Laura Peeters

The trunk in Duchenne Muscular Dystrophy | 75 4 BACKGROUND For patients with Duchenne muscular dystrophy (DMD), performance of daily activities becomes more difficult over time due to progressive muscle weakness. DMD is an x-linked neuromuscular disorder with an incidence of approximately 1 in 6000 live male births [1]. Mean loss of ambulation is around 11 years with use of corticosteroids in the Netherlands [2], but patients report difficulties in performing daily activities involving arm movements already earlier [3]. Decreased upper extremity function is already visible in early stages of DMD and precedes the decline in activity performance [4]. Trunk weakness seems to occur in later disease stages. Trunk function seems relatively good and stable in the ambulatory phase, but starts to decrease when boys become non-ambulant [5, 6]. However, both measures used (Segmental Assessment of Trunk Control [5] and Motor Function Measure [6]) are influenced by upper extremity function too and therefore might not completely represent trunk function alone. Knowledge concerning the relation between upper extremity movement and trunk movement in patients with DMD is completely lacking at present [7]. In healthy adults and children, coordination of upper extremity and trunk motion is essential for accomplishing daily tasks [8, 9]. For DMD patients this may be even more, because clinically they show increased trunk movement to compensate for reduced arm function. Understanding the use of compensatory trunk movements could be beneficial for the development of interventions, such as physical exercise training, seating adjustments and assistive technology. Therefore, the aim of this study was to investigate how DMD patients use trunk movement to compensate for reduced arm function. We hypothesise that compensatory trunk movement is dependent on task difficulty, disease progression and related to increased trunk muscle activity. METHODS Participants Eighteen male DMD patients and twenty-five healthy controls (HC) (13 males) participated in this study. Participants were included if they were between 6 and 21 years of age, able to show arm motor skills at request and could sit independently (without back or arm rests) for at least 10 minutes. DMD patients needed to have a genetically confirmed diagnosis of DMD. Participants were excluded if they had (other) diseases affecting the arm, trunk or head movements, and if they had received