FLOPPY INFANT

A FLOPPY INFANT is described as an infant with marked hypotonia of all the muscles. Flopppiness is characterized by:
1. Bizarre or unusual postures(Frog legged position)
2. Diminished resistance of joints to passive movement
3. Increased range of joint mobility
4. Paucity of spontaneous movements
5. Motor development delay
This may be associated with frequent respiratory infections, feeding difficulties, facial weakness, ptosis, ophthalmoplegia and dislocated hips. Contracturesmay develop at a later stage.

They may be classified as:


Floppy(peripheral)
disorders involving the lower motor unit.
pathology is at the level of anterior horn cell, peripheral nerve, neuromuscular junction or muscle.
Ex: Werdnig Hoffman SMA, congenital muscular dystrophy, congenital myopathies.



Floppy(central)
Have central neurological(UMN) causes.
Ex: Hypotonic cerebral palsy, Down syndrome.


CAUSES

1.CEREBRAL HYPOTONIA
A> Chromosomal disorders
- Down syndrome
- Prader Willi syndrome

B> Static encephalopathy
- Cerebral malformation
- Intracranial hemorrhage
- Atonic cerebral palsy
- Kernicterus
- Cerebellar ataxia

C> Single gene disorders
- Zellweger syndrome
- Lowe's syndrome
- Tay Sach's disease

2. SPINAL CORD DISORDERS
- Hypotoxic ischaemic myelopathy
- Traumatic myelopathy

3. Anterior horn cell diseases
- Spinal muscular atrophy(SMA)
- Polio myelitis

4. Disorders of the peripheral nerves
- Acute poyneuropathy- GBS
- Familial dysautonomia
- Congenital sensory neuropathy

5. Disorders of myoneural junction
- Neonatal myesthenia gravis
- Infantile botulism
- Congenital defect of neuromuscular junction
- Toxic neuromuscular blockade- Hypermagnesaemia, antibiotics-aminoglycosides

6. Disorders of muscles
- Muscular dystrophies
- Congenital myopathies
-
7. Miscellaneous
- Sepsis
- Hypothyroidism
- Renal tubular acidosis
- Rickets
- Malabsorption syndrome



WHEN TO SUSPECT FLOPPY INFANT???
- Slips from hands
- Less movement of limbs
- Baby is alert, but less motor activity
- Delayed motor development
- Able to walk but frequently falls


HISTORY
- Determine the age of onset, mode of onset, presenting complaints, rapidity of progression.

- History of feeding problems, recurrent pneumonias. (Neuromuscular disorder)

- Antenatal History: Decreased fetal movements and polyhydramnios(due to intrauterine swallowing difficulty) seen in SMA.

- Perinatal history: Birth weight, hypoxia, sepsis.

- Developmental History: Delay of motor milestones with normal intellectual development suggests possible defect in the motor unit.

- Family history: Important to determine the pattern of inheritance.

- Look at the parents' face for evidence of myotonic dystrophy

- If this is suspected, the parent is asked to make a fist and then open hands quickly. This will detect myotonia.

- Look for evidence of myasthenia in the mother(neonatal myasthenia).

Look for pes cavus in the mother(Hereditary neuropathy).

MANEUVERS IN EXAMINATION OF A FLOPPY INFANT
To quantify degree of hypotonicity

Traction response: Initiated by grasping hands and pulling the child to sitting position. It is not elicited in premature infants less than 33 weeks of gestation. After 33 weeks, there is considerable head lag, but neck flexors respond to traction by lifting head. At term, only minimal head lag is present. Presence of more than minimal head lag and failure to counter traction by flexion of limb is abnormal and indicates postural hypotonia in full term newborn.

Vertical suspension: Examiner places both hands in axilla and without grasping thorax, lifts straight up. With weakness, infant needs to be grasped around trunk to prevent falling.

Horizontal suspension: Normal infant suspended horizontally in prone keeps head erect, maintains straight back demonstrates flexion at elbows, hips, knees, and ankles. Hypotonic infant drape over examiners hands with head and limbs hanging limply.

Practical measures of strength in infants and young children.
Head and Trunk

- Upright head stability
- Traction response
- Independent sitting with/without hand popping
- Ability to reach overhead without lateral popping and tilting head back

Proximal arm strength
- Arms over head, reaching to defined height
- Length of ball throw
- Combat crawling

Distal arm strength
- ability to grasp and elevate defined objects of various size and weight

Proximal leg strength
- Movement of leg against gravity while supine
- Kneeling and crawling
- Gower's maneuver
- Gait-Trendelenberg's , waddle

Distal leg strength
- Motion against gravity
- Steppage gait with slapping feet