Influence of immobilization on bone mass and bone metabolism in hemiplegic elderly patients with a long-standing stroke

Significant bone mass reduction occurs in stroke patients on the hemiplegic side compared with the intact side, correlating with the degree of paralysis and vitamin D deficiency. To evaluate the influence of long-standing immobilization on this osteopenia, we measured various serum markers of bone metabolism in 93 hemiplegic elderly patients with a long-standing stroke and in 37 controls. The bone mineral density (BMD) of the second metacarpal was determined bilaterally. The scoring of the stroke patients activity was based on the Barthel Index (BI). The serum ionized calcium was higher in the patients than in the controls, correlating negatively with the BI in the patients. The concentrations of parathyroid hormone (PTH), pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen and bone Gla protein were normal or low. The serum 25-hydroxyvitamin D level was low in the patients, correlating positively with the BMD on both sides. The serum 1,25-dihydroxyvitamin D (1,25-[OH]2D) level was markedly reduced in the patients. Hemiplegia from a stroke can result in immobilization hypercalcemia which inhibits PTH secretion and 1,25-[OH]2D production. Bone remodelling may have almost reached an equilibrium, resulting in a steady rate of bone loss. This and the hypovitaminosis D appear to be the dominant causes of immobilization-induced osteopenia in elderly, long-standing hemiplegic stroke patients.