Polymyositis
Polymyositis Symptoms | Causes
of Polymyositis | Polymyositis
Treatment | Polymyositis Cure | Polymyositis
Research
Polymyositis is an inflammatory disease of muscles, causing weakness
in the muscles closest to the torso -- usually the shoulder and hip muscles.
It is an autoimmune disorder, meaning that a person's white blood cells
begin attacking muscles for an unknown reason. The disease is chronic,
but the symptoms may come and go. Anyone can get polymyositis, but it
is slightly more common in females, and people in middle childhood and
their 20s. It is sometimes connected with cancer, scleroderma, and rheumatoid
arthritis
Polymyositis Symptoms
Polymyositis is an inflammatory disease of muscles, which causes muscle
weakness. This weakness usually develops slowly over weeks to months
although rare cases can begin over days. This weakness most commonly
affects the muscles of the arms and legs. Patients often notice trouble
getting out of chairs or climbing stairs. It does not typically involve
the muscles of the eyes, heart, or breathing muscles. However the muscles
involved in swallowing can become weak as well. Muscle pain may also
be a prominent symptom since polymyositis is associated with inflammation
in the muscles.
The diagnosis of polymyositis begins with a neurologist
taking the patient's history. A physician who suspects a diagnosis of
polymyositis may perform blood tests, an EMG, or a magnetic resonance
imaging scan (MRI). The blood tests reveal elevated levels of enzymes
which are found in muscle. Doctors may check a creatine phoshpokinase
(CPK) or an aldolase. Without elevated levels of one of these enzymes
it is very unlikey to have a diagnosis of polymyositis. The EMG test
looks at the function of a patient’s muscles and will reveal evidence
for muscle inflammation and muscle damage. An MRI looks for visual evidence
for inflammation in a group of muscles. It can also be used to choose
which muscle to biopsy.
If these three non-invasive tests suggest a
diagnosis of polymyositis then patients should have a muscle biopsy before
beginning therapy. This is important because many disease can look like
polymyositis but in fact may represent forms of muscular dystrophy or
another related disease called Inclusion Body Myositis. This distinction
is important because polymyositis is treatable but muscular dystrophy
and inclusion body myositis are not treatable. Therefore, a muscle biopsy
is needed in all patients for a definitive diagnosis. Finally there
are a very specific set of blood tests called Myositis Specific Autoantibodies.
These antibodies are found in 20-30% of patients with polymyositis but
are important because they can predict the presence of other associated
conditions.
Polymyositis Cause
Polymyositis is an autoimmune disorder, meaning that a person's white
blood cells which are supposed to fight off bacteria and viruses begin
attacking their own muscles. While we do not know what triggers a person’s
immune system to behave in this way ,there are many theories that suggest
the cause of Polymyositis is a combination of one’s genetic predisposition
and environmental exposures. People of either sex or any age can get
polymyositis, but it is slightly more common in females, and people in
middle childhood and their 20s. It is sometimes associated with other
autoimmune diseases such as sometimes connected with lupus, scleroderma,
and rheumatoid arthritis. In rare cases it can be associated with certain
types of cancers.
| Syndrome |
Distinctive features |
| Idiopathic |
Proximal weakness; High CK;
Inflammatory myopathy |
| Collagen vascular disease |
Myalgias; Younger onset
Scleroderma & Mixed connective tissue disease |
Anti-t-rna synthetase antibodies
Jo-1 antibodies |
Interstitial pneumonitis; Raynauds; Arthritis
Perimysial pathology |
| Signal recognition particle antibody |
Acute onset; Severe weakness
Capillary pathology; Fibrosis |
| MAS antibody |
Acute onset; Rhabdomyolysis |
| Drug-induced |
D-penicillamine |
| Familial |
Homozygosity at HLA-DQA1 locus |
| Graft-vs-host disease |
7 to 24 months post BMT |
| Granulomatous |
Sarcoid; Immune; Infections |
| Sarcoidosis |
Myopathy; Neuropathy; Lung disease |
| Malignancy (Necrotic) |
Rapid onset; Older patients; Necrotic myopathy |
| Mitochondrial (P-COX) |
Quadriceps weakness;
Older onset age; Steroid resistant |
| Other systemic disorders |
HIV; Fasciitis |
Polymyositis Treatment
Polymyositis is an autoimmune disease and therefore therapy is directed
at altering a patient’s immune system. All of these therapies therefore
have some significant risk of side effects and Polymyositis treatment
needs to be undertaken only with physicians accustomed to using these
medications and to monitoring their side effects. Corticosteroids are
often used as a first line therapy to treat polymyositis because they
decrease the muscle inflammation. These can be effective in a matter
of weeks. If corticosteroids are ineffective, other immunosuppressive
medications may be given such as azathioprine, mycophenylate mofetil,
cyclosporine, or methotrexate. Intravenous immunoglobulin has also been
shown to be effective in very refractory cases.
Polymyositis Cure
In most people once this disease begins there is no clear way to cure
Polymyositis. There are however several effective treatments which exist
that can improve a person’s muscle strength. In most cases people can
resume their usual level of function. Further research is being done
and it is hopeful that within years a cure for polymyositis will be found.
Polymyositis Research
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