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Epilepsia. 2020 Jan;61(1):81-95. doi: 10.1111/epi.16410. Epub 2019 Dec 20.

Epileptogenicity in tuberous sclerosis complex: A stereoelectroencephalographic study.

Author information

1
National Institute of Health and Medical Research U1028/National Center for Scientific Research, Mixed Unit of Research 5292, Lyon Neuroscience Research Center, Lyon, France.
2
Department of Functional Neurology and Epileptology, Member of the ERN EpiCARE Lyon University Hospital and Lyon 1 University, Lyon, France.
3
Department of Neuroscience, Faculty of Medicine, Nursing, and Health Sciences, Central Clinical School, Monash University, Melbourne, Victoria, Australia.
4
Department of Pediatric Clinical Epileptology, Sleep Disorders, and Functional Neurology, Member of the ERN EpiCARE Lyon University Hospital, Lyon, France.
5
Epileptology Department, Public Assistance Hospitals of Marseille, National Institute of Health and Medical Research, Institute of Systems Neuroscience, Timone Hospital, Aix Marseille University, Marseille, France.
6
Neurology Department, University Hospital of Nancy, Nancy, France.
7
Department of Neurology, Grenoble-Alpes University Hospital, Grenoble Institute of Neurosciences, National Institute of Health and Medical Research U1216, Grenoble Alpes University, Grenoble, France.
8
Department of Genetics, University Hospital Center-North Hospital, Saint Etienne, France.
9
Department of Functional Neurosurgery, Member of the ERN EpiCARE Lyon University Hospital and Lyon 1 University, Lyon, France.
10
Idée Epilepsy Institute, Lyon, France.

Abstract

OBJECTIVE:

In tuberous sclerosis complex (TSC)-associated drug-resistant epilepsy, the optimal invasive electroencephalographic (EEG) and operative approach remains unclear. We examined the role of stereo-EEG in TSC and used stereo-EEG data to investigate tuber and surrounding cortex epileptogenicity.

METHODS:

We analyzed 18 patients with TSC who underwent stereo-EEG (seven adults). One hundred ten seizures were analyzed with the epileptogenicity index (EI). In 13 patients with adequate tuber sampling, five anatomical regions of interest (ROIs) were defined: dominant tuber (tuber with highest median EI), perituber cortex, secondary tuber (tuber with second highest median EI), nearby cortex (normal-appearing cortex in the same lobe as dominant tuber), and distant cortex (in other lobes). At the seizure level, epileptogenicity of ROIs was examined by comparing the highest EI recorded within each anatomical region. At the patient level, epileptogenic zone (EZ) organization was separated into focal tuber (EZ confined to dominant tuber) and complex (all other patterns).

RESULTS:

The most epileptogenic ROI was the dominant tuber, with higher EI than perituber cortex, secondary tuber, nearby cortex, and distant cortex (P < .001). A focal tuber EZ organization was identified in seven patients. This group had 80% Engel IA postsurgical outcome and distinct dominant tuber characteristics: continuous interictal discharges (IEDs; 100%), fluid-attenuated inversion recovery (FLAIR) hypointense center (86%), center-to-rim EI gradient, and stimulation-induced seizures (71%). In contrast, six patients had a complex EZ organization, characterized by nearby cortex as the most epileptogenic region and 40% Engel IA outcome. At the intratuber level, the combination of FLAIR hypointense center, continuous IEDs, and stimulation-induced seizures offered 98% specificity for a focal tuber EZ organization.

SIGNIFICANCE:

Tubers with focal EZ organization have a striking similarity to type II focal cortical dysplasia. The presence of distinct EZ organizations has significant implications for EZ hypothesis generation, invasive EEG approach, and resection strategy.

KEYWORDS:

electroclinical syndromes; epilepsy surgery; epileptogenic zone; stereo-EEG; tuberous sclerosis complex

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PMID:
31860139
DOI:
10.1111/epi.16410

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