A blocked blood vessel is the most likely cause of stroke

A TIA is defined as an event which lasts less than 24 hours and leaves no disability, but even these may cause permanent damage to tiny regions of the brain, revealed only on a brain scan.

Professor Philip Bath, the Stroke Association professor of stroke medicine at the University of Nottingham, told BBC News Online: "Talking in general terms - every time you have a minor stroke, you chip away - you have done a bit more damage.

"People who have recurrent stroke are more likely to end up in a worse situation."

People who have more than one stroke should be investigated thoroughly by doctors to find out the cause, he said.

As well as being at greater risk of another stroke, there is also an increased risk of heart attack.

The good news is that recurrent strokes are preventable

Professor Philip Bath, University of Nottingham

Patients may be given a cocktail of drugs to help lower the risk of a recurrence.

This includes blood-thinning drugs similar to aspirin, diuretics, blood pressure medication and even drugs to reduce cholesterol levels in the blood stream.

Professor Bath said: "The good news is that recurrent strokes are preventable - although there will always be people who have another, whatever you do.

"But any TIA or minor stroke should be looked into, and a number of investigations carried out on the patient."

There are fears that some doctors are failing to notice TIAs or "mini-strokes" - and that almost one in ten people aged 65 or over have suffered from them, as opposed to the 1% previously thought.

Damage caused

A spokesman for the Stroke Association said that a "mini-stroke" should never be ignored, as about one in four who have one will go on to have a full stroke within a few years.

A spokesman said: "Symptoms should receive urgent medical attention, even if they last for only a few hours."

Approximately 140,000 people have a stroke every year - 30,000 of these will be a recurrence.

The effects of a stroke or TIA depend entirely on where in the brain it has occurred.

The Stroke Association spokesman said: "For some people, their face will be paralysed, in others their speech will slur - again, it depends on where it happens and it's down to the doctor's clinical judgement to decide where the stroke occurred."