Background: Dravet Syndrome is a rare developmental epileptic encephalopathy characterised by epileptic seizures, cognitive impairment and motor disorders. Gait is markedly impaired and could benefit from targeted intervention to improve quality of life for patient and caregivers.Objective: To establish the state of the art regarding gait deviations in patients with Dravet Syndrome.Methods: A systematic search was performed in Pubmed, Web of Science, Science Direct and Embase. Studies that assessed gait deviations in patients diagnosed with Dravet Syndrome using clinical observation, video gait analysis or three dimensional (3D) gait analysis and reported gait characteristics, spatiotemporal or kinematic outcomes were included. Screening, quality assessment and data extraction were performed by independent reviewers.Results: Out of a total of 478 citations, nine articles were included. The total study population had an age range from 2.5 to 47 years. Three studies used clinical observation, three studies video analysis and three studies 3D gait analysis. Crouch gait was observed in about half of the population next to a variety of other gait deviations such as parkinsonian and cerebellar gait. Other findings included abnormalities in spatiotemporal parameters and kinematics, passive knee extension deficits, skeletal malalignment and neurological signs. Conclusions:A variety of gait characteristics was observed with crouch gait being the most reported gait pattern. Inconsistency in methods and findings from clinical and instrumented evaluation impede thorough understanding of the causal mechanism and evolution behind these deviations.

Background: Clinical laboratory testing of locomotor disorders is challenging in patients with intellectual disability (ID). Nevertheless, also in this population gait analysis has substantial value as motor problems are common. To promote its use, adequate protocols need to be developed and the impact on clinical decision making needs to be documented.Research Question: What is the clinical usefulness of instrumented motion analysis in patients with ID?Method: This narrative review consists of three parts. A literature review was performed to describe the gait pattern of patients with ID. Next, benefits and challenges of standard gait analysis protocols are described. Finally, a case of a girl with ID due to genetic cause showing gait abnormalities is discussed. Results:The literature review resulted in 20 studies on "gait" in patients with an "ID", published since August, 1 st 2013. Gait deviations were observed in all studies investigating the ID population with an underlying genetic syndrome. Observed gait deviations in the ID population might be attributed to physical characteristics, cognitive components or both. The main goal of clinical gait assessment is the identification of gait deviations and the evaluation of their progress over time, in order to optimize the treatment plan. The choice of adequate method and measurement modalities depends on the clinical goal, the available resources and the abilities of the patient. In the case report we presented, we succeeded in performing an instrumented 3D gait analysis in a girl with severe ID at the ages of 4y4m, 6y0m, 7y2m and 8y2m. Progressive gait deviations were found suggesting a crouch gait pattern was developing. Results of the gait analysis led to the prescription of rigid ankle-foot orthoses.Significance: Gait analysis has substantial value for patients with ID. Gait analysis allows clinicians to objectify the relationship between physical characteristics and gait features.

Aim To investigate the relation between cognitive and motor development in preschool aged children with Dravet syndrome, in particular between the age of independent walking and cognitive development. Method Results of cognitive and motor developmental assessments and the age of independent walking were retrieved retrospectively from the medical records of 33 children (17 males, 16 females; mean age at last evaluation 33.2mo, SD 8.2mo, range 9–48mo) diagnosed with Dravet syndrome. Cognitive and motor developmental age, derived from the Bayley Scales of Infant Development or through standardized neurodevelopmental assessment, were converted into cognitive and motor developmental quotients. Multiple test scores per child were included. Results A strong positive relation was found between cognitive and motor developmental quotient (Pearson r=0.854; p<0.001) in 20 children (slope=0.75; 95% CI: 0.54–0.95). A later age of independent walking was associated with a lower cognitive developmental quotient (28 children; p<0.001; slope=−1.01; 95% CI: −1.53 to −0.49). A higher cognitive developmental quotient was seen in children with an age at testing younger than 24 months. The cognitive developmental quotient of children with a delay in independent walking (>17.6mo) was significantly lower than those without a delay (p=0.006). Interpretation A strong relation exists between cognitive and motor development. Furthermore, the age of independent walking might be an important indicator of the development of children with Dravet syndrome. What this paper adds Cognitive and motor development are strongly related in children with Dravet syndrome. Later age of independent walking is associated with worse cognitive development in children with Dravet syndrome.

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