Hypotonia, or floppiness, may be central in origin or related to nerve and muscle problems. An acutely ill child (e.g. septicaemic) may be hypotonic on examination. Hypotonia associated with encephalopathy in the newborn period is most likely caused by hypoxic ischaemic encephalopathy

Central causes

• Down's syndrome
• Prader-Willi syndrome
• hypothyroidism
• cerebral palsy (hypotonia may precede the development of spasticity)

Neurological and muscular problems

• spinal muscular atrophy
• spina bifida
• Guillain-Barre syndrome
• myasthenia gravis
• muscular dystrophy
• myotonic dystrophy