Spinal muscular atrophy
- Olaf A Bodamer, MD, PhD, FAAP, FACMG
Olaf A Bodamer, MD, PhD, FAAP, FACMG
- Park Gerald Chair in Genetics and Genomics
- Associate Chief, Genetics and Genomics
- Boston Children’s Hospital/Harvard Medical School
- Section Editors
- Douglas R Nordli, Jr, MD
Douglas R Nordli, Jr, MD
- Section Editor — Pediatric Neurology
- Professor of Neurology and Pediatrics
- Northwestern University Feinberg School of Medicine
- Helen V Firth, DM, FRCP, DCH
Helen V Firth, DM, FRCP, DCH
- Section Editor — Genetics
- Consultant Clinical Geneticist
- Addenbrooke's Hospital, Cambridge, UK
- Richard Martin, MD
Richard Martin, MD
- Section Editor — Neonatology
- Professor, Pediatrics, Reproductive Biology, and Physiology & Biophysics
- Case Western Reserve University School of Medicine
Neuromuscular disorders that present in the newborn period with hypotonia and weakness are caused by a variety of conditions that affect the central nervous system (brain or spinal cord), peripheral nervous system, or skeletal muscle. Conditions that affect the anterior horn cells of the spinal cord are listed in the table (table 1).
This topic will review clinical aspects of spinal muscular atrophy (SMA).
SMA disorders are characterized by degeneration of the anterior horn cells in the spinal cord and motor nuclei in the lower brainstem. These diseases are classified as types 1 through 4 depending upon the age of onset and clinical course.
Classification — SMA type 1, also known as infantile spinal muscular atrophy or Werdnig-Hoffmann disease, is the most common and severe type of SMA. It typically presents in the neonatal period. However, mothers of affected patients may recognize a decrease or loss of fetal movement in late pregnancy. Some experts classify prenatal onset as SMA type 0 [2,3]. In these neonatal forms, symptoms progress rapidly, and the majority of infants die before one year of age from respiratory failure [4,5]. Nevertheless, long-term survivors have been reported [6-8]. This is perhaps due, in part, to advances in the care of chronic respiratory insufficiency and to more aggressive care. (See 'Management' below.)
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- CLINICAL FEATURES
- Genetic counseling
- Muscle biopsy
- DIFFERENTIAL DIAGNOSIS
- Arthrogryposis multiplex congenita
- X-linked infantile spinal muscular atrophy
- Spinal muscular atrophy with respiratory distress type 1
- Congenital myasthenic syndromes
- Congenital myopathies
- Hypoxic-ischemic myelopathy
- Glycogen storage disease II
- Prader-Willi syndrome
- Traumatic myelopathy
- Zellweger syndrome
- SUMMARY AND RECOMMENDATIONS