Polymyositis (pol-e-mi-o-SI-tis)
is an uncommon disease that causes inflammation in your
muscles. It's a type of connective tissue disease. The
most noticeable characteristic of polymyositis is muscle
weakness, especially in the muscles closest to your trunk,
such as your shoulder and
hip muscles. As a result, you may find it difficult to get
out of chairs, climb stairs, brush your hair or work with
your arms over your head.
Polymyositis can occur at any age, but it mostly affects
adults in their 40s and 50s. It's more common in blacks than
in whites, and women have it more often than men do.
Polymyositis usually develops gradually over weeks or
months.
Periods of remission, during which symptoms improve
spontaneously, rarely occur in polymyositis. However,
treatment can improve your muscle strength and function.
Symptoms
Signs and symptoms of polymyositis usually appear gradually,
so it may be difficult to pinpoint when they first started.
They may also fluctuate from
week to week or month to month. The most common polymyositis
symptoms include:
-Progressive muscle weakness, particularly in the muscles
closest to the trunk, such as those in your hips, thighs,
shoulders, upper arms and neck.
This weakness is symmetrical, affecting both the left and
right sides of your body.
-Difficulty swallowing (dysphagia).
-Mild joint or muscle tenderness.
-Fatigue.
Your immune system is responsible for helping to eliminate
invaders (antigens) such as infectious organisms. The key
cells in your immune system
are lymphocytes known as B cells and T cells, which
originate in your bone marrow. After T cells further develop
in your thymus, all your immune system cells gather in your
lymph nodes and
|
|
spleen. Antigens
(triangular shapes) are ingested, partially digeste and then presented to helper T
cells by special cells called macrophages. This process
activates the helper T cell to release hormones (lymphokines)
that help B cells develop.
These hormones, along with recognition of further antigens,
change the B cell into an antibody-producing plasma cell.
The antibodies (Y shapes) produced can be one of several
types (IgG, IgM, IgA, IgE and IgD). The antigen is
thus rendered harmless. The helper T cells also aid in
development of cytotoxic T cells, which can kill antigens
directly. Memory T cells are produced so that re-exposure to
the same antigen will provide a more rapid and effective
response.
Polymyositis belongs to a group of conditions called
inflammatory myopathies. Myopathies are diseases or abnormal
conditions of the muscles. The cause of most inflammatory
myopathies is unknown. Infections caused by bacteria,
parasites or viruses can cause inflammatory myopathies, but
in most cases, doctors aren't able to identify a preceding
infection in polymyositis.
A disease similar to polymyositis is dermatomyositis.
Dermatomyositis leads to many of the same symptoms as
polymyositis, but it causes skin inflammation or a rash as
well.
Click
here to continue
|
|
