More than 10 years ago, I had two similar episodes, each about two years apart, but a load of tests, including an MRI scan, could find nothing wrong.

These episodes never occurred before I contracted Lyme disease 12 years ago. A year after that, I had my first attack. Since then, I have had an irregular and rapid heartbeat, and I am susceptible to everything going, including every type of flu.

Before the TIA, my doctor wanted to put me on beta-blockers to regulate my heartbeat but, according to tests, my heart is fine. He believes there is no imminent danger of a stroke as I have no family history of it, although my grandmother did have a stroke at age 26.

I don’t have high blood pressure or drink and, at 33, I’m probably too young for hardened arteries. My only other symptom is general fatigue, which means I often live on coffee. What should I do?- MM, Maidstone

A Transient ischaemic attacks are mini-strokes, when the blood supply to parts of the brain is temporarily interrupted or blocked. A stroke can be due to lack of blood (thus lack of oxygen) to the brain which, in turn, is caused by atherosclerosis, a ruptured blood vessel or a blood clot from elsewhere in the body which travels to the brain. During a proper stroke, there is brain damage and even death.

While stroke damage can persist for weeks or permanently, a TIA lasts only a few minutes or, at most, an hour, and there is no permanent damage.

It’s a shame you weren’t seen promptly as you need to be medically evaluated within 60 minutes of the attack to determine whether you suffered a genuine stroke or only a TIA.

In our view, your doctor is remiss in dismissing TIAs as just part of your makeup, a typical and now outdated attitude. In a new study (J Am Med Assoc, 2000; 284: 2901-6), only 14 per cent of patients with TIAs were hospitalised and 8 per cent received no subsequent treatment whatsoever to protect them from a serious stroke later.

TIAs should be considered a major warning of a future full-blown stroke, and all possible causes should be ruled out. The same study showed that 10 per cent of those who had TIAs went on to have a major stroke within the next 90 days. Indeed, half the strokes occurred within two days of the TIA.

This makes it imperative that your doctor run the gamut of routine tests on you as a matter of urgency to find out if your episode had any cause - a blockage, clot or haemorrhage - which could lead to a full-blown stroke later. These tests include Doppler ultrasound of your carotids (the neck arteries feeding blood to the brain) and other arteries to see if there is any minor or major blockage. Often, in stroke, both arteriosclerosis (hardened arteries) and arterial occlusions (clots) are present since platelet thickening may occur due to a damaged arterial lining. You should also undergo all the usual tests to determine your risk of stroke.

You also need to check your blood pressure, as high blood pressure can sometimes lead to an aneurysm, where a section of the arterial wall balloons out and bursts, causing a haemorrhage in the brain.

In a sense, you were lucky to have the TIA before taking beta-blockers, as these are just one of a large number of drugs which can cause a stroke in susceptible individuals. Others include sumatriptan, taken for migraines (Intensive Care Med, 1995; 21: 82-3); all hormones, including HRT and the Pill (Acta Neurol Belg, 1992; 92: 45-7); phenylpropanolamine, present in OTC drugs for weight loss, cold preparations and nasal decongestants (Am J Emerg Med, 1987; 5: 163-4); nifedipine, a calcium-antagonist type of antihypertensive (BMJ, 1992; 305: 693); and any sort of nasal decongestants used excessively (J Neurol Neurosurg Psychiatry, 1989; 52: 541-3). Ironically, even drugs used to prevent stroke - such as anticoagulants, streptokinase, heparin and recombinant tissue-type plasminogen activators - can cause a stroke (Circulation, 1991; 83: 448-59; Arch Neurol, 1985; 42: 1033-5).