Comparing the validity of EEG in epileptic patients with and without activation methods

Electroencephalogram (EEG) is the most commonly used main preclinical diagnostic method for epilepsy. However this method has high false negative results (up to 40% in some cases). Therefore different activity methods have been proposed to reduce these false negative results. In this study we aimed to compare the EEG in epileptic patients with ordinary state and different models of activation. In a clinical study, 114 epileptic patients with normal EEG out of 500 epileptic patients referred to neurology clinic of Hajar hospital in Shahrekord were selected and divided into five equal groups as fallows: control group (without any activation), hyper ventilation (HV), photic (light) stimulation (PS), sleep and sleep deprivation. Then new EEGs were obtained from the patients. Data were analyzed using Chi-square (χ2) and Fisher test. Patients with normal EEGs were selected for EEG activation. Fishers test showed that EEG activation was effective in finding positive EEGs (P<0.01). The χ2 test also demonstrated that the amount of positive EEG had no significant difference among the activation groups (P>0.05). Furthermore our results showed that application of different models of EEG activation reduced the false negative EEGs in tonic – colonic seizure (3.3%), absence (9.5%) and other types of epilepsy (12.4%), respectively. Different models of EEG activation reduce false negative EEGs and increase the validity for diagnosis of epileptic patients. The best results were obtained with sleep and photic (light) stimulation that had lower positive results among all types of activation methods.