Facioscapulohumeral muscular dystrophy is a disorder characterized by progressive muscle weakness and loss of muscle tissue, primarily affecting the face, shoulder, and upper arm muscles.
Causes, incidence, and risk factors
Facioscapulohumeral muscular dystrophy is a type of muscular dystrophy that affects the upper body, unlike some other types that affect primarily the lower body (including Duchenne muscular dystrophy and Becker muscular dystrophy ). It is a genetic disorder with a autosomal dominant inheritance pattern (the disorder appears in men and women and may develop if either parent carries the gene for the disorder). This disorder is extremely variable in the extent and severity of the symptoms, and in the age when symptoms appear. Symptoms often do not appear until ages 10 to 26, but it is not uncommon for symptoms to appear much later. In some cases, symptoms never develop. Symptoms are usually mild and very slowly progressive. Facial muscle weakness is common. Shoulder muscle weakness causes deformities such as scapular winging and sloping shoulders. There is difficulty raising the arms because of shoulder and arm muscle weakness. Weakness of the lower legs is possible as the disorder progresses and can be severe enough to interfere with walking. Other body systems are usually not affected, and intellectual function is normal. Facioscapulohumeral muscular dystrophy affects approximately 5 out of 100,000 people. It affects men and women equally.
Signs and tests
An examination indicates weakness of the facial and shoulder muscles. Involvement of other body symptoms (such as the lungs and heart) is rare. High blood pressure ( hypertension ) may occur but is usually mild.
A serum creatine kinase may be slightly elevated.
An EMG ( electromyography ) may be nonspecific or may have mixed features of muscle and nerve involvement.
A muscle biopsy may be nonspecific, or may confirm the diagnosis.
A hearing test may indicate hearing loss An electrocardiogram (EKG) may indicate abnormal heart rhythm
Treatment
There is no known cure for facioscapulohumeral muscular dystrophy. Treatment is aimed at control of the symptoms to maximize the quality of life. Activity is encouraged. Inactivity (such as bedrest) can worsen the muscle disease. Physical therapy may be helpful to maintain muscle strength. Genetic counseling may be advised before having children.
Expectations (prognosis)
Progressive disability occurs very slowly with facioscapulohumeral muscular dystrophy. The patient's disability is often minor and life span is usually not affected.
Calling your health care provider
Call for an appointment with your health care provider if symptoms indicate facioscapulohumeral muscular dystrophy may be present. Call for an appointment with your health care provider if you are planning a family and facioscapulohumeral muscular dystrophy has been diagnosed in yourself, your spouse, or family members.
Prevention
Genetic counseling may be advised if there is a family history of facioscapulohumeral muscular dystrophy.