Tooth-brushing link to epilepsy

Some patients with epilepsy have seizures when brushing their teeth

Tooth-brushing may trigger seizures in some people with epilepsy, say Australian researchers.

The cause seems to be damage in the part of the brain dealing with hand movement and speech.

The findings are reported in Neurology after video cameras and brain scans were used to monitor three patients.

The rhythmic hand movements associated with tooth-brushing may excite a part of the brain which is already overly excitable, the researchers said.

Two of the adults assessed for the study experienced seizures when they brushed certain parts of their mouth.

The rhythmic act of brushing teeth may excite an already overly excitable area of the brain Dr Wendyl D'Souza, study leader

The husband of one of the participants reported that his wife had a seizure when brushing with either hand and she described a numb feeling in her head.

She suffered jerking of the left side of the face and arm and could not release the toothbrush if holding it in her left hand during a seizure.

After confirming by video camera that the patients were in fact suffering seizures when they brushed their teeth, the researchers used MRI scans to try to figure out what was happening in the brain.

Dr Wendyl D'Souza and colleagues at the University of Melbourne found that all three patients had lesions in the somatosensory part of the brain that deals with co-ordination of hand and mouth movements.

"The rhythmic act of brushing teeth may excite an already overly excitable area of the brain," he said.

Trigger

He explained the seizures were similar to those triggered by flashing lights and moving patterns in people with photosensitive epilepsy.

"Since tooth-brushing involves persistent rhythmic action, this may explain why this trigger is more likely to induce seizures in the somatosensory part of the brain compared with other oral stimuli, such as eating," he said.

Dr Matthew Walker, consultant in neurology at the Institute of Neurology in London, said he had patients with epilepsy who had seizures in response to reading or music.

Epilepsy triggered in this way is known as "reflex epilepsy" and occurs in about 5% of cases he said.

"Reflex epilepsies are interesting - they are rare and can be divided into simple (for example in response to flashing lights) and complex (for example, in response to a specific piece of music)."

He said that toothbrush epilepsy was likely to fall into the simple category because it was the stimulus that caused the seizure rather than complex processing such as that involved in reading or listening to music.

"In a way reflex epilepsy is interesting because you have an excitable part of the brain. I suppose the mystery is why there's so few of them.

"Why in the other 95% doesn't activating a certain part of the brain initiate a seizure," he said.