Visual and semiautomated evaluation of epileptogenicity in focal cortical dysplasias — An intracranial EEG study

Abstract Introduction The aim of the study was the evaluation of the added value of depth to subdural electrodes in delineating epileptogenicity of focal cortical dysplasias (FCDs) and to test the Epileptogenicity Index (EI) in this setting. Material and methods Fifteen patients with FCD underwent i...

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Bibliographic Details
Published in:Epilepsy & behavior 2016-05, Vol.58, p.69-75
Main Authors: Gollwitzer, Stephanie, Valente, Ivan, Rodionov, Roman, Scott, Catherine, Ritter, Laura Mantoan, Wehner, Tim, Hamer, Hajo M, Bartolomei, Fabrice, Diehl, Beate
Format: Article
Language:English
Subjects:
Adult
Cohort Studies
Electrocorticography - methods
Electrodes, Implanted
Electroencephalography - methods
Epilepsy surgery
Epileptogenicity Index
Female
Focal epilepsy
Humans
Life Sciences
Magnetic Resonance Imaging - methods
Male
Malformations of Cortical Development - diagnostic imaging
Malformations of Cortical Development - physiopathology
Middle Aged
Neurology
Neurons and Cognition
Retrospective Studies
SEEG
Seizures - diagnostic imaging
Seizures - physiopathology
Subdural Space - physiopathology
Telemetry - methods
Treatment Outcome
Young Adult
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Summary:Abstract Introduction The aim of the study was the evaluation of the added value of depth to subdural electrodes in delineating epileptogenicity of focal cortical dysplasias (FCDs) and to test the Epileptogenicity Index (EI) in this setting. Material and methods Fifteen patients with FCD underwent iEEG with subdural and depth electrodes. Visual/EI analysis was performed in up to three habitual seizures per patient. Results Visual analysis: Grid onset seizures (n = 10) started in electrodes overlying the lesion in 7 and remote from it in 3 cases. Depth onset seizures (n = 7) affected only intralesional contacts in 4, intra- and extralesional in 2, and exclusively extralesional in 1 patient. Seizures started in depth and grid contacts simultaneously in 2 cases. EI analysis: The EI completely confirmed visual localization of seizure onset in 8 cases and depicted ictal onset-time accurately in 13. Beta/gamma ictal patterns were most reliably captured. Impact on surgical decision: Resection outline differed from MRI lesion in 7 patients based on grid and in three based on depth electrode information. Discussion In FCD, seizures can be generated within gyral/deep tissue appearing normal on imaging. Conclusion Investigating FCD with subdural and depth electrodes is efficient to outline the seizure onset zone. The EI is a helpful additional tool to quantify epileptogenicity. Specific ictal patterns are prerequisite for reliable results.
ISSN:1525-5050
1525-5069
DOI:10.1016/j.yebeh.2016.03.009