Summary: Slowing of cognitive skills represents one of the diagnostic criteria of Dravet syndrome. This Italian multicentric study aims at clarifying the roles of epilepsy and/or underlying genetic alteration in determining the cognitive outcome. The study includes infants that were either in follow‐up (retrospective study: 26 cases) and newly diagnosed (prospective study: in progress). Our multicentric study shows that slowing of cognitive achievements becomes evident during the second year of life in all cases, and that the epilepsy phenotype indeed has a prognostic value. In this study the early appearance of absences and myoclonic seizures is associated with the worst cognitive outcome; whereas convulsive prolonged seizures do not seem to represent, per se, a bad prognostic factor for mental outcome. In this study, statistical analysis failed to reveal differences in the cognitive outcome with regard to the presence and type of SCN1A mutation.

Dravet syndrome (DS) is a rare and severe form of genetic epilepsy characterized by cognitive and behavioural impairments and progressive gait deterioration. The characterization of gait parameters in DS needs efficient, non-invasive quantification. The aim of the present study is to apply nonlinear indexes calculated from inertial measurements to describe the dynamics of DS gait. Twenty participants (7 M, age 9–33 years) diagnosed with DS were enrolled. Three wearable inertial measurement units (OPAL, Apdm, Portland, OR, USA; Miniwave, Cometa s.r.l., Italy) were attached to the lower back and ankles and 3D acceleration and angular velocity were acquired while participants walked back and forth along a straight path. Segmental kinematics were acquired by means of stereophotogrammetry (SMART, BTS). Community functioning data were collected using the functional independence measure (FIM). Mean velocity and step width were calculated from stereophotogrammetric data; fundamental frequency, harmonic ratio, recurrence quantification analysis, and multiscale entropy (τ = 1...6) indexes along anteroposterior (AP), mediolateral (ML), and vertical (V) axes were calculated from trunk acceleration. Results were compared to a reference age-matched control group (112 subjects, 6–25 years old). All nonlinear indexes show a disruption of the cyclic pattern of the centre of mass in the sagittal plane, quantitatively supporting the clinical observation of ataxic gait. Indexes in the ML direction were less altered, suggesting the efficacy of the compensatory strategy (widening the base of support). Nonlinear indexes correlated significantly with functional scores (i.e., FIM and speed), confirming their effectiveness in capturing clinically meaningful biomarkers of gait.