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.

Cause of Polymyositis
Cures for Polymyositis
Polymyositis Treatment
Polymyositis Research