What is the concordance between the seizure onset zone and the irritative zone? A SEEG quantified study. Issue 2 (February 2016)

• Record Type: Journal Article
• Authors: Bartolomei, Fabrice; Trébuchon, Agnes; Bonini, Francesca; Lambert, Isabelle; Gavaret, Martine; Woodman, Marmaduke; Giusiano, Bernard; Wendling, Fabrice; Bénar, Christian
• Is Part Of: Clinical neurophysiology. Volume 127:Issue 2(2016:Feb.)
• Page Start: 1157
• Page End: 1162
• Publication Date: 2016-02
• Subjects: SEEG -- Spikes -- Focal epilepsy -- Seizures -- Focal cortical dysplasia; Neurophysiology -- Periodicals; Electroencephalography -- Periodicals; Electromyography -- Periodicals; Neurology -- Periodicals; 612.8
• DOI: 10.1016/j.clinph.2015.10.029
• Languages: English
• ISSNs: 1388-2457

Abstract

Highlights: A total of 539 brain regions from 32 patients were quantified both for spiking frequency (SI) and for seizure initiation (EI). A good concordance between regions with maximal EI and regions with maximal SI was found in 18/32 patients (56%). The proportion of patients with good concordance was ∼75% in focal cortical dysplasia (FCD) group and only 33% in the non FCD group. Abstract: Objective: In focal epilepsies, the accurate delineation of the epileptogenic network is a fundamental step before surgery. For years, the relationship between the interictal epileptic spikes (defining the "irritative zone", IZ) and the sites of seizure initiation (SOZ) has been a matter of debate. Methods: Our goal was to investigate from intracerebral recordings (stereoelectroencephalography, SEEG) the distribution of interictal epileptic spikes (based on a spike frequency index, SI) and the topography of the SOZ (based on the Epileptogenicity Index, EI) in patients having focal neocortical epilepsies. Thirty-one patients were studied. A total of 539 brain regions were quantified in term of both spike generation (SI) and seizure initiation (EI). Results: We found a 56% (18/32) rate of agreement between maximal EI and maximal SI values. When considering separately patients with focal cortical dysplasia (FCD), the proportion of patients with good concordance was ∼75% (15/20), whereas it was only 33% (4/12) in the non FCD group. Conclusions: Our results show that a significant part of patients have some dissociation between regions showing pronounced spiking activity and those showing high epileptogenicity. e is clinically important. Significance: For patients with these dissociations, other markers than spiking frequency remain to be investigated. In the FCD group, the good concordance between SI and EI confirms that the mapping of the irritative zone is clinically important.