Prognostic value of intracranial seizure onset patterns for surgical outcome of the treatment of epilepsy

Diego Jimenez Jimenez, Ramesh Nekkare, Lorena Flores, Katerina Chatzidimou, Istvan Bodi, Mrinalini Honavar, Nandini Mullatti, Robert D C Elwes, Richard P. Selway, Antonio Valentín, Gonzalo Alarcón*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)
281 Downloads (Pure)

Abstract

Objective
To investigate if intracranial EEG patterns at seizure onset can predict surgical outcome.

Methods
Ictal onset patterns from intracranial EEG were analysed in 373 electro-clinical seizures and subclinical seizures from 69 patients. Seizure onset patterns were classified as: (a) Diffuse electrodecremental (DEE); (b) Focal fast activity (FA); (c) Simultaneous onset of fast activity and diffuse electrodecremental event (FA-DEE); (d) Spikes; (e) Spike-wave activity; (f) Sharp waves; (g) Alpha activity; (h) Delta activity. Presence of preceding epileptiform discharge (PED) was also studied. Engel and ILAE surgical outcome scales were used.

Results
The mean follow-up period was 42.1 months (SD = 30.1). Fast activity was the most common seizure onset pattern seen (33%), followed by (FA-DEE) (20%), DEE (19%), spike-wave activity (12%), sharp-waves (6%), alpha activity (6%), delta activity (3%) and spikes (1%). Preceding epileptiform discharges were present in 75% of patients. FA was associated with favourable outcome (p = 0.0083) whereas DEE was associated with poor outcome (p = 0.0025). A widespread PED was not associated with poor outcome (p = 0.9559). There was no clear association between seizure onset pattern and specific pathology, except possibly between sharp/spike waves and mesial temporal sclerosis.

Conclusions
FA activity is associated with favourable outcome. DEE at onset was associated with poor surgical outcome. Widespread/bilateral PEDs were not associated with poor or good outcome.

Significance
FA appears to be the best marker for the epileptogenic zone. Surgery should be contemplated with caution if DEE is the first ictal change. However, a widespread/bilateral PED at onset is common and should not discourage surgery.
Original languageEnglish
Pages (from-to)257-267
Number of pages11
JournalClinical Neurophysiology
Volume126
Issue number2
Early online date23 Jun 2014
DOIs
Publication statusPublished - Feb 2015

Keywords

  • Epilepsy surgery
  • Intracranial EEG
  • Invasive recordings
  • Seizure onset
  • Surgical outcome

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