Transient Ischaemic Attacks (TIAs)

The American Heart Association definition of TIA is now: "a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia, without acute infarction."
- The arbitrary 24 hour limit has been removed (Stroke 2009;40:2276-2293).
- Most (60%) TIAs under the previous "24h" definition resolve completely within one hour and only 14% were of >6 hours duration. The longer the duration of symptoms, the greater the probability of brain infarction on MRI.
- In practical terms, if the patient you are assessing acutely has any residual symptoms or signs you should diagnose "stroke" and manage accordingly. You do not need to wait 24 hours to diagnose "stroke".
All patients presenting with TIA should be started immediately on appropriate secondary prevention medications (see below).
Some patients are at very high risk of early stroke after TIA and need urgent investigations. The risk of stroke within the next 7 days after TIA can be estimated using the ABCD2 score:

ABCD2 - Prediction of Stroke Risk after TIA


ABCD2 - Prediction of Stroke Risk after TIA
	ABCD2 items (Score: 0-7)				Points
A	Age: ≥60 years				1
B	Blood pressure: ≥140/90 mm Hg				1
C	Clinical features:
		unilateral weakness or			2
		speech impairment without weakness			1
D	Duration of symptoms:
		≥60 minutes or			2
		10 - 59 minutes			1
D	Diabetes: (on medication/insulin)				1
Risk of Stroke According to ABCD2 Scores
ABCD2 Score:			0 - 3	4 - 5		6 - 7
Proportion of all TIAs			34%	45%		21%
Stroke Risk (%) at
	2 days		1.0	4.1		8.1
	7 days		1.2	5.9		11.7
	90 days		3.1	9.8		17.8

Include those with ABCD2 scores of 4 or more, crescendo TIAs, atrial fibrillation or who are taking anticoagulants.
Require urgent investigations and Specialist assessment as soon as possible but definitely within 24 hours.
- Urgent CT head.
- Carotid ultrasound within 24 hours.
  Note: Urgent (same/next day) outpatient ultrasound is now available for high-risk patients (ABCD2 4-7).
  - One outpatient Carotid USS slot is held daily (Mon-Fri) at 3.00 pm for this purpose.
  - The Acute Neurology Clinic and Neurology TIA Clinic are available to facilitate ambulatory assessment and management of TIA patients in order to avoid otherwise unnecessary admission (call the Acute Neurology Registrar). However, Neurology clinics are not intended to be used for follow-up of TIA patients who have already been admitted overnight to hospital under a general medical team, unless a Neurology Consultant opinion is specifically required.
    Note: Patients referred for urgent ultrasound who have a >50% ipsilateral stenosis detected will be automatically referred to vascular surgery.
    
    Note: Patients who have definite posterior circulation symptoms only or who would not be considered surgical candidates under any circumstances do not require carotid ultrasound.
- Commence secondary prevention measures before discharge (see below).
- Lifestyle advice including smoking cessation advice.

Those with ABCD2 scores of less than 4 (1.2% 7-day stroke risk) or those who present more than one week after TIA symptoms.
Specialist assessment and investigations within 7 days (NZ TIA guidelines).
- CT head prior to discharge to rule out other diagnoses.
  - If same-day CT is not available the patient should still be prescribed antiplatelet drugs before outpatient CT is performed.
- Secondary prevention medications should be prescribed before discharge.
- "Semi-urgent" carotid ultrasound can be requested as outpatient - these are usually performed within 7-14 days.
Follow-up can be arranged either with the patient's GP or a Specialist clinic.

As soon as the diagnosis is confirmed all people with TIA should have their risk factors addressed and be established on an appropriate individual combination of secondary prevention measures including:
- Antiplatelet agent(s) - clopidogrel, aspirin plus dipyridamole, or aspirin alone.
- Blood pressure lowering therapy, e.g., ACE inhibitor + diuretic.
- Statin - usually atorvastatin 80 mg/day or simvastatin 40 mg/day.
- Oral anticoagulants - if atrial fibrillation or other cardiac source of emboli.
- Nicotine replacement therapy or other smoking cessation aid.
Follow-up, either in primary or secondary care, should occur within one month so that medication and other risk factor modification can be reassessed.

Note: A more detailed TIA management protocol is available in AMAU and ED.


Information about this CDHB document (9729):
Document Owner:	Blue Book Editorial Committee (see Who's Who)
Issue Date:	December 2013
Next Review:	December 2015
Keywords:
Note: Only the electronic version is controlled. Once printed, this is no longer a controlled document.
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Topic Code: 9729