Fast Five Quiz: Spinal Muscular Atrophy Clinical Presentation

Stephen L. Nelson, Jr, MD, PhD


February 01, 2021

SMA type 1, or Werdnig-Hoffmann disease, is the most severe type of SMA. It appears in patients before 6 months of age; in most cases, signs and symptoms are apparent by 3 months. In this and other types of SMA, evidence of cerebral involvement is absent. Patients have bulbar dysfunction, including poor suck ability, reduced swallowing, tongue fasciculations, and respiratory failure. Extraocular muscle involvement is not seen, and facial weakness is frequently minimal or absent. Muscle weakness is severe and progressive and flaccid, and reduced muscle tone (hypotonia) is common.

Learn more about the clinical presentation of SMA type 1.


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