EEG activation and mathematical calculation.

Activation of epileptic seizures of epileptiform EEG abnormalities by specific types of intellectual activity has been documented only rarely. Despite infrequent occurrence, these cases are of interest in the study of epileptic mechanisms and cerebral integrative systems. We describe a 67-year-old woman with long-standing seizures who consistently activated right frontal spike discharges in the EEG when she attempted to perform mental arithmetic. The activating effect was not precisely related to the difficulty of the mathematical problem, nor to alerting or concentrated attention. No EEG activation resulted from reading, writing, reciting, revisualizing, or recalling numbers or other symbols.