focal neurologic deficit, gait intact –No nuchal rigidity or meningismus Labs –unremarkable

Case: JM Differential of Consequence for Severe Headache –Subarachnoid hemorrhage (SAH) –Meningitis, encephalitis –Temporal arteritis –Acute narrow angle closure glaucoma –Hypertensive emergency –CO poisoning –Pseudotumor cerebri –Central venous/dural sinus thrombosis –Acute stroke (esp. hemorrhagic) –Mass lesion (tumor, abscess, intracranial hematoma)

SAH Epidemiology (Edlow JA, et al. N Engl J Med. 2006; 342(1):29-36) Incidence of aneurysmal SAH is 6 to 10 per 100k HA constitutes 1-2% of ED visits and up to 4% of physician office visits SAH makes up about 1% of those presenting to the ED with HA as primary complaint Worst HA of patient’s life –A–Abnormal neuro exam: 25% had SAH –N–Normal neuro exam: 12% had SAH Misdiagnosis is common and causes increases in M&M –2–23% to 53% initial misdiagnosis rate Common source of ED malpractice suits

SAH Quick Pathology & Pathophys Causes –Ruptured aneurysm (75%) M=F, 5 th or 6 th decade, acute ∆ BP Usually congenital berry aneurysms in Circle of Willis –Polycystic Kidney Dz, Coarctation of Aorta, Ehlers-Danlos HTN, alcohol, cigarettes, cocaine 2-3% are mycotic aneuryms (s/p infective endocarditis) –Intracranial AVM (10%) M>F, 2 nd to 4 th decades Source of symptoms –Rupture of intracranial artery → ↑ ICP → distortion of pain-sensitive structures → HA → decreased cerebral perfusion → LOC → compression of intracranial structures → 3 rd n. palsy, …

History Findings History –Sentinel/Warning/Thunderclap HA: 20 to 50% get a distinct, unusual, severe HA that precedes the actual HA that causes the pt to seek medical attention; can come days to weeks earlier –Nausea/vomiting –Exertion at time of HA onset –Depressed consciousness –Neck stiffness or pain –Visual changes –Gait disturbance

Physical Findings (Edlow JA, Caplan LR. N Engl J Med. 2000;342(1):29-36) Nuchal rigidity Diminished level of consciousness Papilledema Retinal and subhyaloid hemorrhage Third nerve palsy Sixth nerve palsy Bilateral weakness in legs or abulias Nystagmus or ataxia Aphasia, hemiparesis, or visual neglect

Current Treatment Algorithm (Suarez JI, et al. N Engl J Med. 2006;354(4):387-96) CT scan without contrast –If positive, perform CT or cerebral angiography* –If negative, perform Lumbar Puncture If abnormal – CT or cerebral angiography* If abnormal but equivocal – CT or cerebral angiography* If normal – Stop * If aneurysm is found, treat promptly. If negative, repeat CT angiogram in 1-3 weeks and image brain, brainstem, and spinal cord.

Sensitivity of 5 th generation CT scanners (Boesiger BM, et al. J Emerg Med Jul;29(1):23-7) Retrospective chart review of 177 patients in 2002 that presented with HA and had CT and LP performed to rule out SAH. Exclusions: trauma within 3 months, age ≤ 17, not having r/o SAH as reason for LP on chart, recent neurosurgery. Patients were followed up for a minimum of 3 months by chart review and/or phone call to assess for complications after CT and LP were performed Sensitivity of CT for SAH: 100% (95% CI %) Specificity of CT for SAH: 99.4% CI 96.8%-99.9%)

Lumbar Puncture (Shah KH, Edlow JA. J Emerg Med. 2002;23(1):67-74) The gold standard for diagnosis of SAH ~100% sensitive in detected blood in the CSF Traumatic tap occurs in ~20% of LPs Interpretation –“Three tube” test: should see a decrease in traumatic tap vs. steady level of RBCs in true SAH –Xanthochromia: 20% in first 6 hr, 65% between 6 and 12 hr, and 100% after 12 hr –Elevated opening pressure (>20 cm H 2 O) seen in 60% of cases

Case: JM Head CT –Normal LP results Phone call follow-up 14 days s/p discharge. –Only one instance of mild HA in past two weeks. –Denies nausea, vomiting, visual disturbance, neck stiffness or any other complaints. 18CSF Protein Opening Pressure CSF Glucose RBC WBC Color Appearance 16 cm H 2 O None Clear Tube 4Tube 1

Incorrect diagnoses in misdiagnosed SAH (Edlow JA. Emerg Med Clin N Am. 2003; 21:73-78) No dx/HA or unknown cause Primary HA disorder (migraine, cluster, tension) Meningitis and encephalitis Systemic infection (flu, gastroenteritis, viral) Stroke or TIA Hypertensive crisis Cardiovascular diagnosis (r/o MI, arrythmia, syncope) Sinus-related HA Neck problem (cervical disc dz, arthritis) Psychiatric dx (alcohol intoxication, malingering) Trauma-related Back pain Number of episodes required for diagnosis according to Int. HA Society 4 8

Misdiagnosis of SAH (Kowalski RG, et al. JAMA Feb 18;291(7):866-9) Inception cohort of 482 SAH patients admitted to Columbia-Presbyterian in NY between 1996 and 2001 Goal –determine the association between initial missed diagnosis and outcome after SAH –identify factors associated with misdiagnosis Main outcome measures –Modified Rankin Scale (functional outcome) and Sickness Impact Profile (QOL) at 3 and 12 months (performed by interview in person or via telephone)

Misdiagnosis of SAH (Kowalski RG, et al. JAMA Feb 18;291(7):866-9) Results –Misdiagnosis occurred in 12% (56/482) of patients –Location of initial misdiagnosis ED (43%) or a physician’s office (32%) –Diagnostic error No CT performed (73%) CT or LP results misinterpreted (16%) CT done, but LP not performed (7%) –Initial misdiagnosis Migraine/tension HA (36%) No diagnosis (12%) Viral syndrome (11%)

Misdiagnosis of SAH (Kowalski RG, et al. JAMA Feb 18;291(7):866-9) Independently associated with misdiagnosis in all patients: –Normal mental status –Small SAH volume –Right-sided aneurysm location Also associated with misdiagnosis in those presenting with normal mental status: –Education ≤ 12 years –Nonfluency in English –Being unmarried

Case Report #1 (Wasserberg J, Barlow P. BMJ. 1997;315(7122):1598-9) 58M p/w LOC x 1 minute, then had severe HA and hematemesis after awakening Initial dx: hematemesis Admitted to hospital, given IM opiates for pain Initial sx attributed to EtOH withdrawal, pt treated with diazepam HA not improved after 2 days SAH was considered, pt booked for elective CT, next appt 2 days later 1 day before scan, pt became unconscious, had fixed, dilated L pupil ER CT shows extensive SAH → tx to NICU → died shortly thereafter

Case Report #2 (Wasserberg J, Barlow P. BMJ. 1997;315(7122):1598-9) 17F p/w HA associated with n/v x 1 week CT to rule out SAH normal → reassured, sent home (CT later reviewed and confirmed normal) 2 days later she is awakened by sudden HA, she vomits, and collapses In coma on arrival, reacting to pain only CT shows SAH, angiogram shows terminal carotid artery aneurysm but patient dies before completion of angiography

Summary Always consider SAH in a patient who presents with the worst HA of their life Avoid certain pitfalls: –The patient with known HA history that presents with a new, distinct severe HA –The patient whose clinical picture is complicated by other complaints, intoxication, etc. Know how to distinguish traumatic tap from SAH to avoid subjecting patients to unnecessary invasive diagnostic testing Despite advancement in CT scanner technology, today’s data does not support the thought that CT without LP can definitively exclude SAH

References 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;29(1):23-7. Coats TJ, Loffhagen R. Diagnosis of subarachnoid haemorrhage following a negative computed tomography for acute headache: a Bayesian analysis. Eur J Emerg Med Apr;13(2):80-3. Edlow JA. Diagnosis of subarachnoid hemorrhage in the emergency department. Emerg Med Clin N Am Feb;21(1): Review. Edlow JA, Caplan LR. Avoiding pitfalls in the diagnosis of subarachnoid hemorrhage. N Engl J Med Jan 6;342(1): Edlow JA, Wyer PC. How good is a negative cranial computed tomographic scan result in excluding subarachnoid hemorrhage? Ann Emerg Med. November 2000;36: Kowalski BS, et al. Initial misdiagnosis and outcome after subarachnoid hemorrhage. JAMA Feb 18;291(7): Subarachnoid hemorrhage. Lange Neurology. The McGraw-Hill Companies, Seehusen DA, Reeves MM, Fomin DA. Cerebrospinal fluid analysis. Am Fam Physician Sep 15;68(6): Shah KH, Edlow JA. Distinguishing traumatic lumbar puncture from true subarachnoid hemorrhage. J Emerg Med Jul;23(1): Suarez JI, Tarr RW, Selman WR. Aneurysmal subarachnoid hemorrhage. N Engl J Med Jan 26;354(4): Review. Wasserberg J, Barlow P. Lesson of the week. Lumbar puncture still has an important role in diagnosing subarachnoid haemorrhage. BMJ Dec 13;315(7122): Wood MJ, Dimeski G, Nowitzke AM. CSF spectrophotometry in the diagnosis and exclusion of spontaneous subarachnoid haemorrhage. J Clin Neurosci Feb;12(2):142-6.