Sonja Mensch

42 Chapter 2 DISCUSSION AND CONCLUSION This systematic review identified eight instruments for the measurement of motor abilities in children with severe disabilities on the activity level. Their psychometric properties were evaluated in 18 studies, mostly covering intra-rater reliability, inter-rater reliability and construct validity. Only two instruments were studied in all three domains (reliability, validity and responsiveness): the MHFMS (Krosschell et al., 2011) (Main, Kairon, Mercuri, & Muntoni, 2003) and WeeFIM (Niewczyk & Granger, 2010). Limited, conflicting or unknown evidence was rated for the majority of studied psychometric properties. Strong levels of evidence were only found for construct validity of LE85, MFM, andWeeFIM, but reliability studies were missing (LE85) or of poor quality for these instruments. The strength of this review was our stepwise selection procedure. We used a generic set of key words to describe the group of persons with disabilities, after which specific in- and exclusion criteria were applied, based on the limited capacities of children with severe disabilities. In paediatric physical therapy, motor abilities of disabled children are often compared to those of children with normal development (Bond, 1996). Due to the severity of the abilities in children with SMD, norm-referenced tests are irrelevant. Evaluative criterion-referenced construct of motor abilities of the child should be the main purpose. As was to be expected, the identified instruments were mostly developed and validated for children with many common specific diagnoses such as cerebral palsy and neuromuscular diseases. One instrument, the Top Down Motor Milestone Test (TDMMT) was specifically developed for children with SMD (Putten van der, Vlaskamp, Reynders, & Nakken, 2005). The TDMMT consists of the movement skills sitting, standing and walking, that are assumed to be the essential physical skills required in order to accomplish functional skills, such as expressive language and self-care. The design of the test seems to fit the needs of the target population, which makes it an interesting candidate for our purpose, but up to recently, its psychometric properties have been insufficiently studied: its test-retest reliability and responsiveness should be evaluated, allowing conclusions regarding the possibility of determining changes over time. Basedon this study, we conclude that currently, completely validated instruments applicable to children with severe disabilities are lacking, but several show potential. Generalization of the available instruments to children with SMD is difficult because of the limited motor capacities in these children, including the severity of the intellectual disabilities. Furthermore, these children have severe limitations in head and trunk control and often require extensive support technology, manual activation and physical support to use their motor abilities. An accurate measurement for children with SMD will have a positive effect in the therapeutic intervention whereby the appropriate level