Gelastic epilepsy: video-EEG, MRI and SPECT characteristics

Gelastic epilepsy, or ictal laughter, is a relatively uncommon type of seizure which may occur singly or, more frequently, with other types of convulsions. Gelastic seizures have been observed to be associated with many different conditions, mainly hypothalamic hamartomas. We report on a patient whose ictal laughter was the only neurologic disturbance. Ictal video-EEG demonstrated seizure arising from the left frontal region with subsequent involvement of the contralateral homologous area and secondary generalization. MRI showed an enlarged left frontal horn of the lateral ventricle. Postictal SPECT, performed 6 min after the seizure had ended, showed hypoperfusion in the bilateral frontoparietal region and in both cerebellar hemispheres; the presence of this abnormality may be due to the spreading of the cortical epileptogenic focus and to the complex intercommunication between the frontal cortex and the cerebellar hemispheres. Interictal SPECT, in accordance with MRI features, demonstrated a left frontoparietal hypoperfusion. The neurofunctional features observed in the reported child could suggest that gelastic epilepsy originates in the frontal cortex. However, further studies are undoubtedly needed to define the pathogenetic mechanisms of ictal laughter.