By Prodyut Das

Floppy Baby Syndrome

Floppy baby syndrome include infants with benign congenital hypotonia who typically exhibit the condition at 6 to 12 months old, with delayed gross motor skills.

Muscle tone is defined as resistance to passive movement.

Hypotonia means "low tone," and refers to a physiological state in which a muscle has decreased tone, or tension.

Neonatal and Infantile Hypotonia

The clinical distinction between upper and lower motor neuron disorders in infants is blurred because incomplete myelinization of the developing nervous system limits expression of many of the cardinal signs, such as spasticity. Neuromuscular and cerebral disorders may produce hypotonia in a young child or infant. The two critical clinical points are whether the child is weak and presence or absence of the deep tendon reflexes. Hypotonia and weakness coupled with depressed or absent reflexes suggest a neuromuscular disorder. A stronger child with brisk reflexes suggests an upper motor neuron source for the hypotonia.  

Hypotonia without Significant Weakness (Central Hypotonia)  

Some infants who appear to move well when supine in their cribs are "floppy" when handled or moved. When placed on their backs, these infants are bright-eyed, have expressive faces, and can lift their arms and legs without apparent difficulty. When lifted, their heads flop, they "slip through" at the shoulders, do not stand upright on their legs, and form an "inverted U" in prone suspension (Landau posture). When placed prone as neonates, they may lie flat instead of having their arms and legs tucked underneath them. Passive tone is decreased, but reflexes are normal. This clinical picture may be associated with significant cerebral disease or may be a benign phenomenon that is outgrown.  

Prader-Willi syndrome presents with severe neonatal hypotonia; severe feeding problems leading to failure to thrive; small hands and feet; and, in boys, small penis, small testicles, and cryptorchidism. Severe hyperphagia and obesity develop in early childhood. Approximately 60% to 70% of affected individuals have an interstitial deletion of paternal chromosome 15q11q13. Many other syndromes also present with severe neonatal floppiness and mental dullness (Table).  

Infants who have a connective tissue disorder, such as Ehlers-Danlos syndrome, Marfan syndrome, or familial laxity of the ligaments, may exhibit marked passive hypotonia, "double jointedness," and increased skin elasticity. They have normal strength and cognition and achieve motor and mental milestones normally. They have peculiar postures of their feet or an unusual gait. 

Signs of Floppy Baby Syndrome

Infants with benign congenital hypotonia typically exhibit the condition at 6 to 12 months old, with delayed gross motor skills. They are unable to sit, creep, or crawl, but have good verbal, social, and manipulative skills and an intelligent appearance. Strength appears normal, and the infants can kick arms and legs briskly and bring their toes to their mouths. The children display head lag, slip-through in ventral suspension, and floppiness of passive tone. Parents may remember that the infant has seemed floppy from birth. The differential diagnosis includes upper and motor neuron disorders and connective tissue diseases.

  • In supine -Frog position
  • Their heads lag when are held up
  • They slip through at the shoulders
  • Do not stand upright on their legs
  • Form inverted U shape in ventral suspention
  • Lie flat when in prone position.
  • Poor ability to cough and clear airway secretions.
  • Poor swallowing ability
  • Crying character [weak, low pitched]
  • Paradoxical breathing pattern. Intercostal muscles paralyzed with intactdiaphragm.
  • Ventral suspension
  • Inverted U position
  • The back hangs over the examiner's hand, and the limbs and head hang loosely
  • Passive extension of the legs
  • Pull to sit-Head lag
  • Vertical suspension:
  • The legs will be extended
  • Decreased tone of the shoulder girdle allows the infant to slip through the examiner's hands
  • Ptosis and external ophthalmoplegia in a floppy weak child.Suggestive of myasthenia gravis

Table . Approach to Differential Diagnosis of the Floppy baby syndrome 

Hypotonia with Weakness 

 Awareness Intact 

 Neuromuscular disease 

  •    Spinal muscular atrophy* 
  •    Myasthenic syndromes 
  •    Congenital neuropathy or myopathy 

 Spinal cord disease (cervical cord trauma or compression) 

  •    Tumor 
  •    Spinal cord infarct 
  •    Malformation 
  •    Spina bifida 
  •    Syringomyelia 

 Consciousness Depressed 

 Severe brain illness* 

 Structural (hydrocephalus) 


 Metabolic (e.g., anoxia or hypoglycemia) 

 Intoxication through mother 

  •    Magnesium sulfate 
  •    Barbiturates 
  •    Narcotics 
  •    Benzodiazepines 
  •    General anesthesia 

 Metabolic abnormality 

  •    Hypoglycemia 
  •    Kernicterus 

 Hypotonia without Weakness 

 Acute systemic illness* 

 Mental retardation 

 Specific syndromes 

  •    Down syndrome* 
  •    Cerebrohepatorenal (Zellweger peroxisomal disorder) 
  •    Oculocerebrorenal (Lowe syndrome) 
  •    Kinky hair disease (Menkes syndrome-copper metabolism disorder) 
  •    Neonatal adrenal leukodystrophy 
  •    Prader-Willi syndrome 

 Connective tissue disorder 

  •    Ehlers-Danlos syndrome 
  •    Marfan syndrome 
  •    Congenital laxity of ligaments 

 Nutritional-metabolic disease 

  •    Rickets 
  •    Renal tubular acidosis 
  •    Celiac disease 
  •    Biliary atresia 

 Congenital heart disease 

 Benign congenital hypotonia 

Investigations For Floppy Baby Syndome

Extensive laboratory investigation is often unrevealing and of questionable value. A complete physical examination, complete blood count, electrolytes, bicarbonate, BUN, creatinine, calcium, creatine phosphokinase, bilirubin, alanine aminotransferase, aspartate aminotransferase, thyroid function studies, and urinalysis are generally necessary and sufficient.

Central Causes

  • Neuroimaging
  • Ultrasound scan in the first instance
  • MRI for structural abnormality
  • EEG: if seizures suspected

Genetic Causes

  • Genetics review if any dysmorphic features present
  • Karyotype (if dysmorphic features)
  • TORCH screen
  • DNA methylation studies or FISH for Prader-Willisyndrome (if clinically indicated after a geneticsreview)
  • Metabolic work up

Peripheral causes

  • Neurology services review
  • Molecular genetics – CTG repeats, deletions in SMNgene
  • Creatine kinase: If elevated in an early sample, repeatafter a few days.
  • Nerve conduction studies

Muscle biopsy

Depending on clinical situation, may be delayed until around 6 months of age as neonatal results are difficult to interpret

Management of Floppy Baby Syndrome

  • Supportive [respiratory, gastrointestinal]
  • Once the correct diagnosis is confirmed, specific treatments should be offered if available
  • Physiotherapy: Regular physiotherapy will prevent contractures. Occupational therapy is important in facilitating activities of daily living.
  • Genetics counseling.

Physiotherapy for Floppy baby syndrome

Physiotherapy for floppy infants is aimed at stimulating normal movement, co-ordination and strength through use of play and functional activities. This makes it more fun for children, more meaningful in terms of everyday activity, and reproducible at home and school. It should encourage as much involvement from parents and carers as possible in their child’s rehabilitation, in order for them to feel very much part of the process. It should be able to give parents specific activities that will help to develop their child’s skills and movement control, and taylor rehabilitation to the needs of individual children.

Some physiotherapy techniques also involve a very hands-on approach in order to change soft tissue length and tension, and facilitate normal movement patterns. Specific stretches, massage techiques and correct handling can be taught to parents in order that the treatment outcome is the most effective it can be.

Physiotherapy can also work along side other Paediatric Health Professionals such as Midwives, Occupational Therpaists and Speech Therapists.

Prognosis of Floppy Baby Syndrome

  • Currently no known treatment or cure for most causes of hypotonia, and objective manifestations can be life long.
  • The outcome in any particular case of hypotonia depends largely on the nature of the underlying disease.
  • In some cases, muscle tone improves over time, or the patient may learn mechanisms that enable him to overcome the most disabling aspects of the disorder.
  • Hypotonia caused by cerebellar dysfunction or motor neuron diseases can be progressive and life-threatening.

Further Reading

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