Study Of The Dipole Source Localization For Pre-operative Localization Of The Epileptogenic Discharges In Patients With Intractable Epilepsy

Objective: In order to evaluate the effectiveness of presurgical dipole analysis of interictal and seizure onset phase spikes as a non-invasive technique for the determination of epileptogenic area, we compared the results of this method with those of electrocorticography (ECoG) localization and MRI.Methods: 25 consecutive patients who had VEM for presurgical evaluation of medically refractorypartial epilepsy were screened. All patients had focal interictal spikes which recorded by the Oxford system. 16 are temporal lobe epilepsy, 7 are occipital lobe epilepsy, and 2 are unclassified. Interictal and seizure onset phase spikes were analysised by BESA software, which provided many kinds of analysis methods, such as Sequential dipole fitting,initial fitting of the spike peak,regional source(4 of them lost the epileptic seizures's EEG in the observation). Different methods of dipole source localization were compared to explore the relationship of the onset region and seizure region. All samples were examined in histology and MRI results were considered to investigate the factors influencing prognosis.Results: The difference in dipole loctions between the individual and grand-averaged data sets was not statistically significant. The method of dipole source localization was better than routine EEG in space-time discrimination. The results using single spike or averaged spike analysis methods had no obviously difference. However, averaged spike analysis was the more effective methods to obtain the background rhythmic. In addition, MRI results indicated the correlation of hippocampus sclerosis and epileptogenic lesin, which confirmed by post operation pathology.Conclusion: The analysis to EEG should be on the basis of neuroanatomy and electrophysiology knowledge. Dipole source localization method was better than routine EEG in space-time discrimination. However, because of the uncertainty ofprimitive EEG data, the explanation to the results of dipole source localization should refer to other examinations and clinical manifestation..