How to identify children with cerebral palsy at risk of low bone mineral density.

Abstract

Cerebral palsy is a common chronic motorically disabling condition in children. The aim of this study was to determine prevalence of low bone mineral density (BMD) in children with cerebral palsy and to examine the association between BMD with risk factors. Cross sectional study of children with cerebral palsy analyzing Dual X-ray Absorptiometry, blood tests, full clinical medical examination including Tanner stage and nutritional status, measurement of anthropometrics and assessment of physical activity. The 81 participants were aged 2.1-17.4 years (median 9 years) and 64 out of 81 had a mild cerebral palsy (Gross Motor Function Classification System score of I-II). Mean BMD z-score was -0.2 (SD = 1.05, range -4.6 to 2.0). GMFCS score was negatively associated with BMD (p < 0.01) as higher score led to 1.43 SD lower BMD [-1.97 to -0.89]. Weight bearing activity was negatively associated with lower BMD z-score (p = 0.01), as having <30 min of weight bearing activity per day lead to 0.98 SD lower BMD [-1.75; -0.22]. Use of anti-seizure medication was negatively associated with BMD (BMD z-score 0.7 SD lower; p = 0.02, [-1.28; -0.12]). Serum vitamin D levels or fracture rates were not statistically significantly associated with BMD changes. We found 17 % of children have low BMD regardless of motoric impairment level. GMFCS score, Sparse weight bearing activity and use of anti-seizure medicine were negatively associated to BMD. No significant associations were found with vitamin D, sex, BMI, puberty.