Genetic Disorders

Common Types of Spinal Muscle Atrophy

Muscle atrophy is a condition that results in muscle wasting mainly due to lack of physical activity. Spinal muscular atrophy (SMA) is a rare genetic disorder that results in muscle wasting around the spinal cord and the brain stems. The loss of motor neurons (nerve cells) results in poor muscle control making it difficult for a person to stand, walk, control head movements and even perform common actions like breathing or swallowing.

Over time, the loss of nerve cells can disrupt normal communication between the brain and the muscle thus resulting in motor and movement problems. Spinal muscular atrophy mainly results in severe muscle weakness and loss of the proximal region rather than the muscles in the distal region. Genetic mutation is the main cause or trigger of Spinal Muscular Atrophy. It causes an imbalance in the SMN proteins that are responsible for normal cellular regulation and regeneration in the body. There are different types of SMA that can affect one’s life expectancy due to the inherent complications as a result of muscle loss. These include the following:

1. Type 1 Infantile-onset SMA
Alternatively referred to as the Werdnig-Hoffmann disease, Type 1 is a serious condition and affects children primarily. The condition is serious in nature and can be quite fatal for infants below the age of 2. Generally, type 1 SMA can be detected before birth due to reduced fetal movement in the final few months of pregnancy and the genetic disorder becomes evident within the first few months after birth. General muscle weakness, a weak birth cry, or even trouble breathing are the few visible indicators of SMA type 1.

2. Type 2 Intermediate SMA
SMA type 2 affects children between the ages of 7 and 18 months before they can walk or even stand on their own without support. Children suffering from type 2 of the muscle loss disorder will develop breathing problems that will affect their life expectancy considerably. However, a majority of the children who develop SMA type 2 can survive into adulthood depending on the severity of the condition.

3. Type 3 Adult-onset SMA
Type 3 is also alternatively referred to as the Kugelberg-Welander disease. The diagnosis of adult-onset SMA is only possible after 18 months up to three years of age. Initially, a person affected with type 3 muscle atrophy can walk but will gradually suffer from varying ranges of immobility during the vital growing and developing years. The severity of the symptoms will vary vastly depending on the progressive nature of the condition. They range from experiencing slight tremors in the fingers to losing complete motor control over vital muscle groups that regulate movement. Visible indicators of the condition include experiencing difficulty running, climbing up steps, or even performing simple tasks like sitting or getting up from a chair.

4. Type 4 Adult SMA
In comparison to type 3, adult SMA is a rare type of muscle atrophy affecting the spinal region. The condition leads to mild motor impairment and teenagers or young adults suffering from the condition need not necessarily experience difficulty walking, standing or supporting their body weight in the initial stages. However, studies show that severe complications will develop after the age of 35 owing to the progressive nature of the condition.