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Muscular Dystrophy: A Quick Overview

Contact Hours: 4

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Contact Hours: 4

This educational activity is credited for 4 contact hours at completion of the activity.

Course Purpose

The purpose of this course is to provide healthcare professionals with a brief overview of muscular dystrophy, its types, how the various types are diagnosed, and interventions to help manage the condition.

Overview

The term “muscular dystrophy” incorporates an assortment of hereditary disorders that lead to progressive, generalized disease of the muscle prompted by inadequate or missing glycoproteins in the muscle cell plasma membrane. Each form of muscular dystrophy has its own pattern of inheritance, onset period, signs and symptoms, and the rate at which muscle is lost. This course will overview muscular dystrophy, its types, how they are diagnosed, and interventions to help manage the condition.

Course Objectives

Upon completion of this course, the learner will be able to:

  • Review the various types of muscular dystrophy and the areas of the body they are likely to affect.
  • Review the pathophysiology as it relates to muscular dystrophy.
  • Understand the diagnostic and laboratory data used to diagnose muscular dystrophy.
  • Analyze nonpharmacological management of patients who are in the  ambulatory and non-ambulatory stages of muscular dystrophy disease progression.
  • Recognize nursing considerations that may be utilized when caring for a patient with muscular dystrophy.

Policy Statement

This activity has been planned and implemented in accordance with the policies of FastCEForLess.com.

Disclosures

Fast CE For Less, Inc and its authors have no disclosures. There is no commercial support.

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Definitions
Angiotensin-Converting Enzyme (Ace) InhibitorsMedicines that help relax the veins and arteries to lower blood pressure.
ApoptosisThe death of cells which occurs as a normal and controlled part of an organism’s growth or development.
AtrophyThe decrease in size or wasting away of a body part or tissue, or the process of such a decrease.
CardiomyopathyAn acquired or inherited disease of the heart muscle which makes it difficult for the heart to pump blood to other parts of the body.
ContracturesThe result of stiffness or constriction in the connective tissues of the body. 
CTG TrinucleotideThe DNA mutation responsible for causing any type of disorder categorized as trinucleotide repeat disorder.
Deoxyribonucleic Acid (DNA)A polymer composed of two polynucleotide chains that coil around each other to form a double helix.
Dystrophia Myotonica Protein Kinase (DMPK)An enzyme that in humans is encoded by the DMPK gene. 
Dystrophin GeneThe largest known human gene.
Dystrophin-Glycoprotein Complex (DGC) ProteinsSituated at the sarcolemma, dynamically remodels during cardiac disease. 
EndomysiaSpecific proteins produced by the immune system in response to a particular threat.
GlycoproteinsProteins which contain oligosaccharide chains covalently attached to amino acid sidechains.
HeterozygotesAn organism who has different genes for a specific trait from one parent and another. 
HypertrophyThe enlargement of an organ or tissue from the increase in size of its cells.
KyphoscoliosisAbnormal curvature of the spine in both the coronal and sagittal planes. 
LordosisThe excessive inward curvature of the spine.
mRNAA type of single-stranded RNA involved in protein synthesis.
Multiplex Ligation-Dependent Probe Amplification (MPLA)A variation of the multiplex polymerase chain reaction that permits amplification of multiple targets with only a single primer pair.
Muscular DystrophyRefers to a group of more than 30 genetic (inherited) conditions that affect the functioning of muscles.
MyoglobinuriaA condition where urine turns dark red or brown due to excess myoglobin, a protein that carries oxygen in muscles.
MyotoniaThe impairment of relaxation of skeletal muscles after voluntary contraction or electrical stimulation.
North Star Ambulatory AssessmentA 17-item rating scale that is used to measure functional motor abilities in ambulant children with Duchenne muscular dystrophy (DMD).
Nuclear Protein EmerinA protein that in humans is encoded by the EMD gene, also known as the STA gene.
Polymerase Chain Reactions (PCR)Amplifies a specific region of a DNA strand (the DNA target).
Proximal MusclesMuscles closest to the center of the body, such as the muscles in the shoulders, upper arms, hips, and thighs. 
PtosisA condition in which there is drooping of upper eyelid either in one eye or both the eyes.
Rand CorporationA research organization that provides fact-based, actionable solutions to improve policy and decision making. 
ScoliosisA condition characterized by sideways curvature of the spine or back bone, often noted during growth spurt just before a child attains puberty.
Somatic CellsThe building blocks of the body, except for the reproductive cells that create new life.
Udd Distal MyopathyA condition that affects the muscles at the front of the lower leg.
Welander Distal MyopathyAn autosomal dominant disorder characterized by adult onset of distal muscle weakness predominantly affecting the distal long extensors of the hands, with slow progression to involve all small hand muscles and the lower legs.
Introduction

The term “muscular dystrophy” incorporates an assortment of hereditary disorders that lead to progressive, generalized disease of the muscle prompted by inadequate or missing glycoproteins in the muscle cell plasma membrane.1 It is a progressive condition that worsens over time, and often begins by affecting a particular group of muscles before affecting the muscles more widely.2

Muscular dystrophy (MD) is a non-communicable disorder with abundant variations. Each form of muscular dystrophy has its own pattern of inheritance, onset period, and the rate at which muscle is lost.1 Alteration in specific genes causes different representations of this disease.1 For instance, there are many kinds of muscular dystrophy, each affecting specific muscle groups, with signs and symptoms appearing at different ages and varying in severity.3 Some MDs eventually affect the heart or the muscles used for breathing. At this point, the condition becomes life-threatening.2

Muscular dystrophies are rare, with little data on how many people are affected.3 This course will give an overview of muscular dystrophies, its types, how they are diagnosed, and interventions to help manage the condition.

Types Of Muscular Dystrophies

Forms of muscular dystrophy differ regarding the age of onset, the severity of symptomatic progression, and the distribution of affected muscles.4 Depending on the molecular etiology, muscular dystrophies can present clinically relevant defects beyond the skeletal muscle compartment.4 In particular, cardiac involvement is present in several forms of dystrophy.4

Some common muscular dystrophy types include:

Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is caused by a mutation of the dystrophin gene located on the X chromosome’s small arm (p) at the Xp21 position.1 It is one of the most common and severe forms and usually affects boys in early childhood.2 The symptoms begin to appear before 5 years of age and affect the upper legs and arms first.3

Duchenne muscular dystrophy patients typically present with progressive weakness of limb muscles, trunk muscles, and the diaphragm, leading to wasting, kyphoscoliosis, and severe respiratory problems.4 Most people afflicted with DMD succumb in their third decade of life due to respiratory complications.4

Female duchenne muscular dystrophy results from an error in female somatic cells whereby one X-chromosome becomes inactivated at an early stage, creating a mosaic representation of heterozygous X-linked genes. This condition generally is sufficient to protect female heterozygotes from X-linked disorders that affect males.1

Becker Muscular Dystrophy

Becker muscular dystrophy is caused by a mutation of the muscle protein dystrophin gene, which codes for the protein dystrophin, with 79 exons, by far the largest gene known in humans.1 It is closely related to Duchenne Muscular Dystrophy, but it develops later in childhood and is less severe. One’s life expectancy is usually not affected.2

Myotonic Muscular Dystrophy

Myotonic muscular dystrophy results from the impaired expression of the dystrophia myotonica protein kinase (DMPK).1 It is caused by an autosomal dominant abnormally expanded CTG trinucleotide repeat sequence located in the 3′ untranslated regions of the DMPK gene.1

Myotonic muscular dystrophy affects about 8 in 100,000 people of all ages.3 Life expectancy is not always affected, but people with a severe form of myotonic dystrophy may have shortened lives.2 Weakness usually appearing in the face, neck, arms, hands, hips, and lower legs.3

Limb-Girdle Muscular Dystrophy

Limb-Girdle muscular dystrophy can be defined as a group of conditions that usually develop in late childhood or early adulthood and is due to gene deletion or mutation.1,2 For instance:

  • LGMB 1B – lamin A/C gene deletion
  • LGMD 1C – caveolin 3 gene deletion
  • LGMD 2A – calpain gene mutation
  • LGMD 2B – dysferlin gene deletion
  • LGMD 2C – sarcoglycan gene deletion
  • LGMD 2D – sarcoglycan gene deletion
  • LGMD 2E – sarcoglycan gene deletion
  • LGMD 2F – sarcoglycan gene deletion
  • LGMD 2G – telethonin gene mutation
  • LGMD 2H – TRIM32 (tripartite motif-containing) gene 32 mutation
  • LGMD 2I – fukutin-related protein gene deletion

Some variants can progress quickly and be life-threatening, whereas others develop slowly.2 It affects males and females equally, and about 2 in 100,000 people of all ages.3 Limb-Girdle muscular dystrophy affects the upper arms and legs, heart, spine, hips, calves, and trunk.3

Facioscapulohumeral Muscular Dystrophy

Facioscapulohumeral muscular dystrophy is caused by an autosomal dominant deletion of 3.3 kb repeat on chromosome 4.1 Approximately 95% of cases are due to a mutation in the D4Z4 region in FSHD1. Other areas, such as the SMCHD1 region in FSHD2, can also cause this disease.1

Facioscapulohumeral muscular dystrophy can develop in childhood or adulthood, progresses slowly, and is usually not life-threatening.2 The face, shoulders, and upper arms show weakness first, and later, eyes, ears, and lower legs can be affected.3

Emery-Dreifuss Muscular Dystrophy

Emery-Dreifuss muscular dystrophy is caused by an X-linked recessive defect in nuclear protein emerin at the Xq27-28 position.1 This variant can also result from an autosomal recessive or autosomal dominant defect in inner nuclear lamina proteins lamin A/C on chromosome 1.1

Emery-Dreifuss muscular dystrophy is most inherited through an X-linked, recessive pattern that primarily affects males, who inherit the disease from their mothers. Another type is autosomal dominant, meaning it can be inherited through either parent. A third, rare type, is autosomal recessive when a faulty gene is inherited from each parent. Emery-Dreifuss muscular dystrophy  most often develops in childhood or early adulthood, and  most people with this condition will live until at least middle age.2

Oculopharyngeal Muscular Dystrophy

Oculopharyngeal muscular dystrophy  is a type of muscular dystrophy that affects the extraocular and pharyngeal muscles is caused by an autosomal dominant GCG trinucleotide repeat resulting in deficient mRNA transfer from the nucleus.1 It does not usually develop until a person is between 50 and 60 years old, and it does not tend to affect life expectancy.2 It affects the extraocular and pharyngeal muscles.1

Congenital Muscular Dystrophy

Congenital muscular dystrophy is caused by a mutation of the sarcolemmal protein merosin gene, deficiencies or mutations in laminin-alpha 2, collagen type VI, integrin-alpha 7, and glycosyltransferases.1 It affects about 1 in 100,000 people of all ages, male and female.3 Congenital MD affects the following body parts:3

  • Neck
  • Upper arms
  • Upper legs
  • Lungs
  • Brain
  • Heart
  • Spine

Distal Muscular Dystrophy

Distal muscular dystrophy is a class of muscular dystrophies that primarily affect distal muscles, which are those of the lower arms, hands, lower legs, and feet.6 Muscular dystrophies, in general, are a group of genetic, degenerative diseases primarily affecting voluntary muscles.6

It begins in either childhood or adulthood and is slowly progressive. It does not affect the intellect and is not considered life-threatening.6 Distal muscular dystrophy is caused by a mutation in any of at least eight genes that affect proteins necessary to the function of muscles. It can be inherited in an autosomal dominant or recessive pattern.6

There are more than 30 different types of muscular dystrophy.7 The different types vary based on the severity of the muscle degeneration and which muscles degenerate.7

Symptoms

Duchenne Muscular Dystrophy

Duchenne muscular dystrophy usually becomes apparent early in childhood.8 Affected children develop weakness and wasting (atrophy) of the muscles closest to the trunk (proximal muscles), such as those of the upper legs and pelvic area and upper arms and shoulder area.Common symptoms include:7

  • A waddling walk
  • Delayed walking age
  • Difficulty running and jumping
  • Frequent falls
  • Toe walking
  • Well-developed or excessively large calf muscles

As the disease progresses, muscle weakness and atrophy spreads to affect the lower legs, forearms, neck, and trunk.8 Another serious complication associated with DMD is weakness and deterioration of muscles in the rib cage.8 This can result in increased susceptibility to respiratory infections (pneumonia), difficulty coughing, and, ultimately, respiratory failure.8

Becker Muscular Dystrophy

Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are often discussed together because they cause similar patterns of weakness and are inherited in the same way.7 However, BMD is less severe than DMD.7

Skeletal muscle weakness in BMD is slowly progressive, with a later onset at around age 8.9 In patients with less cardiac involvement, the onset may be around age 15. Heart failure is the most common cause of death in BMD.9As stated above, signs and symptoms of the condition are like those of DMD but are usually milder and more varied.7

Myotonic Dystrophy

Unlike other muscular dystrophies, muscle weakness in myotonic dystrophy is accompanied by myotonia (delayed relaxation of muscles after contraction) and by various other non-muscular symptoms.7 The first muscles to be affected by weakness are those of the face, neck, hands, forearms, and feet.7

Fifty percent of individuals with myotonic dystrophy show visible signs by about twenty years of age, but most  people with myotonia will develop symptoms by the age of fifty.7 The symptoms can vary from person to person. For instance, for some, the symptoms are extremely mild and adaptable, and for others, the only symptom is a cataract.7In most cases, weakness and muscle wasting slowly progresses to the point of physical inability.7

Limb-Girdle Muscular Dystrophy

Although there are some common themes recognizable in the main types of LGMD, the age at onset, severity, and progression of symptoms associated with LGMD may vary greatly from case to case, even among members of the same family.10 The major symptoms of LGMD are:10

  • Progressive wasting (atrophy)
  • Weakness of the proximal muscles of the hip and shoulder areas. Muscle weakness may spread from the proximal muscles to affect distal muscles.

Additional abnormalities that may develop in individuals with LGMD include:10

  • Abnormal front-to-back curvature of the spine (lordosis)
  • Abnormal side-to-side curvature of the spine (scoliosis)
  • Thickening and shortening of tissue causes deformity and restricts movement of affected areas, especially the joints (contractures), and overgrowth (hypertrophy) of certain muscles such as the calf muscle.

Facioscapulohumeral Muscular Dystrophy

On average, Facioscapulohumeral (FSH) muscular dystrophy progresses slowly, and the level of severity eventually is minimal enough to where patients usually retain the ability to walk and have a normal life span.7

The onset of FSH can occur in infants, but symptoms may appear at any time from childhood until someone is in their 50s.7 Common signs and symptoms include the eyes appearing to be slightly open when the person is sleeping due to weakness of eye closure muscles and fewer than usual facial lines due to age.7

Moreover, muscle weakness in the shoulders and arms can lead to difficulty in bending, straightening, or lifting, in addition to muscle bulk between the shoulder blades.7

Emery-Dreifuss Muscular Dystrophy

The age of onset, severity, and progression of the disease varies from person to person.11 Some affected individuals may experience childhood onset with rapid disease progression and severe complications, while others may experience adult onset and a slowly progressive course.11

Emery-Dreifuss muscular dystrophy is associated with the clinical triad of contractures, muscle weakness, and heart disease.11 Muscle weakness and atrophy are usually slowly progressive during the first three decades of life and may become more rapid later.11 Heart abnormalities are the third prominent feature of EDMD and may result in serious complications.11

Oculopharyngeal Muscular Dystrophy

Oculopharyngeal muscular dystrophy is characterized by progressive weakness of certain muscles around the eyes, in the throat, and less commonly in the pelvic and shoulder areas, including the muscles of the upper legs and arms.12

The two most common initial symptoms of OPMD are drooping of the upper eyelid (ptosis) and difficulty swallowing.12 As the disease progresses, some individuals will develop weakness and degeneration (atrophy) of the muscles of the upper legs (proximal muscles).12

Congenital Muscular Dystrophy

In most cases of congenital muscular dystrophy, the initial symptoms are present at birth or in the first few months.7

  • Babies with CMD often have low muscle tone or floppiness and may have reduced movements.
  • Other common signs are contractures in the ankles, hips, knees, and elbows.
  • Some babies may also have trouble breathing and feeding.

Some improvement may occur in childhood, with the disease having a slow or little progression.7

Distal Muscular Dystrophy

There are many different types of distal muscular dystrophies, each varying in their signs, symptoms, progression, and age of onset.13 For instance, in Welander Distal Myopathy, certain muscles of the hands and feet (intrinsic muscles and long extensors) and certain muscles of the fingers and toes (extensors) are predominantly affected.13 In contrast, in Udd Distal Myopathy, onset is usually after 35 years of age, and progression is slow and is characterized by muscle weakness affecting the ankles that may spread to affect the muscles of the shinbone (tibia).13

Pathophysiology, Diagnosis, And Prognosis Of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a rare muscle disorder, but it is one of the most frequent genetic conditions affecting approximately 1 in 3,500 male births worldwide.8

Pathophysiology

In DMD, both dystrophin and Dystrophin-glycoprotein complex  (DGC) proteins are missing, leading to excessive membrane fragility and permeability, dysregulation of calcium homeostasis, and oxidative damage.14

Dystrophin is a large cytoskeletal protein that facilitates interactions between the cytoskeleton, cell membrane, and extracellular matrix. It is located at the plasma membrane in both muscle and non-muscle tissues.14 Dystrophin is a critical part of the dystrophin-glycoprotein complex, which plays an important role as being a structural unit of muscle.14

These factors play a crucial role in muscle cell necrosis. As patients with DMD age, the regenerative capacity of the muscles appears to be exhausted, and connective and adipose tissue gradually replaces muscle fibers.14

Diagnosis

A diagnosis of DMD is made based upon a thorough clinical evaluation, a detailed patient history, and a variety of specialized tests, including molecular genetic tests.8 If the genetic tests are not informative, surgical removal and biopsy of affected muscle tissue may reveal characteristic changes to muscle fibers.8

Specialized blood tests are also used.8 Laboratory testing involves creatinine kinase measurements, gene testing, and electrocardiogram findings for cardiomyopathy.14

Creatinine Kinase Measurements

Serum Creatinine Kinase (CK) is an enzyme that shows abnormally high levels when a muscle is damaged.Creatinine Kinase measurements are often elevated before the development of clinical symptoms. Levels peak by age two and can be more than 10 to 20 times above the upper limit of normal.14 Asymptomatic carriers may also have elevated CK levels.14

As age and disease progress, serum CK levels decrease as fibrosis and fat progressively replace muscle. Other muscle enzymes, such as aldolase levels and aspartate aminotransferase (AST) levels, may also be elevated.14

Muscle Biopsy

A muscle biopsy will demonstrate endomysial connective tissue proliferation, scattered degeneration, and regeneration of myofibers, muscle fiber necrosis with a mononuclear cell infiltrate, and replacement of muscle with adipose tissue and fat.14 Various techniques such as immunostaining, immunofluorescence, or Western blot(immunoblot) can be used for conducting a muscle biopsy.8 The muscles most  biopsied are the quadriceps femoris in the thigh, and the gastrocnemius in the calf.14

Gene Testing

Molecular genetic tests involve the examination of deoxyribonucleic acid (DNA) to identify mutations, including deletions, duplications, or single-point mutations.8

Patients with DMD demonstrate the complete or near-complete absence of the dystrophin gene.14 Dystrophin immunoblotting can be used to predict the severity of the disease. In DMD, patients are found to have less than 5% of the normal quantity of dystrophin.14

Polymerase chain reactions (PCR) and Multiplex ligation-dependent probe amplification (MPLA) are also used to identify mutation, duplications, and deletions.14 Dystrophin immunocytochemistry can also be used to detect cases not identified by PCR.14

ECG

Characteristic ECG changes are tall R waves in V1-V6 with an increased R/S ratio and deep Q waves in leads I, aVL, and V5-6.14

Conduction abnormalities with arrhythmias may be identified with telemetry. Supraventricular arrhythmias are more common. Intra-atrial conduction abnormalities are more common than AV or infra-nodal defects in DMD.14

Prognosis

The prognosis is typically poor for affected patients.14 Patients are often wheelchair dependent by the age of 12 years. Death occurs due to respiratory or cardiac complications in the teens or 20s. Other causes of death are pneumonia, aspiration, or airway obstruction.14

Duchenne Muscular Dystrophy Interventions

No medical cure exists, and the disease has a poor prognosis.14 Treatments are aimed at the specific symptoms present in each individual.8 For instance; treatment options should include8

  • Braces to prevent the development of contractures.
  • Physical therapy and active and passive exercise to build muscle strength and prevent contractures.
  • Surgery is recommended in some patients to treat contractures or scoliosis.
  • The use of mechanical aids (canes, braces, and wheelchairs) may become necessary to aid walking.

Common treatment options for DMD are:

Glucocorticoid Therapy

Glucocorticoid therapy decreases the rate of apoptosis of myotubes and can decelerate myofiber necrosis.14 Studies have shown that glucocorticoid treatment is associated with improved pulmonary function, delayed development of scoliosis, reduced incidence and progression of cardiomyopathy, and overall improved mortality.14

  • Prednisone is used in patients four years and older in whom muscle function is declining or plateauing.14
  • Deflazacort, an oxazoline derivative of prednisone, is sometimes preferred over prednisone as it has a better side effect profile and has an estimated dosage equivalency of 1:1.3 compared with prednisone.14
  • In 2016, Exondys 51 (eteplirsen) injection was FDA approved to treat DMD and is the first drug approved for this condition.8
  • In 2017, Emflaza (deflazacort) was FDA-approved to treat patients aged 5 years and older with DMD.8
  • In 2019 and 2020, respectively, the FDA approved Vyondys 53 (golodirsen) and Viltepso (viltolarsen) to treat patients with DMD who have a confirmed mutation of the dystrophin gene that is amenable to exon 53 skipping.8
  • In 2021, the FDA approved Amondys 45 (casimersen) to treat patients with DMD who have a confirmed mutation of the DMD gene that is amenable to exon 45 skipping.8

Orthopedic Interventions

These interventions include:14

  • Passive stretching exercises, plastic ankle-foot orthosis during sleep, and long leg braces to assist in ambulation.
  • Physiotherapy to prevent contractures as the mainstay of orthopedic interventions.
  • Surgery to correct scoliosis may improve pulmonary function.
  • Surgery to release contractures may be required for advanced disease.

Pulmonary Interventions

Pulmonary function must be assessed before the exclusive use of a wheelchair.14 This should be repeated twice a year once the patient reaches 12 years of age, must use a wheelchair, or vital capacity is found to be less than 80% of the predicted capacity.14

Exercise And Nutrition

Patients with DMD are recommended to take care of their physical health. Guidelines recommend all patients participate in a gentle exercise to avoid muscular atrophy. A combination of swimming pool and recreation-based exercises is recommended.14 However, activity should be reduced if myoglobinuria is noted or significant muscle pain develops.14

Patients are also at risk for malnutrition, including obesity. Thus, calcium and vitamin D should be supplemented to prevent osteoporosis secondary to chronic steroid use.14

Cardiomyopathy Treatment

Treatment with angiotensin-converting enzyme (ACE) inhibitors and/or beta-blockers is recommended.14 Early studies suggest that early treatment with ACE inhibitors may slow the progression of the disease and prevent the onset of heart failure.14 Heart failure may also be treated with digoxin and diuretics, just as in other patients with cardiomyopathy.14

Management Of Duchenne Muscular Dystrophy

The management of Duchenne muscular dystrophy (DMD) has changed considerably over the last few decades.15 The standards of care have recently been updated based on systematic reviews of the literature and structured, case-based consensus discussions of experts.15 In addition to addressing muscular function, these recommendations cover most areas of organ involvement and psychosocial issues.15

International Standards Of Care

The international standards of care for DMD were first published in 2010 and have recently been updated and expanded.15

Groups of clinical researchers and experts in their respective fields convened meetings by an initiative from the US Centers for Disease Control and advocacy, critically reviewed the available literature, and provided their recommendations for specific clinical scenarios in a structured procedure – the RAND Corporation.15 The result is regarded as an optimal, common baseline for clinical decision-making in diagnosing, monitoring, and treatment of all patients with DMD.15

The international standards of care of 2018 for DMD cover multiple management areas, each specific to the disease stage (diagnosis, early ambulatory, late ambulatory, early non-ambulatory, and late non-ambulatory stages).15

Neuromuscular Management

A neuromuscular specialist is the first-line medical advisor to patients and their families as they define and revise their individual care goals over time, helping them to personalize their risk-to-benefit analysis of therapeutic interventions.15 The advisor also addresses issues such as the transition of care from pediatric to adult clinical providers and the provision of individualized hospital care.15 Standards of neuromuscular management include:15

  • At diagnosis, arrangements for genetic evaluation and family counseling must be made, and female carriers must be referred to a cardiologist.
  • During the patient’s lifetime, regular neuromuscular clinic visits should be offered to assess each patient’s unique disease trajectory over time using validated assessment tools.
  • Function, strength, and range of movement should be assessed every six months to monitor for disease progression.

Rehabilitation Management

During the patient’s lifetime, comprehensive, multidisciplinary examinations should be conducted regularly, including standardized assessments, such as range of motion, the North Star Ambulatory Assessment, timed function tests, and muscle function measures.15

Based on the assessment results, treatments by physical, occupational, and speech therapists should be individualized and performed to accommodate the patient’s needs.15 With physical therapy guidance, a home-stretching program should be implemented on ankles, knees, and hips. After the loss of ambulation, occupational therapy guidance with a focus on the upper extremities should be added.15

During the ambulatory stages, nurses and caregivers should:

  • Assist in preventing contractures or deformities, overexertion of muscles, and prevent falls.
  • Promote appropriate exercise or activity.
  • Provide orthotics, ambulatory equipment, and learning support.

After the loss of ambulation, mobility devices, appropriate seating, supported standing devices, and assistive technology for important tasks should be made available.15

Respiratory Management

  • During the ambulatory stages, spirometry (functional ventilation capacity, [FVC]) or sleep studies are only recommended when suspicious clinical symptoms appear.15
  • Beginning with the early non-ambulatory stage, the respiratory function should be assessed every six months, including FVC, maximum inspiratory/expiratory pressure, peak cough flow, SpO2, and expiratory/transcutaneous partial CO2 pressure.15
  • Sleep studies entailing capnography for signs and symptoms of obstructive sleep apnoea or sleep-disordered breathing are also advisable.15
  • Immunizations should be kept up to date, emphasizing pneumococcal vaccines and a yearly, inactivated influenza vaccine.15
  • Assisted daytime ventilation must be added when, despite nocturnal ventilation, daytime SpO2 is less than 95%, pCO2 greater than 45mmHg, or symptoms of awake dyspnoea are present.15

Orthopedic Management

During the early and late ambulatory stages:15

  • Custom-molded, night-time ankle-foot orthoses set in a neutral position should be prescribed when passive dorsiflexion is less than 10°.
  • Surgery on the foot and Achilles tendon can be conducted to improve the patient’s gait if substantial ankle contracture occurs and as long as quadriceps and hip extensor strength are still good.
  • Surgical therapy should be considered to enable early mobilization in case of lower limb fractures.

During the early non-ambulatory stage:15

  • Custom-molded daytime ankle-foot orthoses should be applied to delay the worsening of equinovarus contracture.
  • A standing program using standing devices or a wheelchair with upright positioning should be initiated to prevent the rapid progression of contractures, scoliosis, and osteoporosis.
  • Healthcare professionals should only refer the patient for foot and ankle surgery to improve foot positioning when the patient specifically requests it. However, from this stage on, conservative treatment of fractures is more advisable.

In the late non-ambulatory stage:15

  • Use of lower-extremity braces should be continued; custom wrist and hand splints may be appropriate.
  • Standing programs should only be used with caution.
  • Foot surgery is only indicated for severe pain or otherwise untreatable skin problems.

Cardiac Management

In the ambulatory stages:15

  • Cardiac function should be assessed at diagnosis (electrocardiogram, echocardiogram, cardiac-magnetic resonance imaging) and then annually, if possible, without anesthesia.
  • Initiation of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers is recommended by age 10 years and, at the latest, when cardiac findings begin to deteriorate.

After the loss of ambulation:15

  • Cardiac function should be assessed at least annually, more often if symptoms or abnormal imaging data are present. This includes monitoring for rhythm abnormalities via Holter-ECG. If the heart function has deteriorated, standard heart-failure medical therapy employing beta-blockers, angiotensin-converting enzyme inhibitors, eplerenone, or other diuretics must be initiated.
  • An ECG and non-invasive imaging must be conducted before any major surgery. Since DMD patients have a higher anesthesia risk, the anesthetist must be aware of the diagnosis and proceed accordingly.

Adherence to the above-mentioned standards of care is the only means to improve or maintain function and quality of life in affected patients.15 Surgery for scoliosis, active respiratory treatment, and meticulous cardiac care have prolonged the life expectancy of patients with DMD by ten or more years.15 However, while many patients and their families derive major benefits from these developments, others may survive for many long years in a severely incapacitated, tetraplegic state; thus, it is up to the patient to decide whether to receive or terminate treatment.15

Nursing Considerations

Nursing considerations for DMD patients can be categorized into the following:

Fatigue

Nursing interventions include:16

  • Ask the patient to rate their fatigability level from mild, moderate, to severe.
  • Encourage activity through self-care and exercises. The patient should balance their physical activity and rest periods.
  • Teach deep breathing exercises and relaxation techniques.
  • The patient should be referred to occupational therapy or physiotherapy if required.

Impaired Physical Mobility

Nursing interventions include:16

  • Assess the patient’s level of functional ability and mobility to perform activities of daily living.
  • Assist patients during exercises and routine activities.
  • Encourage the patient to perform a range of motion exercises to improve venous return, muscle strength, and stamina and prevent stiffness and contracture deformation.
  • Ensure the environment’s safety.

Risk For Falls

Nursing interventions include:16

  • Check if the patient has a history of falls.
  • Check the circumstances and determine the degree of fall risk.
  • Evaluate and consider the age-related physical changes in patients.
  • Evaluate and consider the alterations in the patient’s mental status.
  • Place the patient’s bed in the lowest position possible.
  • Educate patients and family members about how to ambulate at home.

Risk For Injury

Nursing interventions include:16

  • Evaluate and consider the following factors that increase the patient’s risk of injuries, such as age, health status, developmental age, compromised communication, mobility, cognitive awareness, and sensory-perceptual impairment.
  • Check the patient’s ability to ambulate and evaluate their risk of falls.
  • Limit the use of wheelchairs and assist the patient in standing and sitting.
  • Patients should wear non-slip and well-fitting footwear.

Risk For Ineffective Breathing Patterns

Nursing interventions include:16

  • Patient’s vital signs, and respiration characteristics should be assessed at least every 4 hours.
  • Carefully administer the prescribed medicines.
  • Supplemental oxygen should be administered if the oxygen level drops.
  • Assist the patient in assuming a semi-Fowler’s position.
  • Educate the patient about proper breathing techniques, such as diaphragmatic, pursed lips, and deep breathing.
Conclusion

During the last 20 years, the number of preclinical, animal-based studies, and clinical trials in DMD has risen significantly.15 Based on the growing knowledge of the genetics and pathophysiology of this disease, the following therapeutic pathways have been taken via molecular-genetic methods or with small molecules:15

  • Cell therapy (with mostly genetically manipulated myoblasts or other stem cells).
  • Gene therapy (replacement of the defective gene, for example, by virus-mediated transfer of a minigene).
  • Mutation-specific methods changing gene translation (including skipping of exons with antisense oligonucleotides and readthrough of premature stop-codons).
  • Pharmacological therapies.

Thanks to all these encouraging developments, the former nihilistic approach to managing patients with DMD and other genetic neuromuscular diseases is no longer justified.15 Moreover,  significant improvements have been made in supportive and rehabilitative care.15

However, the goal of curing or arresting the progression of DMD has not yet been reached, and treatment is limited to management only.15

The management of patients with DMD is best done with an interprofessional team that includes specially trained nurses and therapists.14 Overall, the most important thing is to ensure that the patients lead a decent quality of life.

References
  1. LaPelusa A, Kentris M. Muscular Dystrophy. PubMed. Published 2021. https://www.ncbi.nlm.nih.gov/books/NBK560582/
  2. ‌NHS Choices. Overview – Muscular Dystrophy. NHS. Published 2019. https://www.nhs.uk/conditions/muscular-dystrophy/
  3. ‌CDC. What is Muscular Dystrophy? | CDC. Centers for Disease Control and Prevention. Published November 27, 2019. https://www.cdc.gov/ncbddd/musculardystrophy/facts.html#:~:text=Muscular%20dystrophies%20are%20a%20group
  4. ‌Biressi S, Filareto A, Rando TA. Stem cell therapy for muscular dystrophies. Journal of Clinical Investigation. 2020;130(11):5652-5664. doi:10.1172/jci142031
  5. ‌Emery-Dreifuss Muscular Dystrophy (EDMD) – Causes / Inheritance | Muscular Dystrophy Association. Muscular Dystrophy Association. Published December 18, 2015. https://www.mda.org/disease/emery-dreifuss-muscular-dystrophy/causes-inheritance
  6. ‌Diseases – Distal Myopathies – Top Level. Muscular Dystrophy Association. Published December 18, 2015. https://www.mda.org/disease/distal-myopathies
  7. ‌Services D of H & H. Muscular dystrophy. www.betterhealth.vic.gov.au. Accessed November 11, 2022. https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/muscular-dystrophy#facioscapulohumeral-dystrophy-fsh
  8. ‌Duchenne Muscular Dystrophy. NORD (National Organization for Rare Disorders). https://rarediseases.org/rare-diseases/duchenne-muscular-dystrophy/#standard-therapies
  9. ‌Salari N, Fatahi B, Valipour E, et al. Global prevalence of Duchenne and Becker muscular dystrophy: a systematic review and meta-analysis. Journal of Orthopaedic Surgery and Research. 2022;17(1). doi:10.1186/s13018-022-02996-8
  10. ‌Limb-Girdle Muscular Dystrophies – NORD (National Organization for Rare Disorders). NORD (National Organization for Rare Disorders). Published 2015. https://rarediseases.org/rare-diseases/limb-girdle-muscular-dystrophies/
  11. ‌Emery Dreifuss Muscular Dystrophy. NORD (National Organization for Rare Disorders). https://rarediseases.org/rare-diseases/emery-dreifuss-muscular-dystrophy/
  12. ‌Oculopharyngeal Muscular Dystrophy. NORD (National Organization for Rare Disorders). https://rarediseases.org/rare-diseases/oculopharyngeal-muscular-dystrophy/
  13. ‌Distal Myopathy – NORD (National Organization for Rare Disorders). NORD (National Organization for Rare Disorders). Published 2019. https://rarediseases.org/rare-diseases/distal-myopathy/
  14. ‌Venugopal V, Pavlakis S. Duchenne Muscular Dystrophy. PubMed. Published 2020. https://www.ncbi.nlm.nih.gov/books/NBK482346/
  15. Korinthenberg R. A new era in the management of Duchenne muscular dystrophy. Developmental Medicine & Child Neurology. Published online December 16, 2018. doi:10.1111/dmcn.14129
  16. ‌Muscular Dystrophy Nursing Diagnosis and Nursing Care Plan. NurseStudy.net. Published January 17, 2021. https://nursestudy.net/muscular-dystrophy-nursing-diagnosis/
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