Transient Ischaemic Attacks (TIA) are also known as ' Mini Strokes'. They come on suddenly and produce stroke-like symptoms which last for less than 24 hours. Most TIAs resolve within 1 hour and people make a full recovery. Transient ischaemic attacks affect 35 people per 100,000 of the population each year and are associated with a very high risk of stroke in the first month of the event and up to one year afterwards.
They should be looked upon as warnings that a more severe stroke may be waiting to happen and they should be treated as medical emergencies. Research has shown that if patients with a TIA are seen immediately, given certain tests and started on treatment as soon as possible, the chances of suffering a stroke are reduced by up to 80%. It is imperative to seek medical help immediately as most strokes that occur after a TIA do so very early after the warning TIA.
Symptoms of TIA
The symptoms of a TIA are absolutely identical to that of a full blown stroke.
TIAs usually begin very suddenly over a few seconds or minutes.
- Paralysis, weakness or numbness of one side of the body (this may include a drooping face, useless arm or hand and weak leg)
- Difficulty with speech (aphasia or dysphasia) - difficulty finding the right words, jumbled speech, using wrong words, difficulty understanding speech.
- Slurring of speech (dyasrthria) - the person uses the right words but they are come out slurred.
- Sudden loss of vision in one eye or loss of vision on one particular side.
- Sudden loss of balance, loss of coordination or clumsiness (particularly of one side) or sudden trouble walking.
To help people recognise the symptoms of stroke quickly, the Stroke Association supports FAST - which is a simple test that anyone can perform. It is used by paramedics to diagnose stroke and fast track people into hospital for acute treament.
What causes a TIA?
Just like an ischaemic stroke, a TIA is caused by blockage of an artery supplying the brain. This causes part of the brain to become deprived of blood and hence oxygen and nutrients. This leads to the symptoms described above. However, in a TIA, the arterial blockage clears itself spontaneously before permanent damage in the form of a stroke can happen.
Arteries can be blocked by several mechanisms but the most common ones are gradual narrowing of the artery by the deposit of fatty material (atheroma or atherosclerotic plaque) or the blockage of the artery by a clot that has travelled from the heart or from a larger artery upstream in the circulation. This is called embolism. Certain disorders of the rhythm of the heart or valve problems can cause clots to form in the heart. An artery with an ulcerated or irregular plaque can also be a site of clot formation.
How are TIAs treated?
Patients with suspected TIAs are seen very urgently in a 'TIA Clinic'. There are scoring systems which help doctors decide how urgent each case is. Patients at highest risk are usually seen within 24 hours of receipt of referral from the General Practitioner or other referring clinician. Less urgent patients are seen within 7 days.
At the TIA clinic, the patients are examined and a case history taken. The doctor decides whether the symptoms are genuinely due to a TIA or whether other alternative explanations are more likely. The diagnosis depends, in part, on the description of the symptoms given by the patient. It is often useful to have an eyewitness account from friends or relatives particularly if the patient has poor recollection of events.
Depending on the clinical situation, a few tests may be done (some on the same day and some later). These include blood tests, ECG (electrocardiographic recording of the heart), ultrasound scans of the carotid arteries, brain scans and other tests. For further details, please see the Test's section.
Many patients will have already been started on aspirin. Other medication is often started immediately after a TIA. For further details please see the Treatment's page.
Lifestyle measures are extremely important in the prevention of strokes and further TIAs. For further details please see the Treatment's page
TIA and driving
Anyone who has had a stroke or transient ischaemic attack (TIA) is not allowed to drive a car for at least one month after the event. These rules are for safety reasons, to protect the driver, other road users and pedestrians. The Driver and Vehicle Licensing Agency (DVLA) has strict guidelines about who may or may not drive.
There are two DVLA license groups. Group 1 includes motor cars and motor cycles. Group 2 includes large lorries (category C) and buses (category D). The medical standards for Group 2 drivers are very much higher than those for Group 1 because of the size and weight of the vehicle. This also reflects the higher risk caused by the length of time the driver may spend at the wheel in the course of his/her occupation.
Group 1 Regulations -
Must not drive for at least 1 month. May resume driving after this time if the clinical recovery is satisfactory. There is no need to notify the DVLA but the insurance company should be notified.
The DVLA must be notified if one month after the stroke, there are residual symptoms causing limb weakness, visual disturbance, problems with co-ordination, memory or understanding.
Minor limb weakness alone will not require notification unless restriction to certain types of vehicle or vehicles with adapted controls is needed.
A driver experiencing multiple TIAs over a short period of time may require 3 months freedom from further attacks before resuming driving and should notify the DVLA.
If epileptic attacks of any kind have occurred, other than those within the 24 hours following the stroke event, the DVLA has to be informed.
Group 2 Regulations -
Refusal/ revocation for at least 12 months following a stroke or TIA. Can be considered for licensing after this period if there is a full and complete recovery and there are no other significant risk factors. Licensing will also be subject to satisfactory medical reports including exercise ECG testing.
For further details, please see the Driving page.