Mitochondrial changes in acute myopathy after treatment of respiratory failure with mechanical ventilation (acute relaxant-steroid myopathy).

A case of acute myopathy was observed in the course of treatment of respiratory failure with mechanical ventilation combined with prolonged neuromuscular blockade and administration of corticosteroids. A muscle biopsy revealed degeneration of muscle fibres. Electron microscopy showed loss of thick filaments as well as nemaline rods, vacuoles and cytoplasmic bodies. The mitochondria were increased in number, many harbouring paracrystalline inclusions, which were hitherto unknown in this condition.