Feature Article

The floppy baby: a diagnostic challenge



© Charles Milligan/medical images models used for illustrative purposes only
© Charles Milligan/medical images models used for illustrative purposes only


The prognosis and treatment of infantile hypotonia are contingent on the underlying diagnosis. Distinguishing between normal and abnormal hypotonia, and central and peripheral causes, is key in initiating a diagnostic pathway for affected babies.

Key Points

  • In most infants with hypotonia the condition is benign and resolves spontaneously; however, in a small number it is a symptom of a serious underlying neurological disorder.
  • The GP is the first port of call for parents concerned by floppiness, low muscle tone or weakness in their child, and can initiate the diagnostic pathway for infants affected by hypotonia.
  • The primary question on examining the floppy baby is whether they are floppy and strong, which suggests a CNS disorder, or floppy and weak, suggesting a peripheral nervous system problem.
  • Most babies require only a few screening tests for hypotonia, but early referral to a paediatrician or paediatric neurologist should be considered if the hypotonia is likely to have a central or peripheral cause.
  • Early treatment with the novel drug nusinersen has recently been shown to improve motor development and increase life expectancy in babies with spinal muscular atrophy types 1 and 2.