Optimizing bone health in cerebral palsy across the lifespan

Relationship of anthropometric measurements and percent body fat mass to cardiovascular disease risk factors in adults with cerebral palsy

INTRODUCTION

Adults with cerebral palsy (CP) face high morbidity from cardiovascular disease (CVD). Of concern, classic screening parameters are inconsistent in identifying CVD risk in this population. Dual-energy x-ray absorptiometry (DEXA), which provides direct measurements of fat mass (FM), may be an alternative screening method.

OBJECTIVE

To evaluate whether FM measurement with DEXA is feasible in screening adults with CP and compare FM and anthropometric measures to CVD risk factors.

DESIGN

Cross-sectional study.

SETTING

Outpatient rehabilitation hospital.

PARTICIPANTS

Forty-seven adults with CP.

MAIN OUTCOME MEASURES

Weight, height, waist circumference (WC), and hip circumference (HC) were measured; waist-to-hip ratio (WHR) and body mass index (BMI) were calculated. Blood pressure (BP), FM by DEXA, hemoglobin A1c (HbA1c), and lipid measurements were obtained. Logistic regression models investigated odds ratios (ORs) and 95% confidence intervals (CIs) between anthropometric measurements/FM and CVD risk factors; correlations were assessed using Pearson correlation coefficients.

RESULTS

Elevated BP or hypertension diagnosis was present in 47.8%; HbA1c ≥5.7% in 22.2%; and high-density lipoprotein (HDL) level below optimal for 33.3%. DEXA FM was obtained in 29 of 47 participants, as surgical metal and positioning limited many studies. Excess FM was noted in 75.9% versus 41.3% overweight/obese by BMI. WC correlated with HbA1c (r = 0.46, p = .002), HDL (r = -0.36, p = .018), and triglyceride (TG) levels (r = 0.30, p = .045); however at-risk WC values were associated only with odds of elevated HbA1c (OR 8.53, 95% CI 1.46-50.05; p = .018). HC correlated with HbA1c levels (r = 0.38, p = .011) and systolic BPs (r = 0.35, p = .019); similarly, ORs for elevated HC were weakly associated with elevated HbA1c and BPs (OR 1.08, 95% CI 1.01-1.16; p = .024 and OR 1.07, 95% CI 1.01-1.14; p = .024, respectively). WHR correlated with TGs; however few TG levels were elevated. FM measures were not associated with at-risk lab values or BPs.

CONCLUSIONS

DEXA FM measurements may not be feasible for CVD screening in many adults with CP. Although CVD risk factors are frequently present, anthropometric measurements commonly used for general population screening may not translate well to adults with CP.

Secondary Osteoporosis

Osteoporosis is a global public health problem, with fractures contributing to significant morbidity and mortality. Although postmenopausal osteoporosis is most common, up to 30% of postmenopausal women, > 50% of premenopausal women, and between 50% and 80% of men have secondary osteoporosis. Exclusion of secondary causes is important, as treatment of such patients often commences by treating the underlying condition. These are varied but often neglected, ranging from endocrine to chronic inflammatory and genetic conditions. General screening is recommended for all patients with osteoporosis, with advanced investigations reserved for premenopausal women and men aged < 50 years, for older patients in whom classical risk factors for osteoporosis are absent, and for all patients with the lowest bone mass (Z-score ≤ -2). The response of secondary osteoporosis to conventional anti-osteoporosis therapy may be inadequate if the underlying condition is unrecognized and untreated. Bone densitometry, using dual-energy x-ray absorptiometry, may underestimate fracture risk in some chronic diseases, including glucocorticoid-induced osteoporosis, type 2 diabetes, and obesity, and may overestimate fracture risk in others (eg, Turner syndrome). FRAX and trabecular bone score may provide additional information regarding fracture risk in secondary osteoporosis, but their use is limited to adults aged ≥ 40 years and ≥ 50 years, respectively. In addition, FRAX requires adjustment in some chronic conditions, such as glucocorticoid use, type 2 diabetes, and HIV. In most conditions, evidence for antiresorptive or anabolic therapy is limited to increases in bone mass. Current osteoporosis management guidelines also neglect secondary osteoporosis and these existing evidence gaps are discussed.

Multi-Organ Dysfunction in Cerebral Palsy

Cerebral Palsy (CP) describes a heterogenous group of non-progressive disorders of posture or movement, causing activity limitation, due to a lesion in the developing brain. CP is an umbrella term for a heterogenous condition and is, therefore, descriptive rather than a diagnosis. Each case requires detailed consideration of etiology. Our understanding of the underlying cause of CP has developed significantly, with areas such as inflammation, epigenetics and genetic susceptibility to subsequent insults providing new insights. Alongside this, there has been increasing recognition of the multi-organ dysfunction (MOD) associated with CP, in particular in children with higher levels of motor impairment. Therefore, CP should not be seen as an unchanging disorder caused by a solitary insult but rather, as a condition which evolves over time. Assessment of multi-organ function may help to prevent complications in later childhood or adulthood. It may also contribute to an improved understanding of the etiology and thus may have an implication in prevention, interventional methods and therapies. MOD in CP has not yet been quantified and a scoring system may prove useful in allowing advanced clinical planning and follow-up of children with CP. Additionally, several biomarkers hold promise in assisting with long-term monitoring. Clinicians should be aware of the multi-system complications that are associated with CP and which may present significant diagnostic challenges given that many children with CP communicate non-verbally. A step-wise, logical, multi-system approach is required to ensure that the best care is provided to these children. This review summarizes multi-organ dysfunction in children with CP whilst highlighting emerging research and gaps in our knowledge. We identify some potential organ-specific biomarkers which may prove useful in developing guidelines for follow-up and management of these children throughout their lifespan.

Pubertal abnormalities in adolescents with chronic disease

Pubertal disorders in the context of chronic disease especially in those with chronic inflammatory disorders or those requiring prolonged periods of treatment with glucocorticoid are common reasons for referral to the paediatric endocrine clinic. Disorders of puberty are also common in adolescents with disability requiring management by paediatric endocrinologists. In these adolescents, impaired skeletal development is also observed and this can be associated with fragility fractures. Chronic inflammation, glucocorticoid and sub-optimal nutrition all impact on the hypothalamic-pituitary gonadal axis, and can also impact on skeletal development locally by their effects on the growth plate and bone. Addressing pubertal disorders is important to ensure adolescents with chronic disease are matched with their peers, promote adequate bone mass accrual and linear growth. Careful discussion with primary clinicians, the young person and the family is needed when instituting endocrine therapies to address puberty and manage bone health.

Consensus guidelines on the use of bisphosphonate therapy in children and adolescents

Bisphosphonate therapy is the mainstay of pharmacological intervention in young people with skeletal fragility. The evidence of its use in a variety of conditions remains limited despite over three decades of clinical experience. On behalf of the Australasian Paediatric Endocrine Group, this evidence-based consensus guideline presents recommendations and discusses the graded evidence (using the GRADE system) for these recommendations. Primary bone fragility disorders such as osteogenesis imperfecta are considered separately from osteoporosis secondary to other clinical conditions (such as cerebral palsy, Duchenne muscular dystrophy). The use of bisphosphonates in non-fragility conditions, such as fibrous dysplasia, avascular necrosis, bone cysts and hypercalcaemia, is also discussed. While these guidelines provide an evidence-based approach where possible, further research is required in all clinical applications in order to strengthen the recommendations made.