Epileptic hypothalamic hamartomas impact of topography on clinical presentation and radiosurgical outcome.

Introduction: Evidence exists for the role of the hypothalamic hamartoma's topography as a determinant for the clinical presentation. How the hamartoma relation to the hypothalamic structures can make clinical presentations, severity and surgery outcomes different from patient to patient is largely unknown. Our aim was to analyze the effect of fine anatomical topography on clinical spectrum and radiosurgery outcome.

Methods: Forty-eight epileptic patients with hypothalamic hamartoma were treated by Gamma Knife Surgery and were reviewed for fine topography and morphology using magnetic resonance neuroimaging. We evaluated different topographic patterns; contact to prominent structures (the mammillary body, tuber cinereum and pituitary stalk), the degree of involvement within sagittally-oriented regions, (mammillary, tuberal, and supra optic) coronally-oriented zones (periventricular, medial, and lateral), lesion dimensions (length, width, and height),and volumes (total, intra-hypothalamic, and extra-hypothalamic volumes). This data were statistically analysed for correlation with all clinical variables and epilepsy surgery outcome. We reviewed all the classification protocols in the literature.

Results: Focal onset impaired awareness seizures started at an earlier age of onset with larger hypothalamic hamartoma volume and dimensions. Lateral extension within the hypothalamus was associated with more severe epilepsy, higher seizure frequency, more severe psychiatric comorbidity, hetero-aggression, hyperkinesia, and school difficulties. Presence of precocious puberty was positively correlated to anterior-posterior extension; tuberal region involvement, hypothalamic hamartoma volume, and type III-VI. Larger hypothalamic hamartoma presented precocious puberty at an earlier age of onset. After Gamma Knife Surgery, epilepsy outcome was better and rapid when lesion is smaller. Post-radiosurgical transient increased seizures were present when the mammillary region was more involved.

Conclusion: Clinical presentation of epileptic hypothalamic hamartoma is significantly affected by fine topography patterns and invaded hypothalamic areas. Gamma Knife Radiosurgery effect is better and rapid in smaller hamartoma (Type I-III) and seizure outcome was not affected by the invaded hypothalamic areas.