Treatment of muscular dystrophies and inflammatory myopathies

Respiratory failure due to muscle weakness in inflammatory myopathies: maintenance therapy with home mechanical ventilation

Polymyositis and dermatomyositis are idiopathic inflammatory myopathies. Respiratory complications are a common feature, but ventilatory insufficiency is rare in these patients. We describe here three patients diagnosed with inflammatory myopathy (polymyositis) with respiratory failure due to muscle weakness who did not respond to immunosuppressive therapy. Mechanical ventilation at home with nasal or tracheal intermittent positive pressure resulted in improved chronic hypoventilation. This treatment improves the quality of life of patients with inflammatory myopathies and can be lifesaving in some cases.

Oxidative stress and muscular dystrophy

Oxidative stress may be the fundamental basis of many of the structural, functional and biochemical changes characteristic of the inherited muscular dystrophies in animals and humans. The presence of by-products of oxidative damage, and the compensatory increases in cellular antioxidants, both indicate oxidative stress may be occurring in dystrophic muscle. Changes in the proportions and metabolism of cellular lipids, abnormal functions of cellular membranes, altered activity of membrane-bound enzymes such as the SR Ca2+-ATPase, disturbances in cellular protein turnover and energy production and a variety of other changes all indicate that these inherited muscular dystrophies appear more like the results of oxidative stress to muscle than any other type of underlying muscle disturbance. Particular details of these altered characteristics of dystrophic muscle, in combination with current knowledge on the processes of oxidative damage to cells, may provide some insight into the underlying biochemical defect responsible for the disease, as well as direct research towards the ultimate goal of an effective treatment.