Abstracts

Rationale: Although there is a large body of anecdotal evidence about hypothalamic hamartomas and gelastic seizures, it remains to be determined which specific hypothalamic nuclei are most affected by the location of hamartomas and whether the anatomical localization of the lesions differs in cases with only gelastic seizures or a combination of gelastic and other types of seizures, and whether the location of the lesions correlate with the presence of precocious puberty or cognitive impairment. Methods: In a retrospective review of clinical and structural neuroimaging data from 100 cases of gelastic epilepsy and hypothalamic hamartomas, we aimed to address these questions by analyzing the clinical presentation and the neuroanatomical features of the hypothalamic lesions in these patients. Results: Our findings suggest that in all 100 cases, lesions were centered at the level of the mammillary bodies. Compared to the patients with pure gelastic seizures (n=32), those with gelastic and other types of seizures (n=68) had significantly longer lifetime duration of epilepsy (p<0.001), whereas age of seizure onset, the volume of lesions and the proximity to the mammillary bodies were not different between the two groups. In contrast, patients with cognitive impairment and those with precocious puberty had significantly larger lesions involving not only the anterior but also the posterior hypothalamus.Conclusions: Understanding the precice nuclear anatomy of the HH will provide important clues about the routes of ictal propagation and the neuroanatomical networks that are involved in generating the expression of human laughter.