Gelastic seizures are typically associated with hypothalamic hamartomas but may also arise from neocortical regions.1-3 Reports of parietal lobe origin are rare and often lack histopathological confirmation.4, 5 We report a pediatric case of gelastic seizures secondary to a right parietal dysembryoplastic neuroepithelial tumor (DNET), with resolution after surgical resection and histopathological verification. A 6-year-old boy presented with daily episodes of inappropriate laughter, limb tremors, and slurred speech. Seizures occurred 5–10 times daily during wakefulness, with no postictal confusion. Neurocognitive function was within normal limits. Developmental milestones were normal, and there was no family history of epilepsy. Video-EEG revealed normal background activity. Intricately, frequent spike and polyspike slow waves were recorded over the right frontal-central-parietal and temporal regions, with maximal activity in the anterior temporal lobe. The Ictal EEG showed rhythmic slow waves combined with low-amplitude fast activity over the right centroparietal region evolving into high-amplitude 1.5–2 Hz slow waves (Figure 1). MRI demonstrated gyral swelling in the right posterior parietal lobe. PET-MRI fusion demonstrated focal cortical hypometabolism in the same region (Figure 2). Levetiracetam reduced seizure frequency but did not achieve control. Surgical resection of the superior parietal lobule, precuneus, and posterior cingulate was performed. Histopathology confirmed DNET (Figure 3). The patient has remained seizure-free for 22 months postoperatively, including 16 months off medication. This case broadens the spectrum of known substrates for gelastic seizures. While gelastic seizures are most commonly associated with hypothalamic hamartomas, neocortical origins—including those in the parietal lobe—are increasingly recognized. To our knowledge, this is the first confirmed case of a parietal DNET causing gelastic seizures, supported by both electrophysiological and histopathological evidence.6-8 Laughter can be generated by activity in several cortical regions. In this case, the patient's seizure semiology, combined with EEG and neuroimaging findings, suggests that epileptic discharges originated in the parietal and posterior cingulate cortex and propagated to frontal motor areas, thereby eliciting volitional laughter. The presence of clonic limb movements further supports the involvement of the motor cortex. Notably, ictal smiling originating from the right posterior cortex has also been reported,9 providing additional support for the role of posterior cortical regions in generating emotional motor automatisms such as gelastic seizures. Parietal lobe lesions, though rare, should be considered in gelastic epilepsy. This case emphasizes the importance of comprehensive electroclinical correlation and demonstrates excellent surgical outcomes for DNET-related epilepsy. All authors have been personally and actively involved in substantial work leading to the paper and will take public responsibility for its content. Yan Wu: manuscript drafting, clinical data integration, and analysis. Erjia Wei: surgical planning and primary surgeon. Dong Lin: patient follow-up and treatment. Mengna Xie: psychological evaluation. Ruiyuan Xue: co-surgeon. Jingcong Huang: intraoperative electrophysiological monitoring. Xubing Zheng: MRI and PET-CT acquisition and analysis. Xiyun Zheng: pathological examination. Wenjing Zhou: manuscript review and revision, surgical planning supervision, intraoperative guidance. This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. The authors declare that they have no conflict of interest. Data sharing not applicable to this article as no datasets were generated or analyzed during the current study. Data S1. Data S2. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. Gelastic seizures are classically associated with epileptogenic lesions in which of the following brain regions? Which finding most strongly supported a parietal origin of gelastic seizures in the presented case? Which statement best describes the surgical outcome in this pediatric patient? Answers may be found in the supporting information.
Wu et al. (Tue,) studied this question.