Abstracts

Rationale: Hypothalamic hamartomas (HH), a known cause of gelastic seizures and some secondary seizures, are difficult to approach surgically.  Recently MRI-guided stereotactic laser ablation (SLA) is becoming an accepted method of removing or disconnecting HH’s.  A subset of patients may experience a short-term rise in seizure frequency before a reduction which is referred to as a “run-down” phenomenon.  This is a retrospective review of pediatric cases who underwent SLA for gelastic seizures to determine possible predictors of temporary increased seizure frequency following surgery. Methods: After obtaining IRB approval, a retrospective analysis was performed of 9 patients at Texas Children’s Hospital who underwent SLA of an HH for treatment of gelastic seizures with an increase in seizure frequency of non-gelastic seizures between 2013 and 2017.  Data points included age at time of surgery, demographics, epilepsy types, seizure frequency before surgery, seizure frequency after SLA, repeat SLA, seizure recurrence after repeat SLA, and side of HH attachment. Results: Of the 9 patients in this study, 3 (33%) were female and 6 (67%) were male.  The average age for SLA of HH in these patients is 6.2 years (range 5 months to 11 years old).  Two (22%) patients had only gelastic seizures prior to SLA, two (22%) patients had two seizure types, and five (56%) patients had three or more seizure types with focal seizures with altered awareness as the most common second seizure type.  The patients experienced seizure freedom for 1-25 days before a return of gelastic seizures, other pre-SLA seizures, or a new seizure type in 2 (22%) patients including new onset generalized tonic-clonic seizures.  Two (22%) of the patients underwent a second SLA, and one (11%) of the patients underwent two additional SLA for the treatment of recurrent gelastic seizures with or without recurrent other seizure types.  Five (56%) of the patients had a right-sided attachment of the HH, 3 (33%) of the patients had a left-sided attachment of the HH, and 1 (11%) of the patients had a bilateral attachment. Conclusions: In a subset of patients who undergo SLA of an HH for treatment of gelastic seizures, there will be a temporary increase in seizure burden.  A limitation of SLA with the minimal catheter approach is incomplete destruction of the HH which can be associated with recurrent gelastic or other seizure types.  One consideration is repeat SLA targeting residual HH tissue if there is not a run-down of seizures 3-6 months after surgery. Review of data is ongoing to determine other predictors of the patients who will experience a short-term worsening of seizures following SLA of HH. Funding: N/a