Scoliosis in Prader-Willi syndrome: prevalence, effects of age, gender, body mass index, lean body mass and genotype.

BACKGROUND

The reported prevalence of scoliosis in children with Prader-Willi syndrome varies from 15% to 86%.

OBJECTIVE

To study the prevalence of scoliosis and the effects of age, gender, body mass index (BMI), total lean body mass (LBM), LBM of the trunk (trunkLBM) and genotype.

DESIGN

Radiographs were taken, length and weight were measured (BMI standard deviation scores (BMI SDS) and body surface area (BSA)), and dual energy x-ray absorptiometry was performed, measuring LBM and trunkLBM.

PATIENTS

96 children, median (interquartile range) age 4.8 years (2.1 to 7.5), were included in a multicentre study. None received growth hormone treatment.

MAIN OUTCOME MEASURES

Two types of scoliosis were identified: (1) long C-curve type scoliosis (LCS) and (2) idiopathic scoliosis (IS). Children were divided into age categories (infants, 0-3 years; juveniles, 3-10 years; adolescents, 10-16 years).

RESULTS

The prevalence of scoliosis was 37.5% and increased with age (infants and juveniles, approximately 30%; adolescents, 80%); 44% of children with scoliosis had a Cobb angle above 20 degrees . Children with scoliosis were significantly older than those without. Children with LCS were younger and more hypotonic than those with IS: median (interquartile range) age 4.4 years (1.7-5.9) vs 11.1 years (6.5-12.1) (p = 0.002) and trunkLBM/BSA ratio 7080 (6745-7571) vs 7830 (6932-8157) (p = 0.043).

CONCLUSIONS

The prevalence of scoliosis in children with Prader-Willi syndrome is high (37.5%). Many children with scoliosis (13%) had undergone brace treatment or surgery. The type of scoliosis is affected by age and trunkLBM/BSA ratio.