Categorized as a genetic disorder, Spinal Muscle Atrophy (SMA) affects the nervous system, particularly attacking the part which is the control center for voluntary movement of muscles. The nerve cells that are located in the spinal cord are largely affected, thereby making a lot of difference to the muscles. It is a rare disorder and is approximately found in 1 out of every 6,000 to 1 out of every 10,000 people in the world. It attacks the specialized nerve cells, which are commonly known as lower motor neurons, eventually leading to the death of muscle cells.

SMA is divided based on the severity and the onset of the disease. Discussed below are the main types of Spinal Muscle Atrophy:

• SMA Type 0
  This particular type of SMA is known to be the most severe of all types of Spinal Muscle Atrophy. Babies with this type of SMA often suffer from severe muscle weakness, low muscle tone, and a lack of age-appropriate motor skills. In addition, these babies may have an absence of a healthy respiratory system and therefore, face a lot of respiratory problems. Very few newborns survive post six months from their birth in this case.
• SMA Type 1
  Also referred to as Werdnig-Hoffman Disease, this particular type of SMA is considered to be the most common. It accounts for 50 to 70 percent of childhood onset cases. It is also considered to be severe as the earlier is the onset, the more is its severity. This disease begins in the first six months of a child’s birth and its most prominent symptoms include muscle weakness, low muscle tone, and deficiencies that occur during movement. 68 percent of children affected with this live up to the second year of their birth while many of them die during the first four years.
• SMA Type 2
  The SMA Type 2 is more commonly referred to as Dubowitz Disease and the symptoms start to show between the age of 7 and 18 months. However, as a symptom, weakness in the muscles may be evident since the beginning itself. People affected with this type of SMA achieve their major milestones quite slowly. However, some babies with SMA Type 2 may be able to walk or stand without any help. Most of these cases additionally get affected with scoliosis as they keep growing, which is basically an abnormal curvature occurring in the spine. If proper care is taken, then most kids may make it into adulthood as well.
• SMA Type 3
  This type of SMA is also known as Kugelberg Welander Disease and its symptoms start occurring post the first 18 months. As the type keeps increasing, the severity keeps decreasing. People affected with this type of SMA may keep falling while walking but may live a lifespan of normal adults. Most students are recommended a special exercise program so as to live a healthy and normal life.
• SMA Type 4
  This particular SMA attacks adults. It occurs in either the second or the third decade of one’s life. Its symptoms include muscle weakness which is progressive and is often accompanied by scoliosis. The affected individual may also experience twitching and muscle tremors. However, an exercise program is crucial in alleviating the effects so that people live as normal a life as possible.

Even though Spinal Muscle Atrophy affects the regular life of people, most of them are able to walk unaided until the age of 60, without much of an issue. However, a patient may need to compromise on other muscular movements and hence, treatment is necessary. With the right support, a patient suffering from SMA may be able to lead a normal life.