Myopathy and Neuropathy Associated With Osteomalacia

Abstract

Thirty unselected females with proven osteomalacia were evaluated clinically, electromyographically and histopathologically for muscle dysfunction. Clinical evidence of myopathy was found in all the patients except one; the electromyograms were abnormal in 25 of them, and histopathological abnormalities, although slight and nonspecific, were seen in all the 17 patients who underwent muscle biopsy. Electromyographic findings revealed a myopathic pattern as evidenced by a significant reduction in motor unit potential duration and amplitude, and an increased percentage polyphasicity as compared to the controls. There was a complete absence of denervation potentials. The histopathological abnormalities were nonspecific and slight, and consisted of fatty infiltration, interstitial fibrosis, sarcolemmal nuclear proliferation and variation in muscle fibre thickness. A statistically significant reduction in motor nerve conduction velocities of t h e ulnar and pcroneal nerves was found. I t was considered that this reduction in t h e velocities was due to subclinical neuropathy. Our data suggest that myopathy, neuropathy and osteomalacia in our patients are due to nutritional deficiencies of multiple vitamins.

Cross-sectional association between serum vitamin D concentration and walking speed measured at usual and fast pace among older women: The EPIDOS study

“…This strong positive association may be explained by the combined action of vitamin D on muscles and nerves. (5)(6)(7)(8)(9)(10)30) Even if the association of vitamin D with muscular strength remains controversial 5,7 -which was confirmed by the lack of significant linear association between serum 25(OH)D and quadriceps strength in our study-its action on muscle contraction speed and muscle power seems likely. (5,30) It has indeed been shown that serum vitamin D concentrations influence muscular phenotypic determinism because fast-twitch muscle fiber atrophy was identified in adults with vitamin D deficiency.…”

“…(31) Additionally, vitamin D is a neurosteroid hormone whose insufficiency may cause disturbances in the peripheral nervous system, such as reduced nerve conduction speed, but also in the central nervous system. (8,9,30,31) For example, vitamin D status has been associated with cognitive function such as attention, which is involved in gait control in older adults. (32)(33)(34)(35)(36) Fast-pace walking is precisely considered as a more attention-demanding task than usual-pace walking, (23,36) which could explain in part the close positive association shown in our study.…”

“…(1)(2)(3) Indeed, there is increasing evidence that when accounting not for skeletal health but the salutary effects of vitamin D on nonskeletal organs, the optimal health-promoting concentration of 25(OH)D is around 30 ng/mL. (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11) In particular, adverse neuromuscular events such as muscle weakness, balance impairment, and reduced nerve conduction have been described for serum 25(OH)D concentrations below 30 ng/mL. (3)(4)(5)(6)(7)(8)(9)(10)(11) Walking speed is a simple, objective performance-based measure of lower limb neuromuscular function that not only allows detection of subtle impairments and preclinical diseases but also is a sensitive marker of functional capacity in older adults.…”

“…(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11) In particular, adverse neuromuscular events such as muscle weakness, balance impairment, and reduced nerve conduction have been described for serum 25(OH)D concentrations below 30 ng/mL. (3)(4)(5)(6)(7)(8)(9)(10)(11) Walking speed is a simple, objective performance-based measure of lower limb neuromuscular function that not only allows detection of subtle impairments and preclinical diseases but also is a sensitive marker of functional capacity in older adults. (10)(11)(12)(13)(14)(15)(16) For instance, Suzuki and colleagues recently demonstrated that walking speed in older adults was positively ORIGINAL ARTICLE J JBMR correlated with physical performance tests such as handgrip strength or stork standing time.…”

“…Mixed results also may be explained by the absence or insufficient control of potential confounders such as age, body mass index (BMI), quadriceps strength, cognitive functioning, physical activity, number of chronic diseases, use of psychoactive drugs, and concentrations of serum intact parathyroid hormone (iPTH). (3)(4)(5)(6)(7)(8)(9)(10)(11) Lastly, studies used different cutoff values for low serum 25(OH)D concentrations ranging from 10 to 30 ng/mL, which also may explain the divergent results. (1)(2)(3) Thus, to better understand the association of vitamin D with walking speed, every previously used 25(OH)D threshold must be analyzed: 10, 20, and 30 ng/mL.…”