Are your muscles getting weaker too? This could be myotonic dystrophy!

Have you ever felt like your previously strong limbs are slowly becoming numb or weak? Or do you sometimes find it difficult to open your hand when you hold something tightly? These are things that we sometimes don't pay much attention to, but they could be symptoms of a condition called Myotonic Dystrophy . Let's talk about this in detail and simply today.

What is Myotonic Dystrophy?

Simply put, Myotonic Dystrophy (DM) is a complex genetic condition. The main thing in this is that the muscles in our body gradually atrophy and weaken. The muscles of people with this disease may not relax immediately after use, but may remain contracted. We call this myotonia . It's like holding a doorknob tightly and trying to open it takes a while.

The symptoms of myotonic dystrophy (DM) can be very wide-ranging. It can affect several systems in our body. For example:

• Our skeletal muscles (muscles we control intentionally) and cardiac muscles.
• Eyes.
• Cardiovascular system (circulatory system).
• Endocrine system (hormonal system).
• Central nervous system (brain and spinal cord).

Are there types of myotonic dystrophy?

Yes, there are two main types of DM:

1. Myotonic dystrophy type 1 (DM1): This is also called Steinert disease . DM1 again has four subtypes:

• Classic type
• Mild type
• Congenital type (present at birth)
• Childhood type

2. Myotonic dystrophy type 2 (DM2): This is also called proximal myotonic myopathy .

The symptoms of both types can sometimes be similar. However, DM2 is usually a little milder than DM1, meaning the symptoms are not as severe.

What is the difference between Muscular Dystrophy and Myotonic Dystrophy?

This is something that confuses many people. Muscular dystrophy is a group of inherited (genetic) diseases. This group includes more than 30 types of diseases. All of them cause muscle weakness. These fall into the category of myopathy , which is a disease of our skeletal muscles. Over time, the muscles shrink and become weaker. This makes it difficult to walk and perform daily tasks. Sometimes the heart and lungs can also be affected.

Myotonic Dystrophy is a type of muscular dystrophy. It is the most common type of muscular dystrophy that begins in adulthood (although some types of DM can begin in infancy or childhood).

Who can develop myotonic dystrophy? Is there an age difference?

Different types of DM can start at different ages. Let's see how:

• Classic myotonic dystrophy type 1 (Classic DM1): This usually begins in the 20s, 30s, or 40s.
• Mild myotonic dystrophy type 1 (Mild DM1): This can affect people between the ages of 20 and 70, but is most common after the age of 40.
• Congenital myotonic dystrophy type 1 (Congenital DM1): As the word "congenital" suggests, this is a type that affects infants. This means it is present from birth.
• Childhood myotonic dystrophy type 1 (Childhood DM1): This usually begins around the age of 10.
• Myotonic dystrophy type 2 (DM2): This also begins in adulthood. Symptoms usually begin around the age of 48.

How common is this disease?

Myotonic dystrophy (DM) affects at least 1 in 8,000 people worldwide. However, this number can vary by geographic region and ethnicity. DM is the most common type of muscular dystrophy among people of European descent.

In most populations, DM type 1 (DM1) is more common than DM type 2 (DM2).

What are the symptoms of Myotonic Dystrophy?

These are the main symptoms of DM. They gradually get worse over time, meaning they become more severe:

• Muscle atrophy: Muscle wasting.
• Muscle weakness: Decreased muscle strength.
• Myotonia: We've talked about this before. The inability to consciously relax a muscle. For example, once someone with DM grabs a doorknob, it may be a little difficult to let go.

However, because DM affects different parts of the body, a variety of other symptoms can occur. The severity of these symptoms and the rate at which they develop vary depending on the type of DM.

Symptoms of Classic Myotonic Dystrophy Type 1

Symptoms of this type begin in adulthood. Myotonia is the main symptom that is first seen. This is more noticeable after rest and may decrease slightly after muscle activity.

Other symptoms are:

• Distal muscle weakness: This is weakness in the muscles that are farther from the center of the body (e.g., the muscles in the arms and legs). This can make it difficult to do fine manual tasks (e.g., buttoning, writing). It can also make it difficult to walk due to a condition called foot drop (the bottom of the foot drags along the floor).
• Atrophy of facial muscles causes the face to take on a thin, pointed shape (myopathic face) .
• Heart conduction abnormalities.

Symptoms of Congenital Myotonic Dystrophy Type 1

Because this type is present at birth, the baby may show some symptoms while still in the womb:

• Decreased fetal movement in the womb.
• Polyhydramnios is an excessive amount of amniotic fluid surrounding the fetus during pregnancy.
• Clubfoot ( foot turned inward).
• Ventriculomegaly (enlargement of the ventricles of the brain) (due to accumulation of cerebrospinal fluid).

Symptoms seen in children and adults after birth:

• The upper lip looks like a tent due to facial muscle weakness.
• Slurred speech (Dysarthria) .
• Intellectual disabilities.
• Instead of myotonia, there is decreased muscle tone (Hypotonia) .

Symptoms of Mild Myotonic Dystrophy Type 1

Symptoms of this type usually begin between the ages of 20 and 70. They include:

• Mild muscle weakness.
• Myotonia (Myotonia).
• Cataracts .

Symptoms of Childhood Myotonic Dystrophy Type 1

Symptoms of this type usually begin around the age of 10. They include:

• Learning difficulties and psychosocial problems (e.g. family problems, depression, anxiety).
• Slurred speech.
• Myotonia of the muscles of the hands.
• Heart conduction abnormalities.

Symptoms of Myotonic Dystrophy Type 2

Symptoms of type 2 DM usually begin in adulthood and can vary.

Symptoms may include:

• Weakness or tightness in the muscles near the center of the body (e.g., muscles around the hips and shoulders).
• Myofascial pain (pain in muscles and connective tissues) .
• Early onset of cataracts (before age 50).
• Myotonia of varying degrees occurs when grasping something with the hand.
• Hearing impairment.

Pain is a major complaint among people with DM2. These people report pain in the abdomen, skeletal muscles, and during exercise.

What causes Myotonic Dystrophy?

Myotonic dystrophy (DM) is a genetic disease , meaning it is passed down from parents to children through genes.

DM type 1 (DM1) is caused by mutations (changes) in the gene called DMPK . DM type 2 (DM2) is caused by mutations in the gene called CNBP .

Similar changes in the structure of both genes, DMPK and CNBP, are what cause DM1 and DM2. In each case, a section of DNA is repeated many times in an abnormal manner. This creates an unstable region in the gene. The more times this section of DNA is repeated abnormally, the more severe the symptoms of DM become.

Scientific evidence suggests that the excess messenger RNA produced by these abnormal DNA repeats is toxic. This disrupts the production of various proteins in cells, which is what causes the symptoms of myotonic dystrophy in various organs.

How this disease is passed from generation to generation (Myotonic Dystrophy Inheritance)

Both types of DM are inherited in a pattern called autosomal dominant . In this pattern, only one parent needs to have the affected gene for the disease to be passed on to a child. Half of the children of a parent with an autosomal dominant trait will inherit the trait.

As myotonic dystrophy type 1 (DM1) is passed down from one generation to the next, the age of onset usually gets younger and the symptoms get worse. This phenomenon is called anticipation . It's as if the disease is "speeding up" from one generation to the next.

How is Myotonic Dystrophy diagnosed? (Diagnosis)

If you have symptoms of DM, a doctor will first examine you and ask you about:

• Your personal medical history.
• Family medical history, especially whether anyone in the family has DM.
• Your symptoms.

After that, some medical tests may be done to confirm the diagnosis of DM.

What kind of tests are done?

Genetic testing can confirm the diagnosis of DM. These tests look for mutations in the DMPK gene (for DM1) or the CNBP gene (for DM2).

If your doctor suspects that you have DM or another disease, they may do one or more of these tests before referring you for genetic testing:

• Creatine kinase blood test: Creatine kinase is an enzyme found mainly in the heart and skeletal muscles. When these muscle cells are damaged, this enzyme accumulates in the blood. People with mild DM may have this level only slightly elevated, or it may be normal.
• Electromyogram (EMG): In this test, a thin needle-like electrode is inserted into the muscle and the electrical activity of the muscle fibers is measured. People with DM typically have high and low electrical activity in their muscles, even when they are at rest.
• Muscle biopsy: In this, a doctor takes a small tissue sample from your muscle and examines it under a microscope to see if there are signs of DM.

Will further tests be done after the disease is confirmed?

Yes, if these tests confirm DM, your doctor may recommend further tests to check the function of certain organs that may be affected by DM. For example:

• Electrocardiogram (ECG) test to check the functioning of the heart.
• Pulmonary function testing to check for neuromuscular respiratory problems.
• A sleep study to check for obstructive sleep apnea and excessive daytime sleepiness .

Is there a treatment for Myotonic Dystrophy?

Unfortunately, there is still no cure for myotonic dystrophy (DM). Therefore, the primary goals of treatment are:

• Managing symptoms.
• Maintaining the highest level of quality of life and independence.

Because DM affects different parts of the body, treatments may vary depending on your symptoms. These may include:

• Medications to reduce persistent myotonia. For example, sodium channel blockers such as Mexiletine , Tricyclic antidepressants , Benzodiazepines , or Calcium antagonists .
• A CPAP machine to prevent sleep apnea.
• Stimulants such as methylphenidate for excessive daytime sleepiness.
• Cataract surgery is a surgery to remove a cataract that obstructs vision.
• Treatment for diabetes. This may require pills and/or insulin . People with DM are at increased risk of developing diabetes due to insulin resistance .
• Testosterone therapy for male hypogonadism . Men with DM1 often experience low testosterone levels and erectile dysfunction .

Physical therapy and occupational therapy are important treatments for maximizing independence for people with DM. They can help you strengthen your muscles and learn new ways to perform daily tasks. You can also maintain independence by using assistive devices (e.g., braces, canes, wheelchairs).

Speech-language pathology (SLP) can help with swallowing difficulties (Dysphagia) and slurred speech (Dysarthria) .

Can the development of myotonic dystrophy be prevented?

Since DM is a hereditary disease, there is nothing you can do to prevent it.

Before you have a child, if you are concerned about the risk of passing on DM or other genetic conditions to your children, talk to your doctor about genetic counseling .

What is the prognosis with this disease?

The outlook for myotonic dystrophy (DM) depends on the type of disease and the age at which symptoms begin. Generally, if symptoms begin at an earlier age, the outcome may be less favorable and life expectancy may be reduced.

About 50% of people with DM1 will need a wheelchair to get around before they die. People with DM2 usually do not need assistive devices to get around because their symptoms are mild.

What is the life expectancy of someone with Myotonic Dystrophy?

The average life expectancy of someone with DM varies depending on the type of disease.

• Among infants with congenital DM1, the neonatal mortality rate is about 18%. About 25% of those with congenital DM1 die before 18 months of age, and about 50% die before the age of 30.
• People with mild DM1 usually live a normal lifespan.
• People with Classic DM1 have a shorter lifespan than the general population.

Can Myotonic Dystrophy be fatal?

Yes, myotonic dystrophy (DM) can be fatal. However, the age at which death occurs varies depending on the type of disease. The leading cause of death in DM is neuromuscular-associated respiratory failure . Cardiovascular complications can also be a cause of death.

When should you see a doctor about myotonic dystrophy?

If you have symptoms of DM, such as muscle weakness and myotonia, be sure to see a doctor.

If you have DM, you should meet with your medical team regularly to make sure your current treatment plan is working properly.

When you or your child receives a new diagnosis, it can be difficult to cope. But remember, not everyone with myotonic dystrophy (DM) is affected the same way. The best thing you can do is talk to a specialist who researches and treats DM. They can tell you about treatment options and answer any questions you may have.

Let's remember what we talked about as a summary (Take-Home Message)

• Myotonic dystrophy (DM) is a genetic disease that mainly causes muscle weakness and wasting.
• Myotonia is a condition in which muscles have difficulty relaxing after use.
• There are two main types of DM: DM1 and DM2 . DM1 has other subtypes.
• Symptoms can vary depending on the type of DM and from person to person.
• This is due to mutations in genes.
• The disease is diagnosed through genetic testing and other tests.
• Although there is no complete cure, there are treatments that can manage symptoms and improve quality of life.
• If you have any doubts about this, seek medical advice immediately. Early detection is very important.

I hope this information is useful to you. Stay healthy!

` Myotonic Dystrophy, Muscle Weakness, Genetic Diseases, Myotonic Dystrophy, Muscle Diseases, DM, Neurological Diseases