Myopathy

Muscle diseases present with weakness, but not all weakness is due to a specific muscle disease. Some people have weakness because they get out of shape or after a serious illnesses.

However, disease of muscle (myopathy) can cause significant weakness as well. There are many different types of myopathy. General symptoms include weakness of limbs, usually proximally (located close to the center of the body). Depending upon the type of myopathy, one muscle group may be more affected than another. In younger people, genetic causes (muscular dystrophy and congenital myopathies) predominate. In older patients inflammatory causes (polymyositis, inclusion body myositis) are somewhat more common, but toxic causes such as heavy alcohol use and certain medications may also cause muscle problems. Myopathy can also result from endocrine disorders and metabolic disorders.

Most muscle problems should be evaluated by a neurologist or rheumatologist. EMG testing and frequently muscle biopsies are needed to make a specific diagnosis. Of all the causes for myopathies, the inflammatory ones are the only ones with specific treatments.

More information at:
National Institute of Neurological Disorders and Stroke (NINDS)
Muscular Dystrophy Association