Spinal Muscle Atrophy Causes, Types, and Symptoms
Spinal Muscle Atrophy Causes, Types, and Symptoms

Spinal Muscle Atrophy Causes, Types, and Symptoms

Spinal muscle atrophy, or SMA, is a nerve disease that is caused by a gene mutation of the survival motor neuron gene 1 (SMN1). This gene mutation destroys the motor neurons (of the brain and spinal cord), which are responsible for muscle control and impair muscle motion, causing muscle weakness and loss of muscle motion throughout the body. When there are varying levels of SMA, any effect to the motor neurons can greatly affect the ability to walk, crawl, sit up independently, and also breathe, eat, and consume. The death of signalling in the affected motor neurons induces muscle atrophy in a similar way to amyotrophic lateral sclerosis (ALS) or Lou Gehrig’s disease, yet another motor neuron disorder that affects muscular motion. Both ALS and SMA are deadly diseases with no cure.

According to research by Counsyl.com, a genetic screening and counseling services company, approximately 1 in every 6,000 to 10,000 Americans are impacted by spinal muscular atrophy. SMA is also the major genetic cause of death for babies Further data show that SMA is most widespread in Caucasians. SMA can hit at birth or crop up in maturity, if the sufferers carries a particular SMA gene mutation. Spinal muscular atrophy occurs in these main subtypes:


Spinal muscular atrophy type 0 is evident before arrival and is the rarest and most acute form of the status. Affected infants move less in the womb, and consequently they’re generally born with joint deformities (contractures). They have exceptionally weak muscle tone (hypotonia) in birth. Their respiratory muscles are extremely weak and they often do not survive past infancy due to respiratory failure. Some babies with spinal muscular atrophy type 0 also have heart defects that are present from birth (congenital).

Spinal muscular atrophy type I (also known as Werdnig-Hoffmann disease) is the most common form of the condition. It’s a serious form of the disorder with muscle weakness evident at birth or within the first couple of months of life. Most affected children cannot control their head movements or sit unassisted. Children with this type may have swallowing problems that can result in difficulty feeding and poor development. They’re also able to have breathing difficulties due to weakness of respiratory muscles and an abnormally bell-shaped torso which prevents the lungs from fully expanding. Most children with spinal muscular atrophy type I don’t survive beyond early childhood due to respiratory failure.

Spinal muscular atrophy type II (also known as Dubowitz disease) is characterized by muscular weakness that develops in children between ages 6 and 12 months. Children with this kind can sit with support, although they may need help getting to a seated position. However, as the muscle fatigue worsens after in childhood, affected people may require support to sit down. People with spinal muscular atrophy type II can’t stand or walk unaided. They frequently have involuntary trembling (tremors) in their fingers, a spine that stinks side-to-side (scoliosis), and respiratory muscle fatigue which can be life-threatening. The entire life span of individuals with spinal muscular atrophy type II varies, but many people with this condition live into their twenties or thirties.

Spinal muscular atrophy type III (also called Kugelberg-Welander disease) usually causes muscle fatigue following early youth. Individuals with this condition might stand and walk , but over time, walking and climbing stairs may become more and more hard. Many affected people require wheelchair help later in life. People with spinal muscular atrophy type III generally have a normal life expectancy.

Spinal muscular atrophy type IV is rare and often starts in early adulthood. Affected individuals typically experience mild to moderate muscle fatigue, tremors, and moderate breathing problems. People with spinal muscular atrophy type IV have a normal life expectancy.

Spinal Muscle Atrophy Symptoms

As mentioned, the next early signs of SMA Are Extremely similar to ALS, as both diseases chiefly impact overall muscle motion and control:

  1. Troubles sitting up, walking, standing independently.
  2. Early signs of compromised fetal movements are indicative of Type I SMA, and harvest up during late pregnancy.
  3. Insufficient hands in mouth and throat muscles, resulting in diminished swallowing, chewing gum, and eating skills.
  4. Spasms, twitches, or involuntary muscle contractions (called fasciculations).
  5. Insufficient reflexes, such as grasping, catching, or holding objects, or if tapped on knee by a health care provider.
  6. Gradual reduction of muscle tone (or Hypotonia) and increasing muscular weakness.
  7. Prone to respiratory tract infections, such as recurrent pneumonia.
  8. Lack of stamina and muscle motion across the body, normally starting in the legs, arms, buttocks, thighs, shoulders, chest, and upper back, that may lead to orthopedic assisting tools (i.e., cane, walker, wheelchair).


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