Longitudinal study of bone and calcium metabolism and fracture incidence in spinocerebellar degeneration.

Little is known about bone and calcium metabolism and fracture incidence in spinocerebellar degeneration (SCD) despite frequent falls and immobilization. To address bone and calcium metabolism and fracture incidence in SCD, we conducted a 10-year prospective study in a cohort of adult patients with SCD. Bone mineral density (BMD) and serum levels of ionized calcium, parathyroid hormone, 25-hydroxyvitamin D, and pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen (ICTP) were followed in 110 patients with SCD for 10 years. Age-matched healthy volunteers (n = 110) served as controls. At baseline, the SCD patients had a low BMD with high levels of serum ionized calcium and ICTP which correlated with the degree of immobilization (Barthel index). Over 10 years, serum 25-hydroxyvitamin D decreased to the osteomalacic level (<5 ng/ml), and calcium and ICTP further increased in accordance with a decreased Barthel index score. The BMD decreased by 15.2% in men and by 24.6% in women. The incidence of fractures in the patients was significantly higher as compared with the control group (men 8/49 vs. 1/42, p = 0.0428; women 16/49 vs. 2/48, p = 0.0026). Over 10 years, the BMD was significantly reduced in the SCD patients, particularly in women, which increased the risk of a fracture. Vitamin D deficiency due to sunlight deprivation, increased bone resorption due to immobilization, and frequent falls are probable causes of osteoporosis and fractures in these patients. Hypovitaminosis D and increased bone resorption may be corrected readily by the routine use of vitamin D supplements together with bisphosphonate. Copyright (c) 2006 S. Karger AG, Basel.