Polymyositis is an inflammatory muscle disease that causes muscle weakness. Polymyositis is an inflammation of the muscle tissue that leads to weakness. Dermatomyositis is characterized by immune inflammation of muscles as well as by the presence of a rash.The immunological mechanisms that normally provide protection against infection and foreign substances are disrupted and instead, produce antibodies that attack and injure the body's own tissues.Polymyositis affects the muscles that are closest to the trunk of the body. Polymyositis develops gradually over time, and it rarely affects people younger than 18. Polymyositis involves inflammation of the muscles and can affect many parts of the body. When inflammation of skin involved it is called dermatomyositis . It is more common in women (by about two to one). People with polymyositis have trouble when rising from a sitting position, climbing stairs, lifting objects, or reaching overhead. In some cases, muscles that are not close to the trunk of the body become affected as the disease progresses. If the condition is accompanied by an inflammatory process that strikes the skin as well, it is called dermatomyositis.
The factors triggering a T cell–mediated process in polymyositis are unclear. Viruses have been implicated; however, so far, only the human retroviruses HIV and human T-cell lymphotrophic virus type I (HTLV-I), the simian retroviruses, and coxsackievirus B have been etiologically connected with the disease. These viruses may directly invade the muscle tissue, damaging the vascular endothelium and releasing cytokines, which then induce abnormal expression of the major histocompatibility complex (MHC) and which render the muscle susceptible to destruction. Some serum autoantibodies are shared with other autoimmune diseases (ie, myositis-associated antibodies [MAA]), and some are unique to myositis (ie, myositis-specific antibodies [MSA]). The MSA are found in approximately 40% of patients with polymyositis and dermatomyositis, whereas MAA are found in 20-50%. Supporting this conclusion are CD8 T cells, which, along with macrophages, initially surround healthy nonnecrotic muscle fibers and eventually invade and destroy them.
Causes of Polymyositis Dermatomyositis
Common causes of Polymyositis Dermatomyositis
- Damages muscle.
- Autoimmune process.
- Coxsackie B virus.
Symptoms of Polymyositis Dermatomyositis
Common Symptoms of Polymyositis Dermatomyositis
- Muscle weakness.
- Difficulty getting up from chairs.
- Difficulty swallowing.
- Muscle ache.
- Shortness of breath.
- Patchy red.
- Violet rash around the eyes.
- Weight loss.
Treatment of Polymyositis Dermatomyositis
Common Treatment of Polymyositis Dermatomyositis
- Bedrest is often valuable for those patients with severe muscle inflammation.
- In patients with muscle weakness, especially children, a program of physical therapy is useful to help prevent contractures that can complicate the disease when patients do not fully move their joints.
- For patients with dysphagia, recommending elevating the head of their bed and not eating before bedtime is useful, possibly preventing aspiration pneumonitis. Occasionally, nasogastric tube feeding may be needed to increase caloric input
- Use of monthly high-dose intravenous immunoglobulin (IVIG) for 6 months has proved beneficial in the short term.
- Polymyositis is treated with corticosteroids as a first course of treatment.
- Some Medicines (Methotrexate, Azathioprine, Cyclophosphamide, Chlorambucil and Cyclosporine) are useful to Polymyositis Dermatomyositis.