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Cerebral Ischemia and Transient Ischemic Attacks: Definitions and a Historical Perspective

Transient Ischemic Attack Patient Update: The Optimal Management of Emergency Department Patients With Suspected Cerebral Ischemia. Cerebral Ischemia and Transient Ischemic Attacks: Definitions and a Historical Perspective.

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Cerebral Ischemia and Transient Ischemic Attacks: Definitions and a Historical Perspective

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  1. Transient Ischemic Attack Patient Update: The Optimal Management of Emergency Department Patients With Suspected Cerebral Ischemia

  2. Cerebral Ischemia and Transient Ischemic Attacks: Definitions and a Historical Perspective

  3. J. Stephen Huff, MDAssociate Professor of Emergency Medicine and NeurologyUniversity of Virginia Health Systems

  4. CME Disclosure Statement Board Member - FERNE Foundation for Education and Research in Neurological Emergencies

  5. Session Objectives Determine how the definition of TIA is evolving and how this relates to the presentation of TIA patients to the Emergency Department

  6. Definitions - subgroups • TIA • Transient Ischemic Attack • Duration minutes to 24 hours • RIND • Reversible Ischemic Neurologic Deficit • Deficit resolves within 6 weeks • Stroke - Enduring symptoms

  7. Older definitionsTIA’s - unpredictable • Old – “rule of thirds” • 1/3 stroke, 1/3 more TIA’s, 1/3 no further • Neuroimaging / assessments • Angiography • PEG (pneumoencephalogram) • EEG

  8. Pathophysiology • Thrombotic • Recurrent episodes same pattern • Embolic • Multiple episodes of different patterns Fisher CM: NEJM 2002;347:1642-3

  9. Epidemiology • Annual incidence 200,000 – 500,000 • Estimated from patients seeking care • may be higher – not seeking attention • 5 million US given diagnosis of TIA

  10. US TIA Estimates from Different Population Based Studies Ovbiagele B et al. Stroke 2003;34(4):919-24.

  11. Changes in Diagnostic Evaluation • Change in imaging • CT • Ultrasound • MRI • Defining natural history of process

  12. Continuum or Subgroups? • CT findings in 2082 patients • Anterior circulation; CT’s > 24 hours • TIA’s - 13% with CT findings of stroke • RIND – 35% with CT findings • Minor stroke – 49% with CT findings Koudstaal PJ et al. J Neurol Neurosurg Psych 1992;55:95-97

  13. Continuum or Subgroups? • TIA’s • More infarcts the longer the duration • Stroke still imaged (CT) in patients with TIA’s lasting less than one minute Koudstaal PJ et al. J Neurol Neurosurg Psych 1992;55:95-97

  14. Continuum or Subgroups? • Suggested that the ischemic syndromes were not subgroups with different natural history • Ischemic syndromes on a continuum Koudstaal PJ et al. J Neurol Neurosurg Psych 1992;55:95-97

  15. CT and TIA’s • CT’s within 48 hours of presentation • 322 patients with TIA • 4% new infarct • 21% old infarction • 1.2 % non-ischemic cause • CT positive for acute stroke predicted increased risk of additional stroke Douglas VC et al: Stroke 2003;34:2894-8

  16. MRI versus CT • DWI imaging on MRI can detect ischemic lesions within minutes of the event

  17. MRI abnormalities and TIA • 129 consecutive patients • MRI within 14 days of TIA • DWI showed 44% abnormal MRI • Associated with longer symptoms • Associated with disturbance of cerebral functions • Aphasia, spatial neglect, hemianopia Inatomi Y et al: Neurology 2004;62:376-380

  18. Frequency of Positive Diffusion MRI:5 Reported Series of TIAs Ovbiagele B et al. Stroke 2003;34:919-24

  19. TIA Definition Changing • TIAs almost all resolve within 1 hour • Most last less than 10 minutes • <15% patients with symptoms lasting > 1 hour will have resolution at 24 hours • Several series of patients with “normal” neuro exams who underwent acute MRI scanning have demonstrated injury Albers GW et al. N Engl J Med 2002;347:1713–1716

  20. TIA Definition Changing • Current – time-based definition • Proposed – tissue-based definition Albers GW et al. N Engl J Med 2002;347:1713–1716

  21. TIA Working Group Definition • “Brief episode of neurologic dysfunction caused by focal brain or retinal ischemia, with clinical symptoms typically lasting less than one hour, and without evidence of acute infarction” • Implies need for MRI before diagnosis Albers GW et al. N Engl J Med 2002;347:1713–1716

  22. Risk stratification TIAs has changed • In past – regarded as low risk events • Workup over weeks • Contemporary view • High risk sentinel events • Prompt evaluation, interventions

  23. Questions?www.ferne.orgjshuff@virginia.edu ferne_clindec_2008_tia_huff_definitions_extended_062508_final

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