Spinal Muscular Atrophies (SMAs) By Michael Rubin, MDCM, New York Presbyterian Hospital-Cornell Medical Center Reviewed / Revised Apr 2022 | Modified Sep 2022 View Patient Education Diagnosis Treatment Key Points Spinal muscular atrophies include several types of hereditary disorders characterized by skeletal muscle wasting due to progressive degeneration of anterior horn cells in the spinal cord and of motor nuclei in the brain stem.