Avoiding pitfalls in the diagnosis of Subarachnoid Hemorrhage Sitges, EspaaSeptember 17, 2003

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Avoiding pitfalls in the diagnosis of
Subarachnoid HemorrhageSitges,
España September 17, 2003

• Jonathan A. Edlow, MD, FACEP
• Associate Chief, Department of Emergency Medicine
• Beth Israel Deaconess Medical Center
• Assistant Professor of Medicine
• Harvard Medical School
• Boston, MA

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It is more important to know what patient has a
disease, than what disease the patient has

• Sir William Osler

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(No Transcript)
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History

• 32 yo female with head pressure for 3 hours.
• She developed acute head pressure as she lifted
  a heavy suitcase at the airport, having just
  arrived home from a 6 hour flight from Paris.
  This was not a headache, but it was distinctly
  unpleasant and was accompanied by dizziness,
  like I might faint
• No associated nausea, vomiting, diplopia,
  syncope, neck pain or stiffness or facial pain

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History of Present Illness

• Severity 7/10, gradually getting slightly better
• Quality pressure, like a rush, different
  from the every other month migraines that she
  gets
• Onset abrupt
• Location all over

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Past History, Meds, Allergies

• Anxiety
• Mild, not currently being treated with
  medications
• Migraine HA
• Gets them 4-6 times per year, often
  peri-menstrual
• Go away with acetaminophen or if bad, sumatriptan
• No allergies
• No medications except for sumatriptan used as
  needed for migraine
• Non-smoker, non-drinker, works in computer sales

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Physical Examination

• Alert, oriented, looks well
• Vital signs
• Temp 98.4
• P 72 BP 128/72 R 14
• General physical exam, including a careful HEENT
  exam, is entirely normal neck is supple

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Neurological Examination

• MS normal (other than being mildly anxious)
• CN 2-12 normal, including good venous pulsations
• Motor 5/5 strength with no pronator drift
• Sensory, gait and cerebellar all normal
• Reflexes normal, toes down-going

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Cannot miss diagnoses(life, limb, vision or
brain threatening and treatable)

• SAH
• Meningitis, encephalitis
• Stroke
• Hypertensive encephalopathy
• CVST
• Pseudotumor cerebri

• Arterial dissection
• Mass
• Abscess
• Tumor
• Hematoma
• Temporal arteritis
• ANAG
• CO poisoning

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The bell-shaped curve
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SAH - misdiagnosis

• Least ill patients are most commonly misdiagnosed
• Correctly diagnosed, they have the best outcomes
• Misdiagnosed patients have worse outcomes from
  early complications (mostly re-bleeding)

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History the 4 questions

• Onset
• Severity
• Quality
• Associated symptoms
• Nausea and vomiting
• Diplopia
• Seizures, syncope

Thunderclap HA (TCH)
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Risk Factors
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SAH classic story

• Abrupt onset of severe HA - worst of life
• Occurs during exercise or Valsalva
• Transient LOC (syncope)
• Nausea and vomiting
• HA is nearly universal in conscious patients

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SAH atypical story

• HA not abrupt in onset, begins at rest, not the
  worst HA of life, can be mild, respond to
  non-narcotic analgesics, remit spontaneously or
  occur in the context of pre-existent HA syndrome
• But it is unique, distinctive for the patient
• Presents as a syndrome suggesting another
  diagnosis

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Other presenting syndromes

• Mild fever, meningismus, HA and/or N/V
• Flu, sinusitis, viral syndrome, viral meningitis
• Gastroenteritis
• Primary neck pain, paucity of HA cervical
  strain
• Migraine-like (unilateral HA with N/V)
• Migraine is 1000x more common than SAH in
  general population ( 30-50x more common in an ED
  cohort)
• Unruptured aneurysms
• May present without headache, including seizure,
  ischemia and mass effect

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Unruptured Aneurysm
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Physical Exam
Jonathan A. Edlow, MD,
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Physical exam
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So who do you work up?

• History
• Headache onset, severity, quality, associated
  symptoms
• Risk factor assessment and epidemiological
  context
• Physical exam
• Careful cranial nerve exam, visual fields
• Optic - sub-hyaloid hemorrhage
• Decision-making
• Is there a plausible alternative explanation for
  symptoms? (first or worst)

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What is the work up?

• Non-contrast CT scan
• Lumbar puncture (if CT is negative, equivocal or
  technically inadequate)
• In exceptional cases where both CT and LP are
  normal, cerebrovascular imaging
• MRA
• CT angiography
• Conventional catheter cerebral angiography

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Limitations of the CT scan

• Timing - sensitivity decays with time
• Spectrum bias small volume bleeds (warning
  bleeds)
• Errors in interpretation (stroke data)
• Technical factors - thick cuts, quality of
  scanner
• Hematocrit (lt 30) can lead to negative scan

Jonathan A. Edlow, MD,
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(No Transcript)
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Errors in interpretation
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Limitations of lumbar puncture

• Failure to do an LP after negative CT scan
• Failure to distinguish a traumatic tap from true
  SAH
• Incidence is 10 (400 RBCs) to 15 (1000 RBCs)
• Failure to recognize that visual inspection for
  xanthochromia is less sensitive than
  spectrophotometry
• Data are weak
• gt 99 of US hospital labs use visual inspection
  anyway
• Failure to recognize that xanthochromia may be
  absent in the early hours following SAH

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May help in CVST, BIH, distinction between
traumatic tap and true SAH
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Xanthochromia
Should I wait 12 hours to perform the LP?
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Walton study (1955)

• All patients tapped in the first 12 hours after
  onset of HA had bloody CSF, including several in
  the first few hours
• 60 of those tapped between hours 6-12 had
  xanthochromic CSF (measured visually)
• 60 had elevated opening pressure

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Jonathan A. Edlow, MD
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SAH when to stop the work-up?

• Case reports (Day Raskin, Raps et al)
• Patients with TCH (and negative CT and LP) very
  rarely have symptomatic aneurysms
• Retrospective evaluation (71 patients) for
  average of 3.3 years found none with subsequent
  sudden death or SAH
• Four prospective studies (254 patients), followed
  for up gt1 year identified none with subsequent
  sudden death or SAH

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SAH when to pursue the work-up?

• Consider vascular imaging and/or specialist
  consultation in patients with
• very high pre-test risk
• first presentation gt 2 weeks after onset of
  symptoms
• Significant ambiguity in results of CT scan or
  CSF analysis
• CSF unobtainable due to patient refusal or
  technical problems

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Dont be smug!
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It is more important to know what patient has a
disease, than what disease the patient has
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Key teaching points

• Some patients with SAH present with mild symptoms
• Take a very detailed history, paying special
  attention to
• Onset
• Severity
• Quality
• Associated symptoms
• The work-up for patient who may have SAH is
  cranial CT followed by LP (if CT negative or
  non-diagnostic)

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Outcome of Case

• Patient underwent angiography she had an ACom
  aneurysm
• The aneurysm was clipped later the next morning
  (its anatomy was not favorable for an
  endovascular approach)
• Patient was discharged 5 days later with normal
  neurological function

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Questions?