Can CTA or MRA replace intraarterial digital subtraction angiography DSA in the investigation of iso

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Can CTA or MRA replace intra-arterial digital
subtraction angiography (DSA) in the
investigation of isolated third nerve palsy?

• William A. Fletcher, M.D., FRCPC
• University of Calgary

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DSA?Or is MRA or CTA sufficient? Kissel et al
(1983)25 aneurysmal palsies 12 pupil-sparing
incomplete
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Third Nerve Palsy Can CTA or MRA Replace DSA?

• 3 Questions
• Sensitivity of CTA and MRA in detecting
  aneurysms?
• Prevalence of aneurysm in III palsy?
• With pupil-sparing incomplete palsy
• With relative pupil-sparing palsy
• Risk of complications from DSA?

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III Nerve Palsy MRA?

• Jacobson and Trobe (1999)
• Risk of MRA missing P Comm aneurysm
• 1.5

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Posterior Communicating Artery (P-Comm) Aneurysms
Causing Third Nerve Palsy

• Jacobson and Trobe (1999)

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P-Comm Aneurysms Causing Third Nerve Palsy

• Jacobson and Trobe (1999)

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P-Comm Aneurysms

• International Study of Unruptured Intracranial
  Aneurysms (ISUIA) (2003)
• 5-year risk of rupture
• ? 7 mm 2.5
• 7 12 mm 14.5

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Symptomatic Unruptured Aneurysms Risk of Rupture

• Juvela et al (1993 2000)

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Symptomatic Unruptured Aneurysms

• Yanaka et al (2003)
• 16 patients with acute third nerve palsies
• all aneurysms ? 10 mm
• 1 aneurysm (6mm) ruptured on day 3
• ?risk of rupture unknown

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P-Comm Aneurysms Causing III Nerve Palsy

• Jacobson and Trobe (modified)

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MRA Sensitivity for Detecting Aneurysms

• White et al (2000)
• ? 3 mm 94
• Kupersmith et al (2005)
• Prospective study of MRA

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MRA Sensitivity for Detecting Aneurysms

• Kupersmith et al (2005)

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MRA Sensitivity for Detecting Aneurysms

• White et al (2000)
• ? 3 mm 94
• Kupersmith et al (2005)
• Prospective study of MRA
• ? 3 mm 100 (n 42)
• Confidence interval 93 - 100

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P Comm Aneurysms Causing Third Nerve Palsy

• Jacobson and Trobe (modified again)

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CTA Sensitivity for Detecting Aneurysms
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CTA Sensitivity for Detecting Aneurysms

• Hoh et al (2004)
• 225 aneurysms
• 109 ruptured
• 114 unruptured
• 28 P Comm aneurysms
• Sensitivity 100
• CI95 overall 98.7 - 100
• CI95 unruptured aneurysms 97.4 100

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CTA Sensitivity for Detecting Aneurysms

• Kangasniemi et al (2004)
• 168 aneurysms ? 2 mm
• Sensitivity 99.4 (CI 97 100)

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CTA Sensitivity for Detecting Aneurysms

• 8 studies of multi-slice CTA and aneurysms
• 712 aneurysms 3mm on DSA
• 1.1 not visible on CTA ( 98.9 sensitivity)
• 1.4 observer error ( 97.5 sensitivity)
• ? Lower CI95 CTA senstivity 96 - 97.8

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CTA Sensitivity for Detecting Aneurysms

• Multislice helical CT

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Third Nerve Palsy Can CTA replace DSA?

• 3 Questions
• Sensitivity of CTA in detecting aneurysms?
• Prevalence (pre-CTA probability) of aneurysm in
  TNP?
• With pupil-sparing incomplete palsy
• Risk of complications from DSA?

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Pupil-sparing incomplete palsy Pre-CTA
probability of aneurysm

• ? Maximum Pre-CTA probability 12 (2.3/20.3)

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Pupil-sparing incomplete palsyProbability of
aneurysm after normal CTA
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Third Nerve Palsy Can CTA replace DSA?

• 3 Questions
• Sensitivity of CTA in detecting aneurysms?
• Prevalence (pre-CTA probability) of aneurysm in
  TNP?
• With relative pupil-sparing palsy
• Risk of complications from DSA?

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Relative pupil-sparing palsy Pre-CTA probability
of aneurysm

• ? Maximum Pre-CTA probability 28 (2.2/7.8)

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Relative pupil-sparing palsy Probability of
aneurysm after normal CTA
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Third Nerve Palsy Can CTA replace DSA?

• 3 Questions
• Sensitivity of CTA in detecting aneurysms?
• Prevalence (pre-CTA probability) of aneurysm in
  TNP?
• Risk of complications from DSA?

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Risk of complications from DSA?

• Permanent neurological complications
• Cloft et al (1999) meta-analysis
• 3,517 studies 0.3 (upper CI95 - 0.5)
• Willinsky et al (2003) prospective
• 2,899 studies 0.5 (upper CI95 - 0.7)

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Factors modifying CTA sensitivity

• CTA technology, quality, interpretation

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Factors modifying aneurysm prevalence

• Age lt 50-years old
• Chou et al (2004)
• 29 III nerve palsy patients 50-years old
• 86 ischemia, 7 aneurysm

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Factors modifying aneurysm prevalence

• Gender
• MF ratio - 13 for PComm aneurysms
• Capo et al (1992) Renowden et al (1993)
• 75 patients with III palsy women men
• aneurysm 24 7
• ischemia 50 59
• Max. post-CTA risk
• Pupil-sparing incomplete 0.4 0.1
• Relative pupil-sparing 1.2 0.3

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Pupil-Sparing Incomplete PalsyCaveats

• Pupils should be re-examined within a week of
  onset
• Isolated superior division palsy greater risk ?

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Relative Pupil-Sparing PalsiesCaveats

• Pupils should be re-examined within a week of
  onset
• Anisocoria 2.0 mm

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DSA after negative CTA?