[A case of hypothalamic hamartoma with gelastic seizures, precocious puberty, poly- and syndactyly].

We reported a 6-month-old boy, patient of hypothalamic hamartoma with a rare association of poly- and syndactyly, which developed gelastic seizures and precocious puberty. His birth was complicated by poly- and syndactyly in both hands and polydactyly in both feet, but other physical signs were normal. At 5 month of age, he visited our hospital because of a suspected seizure. On admission, physical and neurological examinations revealed increased size in penis and testes, and delayed psychomotor development. Gelastic seizures occurred up to 100 times a day, and were resistant to many anticonvulsants. Ictal EEG showed bursts of generalized high voltage slow waves. His serum LH and testosterone levels were elevated for his age. Brain CT and MRI demonstrated a hypothalamic mass lesion, which proved to be hamartoma by biopsy.