Neuropsychological EEG activation in patients with epilepsy

Abstract

To examine the effects of higher mental activity on the EEG, 480 Japanese patients with different types of epilepsy were subjected to potentially provocative cognitive tasking, termed `neuropsychological EEG activation' (NPA), during standard EEG recordings. NPA tasks consisted of reading, speaking, writing, written arithmetic calculation, mental arithmetic calculation and spatial construction. The NPA tasks provoked epileptic discharges in 38 patients (7.9%) and were accompanied by myoclonic seizures in 15 patients, absence seizures in eight and simple partial seizures in one. Among the cognitive tasks, mental activities mainly associated with use of the hands, i.e. writing (68.4%), written calculation (55.3%) and spatial conction (63.2%), provoked the most discharges, followed by mental calculation (7.9%) and reading (5.3%). Detailed examination of the precipitating events revealed action-programming type activities to be the most crucial in 32 out of the 38 patients (84.2%), followed by thinking type activities in four patients (10.5%). Regarding the classification of epilepsies proposed by the International League Against Epilepsy, seizure-precipitating mental activities in our series were almost exclusively (in 36 out of the 38 patients) related to idiopathic generalized epilepsies (IGEs) including juvenile myoclonic epilepsy, juvenile absence epilepsy, grand mal epilepsy on awakening and childhood absence epilepsy, and were rarely (in only two out of the 38 patients) related to temporal lobe epilepsy. In our IGE patients, the provocative effects of NPA were related to myoclonic seizures rather than absence or generalized tonic–clonic seizures. These results suggest that NPA is a useful tool for examining the relationship between cognitive function and epileptic seizures, and that the IGE patients with myoclonic seizures are vulnerable to higher mental activities requiring action-programming or thinking.