Contralateral hippocampal sclerosis following functional hemispherectomy in children: A report of three cases

Ranjith Kumar Manokaran; Ivanna Yau; Robyn Whitney; Ayako Ochi; Hiroshi Otsubo; Elysa Widjaja; George M Ibrahim; Elizabeth J Donner; Puneet Jain

doi:10.1016/j.seizure.2023.08.014

Contralateral hippocampal sclerosis following functional hemispherectomy in children: A report of three cases

Seizure. 2023 Oct:111:147-150. doi: 10.1016/j.seizure.2023.08.014. Epub 2023 Aug 20.

Authors

Ranjith Kumar Manokaran¹, Ivanna Yau², Robyn Whitney³, Ayako Ochi⁴, Hiroshi Otsubo⁵, Elysa Widjaja⁶, George M Ibrahim⁷, Elizabeth J Donner⁸, Puneet Jain⁹

Affiliations

¹ Division of Neurology, Department of Paediatrics, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada. Electronic address: ranjith.manokaran@sickkids.ca.
² Epilepsy Program, Division of Neurology, Department of Paediatrics, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada. Electronic address: ivanna.yau@sickkids.ca.
³ Division of Neurology, Department of Paediatrics, McMaster University, Hamilton, ON, Canada. Electronic address: whitner@mcmaster.ca.
⁴ Epilepsy Program, Division of Neurology, Department of Paediatrics, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada. Electronic address: ayako.ochi@sickkids.ca.
⁵ Epilepsy Program, Division of Neurology, Department of Paediatrics, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada. Electronic address: hiroshi.otsubo@sickkids.ca.
⁶ Department of Medical Imaging, Lurie Children's Hospital of Chicago, Chicago, United States of America. Electronic address: ewidjaja@luriechildrens.org.
⁷ Division of Neurosurgery, Hospital for Sick Children, Toronto, ON, Canada. Electronic address: george.ibrahim@sickkids.ca.
⁸ Epilepsy Program, Division of Neurology, Department of Paediatrics, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada. Electronic address: elizabeth.donner@sickkids.ca.
⁹ Epilepsy Program, Division of Neurology, Department of Paediatrics, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada. Electronic address: puneet.jain@sickkids.ca.

PMID: 37634352
DOI: 10.1016/j.seizure.2023.08.014

Abstract

Purpose: Hippocampal Sclerosis (HS) may co-exist with temporal or extratemporal lesions (dual pathology) in children and is usually ipsilateral to the radiological lesion. Here were report three cases with extensive hemispheric cortical malformation and drug resistant epilepsy who had persistent seizures after functional hemispherectomy (FH) and developed contralateral HS after the surgery.

Methods: This retrospective study enrolled children who underwent FH and developed contralateral HS after surgery. Their clinical, EEG, radiological and pathological data were reviewed and summarized.

Results: Ninety-five children underwent FH during the study period; Three cases (3.2%) were eligible. They all had unilateral extensive hemispheric cortical malformation who underwent FH between 3 and 5 months of age with no clinical, EEG or radiological suggestion for involvement of contralateral hemisphere prior to FH. All three patients had persisting seizures after FH. Contralateral HS was detected between 2.2 to 3.7 years after FH in all three cases. Two of the patients showed pathogenic variants in GATOR1 pathway genes.

Conclusions: The genesis of contralateral HS in the reported patients remains unexplained. The presence and distribution of "second-hit" somatic mutations may play an important role in governing the seizure outcomes of epilepsy surgery in patients with apparently unilateral malformations of cortical development.

Keywords: Epilepsy surgery; Focal cortical dysplasia; GATOR1; Hemimegalencephaly; Infantile spasms; VNS.