Three patients with hypothalamic hamartoma and gelastic seizures were studied using ictal single-photon emission computed tomography and EEG recordings with depth electrodes at the University of Alabama at Birmingham Epilepsy Center. Precocious puberty developed by age 7, and the patients were large for their age, above the 95th percentile. Cognitive and behavioral abnormalities were revealed on neurologic examination, with impulsivity, irritability, and aggressive tendencies. Laughing seizures began in the newborn period in 2 patients and before 6 years in a third. The frequency of attacks ranged from 1 to 5 minor episodes daily to 10 complex partial seizures each month. Interictal EEGs showed rare sharp waves from various areas. Ictal EEGs revealed diffuse theta. MRIs showed hypothalamic hamartomas, with displacement of the floor of the third ventricle. Ictal SPECT showed focal hyperperfusion of the hamartoma and thalamus. Depth electrode EEG within the hamartoma recorded focal spikes. Stereotactic radiofrequency surgical treatment of the hamartoma of one patient resulted in seizure remission. 
COMMENT. Gelastic (‘gelos’ Gr for mirth) seizures in children with precocious puberty and hypothalamic hamartoma originate from the hamartoma and involve adjacent diencephalic areas. Seizures occur more commonly when the tumor displaces structures adjacent to the hypothalamus. See Progress in Pediatric Neurology II, PNB Publ, 1994;p41, for further articles on gelastic epilepsy. The anterior cingulate region may also be involved in some cases.