How does polymyositis progress?

The progression and severity of polymyositis (PM) can vary among individuals. The course of the disease can be divided into several phases:

1. Early phase:

- The early phase of PM is characterized by the onset of muscle weakness and fatigue, which may be symmetrical and involve the proximal muscles (such as the thighs and shoulders) primarily.

- Difficulty in rising from a seated position, climbing stairs, or lifting objects may be experienced.

- There may also be generalized aches and pains, as well as a fever.

2. Active phase:

- As the disease progresses to the active phase, muscle weakness becomes more pronounced and affects a wider range of muscles, leading to significant functional limitations.

- Difficulty in swallowing (dysphagia) and respiratory problems may occur if the muscles involved in these functions are affected.

- Joint pain or swelling (arthritis) can also accompany PM in some individuals.

- Skin rashes, such as Gottron's papules (raised reddish-purple lesions) over the knuckles or heliotrope rash (violet discoloration) around the eyes, may develop.

3. Plateau phase:

- After the active phase, some patients may enter a plateau phase, where the symptoms remain relatively stable for a period of time.

- The extent of muscle weakness and disability during this phase can vary depending on the individual.

4. Chronic phase:

- In the chronic phase, muscle weakness may persist, and some degree of disability may be present.

- Muscle atrophy (wasting) can occur in severely affected individuals.

- Contractures (permanent shortening of muscles) may develop, limiting joint movement.

- Other complications, such as interstitial lung disease (lung involvement) or heart problems, may arise in some cases.

The rate of progression and the severity of PM can vary considerably from person to person. With early diagnosis, appropriate medical management, including medications and physical therapy, it is possible to slow the progression and improve muscle strength in many individuals. However, the course of the disease can be unpredictable, and some patients may experience flare-ups or relapses.