Laura Peeters

114 Chapter 6 SUMMARY Trunk and head control are indispensable when performing seated upper extremity tasks. The trunk interacts with the upper extremities (UE) and the head as part of a kinematic chain and it provides a stable base for performing voluntary UE and head movements [1-3]. The trunk can become impaired due to muscle weakness (e.g. Duchenne muscular dystrophy (DMD) or spinal muscular atrophy (SMA)) or central neurological disorders (e.g. cerebral palsy (CP) or spinal cord injury (SCI)). Impairment of the trunk in (early) childhood can affect motor development and it increases the risk of developing spine deformities due to muscle weakness [4]. In turn, spine deformity also affects trunk movement and stability [4]. Although the trunk plays a vital role during seated UE tasks, little research has been done concerning trunk function in patients with DMD and SMA. It is of utmost importance to gain more insight in the interaction between trunk, UE and head when performing seated tasks, since most patients with DMD or SMA who are symptomatic in early childhood will not be able to walk once they have reached adulthood. Additionally, the scarce literature on these interactions in typically developing children only focuses on the trunk as one rigid segment and ignores the substantial flexibility of the spine. Therefore, the aim of this thesis was to gain insight in trunk function and the interaction between trunk, UE and head movements in patients with DMD and SMA using typically developing children and young adults as a reference. This knowledge is essential for developing dynamic supportive devices for the trunk and head to support people with DMD and SMA when performing seated daily tasks. Development of supportive devices for patients with neuromuscular disorders was the overall aim of the Symbionics project, of which the research reported in this thesis is a part. Review: interaction trunk, head and upper extremity Chapter 2 is a literature review describing patients with a flaccid trunk caused by both neuromuscular disorders (i.e. DMD and SMA) and central neurological disorders (i.e. CP and SCI), with a main focus on childhood. The aim was to evaluate what is known about trunk involvement when performing seated UE tasks and head movements. Both trunk involvement in the kinematic chain and in the context of providing a stable base were taken into account. We performed a literature search in PubMed with the use of broad key terms. Studies were included if they covered the topic of task performance in seated position, involved both trunk and arm or head movement, and presented outcome measures related to kinematics (i.e. range of motion, movement trajectory, and/or spatiotemporal parameters) or stability (i.e.