The EEG supports the clinical diagnosis of epilepsy when interictal epileptiform discharges (IEDs) are present. Use of the term "seizures activity" does not represent ictal activity but as in our case interictal discharges. The distribution of IEDs helps to classify the epileptogenic zone. Discharges localized to the anterior and mid-temporal electrode derivations (as above) suggest one of the temporal lobe epilepsies. The intra-discharge frequency of generalized spike-and-slow waves (GSW) carries clinical ramifications with < 3 Hz a surrogate for encephalopathy and those > 3 Hz of presumed genetic origin. Epilepsy syndromes may be suggested by "faster" (> 3 Hz) frequencies as in JME where frequencies of up to 5 Hz are seen. High clinical seizure frequencies have previously been associated with a greater likelihood of detecting IEDs. However the relationship between IED frequency and clinical epilepsy severity is incongruent (1). Our patient had no impairment despite the high frequency of the IEDs and probably demonstrated the greater number of IEDs on EEG due to the recent seizure which has been found to have a higher incidence when EEG is obtained in the immediate post-ictal time period (2).
© 2013 Epilepsy.com. All rights reserved.