Muscular dystrophy

Muscular Dystrophy (MD) is a group of rare hereditary muscle diseases characterized by progressive skeletal muscle weakness. Lack of a protein called dystrophin, causes problems with walking, swallowing, and muscle coordination. There are about 30 different types of MD. An estimate of overall prevalence of MD is 29 per 100,000 population, which means 1 in 3500 people may have muscular dystrophy.

Definition 

The Rights of Persons with Disabilities Act, 2016 defines Muscular Dystrophy as a group
of hereditary genetic muscle disease that weakens the muscles that move the human
body and persons with multiple dystrophy have incorrect and missing information in
their genes, which prevents them from making the proteins they need for healthy
muscles. It is characterised by progressive skeletal muscle weakness, defects in muscle
proteins, and the death of muscle cells and tissue.


It is a group of inherited diseases that damage and weaken muscles over time. This
damage and weakness is due to the lack of a protein called dystrophin, which is
necessary for normal muscle function. The absence of this protein can cause problems
with walking, swallowing, and muscle coordination. Muscular dystrophy can occur at any
age, but most diagnoses occur in childhood. Young boys are more likely to have this
disease than girls. The prognosis for muscular dystrophy depends on the type and the
severity of symptoms. However, most individuals with muscular dystrophy do lose the
ability to walk and eventually require a wheelchair. 

Light green ribbon representing Multiple Dystrophy Day | © Pixaway

Variations 

There are more than 30 different types of muscular dystrophy, which vary in symptoms
and severity. There are nine different categories used for diagnosis.


Duchenne muscular dystrophy
This type of muscular dystrophy is the most common among children. The majority of
individuals affected are boys. It’s rare for girls to develop it. The symptoms include:

  • trouble walking
  • loss of reflexes
  • difficulty standing up
  • poor posture
  • bone thinning
  • scoliosis, which is an abnormal curvature of your spine
  • mild intellectual impairment
  • breathing difficulties
  • swallowing problems
  • lung and heart weakness

People with Duchenne muscular dystrophy typically require a wheelchair before their
teenage years. The life expectancy for those with this disease is late teens or 20s.

Becker muscular dystrophy
Becker muscular dystrophy is similar to Duchenne muscular dystrophy, but it’s less
severe. This type of muscular dystrophy also more commonly affects boys. Muscle
weakness occurs mostly in arms and legs, with symptoms appearing between age 11 and
25.


Other symptoms of Becker muscular dystrophy include:

  • walking on your toes
  • frequent falls
  • muscle cramps
  • trouble getting up from the floor

Many with this disease don’t need a wheelchair until they’re in their mid-30s or older, and
a small percentage of people with this disease never require one. Most people with
Becker muscular dystrophy live until middle age or later.


Congenital muscular dystrophy

Congenital muscular dystrophies are often apparent between birth and age 2. This is
when parents begin to notice that their child’s motor functions and muscle control aren’t
developing as they should. Symptoms vary and may include:

  • muscle weakness
  • poor motor control
  • inability to sit or stand without support
  • scoliosis
  • foot deformities
  • trouble swallowing
  • respiratory problems
  • vision problems
  • speech problems
  • intellectual impairment

While symptoms vary from mild to severe, the majority of people with congenital
muscular dystrophy are unable to sit or stand without help. The lifespan of someone with
this type also varies, depending on the symptoms. Some people with congenital
muscular dystrophy die in infancy while others live until adulthood.

Myotonic dystrophy

Myotonic dystrophy is also called Steinert’s disease or dystrophia myotonica. This form of muscular dystrophy causes myotonia, which is an inability to relax your muscles after they contract. Myotonia is exclusive to this type of muscular dystrophy.

Myotonic dystrophy can affect:

  • facial muscles
  • central nervous system
  • adrenal glands
  • heart
  • thyroid
  • eyes
  • gastrointestinal tract

Symptoms most often appear first in your face and neck. They include:

  • drooping muscles in your face, producing a thin, haggard look
  • difficulty lifting your neck due to weak neck muscles
  • difficulty swallowing
  • droopy eyelids, or ptosis
  • early baldness in the front area of your scalp
  • poor vision, including cataracts
  • weight loss
  • increased sweating

This dystrophy type may also cause impotence and testicular atrophy in males. In
women, it may cause irregular periods and infertility.

Myotonic dystrophy diagnoses are most common in adults in their 20s and 30s. The
severity of symptoms can vary greatly. Some people experience mild symptoms, while
others have potentially life-threatening symptoms involving the heart and lungs.

Facioscapulohumeral (FSHD)

Facioscapulohumeral muscular dystrophy (FSHD) is also known as Landouzy-Dejerine
disease. This type of muscular dystrophy affects the muscles in your face, shoulders, and
upper arms. FSHD may cause:

  • difficulty chewing or swallowing
  • slanted shoulders
  • a crooked appearance of the mouth
  • a wing-like appearance of the shoulder blades

A smaller number of people with FSHD may develop hearing and respiratory problems.

FSHD tends to progress slowly. Symptoms usually appear during your teenage years, but
they sometimes don’t appear until your 40s. Most people with this condition live a full
life span.

Limb-girdle muscular dystrophy

Limb-girdle muscular dystrophy causes weakening of the muscles and a loss of muscle
bulk. This type of muscular dystrophy usually begins in shoulders and hips, but it may also
occur in your legs and neck. Patients may find it hard to get up out of a chair, walk up and
down stairs, and carry heavy items if they have limb-girdle muscular dystrophy. They may
also stumble and fall more easily.

Limb-girdle muscular dystrophy affects both males and females. Most people with this
form of muscular dystrophy are disabled by age 20. However, many have a normal life
expectancy.

Oculopharyngeal muscular dystrophy (OPMD)
Oculopharyngeal muscular dystrophy causes weakness in your facial, neck, and shoulder
muscles. Other symptoms include:

  • drooping eyelids
  • trouble swallowing
  • voice changes
  • vision problems
  • heart problems
  • difficulty walking

OPMD occurs in both men and women. Individuals usually receive diagnoses in their 40s
or 50s.

Distal muscular dystrophy
Distal muscular dystrophy is also called distal myopathy. It affects the muscles in:

  • forearms
  • hands
  • calves
  • feet

It may also affect the respiratory system and heart muscles. The symptoms tend to
progress slowly and include a loss of fine motor skills and difficulty walking. Most people,
both male and female, are diagnosed with distal muscular dystrophy between the ages
of 40 and 60.

Emery-Dreifuss muscular dystrophy
Emery-Dreifuss muscular dystrophy tends to affect more boys than girls. This type of
muscular dystrophy usually begins in childhood. The symptoms include:

  • weakness in upper arm and lower leg muscles
  • breathing problems
  • heart problems
  • shortening of the muscles in spine, neck, ankles, knees, and elbows

Most individuals with Emery-Dreifuss muscular dystrophy die in mid-adulthood from
heart or lung failure.

Causes

Certain genes are involved in making proteins that protect muscle fibers from damage.
Muscular dystrophy occurs when one of these genes is defective.
Each form of muscular dystrophy is caused by a genetic mutation particular to that type
of the disease. Many of these mutations are inherited. But some occur spontaneously in
the mother's egg or the developing embryo and can be passed on to the next
generation.

A ramp from ground to the back of a van, up on which is a motorized wheelchair. | © Pixaway

Treatments

There's no cure for any form of muscular dystrophy. But treatment can help prevent or
reduce problems in the joints and spine to allow people with muscular dystrophy to
remain mobile as long as possible. Treatment options include medications, physical
therapy, and surgical and other procedures.


Medications
Doctor may recommend:

  • Corticosteroids, such as prednisone, which can help improve muscle strength and delay the progression of certain types of muscular dystrophy. But prolonged use of these types of drugs can cause weight gain and weaken bones, increasing fracture risk.
  • Heart medications, such as angiotensin-converting enzyme (ACE) inhibitors or beta blockers, if muscular dystrophy damages the heart.

Therapy
Several types of therapy and assistive devices can improve quality and sometimes length
of life in people who have muscular dystrophy. Examples include:

  • Range-of-motion and stretching exercises: Muscular dystrophy can restrict the flexibility and mobility of joints. Limbs often draw inward and become fixed in that position. Range-of-motion exercises can help to keep joints as flexible as possible.
  • Exercise: Low-impact aerobic exercise, such as walking and swimming, can help maintain strength, mobility and general health. Some types of strengthening exercises also might be helpful. But it's important to talk to your doctor first because some types of exercise might be harmful.
  • Braces: Braces can help keep muscles and tendons stretched and flexible, slowing the progression of contractures. Braces can also aid mobility by providing support for weakened muscles.
  • Mobility aids: Canes, walkers and wheelchairs can help maintain mobility and independence.
  • Breathing assistance: As respiratory muscles weaken, a sleep apnea device may help improve oxygen delivery during the night. Some people with severe muscular dystrophy may need to use a machine that forces air in and out of their lungs (ventilator).

Surgery
Surgery may be needed to correct a spinal curvature that could eventually make
breathing more difficult.

Statistics in India

As per a global research “Prevalence of Muscular Dystrophies: A Systematic Literature
Review” the total combined prevalence for all muscular dystrophies for studies classified
as having a low risk of bias ranged between 19.8 and 25.1 per 100,000 person-years.
Myotonic dystrophy (0.5-18.1 per 100,000), Duchenne muscular dystrophy (1.7-4.2) and
facioscapulohumeral muscular dystrophy (3.2-4.6 per 100,000) were found to be the
most common types of disorder. However estimates vary significantly, and it is difficult
to ascertain the accurate prevalence rate of muscular dystrophy in India and the world.

References for More Reading and Understanding/Sources

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