03/04/2021
What do you know about Transient Ischaemic Attack(TIA)?
Transient ischaemic attack (TIA) is now defined as a transient episode of neurological dysfunction caused by central nervous system ischemia without acute infarction . This tissue-based definition with a focus on the absence of infarction has replaced the previous time-based definition(The arbitrary time of less than 24 hours is no longer used).
How do you diagnose TIA?
Its mainly a Clinical diagnosis
Note: Several scoring systems were used for risk stratification of TIAs to guide patient selection for early treatment . However, more recent evidence suggested that clinical risk scores alone without additional data on cerebral and carotid imaging were poor at discriminating low from high-risk TIAs.
eg: The ABCD2 score was until recently used to stratify stroke risk in the first 2 days.
How do you investigate TIA?
(Refer immediately people who have had a suspected TIA for specialist assessment and investigation, to be seen within 24 hours of onset of symptoms.)
Imaging for people who have had a suspected TIA or acute non-disabling stroke:(NICE Guideline)
>CT brain scan- It is not done in people with a suspected TIA unless there is clinical suspicion of an alternative diagnosis that CT could detect.
>MRI- After specialist assessment in the TIA clinic, consider MRI (including diffusion-weighted and blood-sensitive sequences) to determine the territory of ischaemia, or to detect haemorrhage or alternative pathologies.
>Carotid imaging- If the patient is considered as a candidate for carotid endarterectomy, he/she should have urgent carotid imaging.
Other investigations: Cardiac echo, ECG and 24 hour tape, MR or CT angiography
Note: Kumar & Clark's Clinical Medicine 10th edition- states that in STROKE immediate (ideally within 1 hour of presentation) Non Contrast Computed Tomography(NCCT) brain is done to exclude a haemorrhagic lesion.
How do you manage TIA?
Immediately start aspirin 300mg daily unless contraindicated, to people who have had a suspected TIA. (immediate initiation of aspirin is recommended to all suspected cases unless contraindicated even without brain imaging, as the benefits outweigh the risks of haemorrhage.)
Start secondary prevention( management of blood pressure, hyperlipidemia, use of antiplatelet agents, treat the underlying cause/source of emboli)
When do you consider carotid endarterectomy ?
It is decided by NASCET criteria or ECST criteria.
(NASCET-North American Symptomatic Carotid Endarterectomy Trial
ECST-European Carotid Surgery Trial)
According to NASCET criteria, people with stable neurological symptoms from acute non-disabling stroke or TIA who have symptomatic carotid stenosis of 50 to 99% are referred for urgent carotid endarterectomy.
According to ECST criteria, people with stable neurological symptoms from acute non-disabling stroke or TIA who have symptomatic carotid stenosis of more than 70% are referred for urgent carotid endarterectomy.
References:
1)THE CEYLON MEDICAL JOURNAL Transient ischaemic attacks: It’s time for timely action! Ceylon Medical Journal 2020; 65: 5-8
2)NICE guideline [NG128] Stroke and transient ischaemic attack in over 16s: diagnosis and initial management - NICE guideline
3)Kumar & Clark's Clinical Medicine 10th edition