Abstracts

Rationale: Gelastic seizures are characterized by stereotyped episodic unprovoked ictal laughter and are traditionally associated with hypothalamic hamartomas. More recently, ictal laughter originating from other cortical regions has been described. Laughter associated with temporal lobe foci are most often described, however, cases of frontal and parietal ictal laughter are also reported (Pearce, J. Eur Neurol 2004; 52:172-174). It has been suggested that laughter consists of an affective component and a motor component. The affective component involves the temporal basal structures and the motor component the frontal cortex. The true prevalence of extra-hypothalamic ictal laughter and the distribution of cortical regions involved is unknown. Methods: In an ongoing collaborative effort, children admitted to the epilepsy monitoring units of Dell Children s Comprehensive Epilepsy Center and Cook Children s Comprehensive Epilepsy Center with gelastic seizures as their primary seizure type were reviewed from January of 2010 to May 30, 2010. The localization, underlying pathology and, in cases where surgery was performed, the seizure outcome was explored. Results: Of 498 admissions, four cases of extra-hypothalamic ictal laughter (0.8%) have been identified. All patients had 3T MRIs to rule out hypothalamic hamartomas and to better define an ictal focus. Three cases had developmental delay and the diagnosis was initially missed in all. The underlying pathology varied greatly. One child had a choroid plexus papilloma with cystic extension into the right occipito temporal region. Another child had hydranencephaly with dysmorphic left frontal and right parietal lobes. A third had a mesial-frontal lesion and the last had primary generalized epilepsy with repetitive diaphragmatic myoclonus causing a laughter-like sound indistinguishable from the ictal laughter heard in the other individuals. Two of 4 patients had epilepsy surgery; both are free of disabling seizures. Conclusions: In this ongoing analysis, 0.8% of patients presented with extra-hypothalamic ictal laughter as a prominent clinical feature of their epilepsy. It is difficult to localize or lateralize itcal laughter to a specific cortical region as previously described. In children various pathological processes may be involved. Neurophysiology and neuroradiological studies should be done in all presenting cases.