Myotonic dystrophy (Steinert's disease) is the most common muscular dystrophy. Progressive loss of muscle strength and muscle wasting are the main symptoms, but not the only one. How is this disease diagnosed and what treatment can be offered to patients who develop this disease?

Myotonic dystrophy(other names are atrophic myotonia, Crushmann-Steinert disease, Steinert disease) was first described in medical literature in 1909 - then it was the German-born doctor, Hans Gustav Wilhelm Steinert, who described 6 cases of this disease in his patients. It was from his surname that another, also used name of this unit, which is Steinert's disease, was derived.

But it wasn't just this man who studied myotonic dystrophy - individual cases of this unit have also been reported by other researchers, Frederick Batten and Hans Curschmann, which is why myotonic dystrophy is sometimes also referred to as Curschmann-Batten-Steinert disease.

Myotonic dystrophy is the most common form of muscular dystrophy. It is estimated that it occurs in one in 8,000 people. The disease occurs with similar frequency in women and men.

There are two types of myotonic dystrophy:

  • myotonic dystrophy type 1- DMPK gene mutation on chromosome 19
  • myotonic dystrophy type 2- mutation of the ZNF9 gene on chromosome 3

Myotonic dystrophy: causes

Genetic mutations cause myotonic dystrophy - they concern the DMPK gene (in the case of type 1 disease) or the CNBP gene (in the case of type 2 disease). Both of the mentioned mutations are associated with an excessive number of triplicate nucleotide repeats. The role of the above-mentioned genes and the proteins encoded by them is not entirely clear, but it is suspected that they may affect the communication between individual cells, as well as the processes related to protein synthesis.

Mutations that lead to myotonic dystrophy are inherited in an autosomal dominant manner - this means that it is enough to inherit one allele of the mutated gene from the parent. Related to this is also that the child of a person suffering from dystrophyIt has a 50% risk that it will inherit the mutant allele of the gene and eventually develop a disease similar to its parent.

Myotonic dystrophy: symptoms

Ailments related to Steinert's disease may appear at any age, but typically the first symptoms of myotonic dystrophy occur in the second-third decade of life.

The basic abnormalities associated with this disease relate to the functioning of the muscles - patients develop, among others, myotonia, which is characterized by a significantly slower muscle relaxation after it starts working.

There is also a progressive loss of muscle strength, muscle atrophy and excessive muscle stiffness.

Depending on the type of disease, different muscle groups suffer from abnormalities characteristic of myotonic dystrophy. In type 1 myotonic dystrophy, the muscles of the limbs, neck and face are primarily affected, while in type 2, the pathology mainly affects the muscles of the neck, shoulders and hips.

Muscle abnormalities aren't the only symptoms of Steinert's disease, however. Patients may also develop:

  • cataract
  • male pattern baldness and testicular atrophy
  • heart rhythm disturbance
  • menstrual disorders in women
  • swallowing disorders
  • hearing impairment
  • insulin resistance (usually leading to diabetes)
  • fertility disorders

It is worth mentioning here about the most severe form of the described disease, which is congenital myotonic dystrophy. Overall, it is estimated to account for 10% of all cases of type 1 myotonic dystrophy, and in its case, as the name implies, the symptoms of the disease are present from birth, and sometimes even earlier.

In the prenatal period, they may occur:

  • impaired fetal movements
  • polyhydramnios
  • dilatation of the ventricles

Later, after birth, patients with congenital myotonic dystrophy may include:

  • muscle flaccidity
  • joint contractures
  • difficulty sucking and swallowing

In a significant proportion of patients with this type of myotonic dystrophy, motor and mental development is delayed.

Myotonic dystrophy: diagnosis

A suspicion of myotonic dystrophy is possible on the basis of the patient's characteristic symptoms. These can be seen during a neurological examination, but only the examination is definitely not enough to make a surediagnosis.

Usually, patients with abnormalities suggesting Steinert's disease are ordered various tests, such as head imaging tests or electromyography (EMG).

A definite and definitive diagnosis of myotonic dystrophy can only be made, however, when genetic tests reveal a mutation characteristic of this disorder.

Myotonic Dystrophy: Treatment

In fact, myotonic dystrophy is, unfortunately, an incurable disease - medicine currently does not have any methods that would allow us to eliminate mutations existing in patients.

Patients are not left completely untreated - they are treated with symptomatic treatment aimed at minimizing the intensity of their symptoms and extending the time they maintain their fitness. In order to achieve these goals, patients are primarily advised to undergo regular rehabilitation.

In addition, it is sometimes recommended that patients take painkillers to alleviate the pain associated with excessive muscle tension.

It should be added here that patients with myotonic dystrophy are usually under the care of various medical specialists - it is extremely important for them to manage their various abnormalities.

If a cataract develops, it can be removed by surgery, fertility disorders can be eliminated by supplementation with appropriate hormones, and heart rhythm disturbances can be eliminated by using antiarrhythmic drugs.

Myotonic dystrophy: prognosis

The prognosis of patients with myotonic dystrophy depends primarily on the type of their disease - in all of them the symptoms worsen over time, however, in some types of this disease the progression is slower, and in others it is faster.

The prognosis for congenital myotonic dystrophy is worst - here patients usually live to 3-4. decades of life.

Reduction in life expectancy - although not as significant as mentioned above - also occurs in the course of myotonic dystrophy type 1.

Patients with type 2 myotonic dystrophy have the best prognosis, in which patients have a life expectancy similar to that of the general population, additionally they remain fit for a long time (patients usually maintain their ability to walk until the age of 60 or even and longer).

About the authorBow. Tomasz NęckiA graduate of medicine at the UniversityMedical Department in Poznań. An admirer of the Polish sea (most willingly strolling along its shores with headphones in his ears), cats and books. In working with patients, he focuses on always listening to them and spending as much time as they need.

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Category:

Genetic diseases