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

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. DSA? Or is MRA or CTA sufficient? Kissel et al (1983) 25 aneurysmal palsies: 12% pupil-sparing incomplete.

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

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  1. 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

  2. DSA?Or is MRA or CTA sufficient? Kissel et al (1983)25 aneurysmal palsies: 12% pupil-sparing incomplete

  3. 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?

  4. III Nerve Palsy – MRA? • Jacobson and Trobe (1999): • Risk of MRA missing P Comm aneurysm: 1.5%

  5. Posterior Communicating Artery (P-Comm) Aneurysms Causing Third Nerve Palsy • Jacobson and Trobe (1999):

  6. P-Comm Aneurysms Causing Third Nerve Palsy • Jacobson and Trobe (1999):

  7. 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%

  8. Symptomatic Unruptured Aneurysms: Risk of Rupture • Juvela et al (1993 & 2000):

  9. 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

  10. P-Comm Aneurysms Causing III Nerve Palsy • Jacobson and Trobe (modified):

  11. MRA Sensitivity for Detecting Aneurysms • White et al (2000): •  3 mm: 94% • Kupersmith et al (2005): • Prospective study of MRA

  12. MRA Sensitivity for Detecting Aneurysms • Kupersmith et al (2005):

  13. 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%

  14. CTA Sensitivity for Detecting Aneurysms

  15. 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%

  16. CTA Sensitivity for Detecting Aneurysms • Kangasniemi et al (2004): • 168 aneurysms  2 mm • Sensitivity: 99.4% (CI: 97% – 100%)

  17. 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%

  18. 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?

  19. Pupil-sparing incomplete palsyPre-CTA probability of aneurysm  Maximum Pre-CTA probability = 12% (2.3/20.3)

  20. Pupil-sparing incomplete palsyProbability of aneurysm after normal CTA

  21. 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?

  22. Relative pupil-sparing palsy Pre-CTA probability of aneurysm  Maximum Pre-CTA probability = 28% (2.2/7.8)

  23. Relative pupil-sparing palsyProbability of aneurysm after normal CTA

  24. 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?

  25. 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%)

  26. Factors modifying CTA sensitivity • CTA technology, quality, interpretation

  27. Factors modifying aneurysm prevalence • Age < 50-years old • Chou et al (2004): • 29 III nerve palsy patients ≥ 50-years old • 86% ischemia, 7% aneurysm

  28. Factors modifying aneurysm prevalence • Gender • M:F ratio - 1:3 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

  29. Pupil-Sparing Incomplete PalsyCaveats • Pupils should be re-examined within a week of onset • Isolated superior division palsy: greater risk ?

  30. Relative Pupil-Sparing PalsiesCaveats • Pupils should be re-examined within a week of onset • Anisocoria ≥ 2.0 mm

  31. DSA after negative CTA?

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