KEY POINTS:
SYDNEY - Brushing teeth can trigger epileptic seizures in people with damage to a small, specific spot in the brain, Australian researchers have discovered.
The breakthrough in this rare trigger will help neurologists understand how the most common triggers -- sleep and stress -- can spark fits.
"The tooth-brushing trigger is very, very unusual but now we understand what's behind it, the implications are great," said Dr Wendyl D'Souza, leader of research published in the US journal Neurology today.
The team from St Vincent's Hospital Melbourne investigated three middle-aged people who had jerking or twitching-type seizures when brushing certain areas of their mouth.
Using head scans, the researchers discovered that all three patients had a lesion in the somato-sensory part of the brain, which is close to the hand and speech motor areas.
"The rhythmic act of brushing teeth may excite an already overly excitable area of the brain," Dr D'Souza said.
"It sends an electrical signal to a part of the brain which has this lesion and causes these jerking sorts of seizures."
He said this type of epilepsy was extremely rare, with less than a dozen reports worldwide, but it had many similarities to the more common photosensitive type, which is triggered by strobe lights and moving patterns.
The specialists were able to medicate these epileptics with a specific dose which "overrides the tooth-brushing trigger" and were now investigating the significance for other triggers.
About two per cent of Australians have the condition -- one half inherited and the other sparked by a mark or lesion somewhere in the brain.
Sleeping problems and stress are the most common triggers but specialists are yet to fully understand how they work.
"By learning about one very rare trigger we can start to work out how epilepsy in general can occur and what's behind the more common triggers," Dr D'Souza said.
"If we can't cure this condition we can at least try to prevent what sets them off."
- AAP
