Floppiness/hypotonia is a common neurologic symptom in infancy. A variety of neuromuscular disorders and central nervous system (CNS) disorders cause floppy infant syndrome (FIS). CNS disorders are the much more common causes of the syndrome than neuromuscular disorders. On long-term follow up, cerebral palsy and mental retardation turn out to be the 2 most common causes of FIS.
Depending on the origin of hypotonia, the infant will present with different symptoms that ultimately have the characteristic feature of hypotonia.
Regardless of whether the underlying cause of hypotonia is peripheral or central in origin, the presentation of floppy infant syndrome focuses on observing for the presence or absence of specific signs
Significant head lag on traction
Rag-doll posture on ventral suspension
‘Slipping through the hands’ when the infant is held under the arms.
The clinical examination is crucial in diagnosing floppy infant syndrome in the neonate period, but the most critical factor is investigating and diagnosing the underlying cause of hypotonia.
The differential diagnosis for neonatal hypotonia is extensive and a methodical approach helps in localizing the problem to a specific region of the nervous system and formulating a differential diagnosis.
Depending on the underlying causative disorder leading to the presence of floppy infant syndrome, the treatment will vary considerably.