`20 p.c. of epilepsy patients develop drug-resistant seizures'

BANGALORE JAN. 28. Scientists have found that 20 per cent of people suffering from epilepsy run the risk of developing seizures that become resistant to medication over several years.

Many of these people have "partial epilepsy" and develop seizures that cannot be controlled after initially responding to medication, scientists have found in a new study, according to a press release from the National Institutes of Health.

Results of the study, funded by the National Institute of Neurological Disorders and Stroke (NINDS), are published in the Tuesday's issue of the journal, Neurology.

Anne T. Berg of Northern Illinois University in DeKalb, author, says that the long-term aim is to come up with early warning systems to identify and help patients who may develop drug resistant epilepsy.

Dr. Berg is part of a team directed by Susan Spencer, M.D., Yale University of New Haven in Connecticut.

Epilepsy is a disorder in which clusters of nerve cells or neurons in the brain display patterns of abnormal activity. This can cause a variety of symptoms, including convulsions.

"It is not a single disorder. It is a multitude of disorders with varying symptoms, prognoses, and implications for specific treatment," Dr. Berg says.

Partial epilepsy results from abnormal neuronal activity originating in one of the temporal lobes.

Partial epilepsy accounts for about 40 to 50 per cent of childhood epilepsy and 90 per cent of adult-onset epilepsy.

Other types of epilepsy result from abnormal neuronal activity in many parts of the brain.

The study examined 333 patients who had surgery for drug-resistant partial epilepsy. Most of them had temporal lobe epilepsy (TLE).

The idea was to identify factors that predict when seizures would go out of hand despite medications.

The researchers examined medical records and interviewed patients to determine the duration, frequency, and types of seizures.

They found that patients' average age when they had their first seizure was 14.6 years.

The average age at which they had surgery was 36.7 years. As many as 282 patients, whose historical data was available, were diagnosed with epilepsy an average of nine years before it became "intractable", a failure of medication to control seizures, the release said.

The study also found that there were times when the patients were free of seizures. About one quarter of the patients said they had had seizure-free periods of a year or more. Twenty-four patients (8.5 per cent) had seizure-free periods of five or more years.

A seizure-free period of one year or longer was most common in people who were younger than five when they were diagnosed.

The results showed that a history of seizure-free periods was common in people who later developed "intractable" seizures, the release said.

The factors influencing the amount of time before seizures became "intractable" included "age of onset, type of surgery the patients received, history of febrile (fever-related) seizures, and atrophy of the hippocampus, the region of the brain that is affected in TLE", the release said.

Age of onset has the strongest influence, Dr. Berg says. In patients whose seizures began before the age of five, it took an average of 15 years for seizures to become "intractable".

In patients whose epilepsy began during their 30s and 40s, however, seizures tended to become resistant to medication immediately or within only a few years.

Many patients had developed drug resistant epilepsy a short time after they first got it.

That many of them had long periods of seizure control was more promising as a clue to understanding epilepsy better.

It would, however, need many years more of study, before the doctors found a way of identifying patients whose epilepsy might become drug-resistant, the release said.

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