Muscular Dystrophy vs. Muscle Atrophy

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Muscle atrophy refers to the shrinking or "wasting away" of muscles. It is usually a symptom of another condition rather than a condition in and of itself. In addition to a loss in the size of muscles, muscle atrophy can also cause muscle weakness.

Muscular dystrophy is a rare genetic disorder that affects the proteins that build and maintain healthy muscles. While muscular dystrophy can cause muscle atrophy, they are different conditions with different causes, symptoms, and treatments.

A woman looks happy and confident as she leads a group discussion at her place of work. She is a wheelchair user and has muscular dystrophy.


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Causes

Causes of Muscular Dystrophy
  • Spontaneous gene mutation


  • Inherited autosomal dominant gene mutation

  • Inherited autosomal recessive gene mutation

  • Inherited X-linked gene mutation

Causes of Muscle Atrophy
  • Injury

  • Illness/health conditions

  • Inactivity

  • Aging

  • Malnutrition

Muscular Dystrophy Causes

All types of muscular dystrophy are caused by a genetic mutation, but not all cases of muscular dystrophy are inherited.

Noninherited

Spontaneous mutations can occur in one of the thousands of genes that program the proteins needed to make and maintain muscles. This can result in altered, insufficient, or missing proteins, and prevent body cells from working properly.

While these spontaneous mutations are not inherited from parents, they can be passed down to the children of the person with muscular dystrophy, resulting in inherited muscular dystrophy or in an individual who is a carrier of a mutated gene that can cause muscular dystrophy.

Inherited

A person receives 23 chromosomes from each parent—one sex chromosome and 22 nonsex chromosomes—for a total of 46 chromosomes, arranged in pairs.

Each of these pairs of chromosomes contains two of the same chromosomes except for sex chromosomes. People who carry two X chromosomes (female genetic sex) will pass on one of their two X chromosomes to their offspring. People who carry XY chromosomes (male genetic sex) will pass either an X or a Y chromosome to their offspring.

Mutated genes can be passed on to offspring through any of these chromosomes from either parent.

A mutated gene that can cause muscular dystrophy can be inherited in one of three ways:

  • Autosomal dominant: The mutated gene occurs on any of the nonsex chromosomes, and only one parent must pass down the defective gene to produce the disorder. This disorder will develop if the offspring receives a defective gene from one parent or a defective gene from each parent. There are no carriers in this case. If a person has a defective gene, they have the disorder.
  • Autosomal recessive: For the disorder to present, a person must have two of the defective genes (one from each parent). The parents do not have to have the condition themselves, they may be carriers only, meaning they each only have one defective gene and one normal gene. If two people who are carriers have children, the child has a 25% chance of receiving both defective genes and having the disorder, a 25% chance of the child receiving no defective genes, neither having the disorder nor being a carrier, and a 50% chance of the child receiving only one defective gene and being a carrier.
  • X-linked (sex-linked): This involves a gene mutation on one of the sex chromosomes. With muscular dystrophy, it is the X chromosome that is affected. A parent with two X chromosomes can pass either an affected X chromosome (if they have at least one affected X) or an unaffected X (if they are a carrier only). A parent with XY chromosomes can only pass along the mutated gene if they have the disorder, and only if they pass on an X, not a Y chromosome.

Inherited Muscle Dystrophy and Children

Here is an example of how it maps out:

  • A child with an affected X chromosome and a Y chromosome will have the disorder.
  • A child with one affected X and one unaffected X will be a carrier and is unlikely to show symptoms.
  • A child who has two affected X chromosomes will have the disorder, but in the case of muscular dystrophy, this is very rare.

Muscle Atrophy Causes

Because muscle atrophy is primarily a symptom, it can be caused by a number of factors.

These can include:

  • Injury
  • Malnutrition
  • Disease
  • Inactivity such as bed rest
  • Nerve damage
  • Aging
  • Burns
  • Other health conditions (both genetic and acquired) that affect the muscular system, such as muscular dystrophy, osteoarthritis, and rheumatoid arthritis

Types

Muscular Dystrophy Types
  • Duchenne muscular dystrophy

  • Becker muscular dystrophy

  • Congenital muscular dystrophy

  • Distal muscular dystrophy

  • Emery-Dreifuss muscular dystrophy

  • Facioscapulohumeral muscular dystrophy

  • Limb-girdle muscular dystrophy

  • Myotonic muscular dystrophy

  • Oculopharyngeal muscular dystrophy

Muscle Atrophy Types
  • Physiologic (disuse)

  • Pathologic

  • Neurogenic

Muscular Dystrophy Types

While muscular dystrophy refers to more than 30 genetic diseases, there are nine main types.

Duchenne Muscular Dystrophy

Duchenne muscular dystrophy is a form of muscular dystrophy that tends to worsen quickly. More information on Duchenne muscular dystrophy includes:

  • Most common of all muscular dystrophy types
  • Results from an absence of the protein dystrophin (a protein found in muscle that helps muscles stay healthy and strong) 
  • X-linked (mutated gene is carried on the X chromosome)
  • Mainly affects people with XY chromosomes (two affected X chromosomes are rare)
  • Carriers (people with one affected X and one unaffected X) may show some symptoms, but if symptoms appear they are usually milder
  • Usually becomes apparent during toddlerhood
  • Affects about six out of every 100,000 children in North America and Europe
  • Involves progressive weakness and muscle atrophy
  • First affects upper legs and upper arms
  • Eventually affects all voluntary muscles
  • Can cause other health problems with lungs, heart, spine, and other areas
  • Without aggressive treatment, life expectancy is late teens to early 20s
  • Modern treatments have improved quality of life and life expectancy (some people with Duchenne muscular dystrophy live into their 30s or 40s)

Becker Muscular Dystrophy

Becker muscular dystrophy is the second most common muscular dystrophy. More information on Becker muscular dystrophy includes:

  • Mainly affects people with XY chromosomes
  • Approximately one out of 18,000 to 30,000 Americans with XY chromosomes develop Becker muscular dystrophy
  • Age of symptoms onset is usually in the teens but can occur at any age between 5 years and 60 years
  • Caused by mutations in the same gene as Duchenne muscular dystrophy
  • Similar to Duchenne muscular dystrophy, but usually less severe
  • Partial but insufficient function of the protein dystrophin
  • Rate of progression of muscle weakness and atrophy varies greatly between individuals
  • Life expectancy is usually middle age or older
  • First affects upper legs and upper arms
  • Cardiac complications are seen less consistently with Becker muscular dystrophy compared to Duchenne muscular dystrophy but can be as severe in some cases
  • Cognitive and behavioral impairments can occur but are not as common or severe as in Duchenne muscular dystrophy

Congenital Muscular Dystrophy

Congenital muscular dystrophy is an inherited condition that predominantly affects the muscles, brain, and eyes. More information includes:

  • Group of autosomal recessive muscular dystrophies that are present at birth or become evident before age two
  • Affects all sexes equally
  • Muscle degeneration may be mild or severe and primarily affects skeletal muscle
  • The severity and progression of muscle weakness and degeneration vary depending on the type of disorder
  • Defects in the protein merosin are responsible for almost half of congenital muscular dystrophy cases
  • Occurs in about one in 100,000 people of all ages

Distal Muscular Dystrophy

Distal muscular dystrophy (DD) is a group of rare diseases that affect your muscles (genetic myopathies). More information includes:

  • Also called distal myopathy
  • A group of at least six specific muscle diseases that primarily affect distal muscles (forearms, hands, lower legs, and feet)
  • Affects less than one in 100,000 people
  • Affects all sexes equally
  • Onset is typically between the ages of 40 to 60 years
  • Typically less severe, progresses more slowly, and involves fewer muscles than other forms of muscular dystrophy
  • Can spread to other muscles later in the progression of the disease
  • Can affect the heart and respiratory muscles
  • Primarily an autosomal dominant disorder, but autosomal recessive forms have been reported in young adults

Emery-Dreifuss Muscular Dystrophy

Emery-Dreifuss muscular dystrophy is a condition that primarily affects muscles used for movement (skeletal muscles) and the heart (cardiac muscle). More information includes:

  • Can affect throat, shoulders, and hips
  • Has two forms: X-linked recessive and autosomal dominant
  • Primarily affects people with XY chromosomes
  • Symptoms usually present by age 10 but can appear as late as the mid-20s
  • Cardiac symptoms can be the earliest and most severe symptoms, sometimes occurring before the onset of muscle weakness
  • People with XX chromosomes who are carriers may experience cardiac complications without muscle weakness
  • Often fatal in mid-adulthood from progressive pulmonary or cardiac failure

Facioscapulohumeral Muscular Dystrophy

Facioscapulohumeral muscular dystrophy gets its name from the muscles that are affected most often: those of the face, around the shoulder blades, and in the upper arms. More information includes:

  • Also known as Landouzy-Dejerine disease
  • The third most common form of muscular dystrophy, affecting about four out of 100,000 people in the United States
  • Affects all sexes equally
  • Autosomal dominant disorder
  • Can affect eyes, ears, and lower legs
  • Usually begins in the teenage years but symptoms may present as early as childhood or as late as age 40
  • People with this form of muscular dystrophy usually have a normal lifespan, but some become severely disabled
  • Muscle weakness is commonly asymmetric
  • Typically a slow progression, with intermittent spurts of rapid muscle deterioration

Limb-Girdle Muscular Dystrophy

Limb-girdle muscular dystrophy is a term for a group of diseases that cause weakness and wasting of the muscles in the arms and legs. More information includes:

  • A group of more than 20 hereditary conditions involving progressive loss of muscle bulk and symmetrical weakening of the voluntary muscles closest to the body (particularly in the shoulders and around the hips)
  • Heart, spine, hips, calves, and trunk can also be affected
  • Affects approximately two out of 100,000 people in the United States
  • Affects all sexes equally
  • The autosomal recessive types of limb-girdle muscular dystrophy are more common than the dominant forms, and typically begin in childhood or teenage years
  • The autosomal dominant types of limb-girdle muscular dystrophy typically appear in adulthood
  • The rate of progression, severity, and consistency of progression vary depending on the type, but generally the earlier the symptoms appear, the more rapid the rate of disease progression
  • Many people with limb-girdle muscular dystrophy become severely disabled within 20 years of the onset of the condition

Myotonic Muscular Dystrophy

Myotonic dystrophy is the most common form of muscular dystrophy that begins in adulthood. More information includes:

  • Also known as Steinert's disease and dystrophia myotonica
  • Tends to affect adults of European descent
  • Affects approximately 10 out of 100,000 people
  • Only form of muscular dystrophy that exhibits myotonia (an inability to relax muscles following a sudden contraction), but myotonia also occurs in other nondystrophic muscle diseases
  • Typical onset is between ages 20 and 30, but can happen anywhere within the range of birth to age 70
  • Can affect many areas of the body including first face, neck, arms, hands, hips, and lower legs, then heart, lungs, stomach, intestines, brain, eyes, and hormone-producing organs
  • A severe form of myotonic muscular distrophy can occur at birth and almost exclusively in children who have inherited the defective gene from their biological parent with XX chromosomes. The parent may have very few or mild symptoms and not be aware aware that they have the disease until an affected child is born.

Oculopharyngeal Muscular Dystrophy

Oculopharyngeal muscular dystrophy (OPMD) is a rare genetic condition that causes weakness in the muscles around the upper eyelids and part of the throat called the pharynx. More information includes:

  • Rare, affecting less than one in 100,000 people
  • Affects all sexes equally
  • Affects eyes and throat first
  • Shoulders, upper legs, and hips can also be affected
  • Usually begins between age 40 to 60
  • Can cause complications such as vision problems, difficulty speaking and swallowing, and mobility problems

What Is Spinal Muscular Atrophy?

While spinal muscular atrophy sounds like muscle atrophy, it is actually a genetic disorder with symptoms that have some similarities to muscular dystrophy.

Muscle Atrophy Types

Muscle atrophy generally falls under three types:

Physiologic (Disuse)

Physiologic muscle atrophy occurs from prolonged periods of time when muscles are not used at all or not used enough. In other words, "use it or lose it" as the adage goes.

While significant muscle atrophy can take time, signs of atrophy on a molecular level can begin as early as after a week of reduced activity.

There are a lot of reasons that physiologic muscle atrophy can occur, but some of the common ones include:

  • Being confined to bed
  • Jobs that require a lot of sitting or little activity
  • Health problems or conditions that limit movement or reduce activity
  • Inability to move limbs due to a health condition such as a stroke
  • Anything that results in muscles not being used regularly

Physiologic muscle atrophy can even be caused by space travel because of the lack of gravity.

This type of muscle atrophy can often be reversed by lifestyle changes and increased exercise if the muscle loss was caused by disuse only.

Physiologic muscle atrophy can also occur as a secondary type of atrophy to other types of muscle atrophy when those limit movement and activity.

Pathologic

Pathogenic muscle atrophy can occur as a result of:

  • Poor nutrition or starvation
  • Aging (called sarcopenia)
  • Diseases such as Cushing's disease (resulting from an overuse of corticosteroid medications)

Neurogenic

Neurogenic atrophy affects the nerves that connect to muscle tissue. It is the most serious form of muscle atrophy.

Neurogenic atrophy occurs where there is an injury to these nerves or the nerves are affected by the disease. Because there is damage to the nerve or nerves, this type of atrophy is usually not reversible.

Some conditions and diseases that can affect the nerves that control muscles include:

  • Amyotrophic lateral sclerosis (ALS, or Lou Gehrig disease)
  • Guillain-Barre syndrome
  • Multiple sclerosis
  • Single nerve damage, like as seen in carpal tunnel syndrome
  • Polio (poliomyelitis)
  • Spinal cord injury
  • Nerve injury
  • Diabetes
  • Toxins that damage nerves
  • Alcohol use

Symptoms

Symptoms of Muscular Dystrophy
  • Muscle weakness and atrophy

  • Difficulty walking, climbing, jumping, and other physical activities

  • Enlarged calves

  • Heart problems

  • Breathing problems

  • Curved spine

  • Muscle pain

  • Stiff or loose joints

  • Difficulty swallowing

  • Waddling gait

Symptoms of Muscle Atrophy
  • Muscle weakness

  • Loss of muscle tissue

  • Difficulties with balance

  • Mobility problems

  • Numbness or tingling

  • Muscle twitching, cramps, aches and pains

Muscular Dystrophy Symptoms

The symptoms of muscular dystrophy depend on the type, but generally are progressive, get increasingly debilitating, and include muscular weakness and atrophy.

Duchenne Muscular Dystrophy

Symptoms of Duchenne muscular dystrophy include:

  • Progressive muscle weakness and atrophy beginning in the upper legs and pelvis, then spreading into the upper arms
  • Waddling gait
  • Loss of some reflexes
  • Difficulty getting up from a lying down or seated position
  • Difficulty running, jumping, and climbing stairs
  • Changes to posture
  • Enlarged calves
  • Clumsiness and frequent falls
  • Impaired breathing
  • Lung weakness
  • Cardiomyopathy
  • Respiratory infections
  • Difficulty swallowing
  • Bone thinning and scoliosis (curving of the spine) 
  • Cognitive and behavioral impairments

Becker Muscular Dystrophy

Symptoms of Becker muscular dystrophy include:

  • Muscle weakness first in the upper arms, shoulders, upper legs, and pelvis
  • Walking on toes
  • Frequent falls
  • Difficulty rising from the floor
  • Enlarged calves
  • Muscle cramps
  • Cardiac complications
  • Cognitive and behavioral impairments

Congenital Muscular Dystrophy

Symptoms of congenital muscular dystrophy include:

  • Weak muscles
  • A curved spine
  • Joints that are too stiff or loose
  • Failure to meet age-appropriate milestones in motor function and muscle control
  • Mild or severe skeletal muscle degeneration
  • Inability to sit, stand, or walk without support
  • Respiratory problems
  • Swallowing difficulties
  • Foot deformities
  • Possible intellectual impairments
  • Vision problems
  • Speech problems
  • Seizures
  • Structural changes in the brain

Distal Muscular Dystrophy

Symptoms of distal muscular dystrophy include:

  • Weakness and atrophy of muscles of the hands, forearms, lower legs, and feet
  • Usually progresses slowly, rarely leads to total incapacity
  • Difficulty with fine hand movement and extending the fingers
  • Difficulty walking and climbing stairs
  • Inability to hop or stand on heels

Emery-Dreifuss Muscular Dystrophy

Symptoms of Emery-Dreifuss muscular dystrophy include:

  • Slowly progressing atrophy of the upper arm and lower leg muscles
  • Symmetric weakness
  • Contractures (fixed tightening of muscle) in the spine, ankles, knees, elbows, and back of the neck
  • Elbows locked in a flexed position
  • Rigid spine
  • Shoulder deterioration
  • Toe-walking
  • Mild facial weakness
  • Heart problems, usually by age 30, often requiring a pacemaker or other assistive device
  • Progressive pulmonary or cardiac failure

Facioscapulohumeral Muscular Dystrophy

Symptoms of facioscapulohumeral muscular dystrophy include:

  • Progressive muscle weakness in face, shoulders, and upper arms
  • Muscles around the eyes and mouth are often affected first, followed by the shoulders, chest, and upper arms
  • Asymmetrical weakness
  • Appearance of slanted shoulders and winged shoulder blades
  • Diminished reflexes
  • Changes in facial appearance (crooked smile, a pouting look, flattened facial features, or a mask-like appearance)
  • Inability to pucker lips or whistle
  • Difficulty swallowing, chewing, or speaking
  • Respiratory problems
  • Hearing loss
  • Abnormal swayback curve in the spine
  • Pain in affected limb

Limb-Girdle Muscular Dystrophy

Symptoms of limb-girdle muscular dystrophy include:

  • Progressive muscle loss and symmetrical weakening of voluntary muscles, especially in the shoulders and around the hips
  • Weakness in the legs and neck
  • Waddling gait
  • Difficulty rising from chairs, climbing stairs, or carrying heavy objects
  • Frequent falls
  • Inability to run
  • Contractures in the back muscles, giving an appearance of a rigid spine
  • Impaired proximal (closest to the center of the body) reflexes
  • Cardiomyopathy
  • Respiratory complications
  • Severe disability is common within 20 years of onset

Myotonic Muscular Dystrophy

Symptoms of myotonic muscular dystrophy include:

  • Difficulty or inability to relax muscles following a sudden contraction
  • Weakness in the muscles in the face and the front of the neck
  • Haggard, "hatchet" face and a thin, swan-like neck
  • Atrophy and weakness in forearm muscles
  • Cardiac complications
  • Difficulty swallowing
  • Ptosis ("droopy" eyelids)
  • Cataracts
  • Impaired vision
  • Early frontal baldness
  • Weight loss
  • Erectile dysfunction
  • Testicular atrophy
  • Mild mental impairment
  • Increased sweating
  • Drowsiness/excess need to sleep
  • Irregular menstrual periods/infertility

Infants and children with congenital myotonic muscular dystrophy may exhibit:

  • Difficulty swallowing or sucking
  • Impaired breathing
  • Absence of reflexes
  • Skeletal deformities and contractures (such as club feet)
  • Muscle weakness (especially in the face)
  • Mental impairment
  • Delayed motor development

Oculopharyngeal Muscular Dystrophy

Symptoms of oculopharyngeal muscular dystrophy include:

  • Drooping eyelids (sometimes severe)
  • Weakness in the facial muscles
  • Weakness in pharyngeal muscles in the throat
  • Tongue atrophy
  • Difficulty swallowing
  • Changes to the voice
  • Double vision and problems with upper gaze
  • Retinitis pigmentosa (progressive degeneration of the retina that affects night vision and peripheral vision)
  • Cardiac irregularities
  • Muscle weakness and atrophy in the neck and shoulder area and sometimes limbs
  • Difficulty walking, climbing stairs, kneeling, or bending

Muscular Dystrophy Resources

The Muscular Dystrophy Association Resource Center is a great place to find information, locate programs, and get in touch with other families who are affected by muscular dystrophy.

Muscle Atrophy Symptoms

Muscle atrophy is a symptom. It simply means a loss (or "wasting away") of muscle tissue.

Symptoms that often accompany muscle atrophy (particularly symptoms of neuromuscular disorders) include:

  • Muscle weakness
  • Muscle loss
  • Muscle twitching, cramps, aches, and pains
  • Movement difficulties
  • Numbness, tingling, or painful sensations
  • Trouble swallowing
  • Trouble breathing
  • Droopy eyelids
  • Double vision
  • Problems with balance
  • Difficulty walking
  • Falls
  • Facial weakness
  • Loss of muscle coordination
  • Gradual memory loss
  • Progressive loss of movement

Treatment

Treatments for Muscular Dystrophy
  • Physical therapy

  • Respiratory therapy

  • Speech therapy

  • Occupational therapy

  • Surgery

  • Drug therapy

  • Gene-based therapy

Treatments for Muscle Atrophy
  • Rehabilitation exercises

  • Physical therapy

  • Occupational therapy

  • Resistance training

  • Nutrition

  • Regular physical activity

  • Healthy lifestyle habits

Muscular Dystrophy Treatments

Muscular dystrophy cannot be prevented or cured, but treatments do exist with the goal of relieving symptoms, improving quality of life, and slowing the progression of the disease. Treatments include:

  • Physical therapy: Involves physical activity and stretching exercises to help keep muscles flexible and strong
  • Respiratory therapy: Treatments to prevent or delay breathing problems, and if needed, equipment such as a ventilator to assist with breathing
  • Speech therapy: Helps people with facial muscle weakness learn how to maximize their muscle strength and the introduction of communication devices for those who need it.
  • Occupational therapy: Helps to relearn lost motor skills, work with weakened muscles to do tasks, use personal items such as a hairbrush and utensils, and assistive devices such as a wheelchair
  • Surgery: The type of surgery depends on the condition, but some surgeries include a pacemaker installation, removal of cataracts, or spinal surgery
  • Drug therapy: Medications used in the treatment of muscular dystrophy include glucocorticoids (a type of corticosteroid hormone that reduces inflammation), anticonvulsants (to help control seizures and muscle spasms), immunosuppressants (to help delay some damage to dying muscle cells), heart medications such as beta-blockers, and angiotensin-converting-enzyme (ACE) inhibitors
  • Gene-based therapy: Studies are being done on methods to restore a gene’s ability to produce usable proteins as a way to treat muscular dystrophy

Muscle Atrophy Treatments

Treatment for muscle atrophy often involves treating the underlying condition. The success of these treatments also depends on what is causing the atrophy.

Physiologic atrophy often responds well to treatment and can even be reversed. These treatments include:

  • Exercises such as resistance training
  • Low impact exercises such as swimming and water activities
  • Increased protein consumption
  • Healthy lifestyle habits such as diet, sleep, and mindfulness
  • Rehabilitation exercises such as physical therapy, occupational therapy, and passive movement (movement performed by the therapist)
  • Exercises with assistive devices such as braces or splints

The goal is to get those muscles moving and being used in whatever way is possible.

A Word From Verywell

While muscular dystrophy can cause muscle atrophy, they are not the same condition.

Muscular dystrophy is a genetic condition encompassing nine main types, while muscle atrophy refers to the loss of muscle tissue.

Muscle atrophy can often be reversed with treatments and exercise.

While there is no cure for muscular dystrophy, there are ways to improve quality of life and sometimes to slow the progress of the symptoms.

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Article Sources
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