Osteomalacic Myopathy in Children and Adolescents with Vitamin-D Deficiency.

Background: Osteomalacic myopathy secondary to vitamin-D deficiency is an under-recognized cause of muscle weakness in children and adolescents.

Aim: To describe a cohort of children and adolescents with osteomalacic myopathy.

Settings And Design: Pediatric neurology unit of a tertiary care hospital.

Methods And Material: Charts of children and adolescents with osteomalacic myopathy were retrospectively reviewed for demographics, clinical presentation, laboratory investigations, and treatment response. Diagnosis of vitamin-D deficiency was made on the basis of a combination of clinical, biochemical, and radiographic findings. Response to treatment with vitamin-D confirmed vitamin-D deficiency as the cause of myopathic symptoms.

Results: Twenty-six children-15 girls and 11 boys aged between 20 months and 19 years-with osteomalacic myopathy were identified. Fifteen (58%) children were between 10 years and 19 years of age. Twenty-one (81%) children presented with myopathic symptoms of progressive walking difficulty, with eventual loss of ambulation in six. Four children came to attention through hypocalcemic seizures. One nonambulatory child with cerebral palsy presented with loss of previously attained ability to roll over and sit. All children had proximal muscle weakness on examination. Fifteen (58%) children had clinical signs of rickets. All the children who underwent biochemical (n = 24) and radiographic (n = 16) investigations had results consistent with vitamin-D deficiency. Only in one child, the diagnosis of osteomalacic myopathy was made on the basis of clinical findings. Response to vitamin D was uniformly good.

Conclusions: Vitamin-D deficiency should be considered in the differential diagnosis of proximal myopathy in children and adolescents.