Spinal muscular atrophy (SMA): clinical features

Written and reviewed by Dr Ibrahim Imam, Consultant Neurologist. Last reviewed .

Spinal muscular atrophy (SMA): clinical features. The onset is in infancy: the onset age is 0-6 months. Fully referenced neurology checklist.

SMA type I (Werdnig-Hoffman syndrome)

  • The onset is in infancy: the onset age is 0-6 months
  • The child never learns to sit
  • There is poor head control
  • The tongue is atrophic with fasciculations
  • The limbs are weak and hypotonic
  • There is scoliosis and postural torticollis
  • The chest is bell-shaped
  • The breathing is abdominal and paradoxical
  • Distal digital necrosis occasionally occurs
  • The renal structure and function are impaired
  • There is no electrocardiographic or clinical hand tremor

SMA type II

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SMA type III (Kugelberg-Welander syndrome)

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SMA type IV

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References

  1. Wang CH, Finkel RS, Bertini ES, et al. Consensus statement for standard of care in spinal muscular atrophy. J Child Neurol 2007; 22:1027-1049.
  2. Kostova FV, Williams VC, Heemskerk J, et al. Spinal muscular atrophy: classification, diagnosis, management, pathogenesis, and future research directions. J Child Neurol 2007; 22:926-945.
  3. Moore Burk M, Kelley C, Thinger S, Foster H, et al. Postural torticollis and early-onset scoliosis in infants with SMA identified through newborn screening: single institution experience. Muscle Nerve 2026; 74:1348-1357. 
  4. Carrasco D, Magoulas P, Scull JC, et al. Digital necrosis in an infant with severe spinal muscular atrophy. Neurol Genet 2019 (epub ahead of print).
  5. Rudnik-Schöneborn S, Vogelgesang S, Armbrust S, Graul-Neumann L, Fusch C, Zerres K. Digital necroses and vascular thrombosis in severe spinal muscular atrophy. Muscle Nerve 2010; 42:144-147.
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