MRI-Negative Occipital Lobe Epilepsy Presenting as Gelastic Seizures.

Although gelastic seizures (GSs) with extrahypothalamic epileptogenic zones such as the frontal, temporal, or parietal lobes have been previously reported, reports of GSs arising from the occipital region are rare. Herein, we describe the seizure propagation pattern of mirthless GSs confirmed by intracranial EEG in a case of MRI-negative occipital lobe epilepsy. In this patient, EEG onset was localized to the right occipital lobe while the onset of laughter coincided with seizure propagation to the right basal temporal region. This finding suggested that the symptomatogenic area for GSs in the occipital lobe may reside in the basal temporal region, and the basal temporal region may play a role in laughing behaviors. This case demonstrated that an elaborate analysis of electroclinical features combined with imaging findings may lead to successful seizure localization.