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Possible new treatment for absence seizures discovered

8 July, 2005

A new treatment
for absence seizures has been tested which, it is hoped, may help
children with epilepsy, according to research published in the Journal of Neurophysiology.

The researchers, from Wake Forest University School of Medicine, also hope that the treatment may have fewer side effects than current therapies.

Through
studies in animals, the researchers learned more about the activity in
the brain during absence seizures and tested a drug that revealed a
potential new target for blocking seizures before they spread.

One
theory is that, in a seizure, an abnormal electrical discharge
originates in the cerebral cortex, the part of the brain that controls
thinking and feeling, and travels to the thalamus, a part of the brain
that controls consciousness and certain brain rhythms. The abnormal
discharges that result may then spread to other parts of the brain.

Georgia Alexander, co-author of this new study, commented:

'Many
current therapies act on the entire nervous system and can have such
side effects as sleep disruptions, dizziness and increased risk of
developmental side effects. Because this treatment blocks the pathway
that may cause the spread of seizures, it could be more effective and
have fewer side effects.'

'We
know that the cortex communicates with the thalamus continuously, and
current theories suggest that when the ‘conversation' gets too loud,
seizures can occur. We wanted to see if there was a way to calm the
dialogue.'

It
was already known that cells in the thalamus communicate with cells in
the cortex by releasing the neurotransmitter glutamate. The glutamate
travels across the gap which creates a pathway for cell-to-cell
communication. However, the researchers were the first to show that in
addition to releasing glutamate, thalamus cells also have a special
type of glutamate receptor that slows the release of glutamate when
there is high-intensity brain activity associated with a seizure.

The
report's authors hypothesise that in people with epilepsy, the
glutamate receptors may not function well or that glutamate production
may be abnormal. A treatment that targets the receptors has the
potential to block the pathway involved in seizures.

Dr William Bell, a specialist in epilepsy, also at Wake Forest University Baptist Medical Center, commented:

"If this research leads to drugs that can target these newly discovered receptors, it would be an important advance in therapy."