Categories
Internal Medicine

Floppy infant syndrome (FIS)

Floppy infant syndrome, also sometimes referred to as rag-doll syndrome, is characterized by hypotonia that could present as either peripheral hypotonia or central.

Introduction

Floppy infant syndrome, also sometimes referred to as rag-doll syndrome, is characterized by hypotonia that could present as either peripheral hypotonia or central.


Aetiology

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.

Aetiology of congenital hypotonia among 144 infants. On the left is the percentage of congenital hypotonia due to central, peripheral, and undetermined causes. On the right is a further breakdown of the causes of central congenital hypotonia. | HIE, hypoxic-ischemic encephalopathy; ICH, intracranial haemorrhage. | Neonatal Hypotonia | Obgyn Key. Retrieved December 17, 2020, from https://obgynkey.com/neonatal-hypotonia/#ch017ref11
Cerebral and peripheral abnormalities that manifest as hypotonia in infants. | Howell, R., Byrne, B., Darras, B. et al. Diagnostic challenges for Pompe disease: An under-recognized cause of floppy baby syndrome. Genet Med 8, 289–296 (2006). https://doi.org/10.1097/01.gim.0000204462.42910.b8

Clinical features

Depending on the origin of hypotonia, the infant will present with different symptoms that ultimately have the characteristic feature of hypotonia.

Differentiation between central vs peripheral neonatal hypotonia | Vawter-Lee, M. M., Seals, S. S., Thomas, C. W., & Venkatesan, C. (2016). Clinical Reasoning: A neonate with micrognathia and hypotonia. Neurology, 86(8), e80 LP-e84. https://doi.org/10.1212/WNL.0000000000002397

Physical examination:

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
  • ‘Frog-leg’ posture
  • Significant head lag on traction
  • Pull-to-sit maneuver
  • Rag-doll posture on ventral suspension
  • ‘Slipping through the hands’ when the infant is held under the arms.
Neurological signs during development. The mean postmenstrual age of appearance of neurological signs relevant to muscle tone and strength are shown. The range of mean appearance or presence of each sign is shown as a thick, colored bar or a diamond, with the thin error bars before and after representing 1 standard deviation. | (2020) Neonatal Hypotonia | Obgyn Key. Retrieved December 17, 2020, from https://obgynkey.com/neonatal-hypotonia/#ch017ref19

Diagnosis

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.

Kamity R. (2019) Hypotonia in the Newborn. In: Martin G., Rosenfeld W. (eds) Common Problems in the Newborn Nursery. Springer, Cham. https://doi.org/10.1007/978-3-319-95672-5_16

Differential diagnosis:

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.
Differentiating the features of a floppy neonate according to the site of involvement | Ahmed, M. I., Iqbal, M., & Hussain, N. (2016). A structured approach to the assessment of a floppy neonate. Journal of pediatric neurosciences, 11(1), 2–6. https://doi.org/10.4103/1817-1745.181250
Anatomical-clinical correlation illustrating differential diagnosis of hypotonia in infancy | Leyenaar, J., Camfield, P., & Camfield, C. (2005). A schematic approach to hypotonia in infancy. Paediatrics & child health, 10(7), 397–400. https://doi.org/10.1093/pch/10.7.397

Management

Depending on the underlying causative disorder leading to the presence of floppy infant syndrome, the treatment will vary considerably.

Leave a Reply

%d