The myopathies are neuromuscular disorders in which the primary symptom is muscle weakness due to dysfunction of muscle fiber. Other symptoms of myopathy can include include muscle cramps, stiffness, and spasm. Myopathies can be inherited (such as the muscular dystrophies) or acquired (such as common muscle cramps). Myopathies are grouped as follows:
congenital myopathies: characterized by developmental delays in motor skills; skeletal and facial abnormalities are occasionally evident at birth
muscular dystrophies: characterized by progressive weakness in voluntary muscles; sometimes evident at birth
mitochondrial myopathies: caused by genetic abnormalities in mitochondria, cellular structures that control energy; include Kearns-Sayre syndrome, MELAS and MERRF
glycogen storage diseases of muscle: caused by mutations in genes controlling enzymes that metabolize glycogen and glucose (blood sugar); include Pompe's, Andersen's and Cori's diseases
myoglobinurias: caused by disorders in the metabolism of a fuel (myoglobin) necessary for muscle work; include McArdle, Tarui, and DiMauro diseases
dermatomyositis: an inflammatory myopathy of skin and muscle
myositis ossificans: characterized by bone growing in muscle tissue
familial periodic paralysis: characterized by episodes of weakness in the arms and legs
polymyositis, inclusion body myositis, and related myopathies: inflammatory myopathies of skeletal muscle
neuromyotonia: characterized by alternating episodes of twitching and stiffness; and
stiff-man syndrome: characterized by episodes of rigidity and reflex spasms
common muscle cramps and stiffness, and
tetany: characterized by prolonged spasms of the arms and legs
Treatments for the myopathies depend on the disease or condition and specific causes. Supportive and symptomatic treatment may be the only treatment available or necessary for some disorders. Treatment for other disorders may include drug therapy, such as immunosuppressives, physical therapy, bracing to support weakened muscles, and surgery.
The prognosis for individuals with a myopathy varies. Some individuals have a normal life span and little or no disability. For others, however, the disorder may be progressive, severely disabling, life-threatening, or fatal.
The NINDS supports and conducts an extensive research program on neuromuscular disorders such as the myopathies. Much of this research is aimed at increasing scientific understanding of these disorders, and finding ways to prevent, treat, and cure them.
National Institute of Arthritis and
Musculoskeletal and Skin Diseases (NIAMS)
National Institutes of Health, DHHS
31 Center Dr., Rm. 4C02 MSC 2350
Bethesda, MD 20892-2350
Tel: 301-496-8190 877-22-NIAMS (226-4267)
Muscular Dystrophy Association
National Office - 222 S. Riverside Plaza
Chicago, IL 60606
Office of Communications and Public Liaison
National Institute of Neurological Disorders and Stroke
National Institutes of Health
Bethesda, MD 20892
NINDS health-related material is provided for information purposes only and does not necessarily represent endorsement by or an official position of the National Institute of Neurological Disorders and Stroke or any other Federal agency. Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient's medical history.
All NINDS-prepared information is in the public domain and may be freely copied. Credit to the NINDS or the NIH is appreciated.
Last Modified July 8, 2015