Authors :
Presenting Author: Ream Alashjaie, MD – The hospital for the Sick Children
Elizabeth Kerr, Psychologist PhD – The Hospital for Sick Children; Cynthia Hawkins, Pathologist – The Hospital for Sick Children; Elizabeth Donner, Staff Physician – The Hospital for Sick Children; Weiss Shelly, Staff Physician – The Hospital for Sick Children; Ivanna Yau, Nurse practitioner – The Hospital for Sick Children; George Ibrahim, Surgeon – The Hospital for Sick Children; Elysa Widjaja, Adjunct Scientist – The Hospital for Sick Children; Puneet Jain, Staff Physician – The Hospital for Sick Children
Rationale:
This study aims to study the epilepsy phenotype, radiological and pathological variability, seizure and neurocognitive outcomes after surgery in children with drug-resistant focal epilepsy and isolated radiological hippocampal sclerosis.
Methods:
This retrospective study enrolled children with drug-resistant focal epilepsy and either isolated hippocampal sclerosis or additional subtle T2-Fluid Attenuated Inversion Recovery (FLAR)/Proton Density (PD) signal changes in anterior temporal lobe who underwent epilepsy surgery between January 2005 and December 2021. All children underwent detailed presurgical evaluation. We collected the demographics data, epilepsy phenotype, details of presurgical evaluation, surgery, pathology and follow up.
Results:
Thirty-six patients (10 girls) were included (75% right handed). The median age at first seizure was 3 years, 4 months. A history of febrile seizures and febrile status epilepticus was noted in 23 cases (63.8%) and 18 cases (50%), respectively. Most of the patients had weekly seizures (15 patients; 41.7%). The most frequent comorbidities included learning disabilities (39%), global developmental delay (19.4%), and autism (11%).
The mean number of anti-seizure medications (ASM) tried at the time of surgery was 3 ASMs. MRI brain showed isolated hippocampal sclerosis in 22 patients (61%) and hippocampal sclerosis with subtle signal changes in ipsilateral temporal lobe in 14 patients (39%).
The mean age at surgery was 12.3 years (SD=4.3). Prior invasive EEG monitoring was done in two patients. All patients underwent anterior temporal lobectomy with amygdalohippocampectomy; one patient had additional corticectomy in right posterior parietal region based on subdural grid data. The resections were done more commonly over the left hemisphere (22/26, 61.1%). %). The mean duration of follow up was 2.3 years (SD=1.8). The ILAE seizure outcomes at last follow up were: Class 1 (28, 77.8%), Class 2 (3, 8.3%), Class 3 (2, 5.6%) and Class 4 (3, 8.3%).
On pathology, hippocampal sclerosis was seen in 31 cases (86.1%) and gliosis only in five cases (13.9%). Subpial gliosis in the temporal neocortical specimens was reported in the majority (31/36; 86.1%). Additional findings included FCDIIa [4 patients], FCD IIIa [two patients], mild malformation of cortical development with excessive heterotopic neurons [two patients], and mild malformation of cortical development with oligodendroglial hyperplasia [three patients]. Mild architectural abnormnalities (no definite FCD on histopathology) was reported in four patients. One patient had periventricular nodules of primitive neural-glial tissue. Patients with additional pathological abnormalities (n=11) had similar rates of seizure freedom as compared to children with isolated hippocampal sclerosis/gliosis (63.6% vs 84%, p=0.21).
Conclusions:
Epilepsy surgery in pediatric patients with HS usually result in good seizure outcomes. Additional pathological findings were noted in nearly one-third cases but these had similar seizure outsomes when compared to children with isolated HS or gliosis in this small study.
Funding: No funding