Stereo-electroencephalography pattern and long-term seizure outcome in hypothalamic hamartoma treated by radiofrequency thermocoagulation

OBJECTIVE The aim of this study was to investigate the long-term outcomes and clinical predictors for seizure freedom in patients with hypothalamic hamartomas (HHs) undergoing radiofrequency thermocoagulation (RFTC) guided by stereo-electroencephalography (SEEG). METHODS The authors enrolled 30 patients with HH-related epilepsy who underwent SEEG-guided RFTC and were followed up for at least 3 years. Seizure outcomes were assessed using the International League Against Epilepsy (ILAE) classification, with classes 1 and 2 defined as seizure freedom. Considering the observed time to relapse, the authors defined postoperative follow-up within 1 year as short-term follow-up. They analyzed lesion features, epileptic characteristics, and SEEG patterns for their relationship with short-term and long-term seizure freedom separately. Long-term complications were also reported. RESULTS The mean follow-up was 69.2 months (range 36–107 months) since the first RFTC. At the last follow-up, 20 patients (66.7%) achieved seizure freedom (ILAE classes 1 and 2). Regarding different seizure types, freedom was achieved in 81.8% of patients (18/22, after 2 cases relapsed) with gelastic seizures (GS) and in 52.9% patients (9/17, after 4 cases relapsed) with other types of seizures (i.e., nongelastic seizures [NGS]). Seizures characterized by focal low-voltage fast activity recorded by SEEG were more likely to achieve freedom both in the short term (p = 0.021) and the long term (p = 0.022). A history of HH resection might negatively impact a patient’s outcome at long-term follow-up, whereas lesion location, volume, seizure types, or the seizure duration showed no significant influence on both short-term and long-term outcomes. Weight gain was the most common long-term complication (26.7%). CONCLUSIONS The SEEG signal can guide HH ablation and serve as an important predictor for favorable seizure outcomes in both the short term and long term, a capability not exhibited by other factors thus far. Patients with a history of HH resection but who still experience NGSs should be considered carefully, as there may be a speculated mechanism of an NGS network re-forming, which can partly explain the outcome difference between patients with GSs and those with NGSs, as well as the progression of secondary epileptogenesis.