Abstracts

To elucidate the mechanism of myoclonic jerk elicited by cognitive activity like chess playing.
[italic]Subject [/italic]: A right handed Caucasian white man without a personal or family history of epilepsy, with a normal neurological examination and a normal CT scan, started at age 16 to present with a typical juvenile myoclonic epilepsy, well controlled by Valproate. Valproate was stopped at age 28 and myoclonias reappeared, aggravated by playing chess, in particular when he had to plan his strategy, when he had to choose between two alternatives.
[italic]EEG recording : [/italic]Baseline standard EEG before Valproate treatment showed bilateral, diffuse spike wave and polyspike wave discharges. No photoconvulsive response was observed. While playing chess, numerous spike wave complexes were recorded, either without clinical manifestations or with myoclonias concerning mainly the proximal part of the upper limbs, asymmetrically. Valproate monotherapy was restarted and myoclonias stopped. Informed consent was obtained and two EEG polygraphies were then carried out after 36 and 48 hours without Valproate respectively. During one EEG polygraphy the patient experienced myoclonias while playing chess and manipulating Kohs cubes on neuropsychological testing [ndash] accompanied by spike and wave discharges on the EEG - on test and retest. A back-averaging triggered at the onset of the myoclonic jerks was performed off line.
EEG Recordings with back averaging of myoclonias showed a resulting spike under electrodes C3 and C4 before myoclonias of the right upper limb, under electrodes electrode C3 and C4 before myoclonias of left upper limb and under electrode C4 (spike on the opposite hemisphere partially hidden by the noise) before myoclonias of both upper limbs. [ndash] This is in line with Rey[rsquo]s et al. (1996) EEG findings, showing at the time of myoclonias a spike-wave complex localized in the left rolandic area (phase reversal under the electrode C3 and Cz). In Matsuoka[rsquo]s study (2000) the spike-wave complexes predominated over the central electrode site both with and without lateral asymmetry
Neuropsychological tasks in combination with purposeful motor action (manipulation of Kohs cubes, placing a chess figure) where in our case the most powerful trigger for spike and spike-wave discharges, localized by back averaging to the central region (C3, C4).
REFERENCES :
Matsuoka H, Takahashi T., Sasaka M. et al. Neuropsychological EEG activation in patients with epilepsy. Brain 2000; 123: 318 [ndash] 330
Rey M., Pelletier J., Dalecky A. et al. Epilepsie réflexe avec crises induites par le calcul mental, le jeu d[rsquo]échecs et le jeu du scrabble. Rev Neurol ; 1996, 152 : 116-20