Spinal Muscular Atrophy in Children

Spinal Muscular Atrophy in Children

  Autor NN Team Data: 05.08.2008

Spinal Muscular Atrophy in Children
The spinal muscular atrophy known also as SMA (Spinal Muscular Atrophy) isa degenerative disease which affects the spine and the nerves, leading to muscular weakness. 

The infantile SMA occurs in one of 10.000 birth, and regarding the adults, it affects one person out of 100.000. 

Which are the causes? 
SMA is an autosomal recessive disease, meaning that both boys and girls are affected, if they inherit two copies of the genes from their parents, one from the mother and one from the father. Both parents should be carriers of the gene, for the disease to occur. The genetic mutation which is responsible for the occurance of SMA is quite common, so the chances for two carriers to reproduce are quite high. Still, it is not a rule for their child to have SMA. The risk is of 25% for each pregnancy. In people of all ages who have symptoms of spinal muscular atrophy, the DNA can be tested, starting with a blood sample. Thus it was discovered that in over 95% of the cases of SMA, a gene called SMN (Survival Motor Neuron) whether has a mutation or lacks entirely. 
The testing of each person, in order to see if she has the gene, might be a solution, but it is quite difficult for now so the DNA tests are dome only for the couples who already have relatives with SMA. 

Which are the symptoms? 
The disease is difficult to diagnose because the symptoms might be similar to those of other diseases and every child could have different symptoms. If we consider the symptoms and the age they occur, we have four types of SMA. 

Type 1 - Werdnig - Hoffman disease
This is the most severe type of SMA and might be present since the birth. The babies cannot hold their head, cannot suck, swallow and they usually move very little. They will never be able to sit or to walk without help, and they might develop frequent respiratory infections. The chest muscles are affected too. Their tongue moves like a worm. The diagnosis can be established up to six month and unfortunately, most babies with SMA don't reach two years of age because the muscular weakness does not allow them to breathe. 

Type 2 - the intermediate type
This type of SMA is detected between 6 months and two years of age. Children with weak muscles need help to walk. The life expectancy of these children is up to 20-30 years old. 

Type 3 - Wolhfart - Kugelberg - Welander disease
This type of disease occurs in children between 3 and 17 years old. The sick children seem a little clumsy at the beginning, then they begin having problems with walking and generally with the moves that need some strength. They may develop slower and less than other children, from all points of view, but they may live up to old ages. 

Type 4
The type 4 of SMA occurs in adult between 30-40 years old and makes the walking become more difficult and even impossible. The SMA symptoms are similar to those of other diseases. This is why the diagnosis is established only by the specialist, and based on detailed tests. 

The diagnosis of SMA 
The diagnosis is determined after the sudden or gradual occurance of the disease. During the medical check, the complete history of diseases will be done and the doctor will ask questions regarding the possible family problems. 
Among the tests that can be done, we mention:
  • blood tests 
  • muscle biopsy - a small part of the muscular tissue is taken to be analyzed. 
  • Genetic tests - the study of the DNA structure and the detection of the diseases which might be transmitted in the family. 
  • Electromyography (EMG) - it evaluated the electrical activity produced by a muscle or a group of muscles. This may detect the abnormal electrical activity of muscles, which is caused by neuromuscular diseases. 
Which is the treatment? 
The proper treatment for each child must be established by a medical team formed by many specialists. The treatment will take into account more factors such as: 
  • the child's age 
  • the general health state 
  • the medical history 
  • the type of disease and the spreading level 
  • the child's tolerance to certain drugs, surgeries and therapies 
  • the family's expectancies regarding the evolution of the disease 
  • the family preferences and opinions. 
We must mention that there is no treatment for SMA. In order for the disease to be controlled to a certain extent with medication, it must be detected early. Considering that the muscles used for breathing and swallowing are affected, the treatment has the purpose to prevent the respiratory difficulties and to ensure the nutrition. The severity of the disease is established according to the type of the disease and to the existence of other health issues. In extreme cases, there might be necessary to use a breathing device. The doctors' job is not only to treat the child in the hospital, but also to educate the family regarding the home care. 

Read the English version of this article: Spinal Muscular Atrophy in Children