Background

Dravet Syndrome (DS) is a developmental and epileptic encephalopathy starting in infancy and characterised by treatment resistant epilepsy with cognitive impairment and progressive motor dysfunction. Walking becomes markedly impaired with age, but the mechanical nature of gait problems remains unclear.

Research question

What are the kinetic strategies characterised in gait of patients with DS?

Methods

This case-control study compared 41 patients with DS aged 5.2–26.1 years (19 female, 22 male) to 41 typically developing (TD) peers. Three dimensional gait analysis (VICON) was performed to obtain spatiotemporal parameters, kinematics and kinetics during barefoot, level walking at self-selected walking velocity. The sagittal plane support moment was analysed using Statistical Parametric Mapping (SPM). Three DS subgroups were identified based on differences in kinetic strategies characterised by the net internal knee joint moments and trunk lean. Kinematic and kinetic time profiles of the subgroups were compared to the TD group (SPM t-test). Clinical characteristics from physical examination and parental anamnesis were compared between DS (sub)groups using non-parametric tests (Kruskal-Wallis, Wilcoxon rank-sum, Fisher’s exact).

Results

Support moments in stance were significantly increased in the DS group compared to TD and strongly related to minimum knee flexion in midstance. Persistent internal knee extension moments during stance were detected in a subgroup of 27 % of the patients. A second subgroup of 34 % showed forward trunk lean and attained internal knee flexion moments. The remaining 39 % had neutral or backward trunk lean with internal knee flexion moments. Subgroups differed significantly in age and functional mobility.

Significance

Inefficient kinetic patterns suggested that increased muscle effort was needed to control lower limb stability. Three distinct kinetic strategies that underly kinematic deviations were identified. Clinical evaluation of gait should pay attention to knee angles, trunk lean and support moments.

中文翻译：

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Dravet综合征患者步态问题背后的机理

背景

Dravet综合征（DS）是一种发展性和癫痫性脑病，始于婴儿期，其特征在于具有抗药性的癫痫病伴认知功能障碍和进行性运动功能障碍。随着年龄的增长，步行变得明显受损，但是步态问题的机械性质仍然不清楚。

研究问题

DS患者步态的动力学策略是什么？

方法

这项病例对照研究比较了41例5.2-26.1岁的DS患者（女19例，男22例）与41个典型的发展中（TD）同行。进行了三维步态分析（VICON），以自行选择的步行速度在赤脚，水平步行过程中获得时空参数，运动学和动力学。使用统计参数映射（SPM）分析了矢状面支撑力矩。根据以净内部膝关节力矩和躯干倾斜为特征的动力学策略差异，确定了三个DS亚组。将亚组的运动和动力学时间曲线与TD组（SPM t-测试）。使用非参数测试（Kruskal-Wallis，Wilcoxon秩和，Fisher精确）对DS（亚群）之间的体格检查和父母回忆的临床特征进行了比较。

结果

与TD相比，DS组的站立时支撑力矩显着增加，并且与中途的最小膝盖屈曲密切相关。在27％的患者亚组中，在站立期间发现了持续的内部膝盖伸展时刻。第二亚组为34％，表现出前躯干倾斜和达到内部膝关节屈曲力矩。其余39％的人具有中性或向后倾斜的躯干，并具有内部屈膝力矩。亚组的年龄和功能活动性差异显着。

意义

无效的动力学模式提示需要增加肌肉力量来控制下肢的稳定性。确定了三种运动学差异背后的动力学策略。步态的临床评估应注意膝盖角度，躯干倾斜和支撑力矩。