Nerve, muscle or bone disease? Look before you leap.

Severe muscle weakness in osteomalacia may mimic a primary neuromuscular disorder like spinal muscular atrophy. A 32-year-old woman, initially diagnosed as a case of spinal muscular atrophy based on clinical presentation, electromyography and muscle biopsy, was later found to have osteomalacic myopathy due to primary hyperparathyroidism complicated by vitamin D deficiency. Before diagnosing a progressive, inevitably fatal degenerative condition like spinal muscular atrophy, one must rule out all possible treatable conditions with a similar presentation.