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C3 - TIA - Introduction

Jessica Mason, MD and Stuart Swadron, MD, FRCPC
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C3 2018 02 February TIA Written Summary 340 KB - PDF

C3 – Transient Ischemic Attack (TIA)

Jessica Mason MD, Stuart Swadron MD, Mel Herbert  MD

* Drug doses are a guide only, always check a second source and follow local practice guidelines

Take Home Points

  • TIA exists on a spectrum with stroke - in some cases there will be signs of infarction on advanced imaging (technically a small stroke) and in some there will not
  • The treatment of TIA and small stroke is essentially the same, namely to prevent a major stroke in the near future
  • The ABCD2 score is flawed but still appropriate and effective at identifying high risk patients that should be admitted for expedited work-up
  • It is important in to identify those patients, even with low-risk ABCD2 scores, that may benefit from emergent and urgent interventions such as anticoagulation and invasive vascular procedures

INTRODUCTION

In this episode of C3, we review the management of the patient with transient ischemic attack (TIA).  As a term and as a diagnosis, TIA has undergone significant evolution in the past couple of decades.  Once thought of as a much less important diagnosis, TIA is now recognized as a critical warning sign of an impending stroke.  If this warning sign is heeded, many strokes can be prevented and patient outcomes can be improved.

The old definition of TIA involved a sudden neurologic deficit of vascular origin (typically from loss of blood flow) that resolved with 24 hours.  But we now can see on advanced neuroimaging studies like diffusion-weighted MRI that most patients with deficits that persist this long have evidence of infarction - e.g. completed stroke.  In other words, they do not have anything “transient” at all.  This understanding has led to a progressive change in the formal definition of TIA.  In reality TIA exists on a spectrum with stroke - one contemporary classification is as follows:

  • Stroke
    • Persistent deficits
    • Infarction on imaging
  • Transient Symptoms with Infarction (TSI)
    • Deficits resolve
    • Infarction (stroke) on imaging
  • Transient Ischemic Attack (TIA)
    • Deficits resolve
    • No Infarction (stroke) on imaging

The creation of a new category (TSI) helps us better incorporate the idea that the patient’s deficits and imaging results do not always match up.  There is no precise time cut-off involved in the above definitions and there is a great deal of variation as to when infarction is first seen on neuroimaging.  Some patients display signs of infarction on DWI within minutes of symptoms, in other cases, no lesion is apparent even at 24 hours

As a matter of practical reality for the emergency provider, whether the imaging is positive or negative for infarction, patients with a resolving/fully resolved deficit can essentially be treated in the same fashion.

The degree to which TIA is a warning sign for an impending major stroke was made clear by a well publicized study in California.  In that study, more than 10% or patients had a disabling stroke within 90 days of their visit to the ED with roughly half of those returning within just 2 days.

DIAGNOSING TIA

  • The three key elements of diagnosing TIA
    • Sudden
      • The onset of symptoms in a vascular event is sudden
    • Negative
      • The patient should have a deficit - meaning that something is lost
      • A positive sensation (funny smell or paresthesia) is much more likely to indicate something else such as a seizure, migraine or even a tumor
    • Focal
      • In general, a TIA will result in a focal deficit (e.g. one referable to a certain area of the brain or spinal cord)
      • A global loss of consciousness is more suggestive of cardiac syncope
      • Generalized weakness is unlikely from a TIA
      • Episodes that involve more than one system (e.g. the neurological) are unlikely from a TIA

Krishna P. -

Great work on this but I disagree with your comments on disposition. ACEP clinical policy regarding dispo states "Level B: In adult patients with suspected TIA, do not rely on current existing risk-stratification instruments (eg, ABCD2 score) to identify TIA patients who can be safely discharged from the emergency department."

I dont necessarily agree with that statement for all cases, but I take that as the standard of care as defined by our professional society. As such, I dont think it is medicolegally defensible to discharge TIA patients.

Jess Mason -

I think this is a good point and is applicable to many providers. The risk assessment tools we currently have are far from perfect. However, there are some situations in which discharge is reasonable. For example, you are able to get their full workup and a neuro consult either in the ED or in an expedited fashion, and the patient is low risk by your clinical assessment. Also, some providers may be hundreds of miles away from an MRI, consultants, and the other components of the workup. We try not to be absolute in our recommendations because there is so much variation depending on where you practice.

Ian L., Dr -

Video of the neurological exam that determines full resolution ought be useful.
Useful for all neurological emergencies
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C3 - TIA Full episode audio for MD edition 58:45 min - 82 MB - M4AC3 2018 02 February TIA Board Review Answers 86 KB - PDFC3 2018 02 February TIA Board Review Questions 84 KB - PDFC3 2018 02 February TIA Individual MP3 Files 75 MB - ZIPC3 2018 02 February TIA Written Summary 340 KB - PDF