In this section
atrophy (SMA) is a genetic disease that affects motor nerves.
When we want to
move our body, motor nerves send the message from our brain to our muscles telling the muscles to move. Spinal muscular atrophies affect
the motor nerves and stop these messages getting from the nervous
system to the muscles. Over time, the muscles become weak and
atrophy is usually classified by the approximate age of the child
when they first have symptoms.
Infantile SMA, or SMA1
This is also known as Type 1 SMA, or
Werdnig-Hoffman disease. Symptoms
are sometimes present at birth. This is the most serious form of
Intermediate SMA, or SMA2
Also known as Type 2 SMA or SMA2. Children
with SMA2 can sit when placed, but cannot get to a sitting position
Juvenile SMA, or
Also known as Type 3 SMA or Kugelberg-Welander
disease. People with SMA3 are affected sometime between the age of
18 months to teens or adulthood. It is a much milder form of
SMA. Mobility is affected, however
progression is at a much slower rate.
Type 4, or SMA4
Because SMA is a genetic disorder, there is a
chance that future children born to an affected couple may also be
affected. Prenatal diagnosis, to determine if a child will have
SMA, is available to parents-to-be with a family history of SMA.
Talk to your neurologist or geneticist about this.
Signs and symptoms of SMA include muscle
weakness, poor muscle tone and floppiness. The legs are usually
weaker than the arms. Babies who are affected may have feeding difficulties
and a weak cry. Children who are affected are late to achieve, or do not
reach, milestones such as sitting, crawling or walking. The muscles of
the face are not affected, but swallowing can be weak. Children
with SMA have normal intelligence.
Symptoms are progressive. This causes
increasing weakness in the muscles of the limbs and chest, making
breathing progressively more difficult. Involvement of the breathing muscles is
the most serious complication of all forms of SMA, especially in
SMA is a difficult thing for families to deal
with. Your neurologist has a lot of experience in helping families
and individuals cope with diseases like SMA. He or
she can also put you in touch with other families in a similar
situation. This can be a great source of comfort and support.
While the internet can be a source of good
information, it can also be a source of false hope, inaccurate
and often misleading information including 'magic' pills and
potions which promise to 'cure' your child's SMA. Always read this
information with great scepticism. Rely on your doctor for expert
and professional advice.
The content for this fact sheet has been
contributed to by the RCH Neurosciences Dept and Muscular Dystrophy
Australia. Published in Sept 2007. Revised October