There is great interest in the use of plant extracts, often derived from traditional medicine, to treat epilepsy. A symposium at the American Epilepsy Congress in December 2005 explored how this knowledge is being integrated into conventional medicine.

Herbal medicines are very important in developing countries, as they are more widely available and cheaper than conventional medication. Although in the UK herbal medicines are considered 'alternative' or 'complementary', in many cultures they are perfectly normal treatments. In Japan for example, medicines called 'kampo' are manufactured to the same standards as western medicines, and are only available with a doctor's prescription. Their cost is also eligible for reimbursement in their state-funded healthcare system.

In the UK, herbal medicines are often taken by people with epilepsy. Most people take them to improve their general health, some people to alleviate symptoms of other conditions, and only a few people take herbal medicines to control their seizures. Perhaps worryingly, most people who take complementary or alternative medicines do not discuss this with their doctors.

The symposium heard from Dr Nikolaus Sucher and colleagues from the Children's Hospital and Harvard Medical School, Boston, USA, who had looked at traditional Chinese stroke medicines. These typically contain several compounds which work together to increase their therapeutic impact, reduce or prevent adverse effects and target more than one disease-causing mechanism at once. This is a very sophisticated approach which may be beneficial to apply in epilepsy but which does make these compounds more difficult to investigate.

Professor Siegward Elsas from the Oregon Health and Science University, Portland, USA, presented a summary of the herbal extracts for which there is clinical evidence for efficacy in epilepsy. These include valerian, kava-kava and passiflora incarnata. He explained that conducting clinical trials on herbal preparations is difficult. Choosing a plant to work with is not always obvious, and it can be difficult to ensure reproducibility of the plant extract, which can vary according to season and location of harvest, and weather conditions. Herbal extracts can also have adverse events which are not always well documented. Measures of efficacy may not be the same as those used for standard drugs.

Plant extracts are definitely a good source of compounds with clinical activity. Many mainstream drugs contain compounds that are ultimately derived from plants, including aspirin (from willow bark) and digitalis, used to treat heart conditions (from foxgloves). Studying plant extracts may lead to the discovery of new anti-epileptic drugs which work in new ways and cause only mild side effects.

See videos of the symposium here