Myositis is a group of rare autoimmune conditions that cause chronic muscle inflammation and weakness. The body’s immune system, which normally protects against foreign invaders, mistakenly attacks its own healthy muscle tissue. This misguided attack leads to swelling and damage within the muscles.
Individuals with myositis often experience symptoms such as muscle pain, fatigue, and increasing muscle weakness over time. These symptoms can make daily activities, like getting up from a chair, climbing stairs, or lifting objects, challenging. While there is no cure for myositis, treatments like Intravenous Immunoglobulin (IVIG) can help manage symptoms and improve quality of life.
Understanding Myositis
Myositis is an autoimmune condition where the immune system targets muscle fibers, causing injury and sometimes destruction of these tissues. This can affect muscle function throughout the body.
Symptoms often appear gradually, with individuals experiencing difficulty with movement or using affected muscles. Beyond muscle weakness, people with myositis might also have muscle pain, feel very tired, or experience weight loss. Some types can also lead to problems with swallowing or breathing.
How IVIG Works for Myositis
Intravenous Immunoglobulin (IVIG) is a treatment derived from the plasma of thousands of healthy blood donors, containing a purified solution of antibodies. These antibodies, or immunoglobulins, are designed to help regulate an overactive immune system. IVIG is considered an immunomodulatory therapy, meaning it helps to adjust the immune response rather than suppress it entirely.
The exact ways IVIG works in myositis are still being studied, but several mechanisms are proposed. It may neutralize harmful autoantibodies that are attacking muscle tissue, or it could interfere with the activation of immune cells that cause inflammation. IVIG can also reduce the activity of complement, a part of the immune system that can damage cells, and modify the production of inflammatory cytokines.
IVIG can diminish complement deposition on capillaries and muscle fibers, reduce the expression of adhesion molecules, and alter gene expression in muscle tissue. For example, in dermatomyositis, IVIG has been shown to decrease complement activity and cytokine production.
Receiving IVIG Treatment
IVIG treatment is administered intravenously, meaning it is delivered directly into a vein, typically in the arm. This can occur in various settings, including a hospital, an infusion center, or sometimes even at home under medical supervision. The duration of each infusion can vary, but it often takes several hours.
The frequency of IVIG infusions also varies depending on the patient’s individual needs and response to therapy. An initial course might involve infusions over two to five days, followed by maintenance doses, such as one gram per kilogram of body weight per month for several months. Before an infusion, patients may be advised to hydrate well and might receive pre-medications like acetaminophen or antihistamines to help prevent potential reactions.
During the infusion, patients are monitored by healthcare professionals. The rate of the infusion can be adjusted to ensure comfort and minimize side effects.
Potential Side Effects and Important Considerations
While IVIG therapy is generally well-tolerated, some individuals may experience side effects. Common reactions can include mild headaches, muscle aches, joint pain, chills, fever, and general discomfort, often described as flu-like symptoms. These reactions are typically temporary and may subside within a few days after the infusion.
To manage these common side effects, the infusion rate can be slowed, and pre-medications such as acetaminophen or diphenhydramine can be given. More serious, though rare, side effects can occur, including aseptic meningitis (inflammation of the brain’s lining without infection), acute kidney issues, or blood clots. Allergic reactions, including severe anaphylaxis, are also rare but possible, particularly in individuals with an IgA deficiency, so a blood test for IgA levels is often performed before treatment begins.
It is important for patients to communicate any new or worsening symptoms to their healthcare team. While there are potential risks, for many patients with myositis, the benefits of IVIG in managing their condition often outweigh these considerations.