COMPARATIVE ANALYSIS OF INTERICTAL ELECTROENCEPHALOGRAPHIC FEATURES IN GENERALIZED AND STRUCTURAL FOCAL EPILEPSY
Keywords:
epilepsy, generalized epilepsy, structural focal epilepsy, electroencephalography, interictal EEG, epileptiform activity, focal discharges, generalized dischargesAbstract
The aim of this study was to comparatively evaluate interictal electroencephalographic features in patients with generalized and structural focal epilepsy and to determine their association with epilepsy etiology. A total of 83 patients with a confirmed diagnosis of epilepsy were included, comprising 46 patients with generalized epilepsy and 37 patients with structural focal epilepsy. Interictal EEG recordings obtained during wakefulness and available in the patients’ medical records were analyzed retrospectively. The assessment included background bioelectrical activity, the presence of interictal epileptiform activity, its morphological pattern, and frequency. In patients with generalized epilepsy, background EEG activity was predominantly preserved, while generalized epileptiform discharges were more commonly observed. In the structural focal epilepsy group, focal background slowing and focal epileptiform activity were more frequent. A statistically significant association was found between EEG background activity and epilepsy group χ²=83.00; p<0.001. Interictal epileptiform activity was detected in 42 of 46 patients with generalized epilepsy 91.3% and in all 37 patients with structural focal epilepsy 100%; the between-group difference was not statistically significant according to Fisher’s exact test p=0.125. Among patients with interictal epileptiform activity, its morphological type showed a strong association with the epilepsy group χ²=79.00; p<0.001.These findings suggest that interpretation of interictal EEG should not be limited to the presence of epileptiform activity alone. Combined assessment of the morphological pattern and distribution of epileptiform discharges together with background EEG activity may provide clinically useful information for the differential diagnosis of generalized and structural focal epilepsy.
References
Fisher R.S., Cross J.H., D’Souza C., French J.A., Haut S.R., Higurashi N., et al. Operational classification of seizure types by the International League Against Epilepsy: 2017 update. Epilepsia. 2017;58(4):522–530.
Scheffer I.E., Berkovic S., Capovilla G., et al. ILAE classification of the epilepsies. Epilepsia. 2017;58(4):512–521.
Beniczky S., Trinka E., Wirrell E., et al. Updated classification of epileptic seizures: Position paper of the International League Against Epilepsy. Epilepsia. 2025;66(6):1804–1823. DOI: 10.1111/epi.18338.
Thijs R.D., Surges R., O’Brien T.J., Sander J.W. Epilepsy in adults. Lancet. 2019;393(10172):689–701.
Bastos F., Cross J.H. Epilepsy. Handbook of Clinical Neurology. 2020;174:137–158.
Nilo A., Gelisse P., Crespel A. Genetic generalized epilepsies: Not so good as that. Revue Neurologique (Paris). 2020;176(6):427–438.
Pimentel J., Varanda S., Guimarães P., Lopes da Silva F. Idiopathic generalised epilepsies of adult onset. Epileptic Disorders. 2018;20(3):169–177.
Huguenard J. Spikes, bursts, and synchrony in generalized absence epilepsy. Epilepsy Currents. 2019;19(2):105–111.
Lindquist B.E., Timbie C., Voskobiynyk Y., Paz J.T. Thalamocortical circuits in generalized epilepsy. Neurobiology of Disease. 2023;181:106094.
Peng S.J., Hsin Y.L. Altered structural and functional thalamocortical networks in seizures. NeuroImage: Clinical. 2016;13:55–61.
Morozova E.A., Gusyakov F.I. Faktory evolyutsii geneticheskikh generalizovannykh epilepsiy. Epilepsiya i paroksizmalnye sostoyaniya. 2019;11(2):186–193.
Evstigneev V.V., Malashko E.A., Boksha-Kisten O.V. Neyrovizualizatsionnye klastery generalizatsii pristupov pri strukturnoy visochnoy epilepsii. Meditsinskie novosti. 2022;1(328):33–38.
