Myopathy refers to diseases that affect skeletal muscles (muscles that connect to your bones). These diseases attack muscle fibers, making your muscles weak.
Having a family history of myopathy. This increases the likelihood you might inherit an abnormal gene that causes muscle disease.
Being designated male at birth (DMAB). Some myopathies are carried on the X chromosome, and actually affect more men than women. Other inherited forms of myopathy carried on other chromosomes affect all sexes equally.
Having an autoimmune, metabolic or endocrine disorder.
Being exposed to certain medications or toxins (see toxic myopathy below for a list of some of these medications).
Muscle weakness, most commonly of your upper arms and shoulders and thighs (more common and more severe).
Muscle cramps, stiffness and spasms.
Fatigue with exertion.
Lack of energy.
Blood tests - Muscle enzymes such as creatine kinase (CK) or aldolase may be elevated in certain myopathies as a result of the breakdown of muscle fibers.
Electrolyte levels such as sodium, magnesium, potassium, calcium and phosphorus.
Autoimmune disease testing such as antinuclear antibodies (ANA), rheumatoid factor, sedimentation rate and c-reactive protein.
Endocrine testing such as thyroid hormone.
Electromyography (EMG and nerve conduction studies), including testing the electrical conduction of your nerves and needle examination of your muscles to assess the type and degree of muscle damage.
Magnetic resonance imaging (MRI) of your muscles.
Muscle biopsy, in which your healthcare provider surgically removes a small piece of muscle tissue for testing.
Inflammatory and autoimmune-related myopathies
The goal of treatment is to decrease inflammation and your body’s autoimmune response. These myopathies are often treated with:
Immunomodulatory/immunosuppressant drugs such as methotrexate, cyclosporine, tacrolimus, azathioprine, mycophenolate, rituximab and intravenous (IVIg) or subcutaneous (SubQIg) immunoglobulin.
Corticosteroids such as prednisone or methylprednisolone.
Inherited and genetic myopathies
Most inherited and genetic myopathies don’t have a specific treatment or cure.
Management is largely based on symptom control and different forms of therapy.
There are multiple ongoing clinical trials in various areas of research looking at treatments and gene therapy.
Duchenne muscular dystrophy and Pompe disease are disorders that can be treated with specific medication.
Other acquired myopathies
Healthcare providers manage acquired myopathies including endocrine, toxic and infectious myopathies by treating the underlying disease causing the myopathy.
Toxin-related myopathies are treated by stopping the offending agent (alcohol or toluene, for example) or medication (statins, for example).
Muscle symptoms that result from infections caused by bacteria, viruses or other infectious organisms are improved by treating the infection directly with antibiotics.