Hypothalamic hamartoma with gelastic seizures in Swedish children and adolescents

Hypothalamic hamartoma with gelastic seizures (HHGS) is an uncommon, often unrecognized, epileptic syndrome with onset of symptoms during childhood.

In order to study the occurrence, clinical symptoms and different investigations of HHGS in Swedish children and adolescents, a nationwide survey was undertaken. Methods. Twelve patients, three females, aged 5 to 19 years were identified and their hospital records reviewed. MRI examinations were reinvestigated.

Gelastic seizures were noted before the age of six months in seven patients in at least three as early as the neonatal period. During the course of disease one or more other seizure types developed in 11 patients. Behaviour disorder became subsequently obvious in ten patients, and mental retardation was diagnosed in seven. Precocious puberty was diagnosed in five patients. A total of 46 MRI examinations were performed in 11 patients, revealing hypothalamic tumors, eight of which were drooping with a broad base. Interictal and ictal EEG examinations were pathological in 10 patients with nonspecific results. Nonspecific results were also found on SPECT and PET performed in six and two patients, respectively. Available antiepileptic drugs had little or no effect on gelastic seizures, but some effect on other seizure types. Precocious puberty was treated with a GnRH-agonist. Neurosurgical treatment of the hypothalamic hamartoma, performed in three patients, had a rather good outcome concerning gelastic seizures and behaviour. Vagal nerve stimulation in five patients had no effect.

Review of the literature and experience from this group's own cases confirms that early diagnosis of HHGS is important. Hypothalamic hamartoma should be considered in any child with laughing attacks. MRI investigation is compulsory, and neurosurgery the most important treatment.