Clinical presentation for SMA may differ according to the age of onset and severity, but hypotonia (floppy baby syndrome) and/or muscle weakness and atrophy are common signs or symptoms:1

  • Weakness is usually symmetrical
  • Weakness is more proximal than distal
  • Sensation is preserved
  • Tendon reflexes are absent or diminished
  • Weakness is greater in the legs than the arms
  • Severity of weakness generally correlates with the age of onset

Time to diagnosis is critical – earlier diagnosis and intervention may help improve the outcomes for individuals with SMA.1

Common complaints from parents of
children with suspected neuromuscular
disorders such as SMA may include:1

  • Delays in motor milestones
  • Feeding and respiratory difficulties
  • Abnormal gait characteristics
  • Frequent falls
  • Difficulty ascending stairs or arising from the floor
  • Muscle cramps or stiffness
  • Loss of strength, fatigue, or decreasing endurance
  • Exercise intolerance; episodic weakness
  • Muscle cramps and focal wasting of muscle groups
  • Breathing difficulties or bulbar symptoms relating to speech and swallowing

In the adult patient, a detailed history may help point to a diagnosis, including:7

  • Pattern of progression of symptoms
  • Age at onset of symptoms
  • Age at which bracing was provided to maintain ambulation
  • Age at which wheelchair was required (if applicable)
  • Distribution of weakness
  • Presence of muscle cramps
  • Fatigue; episodic weakness
  • Presence of atrophy or fasciculations
  • Current and past ambulatory distances
  • Ability to transition from floor to standing
  • Problems climbing stairs, reaching overhead, or dressing

If you see symptoms of SMA in your patient, refer immediately for an urgent appointment with a paediatric neurologist.

  1. Prior TW and Finanger E. Spinal muscular atrophy. NCBI Bookshelf Web site. =printable. Updated December 22, 2016. Accessed October 2017.
  2. Wang CH et al. J Child Neurol 2007; 22: 1027–49.
  3. Darras BT et al. Neuromuscular Disorders of Infancy, Childhood, and Adolescence: A Clinician’s Approach. 2nd ed. London, UK: Elsevier; 2015.
  4. Lunn MR and Wang CH. Lancet 2008; 371: 2120–33.
  5. NIH National Center for Advancing Translational Sciences. Genetic and Rare Diseases Information Center. Spinal muscular atrophy type 2. Accessed October 2017.
  6. Rothwell E et al. Am J Med Genet A 2013; 161A: 679–86.
  7. McDonald CM. Phys Med Rehabil Clin N Am 2012: 23: 495–563.