What Are the Treatment Modalities for Spinal Muscle Atrophy?
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Treatment Modalities for Spinal Muscle Atrophy - An Overview

Published on Dec 02, 2022 and last reviewed on Jul 27, 2023   -  5 min read


Spinal muscular atrophy is a genetic neuromuscular disease that causes muscles to weaken and waste away. Read further to know more.


Spinal muscular atrophy (SMA) is a neuromuscular disorder caused by a genetic mutation that causes muscles to weaken and waste away. Motor neurons, a type of nerve cell in the spinal cord that controls muscle movement, are lost in people with spinal muscular atrophy. Muscles do not receive the signals that allow them to move without these motor neurons. Atrophy is a medical term that means "to shrink." Due to a lack of use, certain muscles shrink and weaken in spinal muscular atrophy. In the United States, between 10,000 and 25,000 children and adults suffer from spinal muscular atrophy. It is an uncommon condition that affects one child every 6,000 to 10,000.

Who Might Get Spinal Muscular Atrophy?

A person with spinal muscle atrophy gets two copies of the survival motor neuron 1 (SMN1) gene, which is either absent or defective (mutated). The mother is responsible for one defective gene, while the father is responsible for the other. Adults may be unaware that they have a single copy of the faulty gene that causes spinal muscular atrophy. The mutant SMN1 gene affects around six million Americans (one in 50). There is one healthy SMN1 gene and one missing or faulty SMN1 gene. Carriers do not acquire spinal muscular atrophy, and two carriers have a one in four chance of having a kid with spinal muscular atrophy.

What Types of Spinal Muscular Atrophy Are There?

The following are the four main kinds of spinal muscular atrophy:

  • Type 1 (Abnormally Severe): Type 1, commonly known as Werdnig-Hoffman disease, affects about 60 % of persons with spinal muscular atrophy. Symptoms arise at birth or within the first six months of an infant's life. Sucking and swallowing are challenging for babies with type 1 spinal muscular atrophy. They do not reach regular developmental milestones, such as holding their heads up or sitting. Children are particularly susceptible to respiratory infections and lungs that collapse as their muscles weaken (pneumothorax). Type 1 spinal muscular atrophy kills the majority of youngsters before they reach their second birthday.

  • Type 2 (Intermediate): When a child is between the ages of six and eighteen months, symptoms of type 2 spinal muscular atrophy (also known as Dubowitz disease) occur. This kind usually affects the lower extremities. Type 2 spinal muscular atrophy causes children to be able to sit up but not walk. The majority of children with type 2 spinal muscular atrophy grow up to be adults.

  • Type 4 (Adult): This uncommon adult variant of spinal muscular atrophy usually does not show up until the mid-thirties. Because muscle weakness symptoms appear gradually, most persons with type 4 remain mobile and go about their daily life.

What Causes Spinal Muscular Atrophy?

People with spinal muscular atrophy either miss part of the SMN1 gene or have a changed (mutated) gene. A healthy SMN1 gene produces SMN protein, and motor neurons need this protein to survive and function properly. The motor neurons in people with spinal muscular atrophy shrivel and die due to the lack of SMN protein. Due to this, the brain loses its ability to rule voluntary motions, especially those involving the head, arms, legs, and arms. SMN2 genes produce a tiny amount of SMN protein in people as well. An SMN2 gene can be found in eight copies in a single person. As the extra genes compensate for the missing SMN1 protein, several copies of the SMN2 gene generally lead to less severe spinal muscular atrophy symptoms. Non-SMN gene mutations (non-chromosome 5) are rare causes of spinal muscular atrophy.

What Are the Clinical Presentations of Spinal Muscular Atrophy?

Spinal muscle atrophy symptoms vary depending on the type. People with spinal muscle atrophy experience the following;

  • A progressive loss of muscle control, movement, and strength.

  • Muscle loss worsens with age.

  • The disease severely affects the muscles closest to the torso and neck.

  • Some people with spinal muscle atrophy never walk, sit, or stand.

  • Some individuals gradually lose their ability to do these actions.

How Is Spinal Muscular Atrophy Diagnosed?

Some of the symptoms of spinal muscular atrophy are similar to those of neuromuscular illnesses, including muscular dystrophy. A physical exam and a medical history will be performed by the healthcare professional to determine the origin of the symptoms.

  • Blood Tests: An enzyme and protein blood test can be used to assess for elevated creatine kinase levels. This enzyme is released into the bloodstream by deteriorating muscles.

  • Gene Testing: The SMN1 gene is tested in this blood test to see if there are any problems with it. Spinal muscular atrophy is screened for in several jurisdictions as part of standard newborn screenings.

  • EMG: An electromyogram (EMG) is a test that examines the electrical activity of muscles and nerves.

  • Muscle Biopsy: A physician may do a muscle biopsy on rare occasions. A little sample of muscle tissue is removed and sent to a lab for analysis in this process. Muscle atrophy or loss can be detected with a biopsy.

Is It Possible to Diagnose Spinal Muscular Atrophy During Pregnancy?

Prenatal diagnosis can detect if the unborn child has spinal muscle atrophy if one of the family members has a history of the disease. These tests raise the chance of a miscarriage or pregnancy loss by a small amount. The following are examples of prenatal tests for spinal muscular atrophy:

  • Amniocentesis: During amniocentesis, the obstetrician, inserts a tiny needle into the abdomen. The amniotic sac is then sucked for a little amount of fluid. A pathologist examines the CSF for signs of spinal muscular atrophy. After the 14th week of pregnancy, this test is performed.

  • CVS: Chorionic villus sampling is a procedure in which the physician takes a tiny tissue sample from the placenta through the mother's cervix or stomach. The model is examined by a pathologist for signs of spinal muscular atrophy. CVS can occur as soon as the tenth week of pregnancy.

What Are the Treatment Modalities of SMA?

As there is no such cure for spinal muscular atrophy, treatments depend upon the type of spinal muscle atrophy and its symptoms. Many people with spinal muscle atrophy benefit from physical and occupational therapy and assistive devices, such as orthopedic braces, crutches, walkers, and wheelchairs.

What Are the Risks Associated With Spinal Muscular Atrophy?

People who have spinal muscular atrophy have progressive muscle weakening and a lack of muscle control over time.

  • Bone fractures, hip dislocation, and scoliosis are all possible problems (spine curvature).

  • Malnutrition and dehydration caused by difficulties eating and swallowing may necessitate the use of a feeding tube.

  • Breathing issues and weakened lungs may necessitate breathing assistance (ventilation).


The hereditary condition of spinal muscular atrophy causes muscles to weaken and waste away. The type of spinal muscular atrophy and its symptoms determine the treatment options. Physical and occupational therapy, as well as assistive technologies, are beneficial to many patients with spinal muscular atrophy. People with different types of spinal muscular atrophy have different quality of life and life expectancy. Spinal muscular atrophy has no known treatment.

Last reviewed at:
27 Jul 2023  -  5 min read




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