A Transient Ischemic Attack

TIAs are quite common among elderly patients. About 10% of these patients have a stroke within one week of TIA. Hence, an accurate diagnosis is important, as administration of appropriate therapy can lessen the risk for an imminent stroke.

Diagnosing TIAs in the ED can be tough as patients may not recall what exactly happened, present in a benign manner; may have a normal neuro exam during the evaluation, and also have normal imaging. Thus, a careful history is fundamental to the diagnosis. Moreover, due to the abovementioned reasons, there can always be a difference of opinion about the diagnosis between the Emergency Physicians and Neurologists.

What is the current definition of TIA?

Dispute exists among Neurologists about the definition of a TIA.

Traditional definition: A sudden focal neurologic deficit caused by a vascular insult that resolves within 24 hours

This description of TIA was given before the availability of cutting-edge MRI scanners. Consequently, clinicians were unable to differentiate TIAs from strokes with reversible ischemic neurological deficits. However, real TIAs usually resolve within 30 to 60 minutes. More than 98% of patients who do not reverse their deficit within 1 hour or rapidly improve within 3 hours have a stroke.

New Definition - Episodes that last typically less than 1 hour and are not associated with acute infarction.

This new proposed definition indicates that an MRI scan has been performed. Any patient who has a persistent neurologic deficit must be treated as an acute stroke victim until proven otherwise.

     

     How does a TIA present?

Anterior Circulation TIAs: Transient Unilateral sensory changes or weakness, slurred speech, transient blindness

Posterior Circulation TIAs: Transient Dizziness, Diplopia, Dysarthria, Dysphagia, Dystaxia in addition to sensory motor defictis.

ED Management of TIAs

Patients with TIA seldom require any emergent interventions. They do need a:

• Blood glucose
• Other routine set of labs
• Neurologic examination
• ECG (to look for arrhythmias)
• TTE (to look for a cardioembolic source)

What kind of imaging do we need for them? CT or MRI?

At least, a plain head CT should be performed to rule out other causes of neurologic dysfunction, such as hemorrhage or mass effect. MRI, however, detects small infarcts in up to two-thirds of patients who have traditionally-defined TIAs.

Anterior circulation TIAs require an urgent carotid evaluation, to look for high-grade stenosis (>70%). Posterior circulation TIAs require radiologic studies of the vertebrobasilar system, such as Doppler ultrasonography.

Who needs admission?

Many experts prefer to admit TIA patients to ensure an accelerated work-up and close monitoring. Admission should be definitely considered for high risk groups such as:

• Patients who failed first-line therapy with antiplatelet agents
• Patients on full anticoagulation, such as enoxaparin or warfarin
• Patients who have crescendo TIAs, defined as three or more TIAs over 72 hours with escalating severity or duration
• Patients who have suspected cardioembolic sources of TIA (Arrythmias or Vegetations)

ABCD2 Score for risk stratification

     Who can be considered for discharge and follow up?

• Patients with amaurosis fugax (transient monocular blindness)
• Elderly patients whose TIA occurred more than 1 week before arrival also may be safe for outpatient work-up, because the period of greatest risk has passed.

Note: Before discharging these patients, do discuss the risk for future stroke with the patient, clearly describe reasons to return to Emergency Department, prescribe an antiplatelet agent or document its contraindication, and ensure timely and appropriate follow-up. If there are social issues, err on the side of admission.

  

What do we discharge them with?

• Oral Antiplatelets
• Emergent anticoagulation (only if TIA in the setting of new onset atrial fibrillation/ flutter) 
• A final discharge conversation about when to come back to the ED

AAuthor:

              

     Lakshay Chanana
     
     Speciality Doctor
     Northwick Park Hospital
     Department of Emergency Medicine
     England

     @EMDidactic