Primary respiratory failure due to inclusion body myositis: think outside the box.

Inclusion body myositis features a slowly progressive inflammatory myopathy characterized by progressive proximal muscle weakness in the lower extremities, followed by proximal, upper-extremity weakness and later involvement of distal muscles groups. Although the most severely affected muscles are those of the limbs, the disease can also involve the respiratory, cardiovascular and gastrointestinal system muscles as well. We describe a unique patient who presented with acute hypercapnic hypoxic respiratory failure secondary to inclusion body myositis. Our patient required mechanical ventilation but responded to corticosteroid therapy. The diagnosis was delayed in part because of the slowly progressive course of the disease and the fact that an extensive investigation had not disclosed a cause. We postulate that muscle biopsy may be warranted in select patients suffering from a protracted muscle weakness.