Abstracts

Rationale: Gelastic seizures with Hypothalamic Hamartoma (HH) is a pharmacoresistant epilepsy syndrome typically presenting in infancy or early childhood and may have a progressive epilepsy course, neurodevelopmental disorder and endocrinopathies. MR-guided Laser Interstitial Thermal Therapy (MRg-LiTT) is a minimally invasive technique to selectively target the epileptogenic zone in drug resistant epilepsy. This study describes experience of pediatric MRg-LiTT for HH at Great Ormond Street Hospital for Children, with a focus on safety and efficacy, as well as to describe post-operative effects including on appetite and weight.

Methods: Retrospective review of consecutive pediatric epilepsy MRg-LiTT cases at GOSH between 2019-2024. Relevant clinical data was abstracted by review of the electronic record. Seizure outcome was categorized by Engel Classification.

Results: 29 patients underwent MRg-LiTT (9F), at age 0.5-16.4 yrs; mean 5.0 yrs. 4/29 had prior surgery with partial resection and 1/29 had previous MRg-LiTT at another centre. 4/29 had a further MRg-LiTT, 3/4 as part of planned staged ablation. One-year outcome data is available for 23 patients; all but one reported worthwhile benefit, with Engel I outcome in 14/23 (61%). Complete ablation of the HH was not necessary to achieve improvement. 8/10 not yet at 1 year follow-up are reporting worthwhile benefit. The two youngest children (aged 0.5 and 0.9 yrs at first MRg-LiTT) had severe Developmental Epileptic Encephalopathy requiring protracted hospital stays before MRg-LiTT; following MRg-LiTT both were able to be discharged home.
Postoperative complications were transient endocrine disturbances - SIADH (2) with resolution of biochemical abnormalities in 3 days, diabetes insipidus (1), adrenal suppression (3) and appetite change (increased appetite (15) and weight (8), decreased appetite (2)). All children had pre-and post-operative high dose dexamethasone as oedema prophylaxis for at least 14 days, median 18. All with increased appetite improved over the first year. Weight gain was less when behavioural and dietary advice was provided from the outset. New permanent endocrinopathies were noted in the year following MRg-LiTT - growth hormone deficiency (1); central hypothyroidism (1). Conversely improvement in pre-operative SIADH was seen (2). One young person had short term memory loss immediately on waking, rapidly improved in 4 weeks but subtle difficulties persisted at 1 year.


Conclusions: Pediatric MRg-LiTT for lesioning of HH is safe and effective in achieving worthwhile reduction in seizures. Post-operative appetite and weight gain are common, can take a year to settle and can respond to behavioural and dietary management. Studies are needed to understand the role of peri-operative steroids and the role of MRg-LiTT in increased appetite and weight in the first post-operative year.

Funding: Research at Great Ormond Street Hospital for Children receives support from the NIHR Biomedical Research Centre at Great Ormond Street Hospital University College London