ABSTRACT
OBJECTIVE: To investigate the effect of physical training combined with growth hormone (GH) on muscle thickness and its relationship with muscle strength and motor development in infants with Prader-Willi syndrome (PWS). METHODS: In a randomized controlled trial, 22 infants with PWS (12.9 ± 7.1 months) were followed over 2 years to compare a treatment group (n = 10) with a waiting-list control group (n = 12). Muscle thickness of 4 muscle groups was measured by using ultrasound. Muscle strength was evaluated by using the Infant Muscle Strength meter. Motor performance was measured with the Gross Motor Function Measurement. Analyses of variance were used to evaluate between-group effects of GH on muscle thickness at 6 months and to compare pre- and posttreatment (after 12 months of GH) values. Multilevel analyses were used to evaluate effects of GH on muscle thickness over time, and multilevel bivariate analyses were used to test relationships between muscle thickness, muscle strength, and motor performance. RESULTS: A significant positive effect of GH on muscle thickness (P < .05) was found. Positive relationships were found between muscle thickness and muscle strength (r = 0.61, P < .001), muscle thickness and motor performance (r = 0.81, P < .001), and muscle strength and motor performance (r = 0.76, P < .001). CONCLUSIONS: GH increased muscle thickness, which was related to muscle strength and motor development in infants with PWS. Catch-up growth was faster in muscles that are most frequently used in early development. Because this effect was independent of GH, it suggests a training effect.
Subject(s)
Exercise Therapy , Human Growth Hormone/therapeutic use , Motor Skills/drug effects , Muscle Strength/drug effects , Muscle, Skeletal/drug effects , Prader-Willi Syndrome/drug therapy , Child, Preschool , Combined Modality Therapy , Female , Humans , Infant , Longitudinal Studies , Male , Muscle, Skeletal/diagnostic imaging , Netherlands , Prader-Willi Syndrome/diagnosis , Single-Blind Method , UltrasonographyABSTRACT
Although severe motor problems in infants with Prader-Willi syndrome (PWS) are striking, motor development has never been studied longitudinally and the results of growth hormone (GH) treatment on motor development are contradictory. The authors studied whether GH treatment can enhance the effect of physical training on motor development in infants with PWS. Twenty-two infants were followed for two years during a randomized controlled trial. The treatment and control groups began GH after baseline or following a control period, respectively. Both groups followed a child-specific physical training program. Motor performance was measured every three months. Multi-level regression analysis revealed that motor development differed significantly between infants (p<.001), and this could be partially explained by baseline motor developmental level (p<.01). GH treatment enhanced the effects of child-specific physical training on both motor developmental rate and motor developmental potential. Moreover, this effect was more pronounced when GH treatment was initiated at a younger age.
Subject(s)
Human Growth Hormone/therapeutic use , Motor Skills/physiology , Physical Therapy Modalities , Prader-Willi Syndrome/drug therapy , Prader-Willi Syndrome/physiopathology , Child Development/drug effects , Child Development/physiology , Developmental Disabilities/physiopathology , Developmental Disabilities/therapy , Female , Humans , Infant , Longitudinal Studies , Male , Regression Analysis , Treatment OutcomeABSTRACT
The clinical evaluation of an infant with motor delay, muscle weakness, and/or hypotonia would improve considerably if muscle strength could be measured objectively and normal reference values were available. The authors developed a method to measure muscle strength in infants and tested 81 typically developing infants, 6-36 months of age, and 17 infants with Prader-Willi Syndrome (PWS) aged 24 months. The inter-rater reliability of the measurement method was good (ICC=.84) and the convergent validity was confirmed by high Pearson's correlations between muscle strength, age, height, and weight (r=.79-.85). A multiple linear regression model was developed to predict muscle strength based on age, height, and weight, explaining 73% of the variance in muscle strength. In infants with PWS, muscle strength was significantly decreased. Pearson's correlations showed that infants with PWS in which muscle strength was more severely affected also had a larger motor developmental delay (r=.75).
Subject(s)
Child Development/physiology , Muscle Hypotonia/diagnosis , Muscle Strength/physiology , Muscle Weakness/diagnosis , Prader-Willi Syndrome/diagnosis , Case-Control Studies , Child, Preschool , Female , Humans , Infant , Linear Models , Male , Muscle Strength Dynamometer , Reproducibility of ResultsABSTRACT
Although motor problems in Prader-Willi syndrome (PWS) are prominent in infants, and continue into childhood and adulthood, there is little insight into the factors important for clinical management. The literature was reviewed to: (1) provide an overview of the characteristics and prevalence of motor problems and (2) evaluate the effects of growth hormone (GH) treatment and physical training on motor performance. A systematic search revealed 34 papers: 13 on motor performance; 12 on GH treatment; and nine on physical training. In infants, motor development is 30-57% of the normal reference values, and children and adults also have significant problems in skill acquisition, muscle force, cardiovascular fitness, and activity level. GH treatment positively influenced motor performance in infants, children, and adults, although not all studies demonstrated an effect. All studies on physical training demonstrated beneficial effects in PWS patients. We suggest a combination of GH treatment and physical training to be started as soon as possible, especially in infants, to improve motor development as this will positively influence general development.
Subject(s)
Human Growth Hormone/therapeutic use , Motor Activity/drug effects , Prader-Willi Syndrome/drug therapy , Animals , Body Composition/drug effects , Humans , Prader-Willi Syndrome/physiopathology , Treatment OutcomeABSTRACT
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.
