Abstracts

Rationale: Gelastic seizures are the hallmark sign of epilepsy due to hypothalamic hamartoma (HH), but the patients usually experience numerous other symptoms, including different seizure types, neuropsychiatric comorbidities, and cognitive impairment. Evaluating these patients based on seizure frequency alone is thus often inadequate and does not account for the multifarious nature of the syndrome. Therefore, we developed a five-dimensional score to comprehensively quantify illness severity in these patients, and we investigated possible reasons for interindividual differences.

Methods: We included all patients with epilepsy due to HH who underwent at least one non-invasive video-EEG monitoring (VEEG) between 2010 and 2020 and without brain surgery prior to that VEEG (n=34). We analyzed these patients’ VEEGs as well as clinical and neuropsychological data and scored them in 5 categories: A) Seizure types, B) Ictal EEG, C) Interictal EEG, D) Cognitive Function, E) Neuropsychiatric Comorbidities. Scores were given based on defined criteria (Fig.1) and ranged between 0 (not affected) and 3 points (severely affected) per category, total score ranged between 0 and 14. We compared the results between different subgroups of our cohort, and correlated scores with patient and hamartoma characteristics including hamartoma size, duration of disease, and patients age at onset of epilepsy.

Results: 44 VEEGs of 34 patients were analyzed. Patients’ age was between 1 and 55 years (mean 15.9, 22 were children) and the mean epilepsy duration was 12.9 years (range 1-48). The total scores of our patients ranged from 0-12 (mean 6.95; mode 8) and were normally distributed (Shapiro-Wilk-Test, p=0.34). Scores across all categories were higher for patients with an early onset of disease (< 48 months of age), this difference was significant for the total score and for category B and D individually (all t-test, p< 0.05 after FDR correction for multiple testing). There was a positive correlation between the volume of the hamartoma and the total score (Spearman, r=0.41, p< 0.05). No significant correlation was found between the duration of the disease and the total score.

Conclusions: We were able to develop a five-dimensional score that proves adequate for comprehensively assessing and comparing illness severity in patients with epilepsy due to HH. The score is based on data that will likely be acquired in the normal diagnostic process or pre-interventional work-up, meaning that no additional procedures are required. It can thus easily be used both in future research projects and in a clinical setting, for example when evaluating a patient’s pre- and postinterventional condition. We could also show that a large hamartoma volume as well as an early onset of symptoms are associated with a more severe course of disease, but further investigations are needed to fully understand the heterogeneity of the disease. In the future, this can lead to a better understanding of the syndrome and might help in the decision for timing and type of interventional therapy.

Funding: Please list any funding that was received in support of this abstract.: K.A.K. and J.S. were supported by the Berta-Ottenstein-Program for Clinician Scientists at the Faculty of Medicine, University of Freiburg.