Authors :
Gracie Trulove, MBA – University of Alabama, Birmingham; Pongkiat Kankirawatana, MD – Pediatrics - University of Alabama, Birmingham; Matthew Thompson, PhD – Psychology - University Of Alabama, Birmingham; Monisha Goyal, MD – Pediatrics - University of Alabama, Birmingham; Kathryn Lalor, MD – Pediatrics - University of Alabama, Birmingham; Curtis Rozzelle, MD – Neurosurgery - University of Alabama, Birmingham; Jeffrey Blount, MD – Neurosurgery - University of Alabama; Ismail Mohamed, MD – Pediatrics - University of Alabama, Birmingham
Rationale: Childhood-onset refractory epilepsy can be associated with long-term effects on a child’s development and cognition. Studies in adults demonstrated structural MRI changes that can be progressive and extend beyond the epileptogenic zone. Adult studies also demonstrated microstructural and volumetric contralateral. hippocampal changes in patients with unilateral temporal lobe epilepsy. Studies examining contralateral hippocampal volumes after temporal lobe surgery are few, yielded conflicting results, examined only adult epilepsy patients, are limited by lack of control groups, are short in duration of follow up, and have small numbers of MRI scans per subject.The purpose of this study is to utilize computational MRI analysis to evaluate longitudinal volumetric changes in the contralateral hippocampus in pediatric patients with DRE following temporal lobe epilepsy surgery in comparison to healthy control group.
Methods: We studied 13 children with drug resistant temporal lobe epilepsy who underwent anterior temporal lobectomy for treatment of intractable epilepsy. We included patients who had at least one MRI scan during their presurgical evaluation and multiple scans after surgery with age at their first MRI less than 18 years old. Control MRIs were obtained on 28 subjects in Pediatric Imaging, Neurogenetics and Genetics (PING) study and accessed from the NIMH data archive. We performed whole-brain volumetric segmentation and cortical surface reconstruction, and we calculated total volume of the hippocampus contralateral to side of surgery through an open-source software FreeSurfer 7.1 (
https://surfer.nmr.mgh.harvard.edu). Hippocampal volumes for patients and controls were normalized with total intracranial volume. Normalized volumes were plotted against age and months following surgery to visualize changes in hippocampal volume over time.
Results: Seizure onset was localized to the right (n=7) and left hemisphere (n=6). Age at seizure onset (mean ± SD) 6.2 ± 5.0 years, at first MRI 8.7 ± 4.7 years, surgery 9.2 ± 4.6 and last MRI 13.3± 5.3 years. Number of post-operative scans ranged from 2-5. Primary pathology was focal cortical dysplasia (8), Ganglioglioma (3), DNET (1) and gliosis (1). Twelve patients were seizure free at last follow up. Following left temporal lobectomy, patients (n=7) showed a relative increase in contralateral hippocampal growth compared to controls and to patients who had right temporal lobectomy; however, there were no long-term differences in hippocampal volumes between patients and controls.
Conclusions: No long-term changes in contralateral hippocampal volumes were observed in children undergoing anterior temporal lobectomy as compared to healthy controls in a small pediatric cohort with lesional epilepsy and good surgical outcome.
Funding: None