Muscular dystrophy
Muscular dystrophy is a group of conditions that damage your muscles over time.
This damage and weakness are due to the lack of a protein called dystrophin. This protein is necessary for normal muscle function. If there is a deficiency of this protein, it can cause problems with walking, swallowing, and muscle coordination.
Most diagnoses happen during childhood although they can occur at any age.
Muscular dystrophies affect people of all genders. However two of the most common types, Duchenne and Becker, are more common in males. Combined muscular dystrophies affect about 1 out of 100,000 people in the United States according to the Centers for Disease Control and Prevention (CDC).
The outlook for muscular dystrophy depends on the kind of muscular dystrophy and the severity of symptoms.
There is no known cure for any of the muscular dystrophies, but there are treatments and therapies that can help some people with a specific gene difference who live with Duchenne muscular dystrophy.
There are several types of muscular dystrophy, each with its own symptoms. Some dystrophies are more severe than others.
Duchenne muscular dystrophy (DMD)
DMD is the most common muscular dystrophy in children. Most individuals who are affected are children who were assigned male at birth, but it is rare for children who were assigned female at birth to develop it.
The symptoms include:
- trouble walking
- loss of reflexes
- difficulty standing up
- poor posture
- bone thinning
- Scoliosis is an abnormal curvature of the spine.
- learning differences
- breathing difficulties
- swallowing problems
- lung and heart weakness
People with DMD typically begin using a wheelchair before their teenage years.
It used to be that people with DMD lived into their late teens or 20s, but now it is more common for people to live into their 30s due to advances in medical treatment. This includes care for the heart and lungs.
About 14 in 100,000 U.S. males between the ages of 5 and 24 years are affected by combined DMD and Becker muscular dystrophy.
Becker muscular dystrophy (BMD)
BMD is a type of muscular dystrophy that is similar to DMD, but it is less severe. This condition is more common in boys who are assigned male at birth.
Weakness in the muscles often starts in the arms and legs between the ages of 11 and 25.
Other symptoms of BMD include:
- walking on the toes
- frequent falls
- muscle cramps
- trouble getting up from the floor
Many people with this condition will not want to use a wheelchair until they are in their thirties or older, and a small percentage of people never require one. Most people with BMD live until middle age or later.
Congenital muscular dystrophy
Some congenital muscular dystrophies are often apparent between birth and 2 years old. This is when parents begin to notice that their child’s motor abilities and muscle control aren’t developing as they should.
Symptoms vary and may include:
- muscle weakness
- poor motor control
- If a person cannot sit or stand without support, they may have a problem.
- scoliosis
- foot deformities
- trouble swallowing
- respiratory issues
- vision problems
- speech problems
- learning differences
There are different symptoms that can occur with this type of muscular dystrophy. Some people have mild symptoms and others have more severe ones. Some people with this condition die in infancy, while others live into adulthood.
Congenital muscular dystrophy is a rare condition that affects about 1 in 100,000 people in the United States of all ages.
Myotonic dystrophy
This form of muscular dystrophy causes myotonia, which is an inability to relax muscles after they are contracted. Myotonic dystrophy is also called Steinert's disease or myotonia.
Some people with other types of muscular dystrophy don't experience myotonia, but it's a symptom of other muscle diseases.
Myotonic dystrophy can affect your:
- facial muscles
- central nervous system (CNS)
- adrenal glands
- heart
- thyroid
- eyes
- gastrointestinal tract
The symptoms of rosacea usually appear first on the face and neck. They may include:
- When the muscles in your face droop, it can make you look thin and drawn.
- The neck of the bottle is difficult to lift because the muscles are weak.
- difficulty swallowing
- droopy eyelids, or ptosis
- A bald front area is a sign of early hair loss.
- poor vision, including cataracts
- weight loss
- increased sweating
This disorder can cause problems with sexual function, including impotence and infertility.
Myotonic dystrophy is most likely to be diagnosed in adults in their 20s. The severity of symptoms can vary greatly, with some people experiencing mild symptoms while others have potentially life-threatening symptoms involving the heart and lungs. Many people with the condition live a long life.
Myotonic dystrophy is a rare disorder that affects both men and women equally.
FSHD is a condition in which there is a problem with the muscles that connect the face to the shoulder.
FSHD affects the muscles in the face, shoulders, and upper arms. This is also called Landouzy-Dejerine disease.
FSHD may cause:
- difficulty chewing or swallowing
- slanted shoulders
- a crooked appearance of the mouth
- The shoulder blades should have a wing-like appearance.
Some people with FSHD may develop hearing and respiratory problems.
FSHD (follicular thyroid disease) usually progresses slowly. Symptoms may not appear until someone reaches their teenage years, but in some cases they may not appear until a person is in their 40s. Most people with FSHD live a full life span.
About one in every four thousand people in the United States has FSHD.
Limb-girdle muscular dystrophy (LGMD)
LGMD is a group of more than 20 inherited conditions that cause weakening of the muscles. The symptoms typically begin in the shoulders and hips, but they may also occur in the legs and neck.
If you have low muscle dystrophy, it may be difficult to get up out of a chair and walk up stairs. You may also stumble more easily and fall more often.
About 2 out of 100,000 people in the United States have LGMD.
Many people with this type of muscular dystrophy experience a lot of disability within a short period of time.
OPMD is a disorder that affects the muscles that control the eye and throat.
OPMD is a disorder that causes weakness in your facial muscles and neck. Some other symptoms may include:
- drooping eyelids
- vision problems
- trouble swallowing
- voice changes
- heart problems
- difficulty walking
M.D. is one of the rarest types of muscular dystrophy affecting fewer than 1 in 100,000 people in the United States. Individuals usually experience symptoms in their 40s or 50s.
Distal muscular dystrophy
Distal muscular dystrophy is a group of six diseases that affect the muscles furthest from the shoulders and hips.
- forearms
- hands
- calves
- feet
The condition can cause problems with your respiratory system and heart muscles. The symptoms often start slowly and may include a loss of fine motor skills and difficulty walking.
Most people who develop distal muscular dystrophy between the ages of 40 and 60 years old experience symptoms.
This condition is very rare, affecting fewer than one in a million people in the United States.
Emery-Dreifuss muscular dystrophy (EDMD)
EDMD is more common in boys than girls at birth. Symptoms of EDMD include:
- A weakened muscle in the upper arm or lower leg could be a sign of a problem.
- breathing problems
- heart problems
- Shortening of the muscles in the back, neck, ankles, and knees can happen.
EDMD is a rare condition that affects only a few people in the United States each year.
Most individuals with EDMD live until mid-adulthood. Nearly all of them have a heart issue that requires intervention, such as a pacemaker. The most common causes of shortened lives are progressive heart or lung issues.
Mutations in genes cause muscular dystrophy.
There are thousands of genes that contribute to the proteins that determine muscle integrity. People inherit these genes on 23 pairs of chromosomes, half from their biological parents.
One of your chromosomes is sex-linked. This means the traits or conditions you inherit as a result of that gene may depend on your sex or the sex of your parent. The other 22 pairs of chromosomes (autosomal) are not sex-linked and are also known as non-sex chromosomes.
A change in one gene can lead to a deficiency of dystrophin, a critical protein. The body may not produce enough dystrophin or it may produce it the wrong way.
Mutations in the genes that cause muscular dystrophy can happen in one of four ways. Normally, these mutations are inherited, but they can also be the result of a spontaneous change.
Autosomal dominant inherited disorder
A person inherits a gene difference from just one parent on one of the 22 pairs of chromosomes.
Muscular dystrophy is a gene that is passed down from one parent, and it affects people of all genders equally. If one parent is a carrier for the gene, their child has a 50 percent chance of inheriting the condition.
Autosomal recessive inherited disorder
A person inherits a gene difference from both their parents on one of the 22 autosomal chromosomes. Carriers of the gene don't develop muscular dystrophy, but they may pass the gene onto their children.
Children have a 50/50 chance of inheriting one copy of the gene and becoming a carrier. All children carry this risk equally.
Sex-linked (X-linked) disorder
This inheritance is connected to the genes on the X chromosome.
Some people have two X chromosomes- one from their mom and one from their dad. If someone has a gene difference on their X chromosome (from their mom who has two X chromosomes or from their dad who has two X chromosomes), they'll be a carrier of that gene difference. A gene that causes muscular dystrophy can develop.
If a child has a faulty X chromosome, they are more likely to develop muscular dystrophy if they also inherit a Y chromosome.
X-chromosomes play a role only if they are received from the other parent (as with children assigned female at birth). This other X chromosome can offset the effect of the X chromosome that carries the gene difference, resulting in dystrophin production.
Spontaneous mutation
In this case, muscular dystrophy will develop because of a spontaneous change in genes. It can happen to people who do not have the same genetic makeup as their biological parents.
If you have a change of heart, your carrier can pass on the change to their children.
Muscular dystrophy is a condition that is caused by a genetic mutation. A family history of muscular dystrophy increases the likelihood of being a carrier or developing the condition.
Male children are more likely to have DMD or BMD if they are assigned a male sex at birth.
Even though children who receive an X chromosome from each parent should have adequate dystrophin production, they can still experience symptoms of DMD or BMD, such as muscle cramps, weakness, and heart issues.
Muscular dystrophy can progress differently for each person. Complications also vary depending on the type of muscular dystrophy. Some common complications include:
- movement
- breathing
- the heart
- the spine
People with muscular dystrophy are at a greater risk for certain complications during pregnancy, such as premature labor.
Mobility changes
Maintaining mobility can be difficult for people with muscular dystrophy. Some people with this condition will eventually need help from aides such as wheelchairs. Wheelchairs that are specially designed may be more comfortable, reduce pain, and provide adequate muscle support.
Respiratory issues
Muscle weakness can cause breathing problems because it makes breathing harder. Swallowing problems can lead to aspiration or inhaling substances into the airway or lungs. It can be more difficult for the respiratory system to do its job of transporting oxygen and exhaling carbon dioxide. Dioxide is a gas that is released when the oil is heated.
Cardiac issues
Lack of dystrophin can affect the heart because it is a muscle.
People with muscular dystrophy often have cardiomyopathy or heart muscle disease. Doctors may recommend treatments to improve your heart health, such as medications.
Contractures and scoliosis
Muscular dystrophy can also affect the skeletal muscles, which can cause flexibility in the tendons and joints to be reduced. This can lead to a permanently contracted position of the muscles and joints.
A weak spinal muscle can cause curvature of the spine or scoliosis.
Surgery may be able to relieve some contractures. Corticosteroids and physical therapy may help prevent the development of scoliosis.
Pregnancy considerations
Pregnancy for people with muscular dystrophy may have some complications. Muscle weakness in the legs, hips, and abdominal muscles can make it difficult to push during labor, which increases the chance of a cesarean delivery or other medical intervention.
If someone has myotonic dystrophy, they may experience general muscle weakness that can lead to pregnancy loss. Pregnancy can also cause people with myotonic dystrophy to develop their condition more quickly and have worse symptoms.
Your doctor can diagnose muscular dystrophy by performing a number of tests. These tests include:
- Blood testing.If high levels of serum creatine kinase, aldolase, and myoglobin are found in a person's blood, this may be an indication that they have muscular dystrophy. More testing may be needed to confirm or rule out this condition.
- Genetic testing.If high levels of creatine kinase are present and there are signs of insufficient dystrophin, genetic testing may be necessary. This type of testing looks for a large mutation of the dystrophin (DMD) gene. If there is no large mutation, subsequent tests look for small mutations.
- Electromyography (EMG).EMG is a test that uses an electrode to measure the electrical activity of your muscle. This can help doctors differentiate muscular dystrophy from a nerve disorder.
- Neurological physical exam.This test can determine if a person has a nervous system disorder and assesses muscle strength and reflexes.
- Cardiac testing.Cardiac testing can identify heart problems that sometimes occur in people with muscular dystrophy. Tests may include an echocardiogram to look at the structure of the heart.
- Imaging tests.MRI and ultrasound imaging help doctors see the amount of muscle inside the body.
- Exercise assessments.A muscle strength assessment looks at how well you can breathe and how exercise affects your body.
There is currently no cure for muscular dystrophy, but treatments can help manage your symptoms and slow the progression of the disease. Treatments depend on the type of muscular dystrophy you have and your symptoms.
Medications
The Food and Drug Administration has approved new treatments for some people with Duchenne muscular dystrophy. Many of these treatments involve replacing the defective segment of the dystrophin gene with a new, patched-over version.
These new treatments include:
- Eteplirsen (Exondys 51). This weekly injection is for people with a specific mutation of the dystrophin gene that allows for exon 51 skipping. According to the FDA's 2016 approval notice, this applies to about 13 percent of people with DMD.
- Golodirsen This injection is for people with a dystrophin gene difference that can be treated with exon 53 skipping. According to the FDA's 2019 approval notice, this applies to about 8 percent of people with DMD.
- Viltolarsen (Viltepso). This is a weekly injection for people who have a dystrophin gene difference that can be treated with exon 53 skipping. The FDA approved viltolarsen in 2020.
- Casimersen (There is a gene difference that allows for exon 45 skipping. This applies to about 8 percent of people with DMD according to the FDA's 2021 approval notice.
- Deflazacort (Emflaza).This is a type of medication that's available as a tablet or oral suspension. It's approved for people 5 years and older with DMD.
Muscle therapy
Some forms of muscle therapy are effective. A professional can help you improve your physical abilities by using different techniques. These include:
- physical therapy
Occupational therapy can help those with muscular dystrophy by focusing on their daily activities.
- become more independent
- gain access to community services
- improve coping skills
- improve social skills
Other treatments
Other treatment options include:
- Corticosteroid drugs help to strengthen muscles and slow muscle deterioration.
- If respiratory muscles are affected, ventilation may need to be assisted.
- medication for cardiac problems
- surgery to treat cardiac problems
- A surgery is performed to help correct the shortening of muscles.
- surgery to repair cataracts
- surgery to treat scoliosis
The age at which a person experiences symptoms and the outlook for their condition depends on the type of muscular dystrophy they have.
Scientists are working on a cure for DMD. In 2018, they found a way to repair a gene in canine models that ensures adequate dystrophin production. They hope to one day use this advanced gene editing technique in people with DMD.
This breakthrough research offers new hope for people with muscular dystrophy and their families. These medications slow the progression of DMD symptoms.
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