Spinal muscular atrophy

Spinal muscular atrophy (SMA) is a congenital disorder characterized by progressive loss of muscle tissue, leading to reduced ability to move. The lower limbs are usually more affected than the upper limbs. Patients also experience difficulties with swallowing and, later, breathing. Disease progression is variable, as it is influenced by many factors. A serious and common complication is respiratory failure, which can also be fatal.

Type I SMA (acute infantile form, Werdnig–Hoffmann disease I):
Named after G. Werdnig and J. Hoffmann, who first described it. It manifests within the first 4–6 months of life as delayed motor development. However, severe muscle hypotonia and reduced movement are usually already evident at birth. Children with SMA type I typically do not survive beyond 2 years of age.

Type II SMA (chronic infantile or intermediate form, Werdnig–Hoffmann disease II):
Symptoms usually appear between 6 and 24 months of age. These children usually learn to sit and may sometimes stand or take a few steps. However, they are never able to walk independently, and there is later a decline in previously achieved motor abilities, including standing. Cognitive development is not affected. Because of preserved hand function, they may be able to operate an electric wheelchair, which is important for their independence. They are highly susceptible to respiratory infections, and death is usually caused by respiratory failure. With proper care, life expectancy can reach approximately 30–50 years. In both SMA I and II, severe scoliosis often develops, which together with respiratory muscle weakness can lead to serious pulmonary complications and death.

Type III SMA (juvenile form, Kugelberg–Welander disease):
This form usually begins in preschool or school age. It typically first manifests as gait disturbances caused by progressive weakness of the leg muscles. Over time, hand function also worsens, and trunk muscle strength decreases. Between 20 and 40 years of age, patients may lose mobility.

Type IV SMA (adult form):
In this form, the first symptoms usually appear after the age of 35. The disease progression is generally very slow.

Treatment:
There is no causal treatment for this disease; therapy is mainly symptomatic. Respiratory support ventilation can significantly improve the condition of some patients and may also slow disease progression. Rehabilitation methods such as the Vojta method, hydrotherapy, and electrotherapy are also used. The main goal is to maintain mobility for as long as possible and, if feasible, ensure an upright posture, for example using standing frames or orthoses. This also helps prevent complications such as scoliosis, osteoporosis, and respiratory and digestive problems.

• progressive loss of muscle mass and ability to move
• There are 4 main groups of this disease:
• infantile (SMA I)
• intermediate (SMA II)
• juvenile (SMA III)
• adult (SMA IV)