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September2004 Vol.41 Issue:        3       (Supp.) Table of Contents
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Dipole Localization, MRI Integration VS Visualized Digital EEG in Detection of Epileptogenic Foci

Obsis Madkour¹, Hanan Hosny²


Departments of Neurology¹ and Clinical Neurophysiology², Cairo University


The combination of the anatomical information from the MRI, visualized digital EEG and dipole position and orientation helps the physician in the diagnosis of epileptic focus location. The aim of our work is to study the pathophysiology of epileptiform EEG activity by providing a simplified way for the analysis of routine clinical EEG data using dipole source localization. Patients &Methods: Thirty-seven child with an active epileptiform EEG activity have been studied. The analysis consisted of studying the EEG data using the 10-20 international system of electrode placement. EEG activity was recorded for 15 to 20 min with a 32-channel, digital EEG machine with a common average reference montage. The recorded epileptiform discharges were identified by visual inspection of the EEG in search of interictal spikes or sharp waves. The EEG  data were then analysed using  the eemagine analysis studies, i.e., reading the EEG, running spike detection and computing dipoles in relation with the underlying anatomy..For all patients, the dipole was projected onto the MRI. MRI provided the anatomical structure underlying these areas. Results: Dipole source analysis confirmed the hemispheric localization side (i.e., left or right sided) detected by visual inspection in 22 cases (59.4%), corresponded exactly to the same epileptogenic lobe in 11 cases (29.7%). The site of maximum negativity detected by automatic spike detection predicted dipolar source in 14 (37.8%) cases, while automated detection of lateralization by digitally analysing the background activity data could predict dipolar source in only 14 (37.8%) cases. Conclusion: Careful analysis of the onset of interictal spikes is mandatory and localization restricted to the spike peak may fail or merely reveal propagated sources.

(Egypt J. Neurol. Psychiat. Neurosurg., 2004, 41 (3) suppl.: 881-894).


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