Fast Five Quiz: Acute Infantile Spinal Muscular Atrophy Type 1, or Werdnig-Hoffmann Disease

Stephen L. Nelson, Jr, MD, PhD


August 12, 2020

In the vast majority of patients (95%), signs or symptoms of SMA type 1 are present by 3 months of age. These include severe, progressive muscle weakness and hypotonia.

Males are affected by all types of SMA, including SMA type 1, more frequently than females.

The extraocular muscles are not affected by SMA type 1. In addition, facial weakness is usually minimal or not present at all. Similarly, patients with SMA type 1 have no evidence of cerebral involvement.

Learn more about SMA type 1.


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