Abstracts

Rationale: To describe a focal reflex epilepsy due to diffuse brain anoxia with seizures induced by cognitive tasks. Methods: We performed EEG-video-monitoring in a 25 year old sport student who was buried by an avalanche resulting in hypoxia for ca. 15 minutes. He suffered a polytrauma and developed Lance-Adams-syndrome and focal motor epileptic seizures. We performed several cognitive tasks (variations of SUDOKU puzzles, mathematical and visual spatial imagination with letters and numbers) in order to elicit epileptic seizures during EEG-video-monitoring. High resolution 3T-MRI, diffusion tensor imaging (DTI), ictal and interictal single photon emission computer tomography (SPECT), and somatosensory evoked potentials (SEP) of the median nerve were performed. Results: Despite the fact that his seizure were well controlled with a combination of 3g levetiracetam /d, 1,5g valproic acid /d and 13,6g piracetam /d, SUDOKU puzzles consistently induced clonic seizures of the left arm which would generalize secondarily when he would continue to find the correct solution. Ictal EEG showed right centro-parietal seizure pattern, which ceased immediately after SUDOKU was discontinued. The SUDOKU task was solved by the patient using a visual spatial approach. The SUDOKU as well as other visual spatial tasks like sorting random numbers in an ascending order consistently elicited clonic seizures of the left arm. MRI including DTI showed no pathological findings. Subtraction of ictal and interictal SPECT revealed hyperperfusion of the posterior gyrus cinguli. Left sided stimulation of the median nerve revealed increased right hemispheric SEP amplitude indicating decreased cortical inhibition over this hemisphere (amplitude left median nerve SEP 6,7uV compared to right median nerve SEP 2,7uV). Conclusions: Diffuse brain anoxia may cause focal reflex epilepsy induced by cognitive tasks. This may be related to focal damage of U-fibers resulting in reduced cortical inhibition in the affected hemisphere.