Authors :
Presenting Author: Vera Dinkelacker, MD, PhD – University of Strasbourg
Mary Mondino, PhD – University of Strasbourg
Syrine Zouaghi, BS – University of Strasbourg
Emmanuel Raffo, MD, PhD – Rothschild Foundation Hospital, Paris, France
Sarah D. Rosenberg, MD – Rothschild Foundation Hospital, Paris, France
Georg Dorfmüller, MD – Rothschild Foundation Hospital, Paris, France
Sarah Ferrand-Sorbets, MD – Rothschild Foundation Hospital, Paris, France
Marie-Thérèse Dangles, MD – Rothschild Foundation Hospital, Paris, France
Julie Bonheur, MD – Rothschild Foundation Hospital, Paris, France
Nathalie Dorison, MD – Rothschild Foundation Hospital, Paris, France
Suzanne Perguilhem, PhD – Rothschild Foundation Hospital, Paris, France
Gregory Torkomian, PhD – Rothschild Foundation Hospital, Paris, France
Pierre Besson, PhD – University of Chicago
Julien Savatovsky, MD, PhD – Rothschild Foundation Hospital, Paris, France
Mathilde Chipaux-Raffo, MD, PhD – Rothschild Foundation Hospital, Paris, France
Christine Bulteau, MD,PhD – Rothschild Foundation Hospital, Paris, France
Rationale:
Drug-resistant focal epilepsy in childhood is often sustained by large scale network dysfunctions. Therefore, the majority of cases require invasive stereo-electroencephalography (SEEG) to ponder the benefit-risk balance of resective surgery. Optimization of diffusion tractography, a pertinent tool to assess alterations in structural connectivity, may in the future help to assess physiological and atypical language asymmetry in the immature brain. With this aim, our pediatric tertiary center carried out a prospective study on language skills and structural network alterations probed with diffusion tractography (EPITRACT).
Methods:
We prospectively included 31 patients from 2019 to 2023 at the Rothschild Foundation Hospital in Paris (17 females, mean age at SEEG 9 years [range 1,9 to 18 years]) with drug resistant unilateral focal epilepsy. Diffusion imaging (60 directions multishell) was added to the clinical MRI. Younger children had MRI with general anesthesia. Image processing included gray matter segmentation with FreeSurfer and computation of white matter tracts on the basis of the John Hopkins University White matter atlas.
Results:
Mean age of onset of seizures was 3.3 years ± 2.7 (range from birth to 7 years). Etiologies were focal cortical dysplasia (21), ischemic vascular sequellae (4), non lesional (1), hippocampal sclerosis (1), other (4). Twenty-three patients (74%) had a left sided implantation. Neuropsychological assessment demonstrated a lower verbal intelligence quotient (VIQ) in the group of patients with left-hemispheric epilepsy (VIQ 79 ±23) compared to the right sided implantations (IVQ 91 ± 12). Children with left hemispheric focal epilepsy showed atypical asymmetry of gray matter landmarks, i.e. diminished volume of the pars orbitalis and triangularis of Broca's area. In a second step, we examined white matter integrity as fractional anisotropy along the superior longitudinal fasciculus and other prominent fiber tracts. Alterations in white matter integrity of the left superior longitudinal fasciculus correlated with poorer scores in verbal comprehension as demontrated in Figure 1 (fractional anisotropy of superior longitudinal fasciculus versus index of verbal comprehension, r2 0,55), thus corroborating diminished verbal proficiency in line with alterations of major white matter tracts.
Conclusions:
Our data emphasize anatomical alterations in gray and white matter landmarks of the left hemisphere in childhood epilepsy. We propose that language circuitry in drug resistant epilepsy is vulnerable from early ages on and warrants detailed exploration of gray and white matter alterations during presurgical work-up.
Funding: Vera Dinkelacker received research grants from the John Bost Fondation, Strasbourg University and the European Union (Interreg Offensive Sciences).