Idiopathic rhabdomyolysis in children

Idiopathic rhabdomyolysis (myoglobinuria) in children differs clinically from adult cases. The childhood form generally presents with fewer attacks of greater severity and without an exertional precipitant. The mortality rate in children is high. Two fatal cases, in patients ages 3 years and 8 months and 9 months respectively, are reported. The second case is the youngest patient reported to have died with rhabdomyolysis. Both children had weakness of a subacute but relentlessly progressive nature. Weakness of the respiratory muscles led to death in each case after a course of several weeks. Myoglobinuria was never a prominent feature of the illness. The pathologic changes in the skeletal muscles of both cases were similar and consisted of widespread necrosis of individual muscle fibers randomly distributed among intact fibers. There was no evidence of inflammatory changes. Electron microscopic study of the muscle of Case 1 showed the affected fibers to be in various stages of necrosis. Phagocytosis and regeneration were also seen. These morphologic alterations of muscle are similar to those seen in adult cases of rhabdomyolysis, despite the differences in the clinical manifestations and in the prognosis.