Intellectual disability and epilepsy in down syndrome

Down Syndrome (DS) is the most common genetic cause of mental retardation, with a reported frequency of epilepsy between 1.4-17% (1). There is a paucity of data in the literature regarding epilepsy in Down syndrome and its relation to intellectual disability.

The purpose of this article is to analyze the association of epilepsy in children with DS - frequency and type of seizures, treatment, outcome and to compare cognitive impairment of children with DS and epilepsy and DS without epilepsy from our cohort.

A four years systematic retrospective analysis of the database of the Pediatric Neurology Clinic (January 2010 - December 2013) identified a cohort of 39 pediatric cases with DS and neurological symptoms, 9 of them (23%) associating epileptic seizures. Following data were analysed: clinical and neurological examination, type/s of seizures, electroencephalography (EEG), cerebral magnetic resonance imaging (MRI), psychological examination, psychiatric evaluation in selected cases, electrocardiography (ECG), cardiac ultrasonography, ophthalmologic examination.

23% (9 patients) of the children with DS of our cohort presented epilepsy. Five patients had epileptic spasms (56%), one of these further developed astatic seizures. Focal seizures were observed in three patients (33%) and absence with eyelid myoclonias in one patient (11%). Two of the nine patients with DS and epilepsy had generalized seizures, both with very good response to levetiracetam (LEV). EEG was abnormal at seizure onset, and was improved after treatment. Of the nine children with DS and epilepsy, two (22%) presented mild mental retardation and seven (78%) had moderate to severe cognitive delay. Of the 30 children with DS and without epilepsy, 21 (70%) had mild mental retardation and 9 (30%) had moderate to severe cognitive impairment.

The most frequent epileptic syndrome associated with DS is West syndrome, with good response to specific antiepileptics. All children with DS from our cohort have intelectual disability, more severe in those with epilepsy. Slight improvement of intelectual and language capabilities were seen after seizures control.