Epilepsy onset and severe neuropsychological impairment in two children with ring chromosome 20 syndrome

Rationale: Ring chromosome 20 [r(20)] syndrome is a well-definied chromosomal disorder characterized by epilepsy, mild to moderate mental retardation and lack of recognizable dysmorphic features. Methods: We describe two children, aged 7 and 9 years, who developed intractable frontal seizures during sleep and awakeness and, after few months of epilepsy history, showed a severe neuropsychological impairment mostly characterized by language loss, confusion and deficit in fine motor skills. Results: EEG demonstrated in both cases a continous spike and wave activity on frontal regions bilaterally during wake and sleep. Seizures were characterized by loss of contact, increased muscular tone at upper limbs with dystonic posture of the hands and motor automatisms at lower limbs. Sometimes clonic jerks at the arms, the eyelids and perioral myoclonias were recorded. Seizures onset was predominant in the frontal regions. In both cases the electroclinical situation evolved in status epilepticus with continous spike and waves interrupted only by overt seizures (up to one seizure every 15 minutes). Brain MRI and neurological examination were normal. No dysmorphic feature was noted. Both seizures and epileptic continous activity were resistant to most antiepileptic drugs; in both children epilepsy and neuropsychological recovery were obtained with valproic acid and lamotrigine. Chromosome analysis revealed mosaic ring 20 chromosome abnormality. IQ at follow-up was 74 and 80 respectively. Conclusions: R (20) syndrome is a rare chromosomal aberration associated with epilepsy. In most cases described in the literature, mental retardation of various degrees was present in early development, as soon as epilepsy started. Nevertheless, few cases of r(20) syndrome with seizure onset in late childhood and adolescence and progressive mental impairment were reported. We would like to stress the importance of searching r(20) syndrome in patients with no dysmorphic features and normal psychomotor development, who started having intractable seizures of probable frontal origin and mental deterioration (loss of language, frontal syndrome). EEG characteristics should address to diagnosis, that need chromosome analysis to be confirmed. Valproate and lamotrigine in association demonstrated a good efficacy in seizure control and neuropsychological recovery, even if the cognitive profile showed an impairment compared to the phase before the epilepsy onset.