Osteoporosis in children with neuromuscular diseases and inborn errors of metabolism.

The effects on bone of cerebral palsy (CP), Duchenne's muscular dystrophy and different metabolic diseases are reviewed from the literature. Children affected with neuromuscular diseases and inborn errors of metabolism may develope osteoporosis. Mechanical stimulation is paramount for bone strengthening, and immobilization is a well-known cause of osteoporosis. CP is the most common cause of disability in pediatrics. The main cause of low bone density in children and adolescents with CP and muscular dystrophy is lack of activity, but nutritional issues and pharmacological treatments can contribute to the clinical picture. Programs to exert mechanical stimulation of their bones are warranted, as much as nutritional programs. Treatment with bisphosphonates shows promising results in this population. The term ''inborn errors of metabolism'' comprise a large list of defects in the metabolism of amino acid transport and metabolism of peptides, carbohydrates, vitamins, minerals, and fatty acids. Other disorders included are errors in mitochondrial energy metabolism, problems with biosynthesis and breakdown of complex molecules, and neurotransmitter defects. Low bone density and fractures in these patients may be consequence of immobilization and muscle weakness, but also of treatments (e.g. steroids, dietary restrictions), and the primary disease. Adequate control of the primary disease is paramount to prevent bone problems.