myotonic dystrophy

Myotonic dystrophy is a rare, inherited disorder in which the muscles contract but have decreasing power to relax. With this condition, the muscles also become weak and waste away.

Myotonic dystrophy is a multisystem disease. It affects various types of tissue and organs. Myotonic dystrophy can cause mental deficiency, hair loss and cataracts. Onset of Myotonic dystrophy usually occurs during young adulthood. However, it can occur at any age and is extremely variable in degree of severity.

Which muscles are affected in Myotonic Dystrophy?

In most cases, the first muscles to be affected by mytonic dystrophy are the muscles in the face, neck, hands, forearms, and feet.

When myotonic dystrophy causes weakness facial muscles, individuals may not have facial expressions or have a mask-like facial appearance. This weakness of the muscle that elevates the upper eyelids causes the eyelids to droop and hang partially in front of the eyes (ptosis).


The most common symptoms of myotonic dystrophy are:

  • Generalized weakness and muscle wasting first affecting the face, lower legs, forearms, hands and neck, with delayed relaxation of muscles after contraction
  • Learning disabilities
  • Slurred speech (because of the weakness of muscles required to speak)
  • Difficulty swallowing
  • Digestive problems
    • This largely affects the functions of the smooth muscle of the stomach and intestines. Weakened muscle contractions in the stomach and intestine causes in abdominal pain, gallstones, constipation, diarrhea, loss of bladder control (incontinence), and pseudo-obstruction.
  • Difficulty breathing.
    • Weakness of muscles necessary for breathing can occur and can lead to hypoventilation, which is the insufficient exchange of carbon dioxide and oxygen in the lungs. Hypoventilation is a process where a person breathes at a slower rate with an increased amount of carbon dioxide in the blood.
  • Cataracts


The exact cause of myotonic dystrophy is unknown.


Respiratory failure late in life is a common complication. This is likely caused by the lifelong difficulty breathing.