ROLE OF THE HYPOTHALAMIC HAMARTOMA IN THE GENESIS OF GELASTIC FITS (AVIDEO-STEREO-EEG STUDY)

Patients having a hypothalamic hamartoma frequently present epileptic attacks of laughter, and they later experience multiple additional sei zure types, which invariably lead to a severe drug-resistant epilepsy. If this association is now well-known, relationships between the hypo thalamic mass and the different types of seizures remain still mysteri ous. We report the case of a 16-year-old girl suffering from this pecu liar epileptic picture, in whom a stereo-EEG study was performed, allo wing us to record both the hamartoma, the neighboring hypothalamic str uctures, and other bilateral cortical areas. It showed that gelastic f its were strictly linked to ictal discharges which began and remained well localized in the hamartoma. Conversely, atonic seizures, which mi ght result from a secondary epileptogenesis, admitted a widely extende d bilateral frontal cortical origin, sparing the lesion, and slightly involving the posterior hypothalamus. Stereotactic radiosurgery of the hamartoma proved to be ineffective on both types of seizures, probabl y because of the too low dose of X-rays delivered (18 grays), as sugge sted by the absence of hypothalamic mass changes on MRI. Such data, ne ver reported to our knowledge, seem able to contribute to a better und erstanding of this very peculiar epileptic syndrome, and perhaps to a better adapted therapeutic management.