Myositis (pronounced my-oh-sigh-tis) is the general term for a group of muscle diseases in which the body’s immune system attacks the healthy muscle cells. Neurologists call the process an inflammatory mypoathy and over a period will lead to muscle weakness and atrophy.
Myositis includes the following disorders:
Juvenile Dermatomyositis (JDM)
Inclusion Body Myositis (IBM)
In all four conditions the muslces of the arms, legs and neck are weakened. Patients may have difficulty stepping down and climbing stairs, rising from chairs, lifting things, brushing hair and swallowing food. There may also be problems with lifting the head and torso when lying down, since core muscles can be affected. After a period of time walking aids or wheelchairs may be required.
Although there is no cure yet for these illnesses, steroid treatments can control the inflammation in patients with PM, DM and JDM and reduce the symptoms. IBM at present has no treatment. None of the illnesses have a cure.
The reason why the body’s immune system attacks muscle cells is unknown. these are not genetic illnesses, although there may be genetic factors that affect development. Some believe that the inflammatory response may be triggered by a virus or other illness but generally there is not clear cause for Myositis.