Spinal Muscular Atrophy (SMA)

Also known as: SMA, Werdnig-Hoffman Syndrome, Kugelberg-Welander Syndrome, infantile onset SMA, chronic SMA, mild SMA

What is spinal muscular atrophy?

Spinal muscular atrophy is a rare degenerative disorder in which the nerve cells in the upper and lower parts of the spinal cord don’t function normally, resulting in muscle wasting and weakness. There are 4 types of SMA (Types I, II, III, and IV) based on symptoms and age of onset.

What causes spinal muscular atrophy?

Spinal muscular atrophy is an autosomal recessive genetic disorder caused by an abnormal gene in each parent which is passed on to their baby.

What are the symptoms of spinal muscular atrophy?

Symptoms depend on the type of SMA.

  • Type I (Werdnig-Hoffman or infantile-onset SMA), the most severe type, may present at birth with generalized weakness, difficulty holding the head up, poor sucking or swallowing ability and poor breathing movements. Death may occur between 2-6 years of age.

  • Type II (juvenile or chronic SMA), presents around 6-18 months of age with generalized muscle weakness which may require braces/a walker or a wheelchair for ambulation. Children affected with Type II frequently live into their 20-30’s.

  • Type III (mild SMA or Kugelberg-Welander syndrome), usually affects children between the ages of 18 months to adolescence. Symptoms include difficulty walking, clumsiness, some muscle weakness and possible developmental delay. Children live well into adulthood.

  • Type IV presents in adulthood with walking difficulties.

What are spinal muscular atrophy care options?

While there is no treatment at present for SMA, early diagnosis, the prevention of lung problems (and its management when present), ensuring adequate nutrition and enhancing mobility opportunities with ongoing rehabilitation support may all be of potential benefit to the child.

Reviewed by: Jack Wolfsdorf, MD, FAAP

This page was last updated on: August 12, 2020 04:11 PM

NeuroMuscular Center

Specializing in the treatment of infants, children and adolescents with muscular dystrophies, neuropathies, spinal muscular atrophy and congenital myopathies.

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