A Sensible Approach to TIA P1

A Sensible Approach to TIA Part 1

Rob Orman MD, Anand Swaminathan MD and Cam Berg MD

 

Take Home Points

❏      Most patients with TIA do not benefit from hospitalization and may have an outpatient workup.

❏      MRI can assist in determining disposition if available from the ED and may help avoid admission.

❏      The most common predisposing condition is a new cardiac arrhythmia. Look for atrial fibrillation.

 

●      A patient presents with weakness that has now resolved. How should we manage patients with TIA?

 

●      What is a TIA? The definition has changed over time. This is a transient neurologic deficit that results in spontaneous resolution. A diagnosis of TIA does not require a negative workup or negative neuroimaging. This is a clinical definition. This is a patient presenting with symptoms consistent with a vascular territory stroke that improved.

 

●      A small proportion of patients may inappropriately receive thrombolytics for stroke mimics such as TIA. The randomized controlled trials only showed improvement at 30 days and rapid resolution after thrombolytics may because it was a TIA.

 

●      What should you do for the patient who does not qualify for thrombolytics and has improved by the time of your assessment?

 

●      Can we reliably predict stroke after TIA? No. Is the ABCD² score useful for us?  Not really.

 

●      There has been recent interest in the use of clinical decision scores in TIA. ABCD² is one of the most commonly described scores (age, blood pressure, clinical features and diabetes). However, external validation at different sites found variable results. Interrater reliability is inconsistent. This gives an estimate of risk at 2 days, 7 days and 90 days.

 

●      What is the risk of stroke after TIA? The annual rate ranges from 2-4% to as high as 20% a year depending on patient population.

 

●      What is the benefit of admitting the patients? Some feel that admitting the patient may result in expedited thrombolytic therapy if the patient has a subsequent acute stroke in the next 48 hours. Outside of this, there is not much benefit of hospitalization compared to a clinic. We need to consider reversible conditions, treatable pathology and address these variables as they pertain to the patient.

 

●      What can we do for these patients? Few patients benefit from hospitalization. We need to act like neurologists and evaluate TIA symptoms, vascular distribution and pattern to help determine if the patient has modifiable risk factors that may lead to benefit.

 

●      The most common predisposing condition is a new cardiac arrhythmia. This is usually atrial fibrillation. We are experts at diagnosing, treatment and risk stratifying atrial fibrillation. We often forget that one of the highest yield tests in TIA is an EKG. Telemetry may rarely identify conditions not identified in EKG.

 

●      Consider the anatomy. TIAs occur due to transient cerebral ischemia. This may result from a thrombotic event or critical vascular stenosis. Classically, we consider carotid stenosis as a risk factor but patients may have stenosis of other vessels including intracerebral vessels. We have studied different interventions in thrombosis, stenosis and occlusions. Intervention is only beneficial when used in the extracranial, anterior circulation (i.e. the carotid). Interventions in the posterior circulation do not benefit patients and may result in harm.

o      Does the deficit reported in the patient map to the anterior or posterior circulation? If it is anterior, you should obtain imaging of the carotid arteries and this may be done either in the emergency department or as an outpatient.

 

●      There are multiple predisposing medical conditions but only one has short term benefit from treatment. Hyperthrombotic states should be treated with antiplatelet agents. Treatment of hypertension, hyperlipidemia, hyperglycemia and lifestyle modifications such as smoking and alcohol cessation, physical activity and weight loss have proven benefit but are not on the timeframe of an ED visit. These can happen as an outpatient.

 

●      What is the ideal work-up of a patient with a TIA?

o      Recent data suggests that urgent or emergent MRI is helpful in risk stratification. You need the basic non-contrast, diffusion weighted brain series. This may be done in 10 minutes. If the MRI shows ischemia, the patient is at very high risk of short term of stroke.  Some data shows a risk of stroke of around 10% in the next 72 hours. This is better than the ABCD2 score and allows you to rule out other causes such hemorrhage, trauma, mass lesions, etc.

o      Generally speaking, patients with TIA should have a normal MRI. About 10% of cases with clinical improvement have an abnormality noted on MRI. This is a TIA with diffuse weighted imaging abnormality. These patients should be admitted to the hospital.

o      The carotid arteries may be imaged on MRI. This is a better test than the ultrasound. If you have the ability, it is reasonable to obtain an MR angiogram at the same time as MRI.

o      However, most do not have the option to obtain an MRI at all hours for this level of neuroimaging and the use of MRI is controversial. What if you do if you do not have MRI available?

 

●      MRI does not change your management although it may guide your disposition. If you do not have an MRI available, you need some form of brain imaging. You need to obtain an electrocardiogram and consider other predisposing conditions and the use of a clinical decision rule such as ABCD².

o      The guidelines provide a lot of leeway as to the timing of these tests. Both the American Heart Association and American Stroke Association say it is reasonable to perform this entire work-up as an outpatient within the next week. If you are unable to get follow-up, the patient may be kept in house.