Neuropediatrics 2011; 42 - P013
DOI: 10.1055/s-0031-1273985

Invasive pre-surgical epilepsy diagnostic in children: The advantage of depth electrodes combined with subdural grids in the evaluation of focal cortical dysplastic lesions

T Pieper 1, M Kudernatsch 2, S Kessler-Uberti 1, H Eitel 1, B Pascher 1, I Blümcke 3, PA Winkler 2, M Staudt 1, H Holthausen 1
  • 1Schön Klinik Vogtareuth, Epilepsie Zentrum für Kinder und Jugendliche, Vogtareuth, Germany
  • 2Schön Klinik Vogtareuth, Klinik für Neurochirurgie und Epilepsiechirurgie, Vogtareuth, Germany
  • 3Institut für Neuropathologie, Universitätsklinik Erlangen, Erlangen, Germany

Objective: Patients suffering from intractable focal epilepsy due to focal cortical dysplasia type II (FCD II) acc. Palmini & Lüders and tubers are often considered suitable for surgery. Complete removal of the dysplastic lesion and the ictal onset zone are accepted as crucial for a favorable postoperative outcome. A significant portion of the lesions extends into juxtacortical areas and is insufficiently recorded by superficial subdural grids. Depth electrodes (DE) were implanted into the lesions to achieve improved definition of the epileptogenic cortex, in addition to subdural grid electrodes (SGE).

Methods: Out of 311 patients, who underwent epilepsy surgery between 09/1998 and 11/2010at the Epilepsy Center for Children and Adolescents, Schoen Klinik Vogtareuth, retrospective data of 11 patients (f: 3, m: 8) after invasive evaluation with DE and SGE are presented. DE and SGE were provided by Ad-Tech Corp. Trajectories were planned using iPlan Cranial 2.6 software and DE were implanted using the VarioGuideTM system (BrainLAB AG). Electrodes were localised by post-implantation cMRI and cCT. Video-EEG monitoring was carried out for 10 days.

Results: Etiology: FCD II in 8 and tuberous sclerosis in 3 patients. Age at: onset of epilepsy: 3.25yrs (0.1–11), surgery: 9.3yrs (3–13), postoperative follow-up 8.6 mth (3.7–15.4). Localization of epilepsy: frontal: 9, centro-parietal: 1, temporo-parieto-occipital: 1 patient. Post-surgical seizure outcome: seizure-free: 6, >90% seizure reduction: 1, >50% seizure reduction: 2, unchanged: 1 patient. DE implantation hit all target areas; complications due to the DE were not observed. Interictal epileptiform abnormalities were recorded: DE only: 2, DE & SDG: 6, SDG only: 3 patients, Ictal findings: DE only: 3, DE & SDG: 5, SDG only: 2 patients.

Conclusion: Implantation of DE combined with SGE is safe and feasible. With the help of DE, an improved spatial and temporal analysis of interictal and ictal findings is achieved. By complementing brain convexity data, DE add valuable information required for appropriate resection planning.