Emery Dreifuss Muscular Dystrophy

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Original Editors - Kori Ivanchak & Madelaine Nolan from Bellarmine University's Pathophysiology of Complex Patient Problems project.

Top Contributors - Madelaine Nolan, Kim Jackson, Rucha Gadgil, Elaine Lonnemann, Wendy Walker, Evan Thomas, WikiSysop, Meaghan Rieke, Lucinda hampton, Kehinde Fatola and Shreya Pavaskar  

Definition/Description

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Prevalence

There are approximately 250,000 individuals in the United States affected by some type of muscular dystrophy.

The incidence of X-linked Emery Dreifuss Muscular Dystrophy is estimated to affect 1 in 100,000 people in the general population, and it is believed to be the third most common type of muscular dystrophy. X-linked EDMD is fully expressed in males only; however, 10-20% of female carriers for X-linked EDMD will develop heart conduction defects and/or muscle weakness.

The frequency of autosomal dominant EDMD is unknown. The autosomal recessive type of the disorder is very rare, with only a few reported cases worldwide. The autosomal types of EDMD affect males and females equally. 

Characteristics/Clinical Presentation

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Associated Co-morbidities

Individuals with EDMD present with a wide variety of cardiac abnormalities including atrial standstill, atrial fibrillation, congestive heart failure, and cardioembolic stroke. The population is at high risk for devloping severe bradyarrhythmias which carries a risk of sudden death, and supraventricular tachyarrhythmias which are associated with a high risk for thromboembolic stroke.  It is important to note that cardiac and muscular involvement have not been shown to be closesly related, with cases of severe cardiomyopathy occuring in patients with only mild muscular symptoms. It is possible for stroke to be the first clinical manifestation of EDMD.

Medications

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Diagnostic Tests/Lab Tests/Lab Values

Clinical Diagnosis

The clinical diagnosis of EDMD is made based on the presence of the triad that characterizes it:

1. Early Contractures
2. Slowly progressive wasting and weakness of the humero-peroneal muscles
3. Cardiac conduction defects and arrhythmias

Other Nonspecific Clinical Findings

• Electromyogram (EMG) usually show myopathic features with normal nerve conduction studies. However, neuropathic patterns have been discovered in X-Linked EDMD and autosomal dominant EDMD.
• CT scan shows a diffuse pattern of involvement in muscles including the biceps, soleus, peroneal, external vasti, gluteus, and paravertebral muscles. Findings in the calf and posterior thigh have been reported in patients with Autosomal Dominant EDMD.

Nonspecific Laboratory Findings

• Serum CK Concentration may be normal or moderately elevated up to 2-20x upper normal level. Increases are seen more often at the beginning of the disease as opposed to later stages.
• Muscle Histopathology shows nonspecific myopathic or dystrophic changes: variation in fiber size, increase in internal nuclei, increase in endomysial connective tissue, necrotic fibers. Electron Microscopy may show specific alterations in nuclear architecture. Muscle Biopsy is rarely performed for diagnostic purposes due to lack of specificity.

Immunodetection of Emerin (detected by immunofluorescence and/or by western blot): Absent in 95% of individuals with X-Linked EDMD. Normally expressed in individuals with Autosomal Dominant EDMD. Immunodetection of FHL1 (detected by immunofluorescence and/or by western blot): Absent or significantly decreased in individuals with FHL1-related X-Linked EDMD.

Genetic Testing

Genetic testing can determine the presence of particular defects that cause EDMD and can help predict the course of the disease, as well as help assess the risk of passing the disease on to the next generation.

 

Etiology/Causes

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Systemic Involvement

Emery Dreifuss Muscular Dystrophy affects voluntary muscles, as well as the heart. Symptoms typically reveal themselves by the age of 10. Early symptoms include weakness and atrophy in a humero-peroneal distribution, that will eventually affect the scapular and pelvic girdle muscles. Contractures will occur, and can make arm, neck, ankle, and spine movements difficult, leading to to "toe-walking" and difficulty bending the elbows.

Cardiac conduction defecits and arrythmias may occur, resulting in dilated cardiac myopathy, poor exercise tolerance, bradycardia, syncope, congestive heart failure, and an increased risk of stroke and sudden death.

Women who are genetic carriers for X-linked EDMD may also be at risk for cardiac problems, with the risk increasing with age. However, carriers tend not to present with muscle weakness or contractures.  

Medical Management (current best evidence)

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Physical Therapy Management (current best evidence)

Physical Therapy for patients with Emery Dreifuss Muscular Dystrophy is centered on treating the impairments that result from the disease. Active and passive exercises to build muscle strength and prevent contractures are the primary focus. Assistive devices including canes, braces, and wheelchairs may be used to aid in ambulation.

Alternative/Holistic Management (current best evidence)

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Differential Diagnosis

Emery Dreifuss Muscular Dystrophy must be differentiated from other diagnoses, primarily, the other types of muscular dystrophies. 

• Duchenne Muscular Dystrophy- First recognized at age 3 to 6. Characterized by muscle weakness and atrophy starting in the pelvic area, progressing to shoulders, and eventually most major muscles of the body.
• Becker Muscular Dystrophy- Begins during second or third decade of life. Affects males almost exclusively. Hip and shoulder muscles are weakened, gait abnormalities develop, as well as possible mild mental retardation.
• Fascioscapulohumeral Muscular Dystrophy (Landouzy-Dejerine Muscular Dystrophy)- Onset is usually during adolescence or early adulthood. Characterized by weakness of facial, shoulder, and upper arm muscles. Impaired ability to close eyes, move the lips, and raise arms overhead may occur. Eventually weakness and atrophy may affect the lower extremity as well.
• Limb Girdle Muscular Dystrophy- a group of rare progressive genetic disorders characterized by atrophy and weakness of the hip and shoulder girdles.
• Rigid Spine Syndrome- rare neuromuscular disorder characterized by hypotonia, weakness, contractures, and atrophy of muscles. Scoliosis often occurs. May occur in conjunction with EDMD. 
• Myopathies- Diseases to consider may include Pompe disease, dermatomyositis, polymyositis, and nemaline myopathy.
• Myasthenia Gravis- autoimmune disorder of the peripheral nerves characterized by weakness with repetitive use of a muscle, followed by recovery during a period of rest. Most commonly affects the bulbar muscles with fluctuating generalized weakness.
• Spinal Muscular Atrophy- Presents with weakness and atrophy in the limbs, respiratory, and bulbar muscles.

Case Reports/ Case Studies

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Resources

Resources for patients and families affected by Emery Dreifuss Muscular Dystrophy:

The Muscular Dystrophy Association mda.org/

National Libray of Medicine Genetics Home Reference ghr.nlm.nih.gov/condition/emery-dreifuss-muscular-dystrophy

Muscular Dystrophy Campaign www.muscular-dystrophy.org/

World Muscle Society www.worldmusclesociety.org/

Support Groups mda.org/services/finding-support/support-groups

NIH/National Institute of Neurological Disorders and Stroke www.ninds.nih.gov/

Children's Cardiomyopathy Foundation www.childrenscardiomyopathy.org

New Horizons Unlimited www.new-horizons.org

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Genetic and Rare Diseases (GARD) Information Center rarediseases.info.nih.gov/GARD/AboutGARD.aspx

Madisons Foundation www.madisonsfoundation.org

Cure CMD (Congenital Muscular Dystrophy) www.curecmd.org

Child Neurology Foundation [[ http://www.childneurologyfoundation.org%7Cwww.childneurologyfoundation.org]]

Recent Related Research (from Pubmed)

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References

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