Abstracts

Rationale: ILAE Commission on Diagnostic Methods published a task force report on the international consensus classification of hippocampal sclerosis (HS) in temporal lobe epilepsy (TLE) in 2013. We reviewed the pathological findings of our pediatric patients who underwent epilepsy surgery and temporal resections in light of the new classification.Methods: A total of 236 children underwent epilepsy surgery at Hacettepe University Children's Hospital between 1994-2015. 110 patients had temporal resections; 81 patients who had temporal resection with amygdalohippocampectomy (AH) were evaluated according to the International Consensus Classification of HS in TLE. 11/81 specimens were excluded due to technical reasons. Medical records were retrospectively reviewed regarding patient information.Results: The median age at seizure onset was 4 years (first day of life- 11 years); the median age at surgery was 10.75 years (10 months–19.8 years). Neuropathologic evaluation revealed no-HS in 9 patients, HS ILAE type 1 in 38, HS ILAE type 2 in 3, and HS ILAE type 3 in 20 patients. 23 patients had additional temporal lobe pathology, and 15 of them were classified as HS ILAE type 3 with central nervous system (CNS) tumor (65%). The underlying etiologies before surgery were; CNS tumor in 25 patients (%35.7), history of febrile seizures in 21 (%30), brain injury due to variety of causes (CNS infection, head trauma, neonatal insult, intracranial haemorrhage, metabolic disorders) in 13 (%18.6), unknown in 7, developmental abnormalities of CNS in 2 (%2.9), Rasmussen encephalitis in 2 (%2,9) patients. History of febrile seizures was most common in patients with HS ILAE type 1 (18/38 patients), whereas CNS tumors were predominantly seen in patients with HS ILAE type 3 (15/20 patients). 61/70 patients had a minumum post-op follow up of one year, and 44/61 (%72) were seizure free; 23/44 patients (%52.3) were classified as HS ILAE Type 1, 11 (%25) as HS ILAE Type 3, 8 (%18,2) as no-HS, and 2 patients as HS ILAE Type 2 (%4,5). Seizure outcome with respect to pathological classification revealed that 8/9 patients with no-HS, 23/34 patients with HS ILAE Type 1, 2/2 patients with HS ILAE Type 2, 11/16 patients with HS ILAE Type 3 were seizure free.Conclusions: Our neuropathological study showed that majority of children with temporal resection and AH were classified as HS ILAE type 1, followed by HS ILAE type 3. HS ILAE type 3 is a rare variant of adult TLE surgical cases. However ~29% of our patients had HS ILAE type 3 which may reflect etiological diversities between children and adults, or may be due to patient selection bias. Overall 72% of patients became seizure-free following surgery. All patients with HS ILAE type 2 were seizure free; yet we cannot comment on seizure outcome with respect to pathology due to the small sample size. Patients with HS ILAE type 1 and type 3 yielded similar seizure outcome. A significant association between history of febrile seizures and HS ILAE type 1 was noted, whereas CNS tumors were mostly associated with HS ILAE type 3.