Myotonic Dystrophy

Myotonic Dystrophy is a highly degenerative muscular condition that affects 1 in every 8,000 people around the world. Read and know what is Myotonic Dystrophy as well as its causes, symptoms, diagnosis and treatment.

Myotonic Dystrophy Definition

It is a type of muscular dystrophy that is characterized by problems in muscles as well as many other organs in the human body. Unlike other types of muscular dystrophy, this condition does not become a problem until people each their adulthood.

Picture 1 – Myotonic Dystrophy

The disorder is also known as Myotonic Muscular Dystrophy (MMD).

Myotonic Dystrophy Types

Myotonic Dystrophy can be differentiated into two main types:

Myotonic Dystrophy Type 1

This condition is marked by muscle fatigue affecting different regions of the body, such as hands, face, neck and lower legs.

Myotonic Dystrophy Type 2

It is milder than Type 1 but involves similar type of weakness in the muscles of regions like shoulders, neck, elbows and hips.

The signs and symptoms of both types tend to overlap, making it difficult to distinguish Type 2 from Type 1. Both types result from mutations in various genes.

Congenital Myotonic Dystrophy

This is a variant of myotonic dystrophy type 1 and is usually evident at birth. The problem is mainly characterized by discomforting symptoms, such as:

  • Weakened muscle tone (Hypotonia)
  • Foot turned inward and upward (Clubfoot)
  • Respiratory problems
  • Retarded maturation
  • Intellectual disability

Some of these problems can even threaten the life of a patient.

Myotonic Dystrophy Symptoms

This condition is characterized by a number of discomforting symptoms. Some of the main signs and symptoms of Myotonic Dystrophy are:

  • Gradually progressive muscular weakness
  • Slow atrophy, particularly of the neck and facial regions
  • Early baldness
  • Formation of cataracts (cloudy vision)
  • Gonadal atrophy
  • Abnormal glucose tolerance curve
  • Mental deficiency
  • Cardiac conduction defects (abnormalities of electrical signals controlling the heartbeat)
  • Foot drop

However, this disease is mainly characterized by weakness and prolonged muscle contractions (myotonia). People with this condition are often unable to relax some muscles after contracting them. For example, they may experience difficulties in releasing their grip on a handle or doorknob. They may also suffer from slurred speech. Some patients may also have a temporary locked-jaw sensation.

Men affected with this disease may suffer from hormonal changes, which may cause problems like:

  • Early baldness
  • Inability to produce a child (Infertility)

The symptoms of this condition often arise during the third or fourth decade of the life of a person. However, they can manifest at any age. The intensity of this disorder widely varies among affected individuals, even among people who are members of the same family.

In rare cases, sufferers may also experience problems like obstetric complications, recurrent abdominal pain and constipation.

Myotonic Dystrophy Causes

This is an autosomal dominant hereditary disease and results from single or double mutated genes. Simply put, MD sufferers inherit this disorder from either any or both of their parents. Type 1 MMD is caused by a mutation in Chromosome 19 while Type 2 results from a mutation in Chromosome 3.

Myotonic Dystrophy Diagnosis

The diagnosis of Myotonic Dystrophy is typically conducted by any of the following methods:

Physical Examination

A doctor experienced in treating neuromuscular disorders can suspect this disorder based on physical examination as well as interaction with the sufferer. Physical testing can help reveal problems like Myotonia and muscle fatigue. The pattern of wasting and involvement of the muscles in the neck, face, legs and lower arms can be used to determine the disease. Men affected by this disorder also tend to have a characteristic facial appearance as displayed by frontal baldness and long face.

Muscle Biopsy

This is a special test that involves withdrawing a tiny part of the affected muscle with the aid of a fine needle and analyzing it afterwards under a microscope. A specific muscle architecture pattern may help a pathologist diagnose MD.


It involves testing the electrical activity of the nerves and muscles, which provides valuable information about the diagnosis. The test includes inserting small needles into the affected muscles and testing the electrical activity.

Genetic Tests

A genetic analysis provides a definite conclusion regarding this clinical condition. Extracting DNA from the blood sample of a patient and testing it for MD can be conclusive. DNA testing can help find out the number of CTG repeats occurring on the DMPK gene.

Presymptomatic testing

It is performed for sufferers who do not display any features of MD but have a family history of the condition.

The condition may also be diagnosed with the help of eye examination and prenatal testing. Examination of the eyes can help detect cataract problems, as commonly seen in MMD sufferers.

Myotonic Dystrophy Treatment

As of now, no specific cure is known to be available for Myotonic Dystrophy, or any other type of muscular dystrophy. Treatment is generally aimed at providing relief from the symptoms. The complications arising from this condition, such as cataracts and heart problems, can only be treated temporarily but not cured. Certain medicines help in relieving symptoms like pain, extreme sleepiness, gradual muscular degeneration and Myotonia.

Problems like cataract require patients to undergo surgery for correction of vision. Physical therapy may also help improve strength and muscle tone, as well as preserve joint flexibility. Strength training and aerobic exercises can help cure problems like Foot Drop.

Myotonic Dystrophy Life Expectancy

Individuals with this condition may have a reduced life span. On an average, MD sufferers are found to be around 48-55 years of age at the time of death. Such people usually die suddenly due to conditions like,

  • Arrhythmia
  • Tumors
  • Pneumonia
  • Respiratory failure
  • Cardiovascular problems

Myotonic Dystrophy Prognosis

The disorder varies significantly during its course, which makes it difficult to predict its outcome. The disability has a tendency of becoming severe if symptoms begin to arise at an early stage of life. In such cases, some affected individuals may need a wheel chair to move about later in life. They may also require tailor-made educational programs as well as physical and occupational therapies early on in life to manage the condition later. However, most sufferers are usually able to walk freely and live their life as independently as individuals not having the disease.

If you are experiencing symptoms of this disease or have this condition in your family and planning for pregnancy, get in touch with a healthcare provider. Timely medical consultation will help you manage any possible complication in future. It may also aid you in managing your life in a much better way.

One Response

  1. JoAnn S. Bjarnson August 24, 2012

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