Gelastic seizures due to right temporal cortical dysplasia.

Gelastic seizures are an uncommon seizure type. They are most frequently observed in patients with hypothalamic hamartoma. Their association with other types of cerebral lesions is rare. Depending on the location of the lesion, gelastic seizures may or may not be accompanied by a subjective feeling of mirth. The pathophysiological mechanisms of this type of seizure are still undefined, and little is known about which pathways promote laughter and its emotional content, mirth. We present a young man with drug-resistant, gelastic seizures due to focal cortical dysplasia of the right inferior temporal gyrus. The lesion was evident on cranial MRI. Interictal EEG displayed a right temporal focus, whereas ictal EEG was not informative. Ictal loss of consciousness precluded reporting of any possible emotional experience. The patient underwent surgical resection of the lesion and has been seizure-free with anti-epileptic medication for two years. Although various anatomical regions may elicit laughter, in view of the current literature it seems that the anterior cingulate region is involved in the motor aspects of laughter, while the basal temporal cortex is involved in the processing of mirth. The fact that the present case exhibited gelastic seizures stresses once more the importance of the baso-lateral temporal cortex in the genesis of this type of seizures.[Published with video sequences].