Which clinical history findings are characteristic of spinal muscular atrophy (SMA) type III - chronic juvenile or Kugelberg-Welander syndrome?

Updated: May 29, 2019
  • Author: Jeffrey Rosenfeld, MD, PhD, FAAN; Chief Editor: Stephen L Nelson, Jr, MD, PhD, FAACPDM, FAAN, FAAP  more...
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This is a mild form of autosomal recessive spinal muscular atrophy that appears after age 18 months.

SMA type III is characterized by slowly progressive proximal weakness. Most children with SMA III can stand and walk but have trouble with motor skills, such as going up and down stairs.

Bulbar dysfunction occurs late in the disease.

Patients may show evidence of pseudohypertrophy, as in patients with SMA type II.

The disease progresses slowly, and the overall course is mild. Many patients have normal life expectancies.

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