Corticosteroid-Induced Myopathy Mimicking Therapy-Resistant Asthma

Background: Therapy-resistant asthma is an important clinical problem. However, before considering asthma truly therapy resistant, it is essential to exclude diagnoses that may masquerade as therapy-resistant asthma, such as vocal cord dysfunction and recurrent aspiration, as well as factors related to loss of asthma control, including poor compliance, exposure to allergens, and sinusitis. Corticosteroid-induced myopathy may be an unrecognized but potentially important consideration in both settings.Objectives: To describe a patient with corticosteroid-induced myopathy complicating recurrent exacerbations of asthma, which presented with persistently reduced airflow that mimicked therapy-resistant asthma.Methods: A 20-year-old Japanese woman with severe intractable asthma who had a history of near-fatal attacks was admitted with recurrent asthma exacerbations that required long-term systemic corticosteroids.Results: Wheezing episodes decreased but airflow limitation persisted, which was due to not only uncontrolled asthma but also corticosteroid-induced myopathy. Myopathy prevented the adequate use of inhalers, which in turn complicated the tapering of corticosteroids, leading to a vicious cycle. Careful and gradual reduction of corticosteroid dose, while continuing systemic administration of nonsteroidal antiasthma medications, resulted in a resolution of clinical and electromyographic signs of myopathy and pulmonary function abnormalities.Conclusions: Corticosteroid-induced myopathy can masquerade as therapy-resistant asthma and can cause poor asthma control.