The effect of cognitive tasks during electroencephalography recording in patients with reflex seizures

Abstract

Objective We aimed to research the effect of cognitive tasks on interictal electroencephalographic (EEG) recordings in patients with epilepsy who had reported cognitive functions as a seizure trigger. We investigated the usefulness of cognitive function tasks as a method of activation in standard-awake EEG in daily practice. Methods Standard-awake EEG with cognitive activation tasks consisting of verbal and arithmetic tasks was administered to 35 (11.7%) of 299 patients with epilepsy who reported cognitive functions as a reflex seizure stimulus. During the background EEG, patients were divided into 2 groups: group 1 (17 patients) with interictal epileptiform discharges (IEDs), and group 2 (18 patients) without IEDs. Results IEDs were activated by a verbal task in 11.4% of patients and by an arithmetic task in 5.7%. All activated patients were in the genetic/idiopathic generalized epilepsy (IGE) group. In group 1, IEDs were activated in 17.6% of patients by a verbal task and in 5.9% by an arithmetic task. Both verbal and arithmetic tasks showed provocative effect in one patient in group 2. Hyperventilation was the most effective activation method, followed by cognitive activation tasks and photic stimulation. The provocative effects of verbal and arithmetic tasks were comparable to those of photic stimulation. Conclusion Cognitive tasks might activate the IEDs in patients reporting cognitive functions as a seizure trigger, particularly in IGE. Brief and standardized cognitive activation tasks should be developed and applied as a method of activation during standard-awake EEG recordings to increase the diagnostic yield of EEG.