Muscular Dystrophy

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Muscular Dystrophy

• Definition
• Refers to a group of hereditary progressive
  diseases. Muscular Dystrophy affects muscular
  strength and action, some of which first become
  obvious in infancy, and others which develop in
  adolescence or young adulthood. The syndromes
  are marked by either generalized or localized
  muscle weakness, difficulties with walking or
  maintaining posture, muscle spasms, and in some
  instances, neurological, behavioral, cardiac, or
  other functional limitations.
  

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Progressive Muscular Dystrophy
Type Onset Age (years) Clinical Features Other organ systems involved
Duchenne Before 5 Progressive weakness of girdle muscles. unable to walk after age 12 progressive kyphoscoliosis Respiratory failure in 2dor 3d decade. Cardiomyopathy Mental impairment
Becker 5-25yr early childhood to adult Progressive weakness of girdle muscles 2. able to walk after age 15. 3. respiratory failure may develop by 4th grade Cardiomyopathy
Emery-Dreifuss Childhood to adult Elbow contractures, humeral and perineal weakness Cardiomyopathy
Limb-Girdle early childhood to adult Slow progressive weakness of shoulder and hip girdle muscles Cardiomyopathy
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Progressive Muscular Dystrophy
Type Onset Age (years) Clinical Features Other organ systems involved
Congenital At birth or within 1st few months .Hypotonia, contractures, delayed milestones Progression to respiratory failure in some CNS and Eye abnormalities
Facioscapulohumeral Before age 20 Slowly progressive weakness of face, shoulder girdle, and foot dorsiflexion Deafness Coats (eye) disease
Oculopharyngeal 5th to 6th decade Slowly progressive weakness of extraocular, pharyngeal, and limb muscles ______
Myotonic Usually 2nd decade May be infancy if mother affected Slowly progressive weakness of face, shoulder girdle, and foot dorsiflexion Cardiac conduction defects Mental impairment Cataracts Frontal baldness Gonadal atrophy
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Pathophysiologic the exact mechanism is unknown,
but there are 3 theories

• Vascular theory the lack of blood flow causes
  the typical degeneration of muscle tissue.
• Neurogenic theory Disturbance in nerve-muscle
  interaction.
• Membrane theory the cell membranes are
  genetically altered, causing a compromise in cell
  integrity. An increase in the activity of muscle
  proteolytic enzymes may accompany the membrane
  alteration. Leaving the muscle cell vulnerable to
  degeneration.

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Symptoms

• Muscle weakness
• Delayed development of muscle motor skills
• Problems walking (delayed walking)
• Difficulty using one or more muscle groups
  (depends on the type of dystrophy)
• Eyelid drooping (ptosis)
• Drooling
• Hypotonia
• Mental retardation ( only present in some types
  of MD)
• Joint contractures (clubfoot, clawhand or others)
• Scoliosis

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Signs and Tests

• Examination and history help to distinguish the
  type of MD. Specific muscle groups are affected
  by different types of MD. Often, there is a loss
  of muscle mass (wasting), which may be disguised
  in some types of muscular dystrophy by an
  accumulation of fat and connective tissuethat
  makes the muscle appear larger (pseudohypertrophy)
  .Joint contractures are common. Shortening of
  the muscle fibers, fibrosis of the connective
  tissue and scarring slowly destroy muscle
  function. Some types of MD involve the heart
  muscle, causing cardiomyopathy or arrhythmias.A
  muscle biopsy may be the primary test used to
  confirm the diagnosis. In some cases a DNA test
  from the blood may be sufficient.

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Laboratory Test

• Muscle biopsy the primary test used to confirm
  the diagnosis.
• DNA test
• Serum CPK (creatine phosphokinase-an enzyme
  found in muscle) may be elevated.
• EMG (electromyography) may confirm that weakness
  is caused by destruction of muscle tissue rather
  than damage to nerves.
• ECG (electrocardiography) to monitor changes in
  cardiac status.
• Myoglobin - urine/ serum    When muscle is
  damaged, the myoglobin is released into the
  bloodstream. It is filtered out of the
  bloodstream by the kidneys, and eliminated in
  urine. In large quantities, myoglobin can damage
  the kidney and break down into toxic compounds,
  causing kidney failure.
• LDH   LDH is most often measured to evaluate the
  presence of tissue damage. The enzyme LDH is in
  many body tissues, especially the heart, liver,
  kidney, skeletal muscle, brain, blood cells, and
  lungs.
• Creatinine A normal (usual) value is 0.8 to 1.4
  mg/dl.  Creatinine is a breakdown product of
  creatine, which is an important constituent of
  muscle. A serum creatinine test measures the
  amount of creatinine in the blood. 
  Greater-than-normal levels may indicate Muscular
  dystrophy. Lower-than-normal levels may indicate
  Muscular dystrophy (late stage)
• AST The normal range is 10 to 34 IU/L. An
  increase has many indications, one of them being
  progressive MD.
• Aldolase Why the test is performed?   This test
  is indicator ofmuscle damage.

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Nursing Diagnosis

• Impaired mobility, activity intolerance, risk
  for injury, risk for aspiration, risk for
  impaired skin integrity, self-care deficit,
  knowledge deficit, caregiver role strain, low
  self-esteem, social isolation, disturbed body
  image, and hopeless to name a few.

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Nursing Implications and interventions

• Multidisciplinary. Care for these patients
  involves arranging for consultations with
  physical therapy, occupational therapy,
  respiratory therapy, speech therapy, psychosocial
  therapy, and dieticians.
• Reinforce techniques learned in all of the above
  therapies.
• Educate client and family members thoroughly
  about expected outcomes and possible problems.
• Encourage exercise while teaching s/s of
  exercise overload feeling weaker rather than
  stronger after exercise, excessive muscle
  soreness, severe muscle cramping, heaviness of
  extremities, and prolonged shortness of breath.
• Ensure braces are a good fit to prevent pressure
  ulcers and promote stability.
• Have equipment (braces, wheelchairs) evaluated
  by PT, OT to ensure proper fit.
• Be sensitive to psychosocial needs and make
  appropriate referrals.
• Refer to support groups and clinics.

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Bibliography

• Cart, Greg. Rehabilitation Management of
  Neuromuscular Disease. http//www.emedicine.com
  /pmr/topic233.htm.
• Cox, Helen C., RN, C, EdD, FAAN. Clinical
  Applications of Nursing Diagnosis. 4th Edition.
  F.A. Davis Company. Philadelphia, PA 2002.
• Ignatavicius, Donna, MS, RN, CM.
  Medical-Surgical Nursing. 4th Edition. W.B.
  Saunders Company. Philadelphia, PA 2002.
• Muscular Dystrophy Association website
  http//www.mdausa.org.
• Harrisons Principles of internal Medicine 15th
  edition, McGraw-Hill Medical Publishing Division,
  New York. 2002.