Seizure-onset patterns in focal cortical dysplasia and neurodevelopmental tumors: Relationship with surgical prognosis and neuropathologic subtypes

authors

  • Lagarde Stanislas
  • Bonini Francesca
  • Mcgonigal Aileen
  • Chauvel Patrick
  • Gavaret Martine
  • Scavarda Didier
  • Carron Romain
  • Régis Jean
  • Aubert Sandrine
  • Villeneuve Nathalie
  • Giusiano Bernard
  • Figarella-Branger Dominique
  • Trébuchon Agnès
  • Bartolomei Fabrice

keywords

  • Stereoelectroencephalography
  • Malformation of cortical development
  • Neurodevelopmental tumors
  • Focal cortical dysplasia
  • Epilepsy
  • Epileptogenic zone
  • Seizure onset
  • Epilepsy surgery

document type

ART

abstract

Objectives: The study of intracerebral electroencephalography (EEG) seizure-onset patterns is crucial to accurately define the epileptogenic zone and guide successful surgical resection. It also raises important pathophysiologic issues concerning mechanisms of seizure generation. Until now, several seizure-onset patterns have been described using distinct recording methods (subdural, depth electrode), mostly in temporal lobe epilepsies or with heterogeneous neocortical lesions. Methods: We analyzed data from a cohort of 53 consecutive patients explored by stereoelectroencephalography (SEEG) and with pathologically confirmed malforma-tion of cortical development (MCD; including focal cortical dysplasia [FCD] and neu-rodevelopmental tumors [NDTs]). Results: We identified six seizure-onset patterns using visual and time-frequency analysis: low-voltage fast activity (LVFA); preictal spiking followed by LVFA; burst of poly-spikes followed by LVFA; slow wave/DC shift followed by LVFA; theta/alpha sharp waves; and rhythmic spikes/spike-waves. We found a high prevalence of patterns that included LVFA (83%), indicating nevertheless that LVFA is not a constant characteristic of seizure onset. An association between seizure-onset patterns and histologic types was found (p = 001). The more prevalent patterns were as follows: (1) in FCD type I LVFA (23.1%) and slow wave/baseline shift followed by LVFA (15.4%); (2) in FCD type II burst of polyspikes followed by LVFA (31%), LVFA (27.6%), and preictal spiking followed by LVFA (27.6%); (3) in NDT, LVFA (54.5%). We found that a seizure-onset pattern that included LVFA was associated with favorable postsurgical outcome, but the completeness of the EZ resection was the sole independent predictive variable. Significance: Six different seizure-onset patterns can be described in FCD and NDT. Better postsurgical outcome is associated with patterns that incorporate LVFA.

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