Motor problems in Prader-Willi syndrome: a systematic review on body composition and neuromuscular functioning.

Motor problems in Prader-Willi syndrome (PWS) are presumably related to abnormal body composition and certain neuromuscular abnormalities. The authors reviewed the literature to evaluate the extent to which body composition is affected and gathered all findings on neuromuscular functioning in PWS. A systematic review was conducted in four databases (1956-2010). The methodological quality of each included article was evaluated. Thirty-eight papers were included: body composition (9 studies), neuromuscular functioning (7) and growth hormone (GH) effect studies (23). Increased fat mass and decreased lean body mass are characteristics of PWS. As a result, muscle mass is decreased by 25-37%, which might explain partly the weakness and hypotonia. However, there are also structural and functional muscle abnormalities, and cortical motor areas are hypo-excitable in PWS patients. Moreover, disuse as result of decreased activity in PWS could also contribute. GH treatment positively influences body composition, but does not normalize it. Training could prevent disuse and improves body composition. Therefore GH treatment and training will probably enhance one another.