Contents
What is Duchenne muscular dystrophy
Duchenne muscular dystrophy is a degenerative dystrophy caused by changes in the DMD gene. It usually affects boys between 1 and 6 years of age and is characterized by weakness, progressive loss of muscle function and pseudohypertrophy.
The DMD gene is responsible for encoding a protein called dystrophin, an essential part for the formation of muscle fiber, which protects the muscle from damage during the processes of contraction and relaxation. This protein is found in skeletal, smooth and cardiac muscles and, to a lesser extent, in the central nervous system. The person with Duchenne muscular dystrophy has a change in this gene and the production of dystrophin is impaired, often becoming non-existent, which leads to muscle degeneration.
Gradually, the lack of dystrophin causes the fiber to rupture, which increases the passage of calcium into the cells, causing necrosis. These pieces of necrotic fiber are replaced by others, until the process of rupture and necrosis becomes so fast that the speed of regeneration cannot keep up. Then, the tissue is replaced by adipose and connective tissue.
The disease is also known as pseudohypertrophic muscular dystrophy and DMD, and has an incidence of 1 in every 3,500 births of boys.
Causes and Risk Factors
DMD is an inherited genetic disease, but it can also occur through genetic mutations, that is, without a family history.
The affected gene is DMD, located on sex chromosome X. The most common mutation is the deletion of information from the chromosome, but there are still cases of duplicate segments and small abnormalities known as point mutations.
The disease mainly affects the male sex, since boys have only 1 X chromosome, while girls have 2. In these cases, the healthy chromosome can supply the protein demand, making women have no symptoms of the disease and, therefore, they are called carriers.
In rare cases, girls may have 2 altered chromosomes and have symptoms of the disease. This usually happens when she is the daughter of a carrier mother and a father with the disease, or even when other genetic disorders are present.
Even women who do not carry the altered gene may have more than one child with DMD, as the mutation may have occurred in their ovaries.
Symptoms
The symptoms of DMD usually begin between the time the child learns to walk and the age of 6. Boys with the disease often learn to walk about 5 months later than normal boys.
At first, the child begins to present the so-called “classic” symptoms of Duchenne muscular dystrophy, such as:
- Gowers’ maneuver (myopathic lifting), in which the child needs to support his arms on his own legs in order to get up;
- Duck walking (anserine gait);
- Walking on tiptoes;
- Frequent falls;
- Difficulties to climb the stairs, using the same leg for each step instead of using one at a time;
- Pseudohypertrophy in the calf, due to the replacement of muscle tissue by connective and adipose tissues, and there may be pain in the area;
- Excessive curvature of the spine (lumbar hyperlordosis);
- Difficulty in sitting;
- Difficulties to stretch the arms and legs;
- Learning difficulties due to lack of dystrophin in the brain.
Thereafter, the decline in muscle strength is constant and, at 10 years of age, the boy may no longer be able to climb stairs, stand up alone or even walk, requiring the use of a wheelchair.
Bone development occurs abnormally, which can cause bone deformities. It is common for boys with DMD to also have scoliosis , which can affect the heart and breathing. As the disease progresses, the diaphragm muscles contribute to breathing problems.
In all cases, boys develop cardiomyopathy, an increase in heart muscle, which makes it difficult to pump blood and can cause heart failure. Cardiomyopathy can appear in adolescence or early adulthood.
The disease also affects the digestive system, causing gastrointestinal complications. The weakening of the muscles of the esophagus, stomach and intestine can cause a number of symptoms, such as:
- Difficulty swallowing (dysphagia);
- Reflux;
- Vomiting;
- Bad breath;
- Constipation (constipation).
Many of the boys may also have behavioral anomalies similar to those on the autistic spectrum, attention deficit and impulsivity, in addition to the possibility of developing depression .
Women carrying the gene may suffer from muscle weakness and heart problems.
Diagnosis
The professionals trained to carry out the diagnosis and treatment of the disease are: general practitioner, neurologist, pediatrician, geneticist, physical and rehabilitation physician.
In order for the diagnosis to be made, the doctor may request a description of the symptoms and ask how long the child has been doing this. Then, you can order a series of tests to confirm the diagnosis:
- Blood test: Used to measure the level of creatine kinase (CK), an enzyme present in muscle tissue that is present in high levels when there is muscle degeneration. It is important to remember that this test only proves that there is a muscle disorder and, alone, is not enough to diagnose DMD.
- DNA test: To confirm the alteration of the gene.
- Muscle biopsy: Through a sample of muscle tissue, the absence of dystrophin in the body can be confirmed. In the case of DMD, dystrophin is almost or totally non-existent. In this examination, it is possible to perceive the characteristics of degeneration and the presence of connective and adipose tissues, which seek to replace the damaged muscle fiber.
In the past it was common to do neurophysiological exams, such as electromyography and tests of speed of conduction of the nerves, to make sure that the problem was not of neurological origin. However, nowadays, with the advancement of DNA tests, this type of exam is not necessary to diagnose Duchenne muscular dystrophy.
Without the DNA test, DMD can be confused with Becker muscular dystrophy or muscular dystrophies of the waists.
Can Duchenne muscular dystrophy be cured? What is the treatment?
There is no cure for DMD and the treatments available are not able to prevent the disease from advancing, being done only to improve the quality of life of the affected boys. In general, the disease leads to death due to heart and respiratory problems shortly after the beginning of adulthood, between 18 and 25 years old.
Remedies for Duchenne muscular dystrophy
The remedies that can be used during the treatment of DMD are corticosteroids, which help to maintain the strength of the muscles for a longer time, which can prolong the duration of the ability to walk and perform movements. Experts say this is the only possible drug treatment for DMD, since there is no evidence that other substances can help.
In general, the corticosteroids indicated are prednisolone , prednisone and deflazacorte .
It is important that parents are aware of the side effects of medications, which can affect the child’s quality of life in other ways. Some effects observed are weight gain, high blood pressure , behavioral changes and stunted growth.
The use of medications should only be done under the indication and supervision of a qualified professional. The self-medication is not recommended as it can have serious side effects and put the patient’s life at risk.
Wheelchair
One of the first measures to be taken when the child is no longer able to walk is the acquisition of a wheelchair, to ensure the ability to move independently. Over time, it may be necessary to replace the manual wheelchair with an electric one, when the disease affects the muscles of the arms and hands.
Light physical exercises
To avoid muscle shortening in the joint regions, physiotherapy and swimming are recommended. Light physical exercise helps to maintain and prolong mobility, in addition to preventing discomfort and pain, while heavy exercise speeds up the process of muscle degeneration.
The exercise routine should be carried out by a physical therapist or other professional capable of dealing with disabled people. The family should help the DMD patient at home, if there is no possibility of attending a physiotherapy clinic.
Gastrointestinal discomforts
Gastrointestinal problems should also be treated:
- To regulate the bowel and prevent constipation, lactulose can be taken .
- In case of overweight, below average weight and dysphagia, you should talk to a nutritionist.
- If necessary, food may be administered through percutaneous endoscopic gastrostomy (PEG).
Cardiomyopathy
As soon as the diagnosis is made, it is necessary to check the functioning of the heart frequently. From the age of 8, it is possible to develop cardiomyopathy, which can lead to heart failure.
Treatment can be done with angiotensin converting enzyme (ACE) inhibitors, such as benazepril , captopril and enalapril , in addition to beta-blockers, such as bisoprolol , carvedilol and metoprolol . These drugs promote the dilation of blood vessels and reduce blood pressure, which helps blood to circulate normally.
Some signs of heart failure, such as shortness of breath, fatigue , swollen legs and feet, can be treated with heart-stimulating medications and diuretics.
Lung
Another organ that needs to be checked frequently is the lung. With the decrease in muscle strength, it is possible that the boy will develop difficulties in breathing. Healthy people can breathe automatically, without thinking about it, but patients with DMD may lose that ability and need breathing apparatus.
The body may have difficulty recovering from infections in the respiratory tract. Therefore, there may be a need for treatment with antibiotics frequently. Administration of medications by inhalation, or the use of suxamethonium chloride is not recommended .
Bones
The bone health of DMD patients is impaired, both by the deterioration of skeletal muscles and by the administration of corticosteroids. To treat this, supplementation of vitamin D and calcium can be done, in addition to the use of bisphosphonates.
Scoliosis
The development of scoliosis can be delayed with the use of a corset (corset) specially designed for the patient. This treatment usually begins as soon as the child starts using a wheelchair.
Surgeries
Some surgeries can correct certain complications caused by the disease. Are they:
- Orthopedic surgery: It consists of the application of metal plates to correct the spine and prevent the worsening of progressive scoliosis. It improves the patient’s position in the wheelchair and helps prevent complications in the respiratory tract and circulatory system.
- Tenotomy (stretching of tendons): In case of contractions and shortening of tendons, surgery may be necessary to stretch these tendons and recover movements. In patients with DMD, surgery to stretch the Achilles tendon is more common.
Pains
There is little information about the pain experienced by Duchenne muscular dystrophy patients. However, some boys may report pain that must be treated with the help of a qualified physician, such as a general practitioner.
The pain can be the result of uncomfortable positions in the wheelchair or in bed at night. In that case, the help of a physical therapist may be necessary to find a comfortable position and adapt these instruments to the patient.
Drug interactions and side effects can also be responsible for pain and, in this case, you should report to the doctor all the medicines used, so that he can evaluate and, if necessary, change the medications and / or dosages.
Gene therapy
The possibility of a gene therapy is being studied, which consists of the implantation of a synthetic gene in the DNA, capable of compensating for the altered gene. The placement of the new gene is done through an adenovirus as a vector, which introduces the modified DNA into the human cell.
Although there are some cases of successful gene therapy, this treatment is not yet available for all types of hereditary disease. In addition, further studies are needed in patients with Duchenne muscular dystrophy.
Attention!
NEVER self-medicate or stop using a medication without first consulting a doctor. Only he will be able to tell which medication, dosage and duration of treatment is the most suitable for his specific case. The information contained on this site is only intended to inform, not in any way intended to replace the guidance of a specialist or serve as a recommendation for any type of treatment. Always follow the instructions on the package insert and, if symptoms persist, seek medical or pharmaceutical advice.
Living together
Living with Duchenne muscular dystrophy can be complicated, both for the patient and the family. However, this is a challenge that can be overcome.
Psychological support is important for those who live with the disease, because the limitations generated by it are many and can lead patients and their caregivers to depression. In addition, the premature death of the patient can generate major trauma in families and friends.
Treatment with a psychologist is recommended for the family and the patient, in order to minimize the impacts of the disease on the psyche. In addition, the family must understand that they are not alone and can seek out other people who are experiencing the same problem, since identification with the other helps to support psychological pain.
There may be a need for adaptations in the home where the carrier lives, such as the implantation of a lift for a wheelchair or even moving to a house without stairs.
The patient’s school life can also be hampered by the lack of accessibility in schools and universities. Some parents may choose distance learning or hire private tutors.
If you have a child with Duchenne muscular dystrophy, it is important to remember that the disease does not define who the child is and they can still go to school, play and have fun.
Some measures can be taken to improve your child’s quality of life, such as:
Hiking
Walking with the boy and keeping him on his feet for as long as possible can help him keep his bones strong and prevent advanced scoliosis. If necessary, the patient can use walkers to assist his or her walk.
food
While there is no specific diet for children with DMD, a healthy and balanced diet can improve the boy’s quality of life, alleviating possible complications such as weight problems and constipation.
Exercises
Help your child to perform exercises and stretches, as staying active helps the correct functioning of muscles and tendons, and can prevent pain and muscle shortening. If necessary, ask a physical therapist for an exercise routine to prevent the boy from doing exercises he shouldn’t.
Complications
The major complications of DMD are related to the respiratory tract and cardiovascular system, since respiratory complications and cardiomyopathy are the main causes of death in patients with the disease.
The diaphragm and intercostal muscles are affected, as well as scoliosis and other bone deformities impair the opening of the diaphragm, making breathing difficult. In addition, the compression of some veins and arteries, due to the replacement of muscle fiber by other tissues, can hinder blood circulation, causing heart failure.
Other complications may include the inability to go to school, dependence on other people for routine activities, such as bathing or eating, depression and thoughts of suicide.
In the school phase, children may have learning difficulties, including with regard to language, since the disease also affects the nervous system. However, this difficulty does not worsen over time.
Prevention
Since Duchenne muscular dystrophy is a genetic and inherited disease, there is no way to prevent it after birth. However, women can do DNA tests to find out whether or not they have the altered gene.
For women carriers who wish to have children, there are some pre-conception options to avoid having a child with the problem.
The sex of the baby depends on the chromosome that the sperm carries. The egg has the X chromosome and the sperm can have an X or Y chromosome. In union with the egg, it can form a boy (XY) or a girl (XX). One of the options to prevent the disease in the child involves a technology capable of separating sperm containing X chromosomes, to increase the chances of having a girl.
Another option is a pre-implantation genetic diagnosis, which makes it possible to carry out tests on the cells of a fertilized egg. If he carries the altered gene, cells can be implanted without alteration.
DMD is the most common form of muscular dystrophy and can have many consequences for patients and their families. It is important that people are informed about the disease, so that they can plan their lives once the diagnosis is made.
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