Imaging Controversies in Subarachnoid Hemorrhage

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Imaging Controversies in Subarachnoid Hemorrhage

• J. Bradley White, MD PhD
• September 20th, 2008

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Disclosures

• None

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Objectives

• Understand the etiology, risks, treatments, and
  natural history of SAH.
• Understand the imaging modalities available for
  use in patients that present with SAH.
• Understand the strengths and weaknesses of each
  modality.
• Appreciate the evolving trends in imaging for
  SAH.

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Outline

• Subarachnoid Hemorrhage (SAH)
• Etiology
• Diagnosis
• Treatment
• Imaging
• CT Angiography (CTA)
• MR Angiography (MRA)
• Digital Subtraction Angiography (DSA)

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Case 1

• 58 y/o female
• Sudden onset HA (10/10)
• Neck stiffness
• Nausea/Emesis
• What now?

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CT Scan
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CT Scan

• The first diagnostic test should be a CT scan.
• CT sensitivity
• 12 hours 98-100
• 24 hours 93-95
• SAH detection
• gt 24 hours 90
• gt 5 days 58-80
• gt 7 days 50
• MRI not as sensitive to blood

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Lumbar Puncture
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Lumbar Puncture

• Perform in patients whose clinical presentation
  suggests SAH and whose CT is negative.
• Traumatic tap 20
• Xanthochromia present 6 hours to 2 weeks.
• Of 71 patients with thunderclap headache and
  negative CT and LP, none had a SAH during a
  follow-up of 3.3 years (Lancet 1988 268-70)
• The Gold Standard

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Work-Up
LP Positive ?
No
Yes
No imaging
More Imaging
?
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Incidence of Aneurysmal SAH

• In the USA, 11 cases per 100,000 people per year.
• Autopsy Series
• Author of Cases w/aneurysm
  Ruptd
• Jellinger 87,772 1.6
  1
• Bannerman 51,360 1.43
  1.09
• Less than 2 of the population will have an
  aneurysm.
• Less than 1 of the population will have a
  rupture.

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Aneurysmal SAH Age and Gender

• Aneurysmal rupture is extremely rare in the first
  decade of life.
• Incidence gradually increases each decade and
  peaks in the sixth decade.
• Before age 40, males and females are equally
  affected.
• After age 40, the ratio of females to males is
  1.6 1

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Natural History

• Highest mortality occurs immediately after the
  hemorrhage and then decreases rapidly.
• 12 of patients never make it to the hospital.
• Mortality
• 1 day 32
• 1 week 43
• 1 month 56
• 6 months 60

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Natural History

• Rebleeding is highest within the 1st 24 hours.
• 50-60 of patients die after rebleeding and 25
  are left disabled.

v
v
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Presentation

• Headaches accounts for 1-2 of ER visits
• 1 of these have SAH
• 12 with worst headache of life and normal
  neurological examination
• 25 when the examination is abnormal
• Vomiting
• Neck stiffness
• Change of consciousness

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Presentation

• About 80 of patients with SAH have a ruptured
  saccular aneurysm
• About 10 will have non-aneurysmal
  perimesencephalic hemorrhages.
• Venous hemorrhages
• Occult aneurysms
• Occult vascular malformations

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Multiple Aneurysms
Up to 25 of patients will have multiple
aneurysms.
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Aneurysms by Location
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Genetics of Aneurysms

• First-degree relatives of patient with SAH have
  2-5x increase risk of having an aneurysm.
• First-degree relatives have threefold increased
  risk compared to second-degree relatives
• Anterior communicating artery aneurysms are
  underrepresented, MCA is overrepresented.
• Tend to rupture at smaller size

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Screening

• Why?
• Poor prognosis once ruptured
• Low surgical risk for nonruptured
• (5 morbidity, 2 mortality)
• Indication for surgery for asymptomatic aneurysms
  is still unclear (critical size)
• Who?
• Families with two or more affected members
• Restricted to first-degree relatives (yield 9-29)

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Screening

• When?
• Screening between the ages of 35-65
• Youngest patient with familial ICA is 6 years old
• De novo aneurysms occur at a rate of 2 per year
• Repeat screening at 6-month to 5-year intervals
• How?
• MRA is the most widely used
• Critical size for detection 3-5 mm

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Treatment
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Treatment
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Case 2

• 61 y/o male
• Lifting wood
• Thunderclap HA

Whats the next test?
LP MRI/MRA CTA Angiogram
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CT Angiography
Negative
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Digital Subtraction Angiography
Right ICA
Left ICA
Left Vert
Negative
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Non-Aneurysmal Hemorrhage

• Etiology Unknown
• Venous hemorrhages
• Occult aneurysms
• Occult vascular malformations
• Excellent Outcome
• Low rates of hydrocephalus vasospasm.
• Re-bleed rate nearly zero.

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Non-Aneurysmal Hemorrhage

• Which imaging test?
• CTA alone (rare)
• CTA ? Angiography (standard of care)
• Angiography ? Angiography (utility questioned)
• Early FN rates up to 15
• With biplane and 3D rotational angiography, FN
  rates are 0-2.
• Why ?

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Day of SAH
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1 month later
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2 months later
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Case 3

• 87 y/o female
• Abrupt loss of consciousness
• Exam remained poor
• HH 4-5

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CTA
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CTA
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Angiography
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Case 4

• 61 y/o female
• thunderclap HA

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CTA
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Angiography
Doh !
s/p clipping ACOMM aneurysm
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The DebateCTA vs DSA

• CTA
• Pros
• Non-invasive
• Fast
• Cons
• High false negative rate
• Higher false positive rate

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The DebateCTA vs DSA

• DSA
• Pros
• Gold Standard
• Highest resolution
• Provides flow/perfusion information
• Opportunity to intervene
• Cons
• Invasive (risk)
• Availability

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CTA vs DSAThe Data

• Spatial Resolution
• CTA (64 slice) 0.4 mm1
• DSA (Biplane) 0.1 mm2
• Temporal Resolution
• CTA (64 slice) 0.5 secs1
• DSA (Biplane) 0.25 secs3

• Westerlan et al. AJNR Jun-Jul 2008
• Kallmes et al. AJNR Nov-Dec 2007
• Kaufmann et al. AJR Jun 2008

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CTA vs DSAThe Data

• Stroke Risk
• CTA 0
• DSA lt 0.141
• Mortality
• CTA 0
• DSA 0.06

• Westerlan et al. AJNR Jun-Jul 2008
• Kallmes et al. AJNR Nov-Dec 2007

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CTA vs DSAThe Data

• Sensitivity1
• CTA (64 slice) 94 lt3mm 70
• DSA (Biplane/3D) 100 lt3mm 100
• Specificity1
• CTA (64 slice) 90
• DSA (Biplane/3D) 100

• Lubicz et al. AJNR Nov-Dec 2007

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The Talking Points

• CTA
• Higher false negative rate (10) ? more (vs DSA)
  missed aneurysms ? higher re-hemorrhage rates
  (with 80 mortality) ? unnecessary deaths
• 2.5 deaths per 100 patients1
• DSA
• No false negatives ? deaths are due only to
  inherent risk of angiogram (0.06)
• 0.06 deaths per 100 patients1
• 1/50 death rate of CTA

• Kallmes et al. AJNR 2007

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The Talking Points

• A recent study showed that 75 of patients
  underwent both CTA and DSA.1 Why?
• A substantial number of aneurysms appeared
  favorable for coiling on CTA that then went to
  DSA
• The patients with no aneurysm present on their
  CTA also underwent DSA to ensure the absence of
  the aneurysm (non-aneurysmal hemorrhage?)
• ISAT showed that patients fare better with
  coiling over clipping given clinical equipoise.2

• Westerlan et al. Neuroradiology 2007
• Molyneux et al. Lancet 2002

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The Talking Points

• Why not skip CTA and go straight to DSA so that
  the best diagnostic test can be performed with
  the opportunity to treat in the same setting?
• Eliminates cost of CTA
• Eliminates radiation of CTA
• Reduces chance of unnecessary surgery
• 25 of patients were not considered for coiling1

• Westerlan et al. Neuroradiology 2007

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The Talking Points

• When should CTA be the first line imaging
  modality?
• Unstable patients with large intraparenchymal,
  subdural, or epidural hematomas.
• Patients with relative contraindications to
  angiography
• i.e. Coumadin
• i.e. Connective tissue disorders
• Deficient 3D angiography

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Conclusions

• Conventional angiography remains the diagnostic
  gold standard for subarachnoid hemorrhage.
• Advances in CT angiography continue to bring the
  technology close to DSA capabilities.
• Until that happens, DSA should be performed in
  patients with SAH to ensure the greatest
  diagnostic accuracy coupled with the option for
  endovascular treatment.

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Thank You