Muscular Dystrophy

DefinitionRefers 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.

Progressive Muscular Dystrophy

Type Onset Age (years) Clinical Features Other organ systems involved

Duchenne Before 5 1.Progressive weakness of girdle muscles.2.unable to walk after age 123.progressive kyphoscoliosis4.Respiratory failure in 2dor 3d decade.

CardiomyopathyMental impairment

Becker 5-25yr

early childhood to adult 1.Progressive weakness of girdle muscles2. able to walk after age 15.1.3. 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

Progressive Muscular DystrophyType Onset Age (years) Clinical Features Other organ systems involved

Congenital At birth or within 1st few months

.Hypotonia, contractures, delayed milestonesProgression to respiratory failure in some;

CNS andEye abnormalities

Facioscapulohumeral Before age 20 Slowly progressive weakness of face, shoulder girdle, and foot dorsiflexion

DeafnessCoat’s (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 defectsMental impairment CataractsFrontal baldnessGonadal atrophy

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.

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

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.

Laboratory TestMuscle 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.

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.

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.

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.

• Harrison’s Principles of internal Medicine 15th edition, McGraw-Hill Medical Publishing Division, New York. 2002.