Gelastic seizures: A case of lateral frontal lobe epilepsy and review of the literature

We describe a 40-year-old patient with gelastic seizures triggered by hand movement. Despite nonlesional magnetic resonance imaging (MRI), electroencephalography (EEG), functional magnetic resonance imaging (fMRI), and diffusion tensor imaging (DTI) are concordant with seizure onset in the right frontocentral area. Seizure semiology and EEG recordings imply involvement of mesial frontal structures remote from seizure initiation site. We reviewed all published cases on gelastic seizures of frontal lobe origin to find characteristic features. For further investigation of the phenomenon of movement-induced seizures, fMRI was performed using a finger tapping paradigm. Interictal fMRI revealed widespread activation of right motor cortex during finger tapping on either side outreaching the anatomical representation of the left finger. In line with this finding DTI revealed fiber track impairment in the right frontocentral region, supporting the hypothesis of a focal derangement. This case highlights the importance of complementary functional investigations in MRI-negative epilepsies.