Researchers at Stanford University and other neurological centers in the United States performed a retrospective review and analysis of the clinical presentation and neuroanatomical features of hypothalamic lesions in 100 cases of gelastic epilepsy. Age of seizure onset was 10.52 +/- 18.12 months. Preoperative brain MRI was delayed a mean of 133.2 +/- 126.7 months after reported onset of seizures. All patients had gelastic seizures; 68 had gelastic epilepsy plus other types of seizures, including partial and generalized. Four had infantile spasms. Cognitive or developmental impairment (IQ <70) occurred in 43% (28% of patients with gelastic seizures only and 50% of those with gelastic plus multiple seizure types; p=0.052). All patients had refractory seizures. Patients with gelastic seizures plus had significantly longer duration of epilepsy (p<0.001). Precocious puberty occurred in 23%. Patients with cognitive impairment and those with precocious puberty had significantly larger lesions involving the anterior and posterior hypothalamus, at the level of the mammillary bodies. [1]

COMMENT. Lesions causing gelastic seizures are all localized to the mammillary level of the posterior hypothalamus. The longer duration of the epilepsy determines the development of other seizure types.