Lutgart Goossens

Dipole modelling and intracranial EEG recording: Correlation between dipole and ictal onset zone.

SummaryThis study includes 11 patients (3 males, 8 females) with mean age of 29 years (range: 15–42 years) who underwent a presurgical evaluation for refractory complex partial seizures (CPS). In all patients, neuroimaging (1.5 T optimum-MR) demonstrated intracranial structural abnormalities (space-occupying: n = 2; atrophic: n = 8; dysplastic: n = 1) and video-EEG monitoring showed CPS. Because of discrepancies in the non-invasive examinations, all underwent additional intracranial EEG monitoring. After tailored resective procedures, all but one patient became seizure free. Mean follow-up was 30 months (range: 12–52 months). Results of intracranial EEG recording were compared with spatiotemporal dipole mapping of interictal and ictal epileptic discharges. Interictal dipole modelling revealed two distinct dipole patterns. Patients with lesions located in the medial temporal lobe uniformly presented a combined dipole that consisted of a radial and a tangential component with a high degree of elevation relative to the axial plane. Patients with extrahippocampal lesions had a less stable dipole with a predominant radial component. Dipole modelling of early ictal discharges revealed a striking correspondence with the interictal findings in individual patients. Elevation of ictal dipoles was always congruent with localisation based on intracranial EEG recordings. Interictal and ictal dipole mapping of medial temporal lobe sources may limit the number of surgical candidates for refractory CPS that need intracranial EEG recording. Whether ictal dipole modelling can be equally useful in extratemporal epilepsy remains to be proven.

LP6: Ictal tachycardia in childhood epilepsy

Results: Out of all examined patients with epilepsy and a specific comorbid disease, 916 (56.4%) patients have diffuse changes in the background activity, 32 (2%) patients have generalized paroxysmal activity, 157 (9.6%) patients have disorganized background activity with generalized paroxysmal activity, 591 (32%) of the patients have focal activity. There is a dependency between the EEG changes of some most often encountered somatic and neurological diseases. Conclusions: The presence of comorbid diseases relates to a higher risk for aggravating the condition of the patient, increasing the EEG changes, a presence of interdependence between the separate diseases, as well as between their treatment.