Contralateral Interictal EEG Abnormalities in Hemimegalencephaly : Prognostic Value on Developmental and Epileptic Outcome Following Hemispherotomy
Abstract number :
2.005
Submission category :
3. Neurophysiology / 3A. Video EEG Epilepsy-Monitoring
Year :
2023
Submission ID :
629
Source :
www.aesnet.org
Presentation date :
12/3/2023 12:00:00 AM
Published date :
Authors :
Presenting Author: Emmanuel Raffo, MD, PhD – Rothschild Foundation Hospital, EpiCARE member, 75019, Paris, France
Justine Miguel, MD – Hôpital d'Enfants, CHRU de Nancy, CRMR épilepsies rares, Nancy, France; Sarah Rosenberg, MD, PhD – Rothschild Foundation Hospital, EpiCARE member, 75019, Paris, France; Christine Bulteau, MD, PhD – Rothschild Foundation Hospital, EpiCARE member, 75019, Paris, France; Marie-Thérèse Dangles, MD – Rothschild Foundation Hospital, EpiCARE member, 75019, Paris, France; Sarah Ferrand-Sorbets, MD – Rothschild Foundation Hospital, EpiCARE member, 75019, Paris, France; Georg Dorfmüller, MD – Rothschild Foundation Hospital, EpiCARE member, 75019, Paris, France; Stéphanie Baulac, PhD – Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS; Mathilde Chipaux, MD, PhD – Rothschild Foundation Hospital, EpiCARE member, 75019, Paris, France
Rationale:
Hemimegalencephaly is a rare congenital hemispheric malformation that is most often responsible for motor and cognitive deficits as well as very early onset drug resistant epilepsy. Epilepsy per se dramatically worsens neurodevelopmental prognosis. The potential benefits of hemispherotomy have already been demonstrated in patients with drug resistant epilepsy associated with hemispheric pathology. In patients with hemimegalencephaly, the recognition of contralateral interictal EEG discharges may present a challenge to presurgical assessment. The aim of our study is to determine prognostic factors prior to hemispherotomy for drug-resistant epilepsy in children with hemimegalencephaly.
Methods:
This retrospective monocentric study considered pediatric patients who underwent hemispherotomy between 2010 and 2020 for drug resistant epilepsy linked to hemimegalencephaly. Diagnosis was based on MRI and anatomopathological data. Patients with bilateral onset seizures were contraindicated for surgery. We studied interictal presurgical EEG features such as background maturation and interictal discharges. Simple logistic regression analysis was used to correlate these data with neuropsychological, adaptive behavior and epileptic outcome.
Results:
Eighteen patients with early onset epilepsy (day 1 to 12m) were included. Median age at surgery was 11mo [3mo to 15yrs]. At presurgical assessment, all 18 patients experienced focal or unilateral multifocal seizures with associated epileptic spasms in 6 (33.5%). Contralateral Interictal Background EEG activity was well organized in only half of the cases. Bilateral interictal discharges were common (n=14; 78%), moreover independent asynchronous spikes were found in contralateral hemisphere in five children (28%). Epilepsy features matched a classified syndrome in 11/18 patients: Developmental and Epileptic Encephalopathy (n=6; 33,5%), Infantile Epileptic Spasms (n=2; 11%), Lennox-Gastaut (n=3; 16,5%). Etiology was linked to a neurocutaneous syndrome in six patients (33,5%) including one tuberous sclerosis (5.5%). Genetic testing on brain samples was performed in 17 patients. A mutation was found in 11/17 patients (76%), all of them in the mTOR pathway: 10 somatic mutations (PIK3CA n=4, MTOR n=3, NPRL3 n=1, AKT3 n=1, RHEB n=1), and 1 germline mutation (DEPDC5). Median age at follow up was 4yrs 5mo [2 yrs-18 yrs 10 mo]. Postoperatively a favorable seizure outcome was achieved in 14 (78%) patients with complete seizure control in 12 (Engel 1) or rare seizures in two (Engel 2). All children present cognitive impairment evaluated mild to moderate in seven (39%) and severe in 11 (61%). Contralateral EEG abnormalities, disorganized background activity, and/or contralateral spikes were not correlated to epileptic or cognitive outcome. Early age (< six month) at surgery significantly correlated with a better outcome.
Conclusions:
Children with hemimegalencephaly and intractable unilateral seizures should be considered for very early hemispherotomy despite the recognition of contralateral interictal EEG discharges. Young age at surgery leads to a significantly better epileptic outcome and quality of life.
Funding: N/A
Neurophysiology