Distal myopathy in nephropathic cystinosis.

In long-standing nephropathic cystinosis complications are observed in various organs. Distal myopathy was first described in detail in 1994. The prevalence was calculated to be 24%. We studied seven patients with nephropathic cystinosis with neurophysiological techniques. Only two patients complained of a distal muscle weakness but all showed signs of myopathy on electromyography, which was more pronounced in the distal muscles. Motor and sensory nerve conduction parameters were within normal ranges. One patient with the juvenile form of nephropathic cystinosis also had myopathy. We conclude that distal myopathy can be detected in nephropathic cystinosis even in the absence of clinically overt muscle weakness. Cystine-depleting therapy with cysteamine is recommended for all patients with cystinosis, even after renal transplantation, and the effect on the myopathy should be studied.