Abstracts

Rationale: Hypothalamic hamartoma (HH) are non-neoplastic developmental malformations of tuber cinereum and ventral hypothalamus, which are associated with gelastic seizures and secondary epileptogenesis resulting in refractory epilepsy. The clinical severity can range from focal drug-resistant epilepsy to generalized encephalopathy with severe cognitive and behavioral impairments. Hence, timely diagnosis and optimal treatment is crucial to reverse this potentially catastrophic epilepsy syndrome. There has been an evolution in surgical techniques and strategies to resect, de-bulk or disconnect HHs in order to achieve seizure freedom, not without involved risks, significant morbidity and modest surgical outcomes. MRI guided stereotactic laser ablation (SLA) offers a potentially safer, minimally invasive approach with high rates of efficacy. Methods: We present a retrospective review of 44 patients with hypothalamic hamartoma and refractory epilepsy who were referred to Texas Children’s Hospital, Houston, TX between January 2012 and December 2016. After receiving a comprehensive pre-surgical evaluation, all 44 patients underwent MRI guided stereotactic laser ablation of the HH lesion using the Visualase Thermal Therapy System. An IRB approved REDCap database and retrospective chart review were used to compile data including demographics, seizure history, interictal and ictal EEG data, MRI, prior surgical history, post-ablation complications, duration of hospital stay and clinical outcome using Engel classification. Pearson’s correlation was used to find an association of clinical outcome with patient’s age at the time of surgery or with history of prior surgical intervention using GraphPad Prism software. Results: This diverse cohort represented pediatric epilepsy patients ranging from 10 months to 19 years of age (median 6 y) with duration of epilepsy ranging from 8.6 months to 6 years. 36 out of the 44 patients were referred from within USA and 9 others were referred from countries including Australia, Ukraine, Russia, Netherlands, Spain, Canada and UK. All 44 patients had gelastic seizures (100%) with or without other seizure types such as focal seizures with impaired awareness, tonic, myoclonic, myoclonic-tonic or spasms and generalized tonic-clonic seizures. Interictal EEGs were found to be normal for 25% of the patients. 15 out of the 44 patients had undergone previous surgical interventions such as open or endoscopic transcallosal resection (n=7), gamma knife radiosurgery (n=5) or temporal lobectomy (n=3). All patients underwent minimally invasive MRI guided SLA with an average hospital stay of 1.6 days and no long- term postoperative complications. 22.7% patients had repeat laser ablation of residual HH lesion. 98% of the patients reported dramatically improved clinical outcome with 63% of the patients being completely seizure free (Engel I), 7% with rare disabling seizures (Engel II) and remaining 30% with worthwhile improvement (Engel III). We found no correlation of clinical outcome using Engel classification with age at stereotactic laser ablation or with number of prior surgeries (p values for both were >0.05, Pearson’s correlation coefficient of 0.05 for age and -0.01 for number of prior surgeries). Conclusions: In our single-center experience of 44 patients with HH and refractory epilepsy, MRI-guided stereotactic laser ablation significantly reduced or stopped seizures in 70% (Engel I or II classification) and decreased seizures in all patients. Improved seizure outcome was observed at all ages and was independent of number of prior surgeries (p values for both >0.05). Post-surgical morbidity was minimal as reflected by mean hospital stay of less than 2 days. Funding: None