Cognitive and adaptive evaluation of 21 consecutive patients with Dravet syndrome

In order to assess the cognitive and adaptive profiles of school-aged patients with Dravet syndrome (DS), we proposed to evaluate the intelligence and adaptive scores in twenty-one 6- to 10-year-old patients with DS followed in our institution between 1997 and 2013. Fourteen patients were tested using the Wechsler Intelligence Scale for Children (WISC) and the Vineland Adaptive Behavioral Scales (VABS); 6 patients could not be tested with the WISC and were tested with the VABS only, and one was tested with the WISC only. Data regarding the epilepsy were retrospectively collected. Statistical analysis (Spearman rank order and Pearson correlation coefficient) was used to correlate early epilepsy characteristics with the cognitive and adaptive scores. Sodium channel, neuronal alpha-subunit type 1 (SCN1A) was mutated in 19 out of 21 patients. After the age of 6years, none of the DS patients had a normal intelligence quotient (IQ) using WISC (age at the testing period: mean=100±5; median=105months; mean total IQ=47±3; n=15). Only five patients had a verbal and/or a non verbal IQ of more than 60 (points). Their cognitive profile was characterized by an attention deficit, an inability to inhibit impulsive responses, perseverative responses and deficit in planning function. Administering the Vineland Adaptive Behavioral Scales in the same period, we showed that socialization skills were significantly higher than communication and autonomy skills (age at the testing period: mean=100±4; median=100months; n=20). We did not find any significant correlation between the IQ or developmental quotient assessed between 6 and 10years of age and the quantitative and qualitative parameters of epilepsy during the first two years of life in this small group of patients. Despite an overall moderate cognitive deficit in this group of patients, the Vineland Adaptive Behavioral Scales described an adaptive/behavioral profile with low communication and autonomy capacities, whereas the socialization skills were more preserved. This profile was different from the one usually found in young patients with autism and may require specific interventions.