Abstracts

Rationale: The ring chromosome 20 syndrome (R20s) manifests as refractory epilepsy mainly with nonconvulsive status epilepticus (NCSE) in adults. However various types of seizure have been reported in children. Purpose of this study is to clarify the electroclinical features of R20s in children. Methods: A review of medical records at Shizuoka institute of Epilepsy and Neurological Disorders identified 29 patients with R20s. We evaluated the clinical and EEG feature of 168 seizures in 7 (male 3, female 4) patients in whom ictal video EEG was recorded at 10 years or younger. Results: The patients were between 8 and 42 year of age at the time of study, and ages of seizure onset were between 3.3 to 8.5 years. They were followed for 8 to 40 years. One patient had only NCSE and the remaining six had seizures consisting of nonintegrated or integrated gestural motor behaviors. Four patients manifested facial expression or action suggestive of fear experience. The duration of seizures was usually minutes. Interictal EEG showed frequent spikes, polyspikes, or spike with slow waves with frontal predominance. EEG displayed high-voltage spike rhythms over frontal or temporal regions during seizures with pronounced motor features, and diffuse high-voltage slow waves with frontal predominance during NCSE. Bursts of diffuse but frontally dominant high-voltage fast activity were observed during nocturnal seizures with subtle motor signs. Conclusions: R20s often manifests NCSE sometimes associated with mild myoclonus on the face or upper limbs in adults, but mainly motor symptoms and less NCSE in children younger than 10 years of age. Ictal and interictal spikes are more prominent in children than in adults. Children younger than 10 years with seizures of various gestural motor behaviors or fearful behavior accompanied by frequent spikes or spikes-waves in interictal and ictal EEGs should undergo chromosome testing with suspicion of R20s even in the absence of NCSE.