Polymyositis is a rare inflammatory muscle disease characterized primarily by progressive muscle weakness, but its complications can extend far beyond just muscle symptoms. The complications arise both from the direct effects of muscle inflammation and weakness, as well as from systemic involvement and secondary consequences of the disease and its treatment.
One of the most significant complications involves **respiratory muscles**. When polymyositis affects the muscles involved in breathing, such as the diaphragm and intercostal muscles, it can lead to **respiratory failure**. This occurs because weakened chest muscles impair the ability to breathe deeply and cough effectively, increasing the risk of **hypoventilation** (inadequate ventilation) and **aspiration pneumonia**. Aspiration pneumonia happens when weakened swallowing muscles cause food or liquids to enter the lungs, leading to infection. Additionally, polymyositis patients are at risk for **interstitial lung disease**, a condition where lung tissue becomes inflamed and scarred, further compromising respiratory function.
The **muscle weakness** itself can be severe and disabling. It typically affects the proximal muscles, such as those around the hips and shoulders, making everyday activities like climbing stairs, rising from a chair, or lifting objects difficult. This weakness can progress to the point where patients become dependent on assistance for mobility and self-care. Muscle pain and fatigue often accompany the weakness, further limiting function.
Another serious complication is **dysphagia**, or difficulty swallowing, which results from involvement of the muscles in the throat and esophagus. Dysphagia increases the risk of choking and aspiration, which can lead to malnutrition, dehydration, and respiratory infections. In some cases, the involvement of laryngeal muscles can cause **dysphonia**, or voice changes, and even airway obstruction.
Polymyositis can also affect the heart. Although less common, **cardiac complications** such as myocarditis (inflammation of the heart muscle), arrhythmias (irregular heartbeats), and heart failure can occur. These complications arise because the inflammatory process can involve cardiac muscle, leading to impaired heart function.
Systemic symptoms such as **fever, fatigue, and weight loss** are common and can complicate the clinical picture. The chronic inflammation can also predispose patients to **autoimmune-related complications**, as polymyositis is often associated with other autoimmune diseases or the presence of autoantibodies that may target various organs.
Treatment-related complications are also important to consider. The mainstay of therapy for polymyositis is immunosuppressive medications, including corticosteroids. Long-term steroid use can lead to side effects such as osteoporosis, increased risk of infections, diabetes, hypertension, and muscle wasting, which can compound the muscle weakness caused by the disease itself.
In rare cases, polymyositis can be associated with an increased risk of **malignancies** (cancers), particularly in adults. This association requires careful monitoring and screening for underlying cancers.
In summary, the complications of polymyositis are diverse and can affect multiple organ systems. They include severe muscle weakness leading to disability, respiratory failure due to involvement of breathing muscles and lung disease, swallowing difficulties with risk of aspiration, cardiac involvement, systemic inflammatory symptoms, treatment side effects, and an increased risk of malignancy. Managing these complications requires a comprehensive approach involving careful monitoring, supportive care, and tailored immunosuppressive therapy.
