Abstracts

Rationale: Ring chromosome 20 epilepsy syndrome r(20) is a medically refractory epilepsy no distinct phenotype. This syndrome can only be definitively diagnosed by chromosomal testing as dysmorphic features are lacking. Unfortunately, chromosomal testing is not requested routinely in refractory epilepsy. In this report we present the clinical features identified on 6 patients with this disorder. Methods: Clinical data was collected using a comprehensive clinical questionnaire comprised of over 100 questions developed by a pediatric epileptologist and epilepsy nurse specialists. This format allowed for detailed collection of clinical histories from birth to present. Results: The mean age of onset of seizures was 3.4 years (range 0 months’ to14 years). The mean age at diagnosis of r(20) syndrome was 3.6 years (range 9 months to 19 years). Minor facial dysmorphism was noted in 1/6 patients. One patient had moderate to severe global developmental delay. The average time to diagnose r(20) after seizure onset was 24 months. Frontal lobe complex partial seizures was the initial seizure classification in 3/6 patients. Nocturnal seizures and nonconvulsive seizures were reported in 3/6 patients. Seizures were refractory to antiepileptic drugs in 2/6 patients. Partial improvement occurred with vagus nerve implant in 2 patients. Psychological dependence was reported in 5/6 patients. Neuroimaging was normal in all 6 patients Conclusions: Clinical Diagnosis of r(20) syndrome should be considered in patients with refractory frontal lobe type complex partial seizures in whom neuroimaging studies are normal. Presence of dysmorhism should not be a prerequisite for chromosomal testing in refractory epilepsy patients. Early phenotypic recognition of this disorder will certainly lead to early chromosomal testing and etiologic diagnosis. Further genotyping of these patients may lead to better understanding of their clinical differences.