Spinal Muscular Atrophy Type 3
The diagnosis of Type III, often referred to as Kugelberg-Welander or Juvenile Spinal Muscular Atrophy, is much more variable in age of onset, and children can present from around a year of age or even as late as adolescence, although diagnosis prior to age 3 years is typical.
The patient with Type III can stand alone and walk, but may show difficulty with walking at some point in their clinical course. Early motor milestones are often normal. However, once they begin walking, they may fall more frequently, have difficulty in getting up from sitting on the floor or a bent over position, and may be unable to run.
With Type III, a fine tremor can be seen in the outstretched fingers but tongue fasciculations are seldom seen. Feeding or swallowing difficulties in childhood are very uncommon.
Type III individuals can sometimes lose the ability to walk later in childhood, adolescence, or even adulthood, often in association with growth spurts or illness.