Sudoku and Seizures?

Pauline Anderson

October 22, 2015

Researchers have described a rare case of seizure brought on by completing Sudoku puzzles. The case is unique in that it involved a relatively mild injury that was targeted to a specific area of the brain, the researchers say.

The patient was a 25-year-old right-handed physical education student who had previously been in an avalanche accident, Berend Feddersen, PhD, Department of Palliative Medicine, Klinikum Innenstadt, University of Munich, Germany, told Medscape Medical News.

Buried under snow, the skier was hypoxic for 15 minutes until a friend rescued him and performed cardiopulmonary resuscitation. During the accident, he sustained a ruptured spleen and fractured ribs. He also developed involuntary myoclonic jerking of the mouth and legs, making it difficult to walk or talk.

Later, when he was working on a Sudoku puzzle, he experienced clonic seizures of the left arm.

The case report was published online October 19 in the Clinical Review & Education section of JAMA Neurology.

3-D Imagination

Sudoku puzzles involve filling in a grid so that each row of nine squares, each column of nine, and each section of nine (three squares by three within the grid) contains the numbers from one to nine in any order. Each puzzle has only one solution.

To solve the puzzles, the patient used "3-D imagination," said Dr Feddersen. "He told me that he concentrated on one point or number and then arranged other numbers around it."

Functional MRI showed that this mental imagination while completing a Sudoku led to overactivation of the right central parietal cortex.

Diffusion tensor imaging revealed loss of right centroparietal inhibitory neurons called U fibers. This damage resulted in 3-fold increased evoked potentials at the right postcentral gyrus after somatosensory stimulation of the left median nerve.

The hypoxia the patient sustained likely caused some diffuse widespread damage, as well as a regional loss of right centroparietal U fibers, which resulted in impaired inhibition, explained the authors. Functional activation of this hyperexcitable region resulted in focal epileptic seizures.

Other visual spatial tasks also triggered the seizures. "For example, when we gave him the numbers 7, 2, 1, 8 and asked him to sort them numerically to 1, 2, 7, 8, the same thing happened," said Dr Feddersen.

And it would likely also happen with use of the same mental technique to sort letters, he said. But reading, writing, or simple calculation would not elicit this reaction, he noted.

The case is extremely rare — the only one worldwide, according to Dr Feddersen — partly because the injury was so mild. "Normally, someone suffering hypoxia is more severely injured and then the brain is more damaged, so you can't produce this kind of overactivation, or you aren't damaged and you're in a healthy condition, without any injury," he said.

"It's very seldom that you get a case with damage only to this part of the brain and only to the U fibers that lead to impaired inhibition."

It might be the only region where such an overactivation can be produced. "If it was in the frontal lobe, for example, that would maybe do nothing; you wouldn't really be aware of it," said Dr Feddersen.

Understandably, the patient has stopped doing Sudoku puzzles and has been seizure free for more than 5 years. He has improved with physiotherapy but still has difficulty with speech and walking. He is now working as a journalist, Dr Feddersen said.

Dr Feddersen reported receiving speaker honoraria from UCB Pharma SA and Desitin.

JAMA Neurology. Published online October 19, 2015. Abstract

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