Floppy infant

1. Approach to Floppy
infant

2. Floppy infant syndrome:
a term used to describe reduced muscle tone and
muscle weakness in infants.
Hypotonia :
decrease resistance to passive range of motion
Weakness :
Reduce power of active motion

3. Floppy infant :
 Is not uncommon neurologic condition 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

4.  It is often helpful to divide causes into those
that are
 ‘central’ involving the CNS (so-called
‘floppy strong’)
 and ‘peripheral’ involving lower motor
neurons, neuromuscular junction (NMJ), or
primary muscle disease (‘floppy weak’).

6. History
 Sx :
 weakness :proximal,distal,
 fatigability
 myalgia
 Clinical course of the disease
(static ,progressive)
 Developmental hx : delay , regression
 Associated sx

7.  prenatal, Perinatal , postnatal hx
 Neonatal hx : Respiratory effort, Ability to feed,
Level of alertness, Level of spontaneous activity,
Character of cry
 Nutritional hx: sucking and swallowing
difficulties that ‘fatigue’ or ‘get worse’ with
repetition.
 Family hx : premature death , …

9. Range of clinical features
 Common to ‘central’ and ‘peripheral’
diseases: generalized hypotonia; ‘frog-leg’
posture; respiratory failure; obstetric problems
(e.g. polyhydramnios due to impaired
swallowing, breech presentation); hypoxic–
ischaemic encephalopathy.

11. Central conditions:
encephalopathy; dysmorphism; reasonable
muscle strength; increase or normal tendon
reflexes.

12. Peripheral causes:
normal conscious level; muscle signs
(weakness, myotonia, fasciculations, or
fatiguing); decrease or normal tendon reflexes;
little facial expression; micrognathia; high
arched palate; ptosis; undescended testes;
limbcontracture/deformities; hip dislocation

15. Causes of
‘Floppy strong’ or ‘central’ involving CNS
 Prematurity
 HIE
 Hypoglycaemia
 Sepsis
 Electrolyte disturbance
 Drug-related
 IEM
 Hypothyroidism
 Chromosomal disorders
(e.g. trisomy 21)
 CNS malformations
 Benign congenital
hypotonia
 Underlying syndrome
(e.g. Prader–Willi
syndrome)
 Cervical spinal cord
trauma (birth injury)

16. Causes of ‘Floppy weak’
 ‘Spinal muscular atrophy (SMA), particularly type 1
(previously known as Werdnig–Hoffman disease)
 Myasthenia gravis (transient or congenital)
 Congenital myotonic dystrophy (autosomal dominant
inheritancefrom mother)
 Congenital muscular dystrophies
 Congenital myopathies
 Metabolic myopathies
 Peripheral neuropathies
 Spinal cord injury

17. Anatomical-clinical correlation illustrating differential diagnosis

18. Muscle
– Duchenne muscular dystrophy:
Xlinked recessive,
presents with waddling gait and difficulty
climbing stairs

19. Neuromuscular transmission
– juvenile myasthenia :
>10 years old
*ophthalmoplegia and ptosis
*loss of facial expression and difficulty chewing

20. Peripheral nerve
– Hereditary motor sensory neuropathies
(HMSN): symmetrical wasting of the
distal muscles
– Acute post-infectious polyneuropathy
(Guillain–Barré syndrome): ascending
symmetrical weakness; may be bulbar
palsy and respiratory depression

21. Anterior horn cell
– spinal muscular atrophy:
progressive weakness and wasting of
skeletal muscles; tongue fasciculation
may aid diagnosis

22. Management
 Exclude severe systemic illness: e.g. sepsis that
requires prompt
treatment.
 Treat any respiratory failure with O2 or
ventilatory support as required.
 Examine both parents for possible disease, e.g.
maternal myasthenia gravis or myotonic
dystrophy (possibly undiagnosed!).
 Elicit family history (e.g. maternal myotonic
dystrophy); antenatal history (e.g.
polyhydramnios).

23. ‘Central’ cause:
consider—
blood glucose; U&E; Ca++; Mg++
Septic screen; ESR/CRP;
TFT;
karyotype; cranial ultrasound; CT/MRI; EEG;
IEM (inborn errors of metabolism) screen;
maternal drug screen;
genetics opinion if dysmorphic.

24. ‘Peripheral’ cause:
consider—serum creatinine phosphokinase;
specifi cytogenetics (e.g. myotonic dystrophy);
electromyogram (EMG),
nerve conduction studies; muscle or sural nerve
biopsy; muscle ultrasound;
edrophonium 20micrograms/kg test dose l followed
30s later (if no adverse reaction) with
80micrograms/kg IV
(causes dramatic improvement in some forms of
myasthenia gravis);
echocardiogram (storage diseases)

25. Spinal cord damage (rare):
consider in the infant who has a flaccid
paralysis from birth.
Associated with rotational forceps delivery.
Immobilize neck.
Seek specialist advice.
MRI.

26. Prognosis
 Causation-dependent and very variable.
Some causes are fatal, e.g. type 1 SMA.

27. References
Illustrated Textbook of Pediatrics, Fourth
Edition, Tom Lissauer
Oxford handbook of Pediatrics ,2nd edition,
Robert Tasker