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Overview |
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Definition |
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Muscular dystrophies comprise a group of genetic diseases characterized by
atrophy of muscle tissue and progressive weakness. There are nine clinically
distinct muscular dystrophies.
- Duchenne muscular dystrophy (DMD), the most common form of muscular
dystrophy in children
- Becker muscular dystrophy (BMD), identical to DMD except for age at
onset
- myotonic muscular dystrophy (DM), the most common form of muscular
dystrophy in adults
- congenital muscular dystrophy (CMD), a severe form of DM in infants
- limb-girdle muscular dystrophy (LGMD)
- facioscapulohumeral muscular dystrophy (FSH)
- oculopharyngeal muscular dystrophy (OPMD)
- distal muscular dystrophy (DD)
- Emery-Dreifuss muscular dystrophy (EDMD).
DMD, BMD, DM, and CMD will serve as the focus of this information. The
incidences for DMD, BMD, and DM are 30 in 100,000, 3 in 100,000, 13.5 in
100,000, respectively. |
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Etiology |
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All of the muscular dystrophies are caused by gene mutations. DMD and BMD are
characterized by an X-linked recessive mutation of the dystrophin gene,
affecting males only. DM is an autosomal dominant disorder that is transmitted
by a mutation of the gene on chromosome 19, affecting males and females. The
mutation consists of an unstable expansion of the trinucleotide sequence
(cytosine, thymine, guanidine, or CTG) in muscle cells. |
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Risk Factors |
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Individuals from families in which muscular dystrophy has been identified are
at increased risk of passing the disease to their offspring. Genetic counseling
can help these families make informed reproductive decisions. One-third of cases
are sporadic with no family history. |
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Signs and Symptoms |
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DMD: Although the disease is present at birth, signs and symptoms are not
usually evident until age 3 to 5. These include frequent falls; difficulty
running, jumping, and getting up from a sitting or lying-down position; a
waddling gait; large calf muscles (pseudohypertrophy from adipose and connective
tissue replacing muscle); toe walking; pronounced weakness in the proximal lower
extremities; and mild mental retardation. Respiratory difficulties, often the
result of thoracic scoliosis, and cardiomyopathy develop during adolescence,
usually after patients become wheelchair-bound.
BMD: Early signs resemble those of DMD but occur later between ages 5 and 15
and progress gradually. Cardiac problems may result in heart failure. Patients
may be ambulatory into their 30s and 40s.
DM: Myotonia, delayed muscle relaxation after contraction, and dystrophic
changes in nonmuscular tissue are the hallmarks of DM. Atrophy of facial muscles
resulting in a "hatchet face"; baldness in men and women; weakness in the distal
muscles of the extremities, resulting in weak hand muscles and footdrop;
weakness of pharyngeal, tongue, palatal, and esophageal muscles, affecting
speech and swallowing; cataracts; testicular atrophy or ovarian insufficiency;
intellectual impairment; respiratory insufficiency; and cardiac abnormalities
present in early adulthood.
CMD: Children are severely hypotonic, with facial diplegia, respiratory
difficulties, feeding difficulties, skeletal deformities, and developmental
delay. |
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Differential
Diagnosis |
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- Neuromuscular disease
- Dermatomyositis
- Polymyositis
- Spinal muscular atrophy
- Metabolic and inflammatory myopathies
- Centronuclear and mitochondrial
myopathies
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Diagnosis |
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Physical Examination |
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Children often present with delay in walking, and adults and adolescents
present with progressive muscle weakness. Considerable clinical variability
exists, making sophisticated testing mandatory for a definitive
diagnosis. |
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Laboratory Tests |
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Measurement of serum creatine phosphokinase levels, which are elevated 20 to
100 times normal in DMD and BMD. |
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Imaging |
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Used to assess specific deformities such as equinocavovarus
foot. |
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Other Diagnostic
Procedures |
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- Electromyography (EMG)–detects myopathy in
DMD and myotonia in DM
- Electrocardiogram (ECG)–determines the extent
and type of cardiac abnormalities
- Muscle biopsy—in DMD, identifies
disorganization of muscle fibers and necrosis; in DM, identifies muscle atrophy
- Western blot analysis—identifies protein
products from muscle cells and determines dystrophin levels in DMD and BMD to
confirm the diagnosis and to predict the severity
- Polymerase chain reaction and Southern blot
analysis—in DMD and BMD, determines the mutation of the
dystrophin gene (e.g., deletion, duplication, point mutation); in DM, determines
the number of CTG repeats and predicits the severity of the phenotype
- Linkage analysis—finds genetic loci on DNA
and identifies at-risk female relatives
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Treatment Options |
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Treatment Strategy |
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Muscular dystrophies are incurable, progressive, and fatal. Treatment
regimens are designed to maintain optimal physical and emotional health by
preventing joint and spinal deformities in order to prolong ambulation for as
long as possible. Assisted ventilation is introduced as needed, usually to treat
hypoxia at night but eventually progressing to daytime use as well.
Lifelong physiotherapy is essential to prevent or delay complications such as
painful contractures, loss of ambulation, scoliosis, hypoventilation, and
respiratory failure. Daily passive stretching exercises and orthopedic
appliances (e.g., braces, calipers, night splints), which are used for support
when the muscles become too weak, may prolong ambulation. Hydrotherapy helps to
maintain full range of joint motion. |
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Drug Therapies |
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- Prednisone (0.75 to 1.5 mg/kg/day)—to improve
muscle strength in DMD for up to three years; side effects of obesity,
hypertension, and diabetes limit its use
- Phenytoin (100 mg tid), quinine (300 to 400 mg tid), and procainamide
(0.5 to 1 g qid)—to treat myotonia; caution is required
as quinine and procainamide worsen cardiac
conduction
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Surgical Procedures |
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- Spinal surgery—to correct scoliosis when the
curve is more than 20 degrees
- Tenotomy—to release contractures of the hip,
knees, and Achilles tendon
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Complementary and Alternative
Therapies |
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Diet and nutritional supplements may aid in optimizing overall health. Herbal
treatments can be helpful in addressing symptomatic complaints.
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Nutrition |
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- Emphasize an anti-inflammatory diet, including organic whole foods
such as whole grains, vegetables, fruit, legumes, sea vegetables, and essential
fatty acids (nuts, seeds, and cold-water fish).
- Avoid refined foods, saturated fats (dairy and other animal products),
and all known food allergens.
- Essential fatty acids (e.g., flax, borage, evening primrose, cod
liver) 1,000 to 1,500 mg bid to tid.
- Vitamin E (400 to 800 IU/day), selenium (100 to 200 mcg/day), coenzyme
Q10 (100 mg one to three times/day) are antioxidant nutrients that are
cardioprotective. Coenzyme Q10 also helps oxygenates tissues and alleviates pain
and muscle fatigue while increasing endurance.
- L-carnitine (320 mg once to twice/day) improves the energy metabolism
of the cell.
- B-complex vitamins, especially B12 (1,000 mcg/day) and B6 (100
mg/day), and minerals, such as calcium (1,000 mg/day), magnesium (500 mg/day),
and potassium (100 mg/day), optimize nerve function and conductivity.
- Glutathione (500 mg bid) provides antioxidant protection. However,
oral glutathione may be broken down to its constituent amino acids in the gut,
decreasing its effectiveness.
- N-acetyl cysteine (500 mg bid) is a precursor to glutathione and
enhances pulmonary function.
- Creatine (5 to 7 g/day) may improve intracellular metabolism and
prevents muscle wasting.
- Consider branched chain keto-acids, which reduce muscle protein
degradation.
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Herbs |
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Herbs may be used as dried extracts (pills, capsules, or tablets), teas, or
tinctures (alcohol extraction, unless otherwise noted). Dose is 1 heaping tsp.
herb/cup water steeped for 10 minutes (roots need 20 minutes).
Combine three of the following herbs in equal parts and add two to three
others as needed.
- Mineral-rich herbs: horsetail (Equisetum arvense), nettles
(Urtica dioica), oatstraw (Avena sativa), and kelp (Laminaria
cloustonii)
- With spasm, add black cohosh (Cimicifuga racemosa), cramp bark
(Viburnum opulus).
- With muscle pain, add Jamaica dogwood (Piscidia erythrina),
meadowsweet (Filipendula ulmaria).
- With cardiac involvement, add hawthorn (Crataegus monogyna),
rosemary (Rosemarinus
officinalis).
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Homeopathy |
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May be helpful in strengthening overall health. An experienced homeopath
would consider the individual's constitution.
Topical preparations containing Arnica may provide symptomatic relief
of spasm and muscle pain.
- Causticum (30C) once or twice daily for incontinence
- Magnesia phosphorica (30C) bid for pain with cramps, neuralgic
pain
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Massage |
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Regular massage therapy is essential for minimizing spasm and contractures.
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Patient Monitoring |
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Physicians must perform electrocardiography, pulmonary function studies, and
chest radiographs yearly to monitor cardiac and pulmonary function, and
selective tests to monitor swallowing function. Treatment of respiratory
conditions and typical childhood diseases must be aggressive and prompt,
particularly in patients who are no longer
ambulatory. |
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Other
Considerations |
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Complications/Sequelae |
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- Painful contractures complicate the course of muscular
dystrophy.
- Impaired respiratory function (i.e., hypoventilation, difficulty
clearing secretions) results from scoliosis and lack of ambulation
- Cardiomyopathy (10% of DMD patients) may cause death from congestive
heart failure within two to three years; cardiac decompensation is common in
CMD
- Obesity is common when patients stop walking, and malnutrition can
appear later when swallowing disorders
develop.
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Prognosis |
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Prognosis is variable, depending on the type and severity of the particular
muscular dystrophy. Death in most cases results from infections, respiratory
insufficiency, or cardiac failure. DMD patients usually die in their 20s, BMD
patients in their 50s (although some live a normal life span), and DM patients
in their 40s or 50s. Many patients with CMD die in infancy, but if they survive
to adolescence, they follow a clinical course similar to
DM. |
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Pregnancy |
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Amniocentesis or chorionic villi sampling can detect gene mutations for
prenatal diagnosis. Successive generations of patients with DM have an increased
severity of the clinical phenotype. CMD always occurs in the infants of affected
mothers; thus, these mothers should be referred for genetic
counseling. |
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References |
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Adams RD, et al. Principles of Neurology. 6th ed. New York,
NY: McGraw-Hill; 1997: 1414–1429.
Bartram T. Encyclopedia of Herbal Medicine. Dorset, England: Grace
Publishers; 1995:301.
Edstrom L. Dystrophia myotonica: clinical pathophysiological, and molecular
aspects. Scand J Rehab Med Suppl. 1999; 39:
47–52.
Fauci AS, et al. Harrison's Principles of Internal Medicine.
14th ed. New York, NY: McGraw-Hill; 1998:
2473–2477.
Forst J, Forst R. Lower limb surgery in Duchenne muscular dystrophy.
Neuromuscul Disord. December 9, 1999:
176–181.
Gaby AR. The role of coenzyme Q10 in clinical medicine: Part 1. Alt Med
Rev. 1996; 1(1):11-17.
Kakulas BA. Problems and solutions in the rehabilitation of patients with
progressive muscular dystrophy. Scand J Rehab Med Suppl. 1999; 39:
23-37.
Kroksmark A-K. Physiotherapy in muscular dystrophy. Scand J Rehab Med
Suppl. 1999; 39: 65-68.
Leger P, Leger SS. Respiratory concerns in Duchenne muscular dystrophy.
Pediatr Pulmonology. 1997; 16 (suppl):
137–139.
Samuels MA, Feske S. Office Practice of Neurology. New York, NY:
Churchill Livingstone; 1996; 577–587.
Simon RP, et al. Clinical Neurology. 4th ed. Stamford, CT:
Appleton & Langel; 1999: 189–192.
Stewart PM, Walser M, Drachman DB. Branched chain keto-acids reduce muscle
protein degradation in Duchennes muscular dystrophy. Muscle Nerve. 1982;
(3): 197-201.
Tarnopolsky M. Creatine Monohydrate increases strength in patients with
neuromuscular disease. Neurology. 1999, (52):
854-857. |
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Copyright © 2000 Integrative Medicine
Communications This publication contains
information relating to general principles
of medical care that should not in any event be construed as specific
instructions for individual patients. The publisher does not accept any
responsibility for the accuracy of the information or the consequences arising
from the application, use, or misuse of any of the information contained herein,
including any injury and/or damage to any person or property as a matter of
product liability, negligence, or otherwise. No warranty, expressed or implied,
is made in regard to the contents of this material. No claims or endorsements
are made for any drugs or compounds currently marketed or in investigative use.
The reader is advised to check product information (including package inserts)
for changes and new information regarding dosage, precautions, warnings,
interactions, and contraindications before administering any drug, herb, or
supplement discussed herein. | |