Pediatrics notes about "Floppy infant". These notes were published in 2018. You can download them also from - Telegram: https://t.me/pediatric_notes_2018 - Mediafire: http://www.mediafire.com/folder/u5u60m184t9z7/Pediatric_Notes_2018

1. Floppy Infant
Kareem Alnakeeb P a g e | 1
Neurology 2018
Generalized hypotonia due to insult during fetal or neonatal period.
A. Abnormal postures:
1- Frog leg position:
- lies supine with full abduction and external rotation of legs & flaccid extension of
arms
- It denotes → Hypotonia of limb muscles.
2-Rag doll position:
- Holding the infant in horizontal (Ventral) suspension→ the back hangs over the
examiner's hand, and the limbs and head hang loosely.
- It denotes → Hypotonia of trunk muscles.
B. movements:
 Diminished resistance to passive movement
 Abnormal range of peripheral joint movement
1- Pull to Sit Maneuver:
- Pulling the infant from the supine to sitting position → the head lags & continues
to lag when the sitting position is reached.
- It denotes → Hypotonia of neck muscles.
2- Scarf sign:
- Put the child in a supine position and hold one of the infant’s hands.
- Try to put it around the neck as far as possible around the opposite shoulder.
- Observe how far the elbow goes across the body.
- In normal infant, the elbow does not quite reach the mid sternum
- In a floppy infant, the elbow easily crosses the midline.
3- Slip-through on vertical suspension:
- Holding the infant under the arms → the legs will be extended; decreased tone of
the shoulder girdle allows the infant to slip through the examiner's hands.
Floppy Infant
Definition:
Manifestations:
I. Hypotonia:
A. Abnormal postures
B. Abnormal range of peripheral joint movement
C. Diminished resistance to passive movement
II. Delay in motor milestones

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I. Central / Cerebral hypotonia (UMNL)
Atonic Cerebral Palsy
Cerebral insult:
- Hypoxic Ischemic Encephalopathy (HIE)
- Intracranial Hemorrhage
- Chronic non-progressive encephalopathy
- Cerebral malformation
- Perinatal distress
- Postnatal disorders
Chromosome disorders :
- Down syndrome (Trisomy 21)
- Prader-Willi syndrome
Peroxisomal disorders
- Cerebro-hepato-renal syndrome
(Zellweger syndrome)
- Neonatal adreno-leukodystrophy
Other genetic defects
- Familial dysautonomia
- Oculo-cerebro-renal syndrome
(Lowe syndrome)
Neuro-metabolic disorders
- Acid maltase deficiency
(Pompe disease)
- Infantile GM1 gangliosidosis
Benign congenital hypotonia
II. Peripheral hypotonia (LMNL)
1. Spinal cord
(AHCs)
2. Peripheral motor
nerves
3. NMJ 4. Muscle
- Infantile Spinal
muscle atrophy
“Werdnig Hoffman”
- Congenital
hypomyelination
neuropathy (CHN)
- Giant axonal
neuropathy
- Hereditary motor
sensory neuropathy
(HMSN) e.g.
Charcot–Marie–Tooth
disease
- Acquired:
Guillain-Barré
Syndrome
- Familial
infantile
myasthenia
- Transient
acquired
neonatal
myasthenia
- Infantile
botulism
Muscular Dystrophies
- Bethlem myopathy
- Congenital
dystrophinopathy
- Congenital muscular
dystrophy
- Congenital myotonic
dystrophy
Congenital Myopathies
- Nemaline (rod)
- Central core disease
- Myotubular
(centronuclear)
- Congenital fiber-type
disproportion
Metabolic Myopathies
- Acid maltase deficiency
- Cytochrome-c oxidase
deficiency
Etiology:

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Figure: Anatomical-clinical correlation illustrating differential diagnosis of hypotonia in infancy

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I. History :
Family history • Affected parents or Siblings
• Consanguinity
• Stillbirths
• Childhood deaths
Maternal disease • Diabetes
• Epilepsy
• Myotonic dystrophy
Pregnancy & delivery History
( Obstetric History )
• Drug or teratogen exposure
• Decreased fetal movements
• Abnormal presentation e.g. Breech delivery
• Amount of amniotic fluid (Polyhydramnios/
oligohydramnios)
• Apgar scores
• Resuscitation requirements
• Cord gases
Since delivery History
( Developmental & Dietetic
History )
• Respiratory effort
• Ability to feed
• Level of alertness
• Level of spontaneous activity
• Character of cry
II. Identification of hypotonia
• Holding the infant in horizontal suspension – the back hangs over the examiner's hand, and
the limbs and head hang loosely. (Rag doll position)
• Passive extension of the legs at the knees – no resistance is met.
• Pulling the infant from the supine to sitting position – the head lags and continues to lag
when the sitting position is reached. (Pull to Sit Maneuver)
• Holding the infant under the arms – the legs will be extended; decreased tone of the
shoulder girdle allows the infant to slip through the examiner's hands.
(Slip-through on vertical suspension)
Diagnosis

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III. Physical Examination
Central AHCs Peripheral Nerves NMJ Muscle
Muscle power Normal Weakness
(Generalized)
Weakness
(distal > proximal)
Weakness
(face, eyes, bulbar)
Weakness
(proximal > distal)
Deep tendon
reflex ( DTR )
Normal /↑ / absent  Normal /   / Absent
Fasciculations Absent Prominent Absent Absent Absent
 Clues & Pitfalls :
1- Localize cause of hypotonia :
Central “ UMNL “
(brain/spinal cord)
Peripheral “ LMNL “
(AHCs, peripheral nerve, NMJ, muscle)
Muscle mass • Normal bulk • Decreased bulk “muscle atrophy”
Muscle power • Normal/mild weakness “floppy
strong“
• Predominant axial weakness
• Weakness is uncommon
Except in the acute stages
• Marked weakness “floppy weak “
• Weak antigravitational limb muscles
Deep tendon reflex
( DTR )
• normal/increased reflexes • decreased reflexes
Plantar reflex • Plantar Extension “ + ve Babinski “ • Plantar Flexion
Dysmorphic features • Dysmorphisms • No dysmorphisms
CNS features • Encephalopathy, microcephaly
• Early onset seizures
• Depressed level of consciousness
• Global developmental delay
• Sustained Ankle clonus
• Scissoring on vertical suspension
• Awake, Alert
• Low-pitched weak cry
• Preserved social interaction
• Selective motor delay
• Paradoxical chest movements
• Tongue fasciculations
2- Clues to specific diagnosis :
Clues Diagnosis
Hepatosplenomegaly Storage disorders
Congenital infections
Renal cysts, high forehead, wide fontanelles Zellweger’s syndrome “cerebro-hepato-renal”
Hepatomegaly, retinitis pigmentosa Neonatal adrenoleukodystrophy
Abnormal odour metabolic disorders
Hypopigmentation, undescended testes Prader Willi
Examination of the mother Congenital myotonic dystrophy
Myasthenia gravis

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IV. Investigations:
By History and examination
► Hypotonia + a degree of strength: Central cause is most likely
► Hypotonia + weakness: Peripheral cause is possible
Central Causes Peripheral causes
o Neuroimaging
 Ultrasound scan in the first instance
 MRI for structural abnormality
 EEG: if seizures suspected
o Genetics review
(if any dysmorphic features present)
o Karyotype (if any dysmorphic features present)
o DNA methylation studies or FISH
for Prader-Willi syndrome
(if clinically indicated after a genetics review)
o TORCH screen
o Metabolic work up
o Early review by the neurology service
o Molecular genetics – CTG repeats, deletions
in SMN gene
o Nerve conduction studies
o Creatine kinase: If elevated in an early
sample, repeat after a few days.
o Muscle biopsy
-Depending on clinical situation
-May be delayed until around 6 months of age
as neonatal results are difficult to interpret
1. Atonic Cerebral Palsy
2. Infantile Botulism
3. Werdnig-Hoffman disease (SMA I)
4. Myasthenia gravis
5. Metabolic Myopathies
Common causes of floppy infant

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1. Atonic cerebral palsy
- Mostly atonic diplegia
- Many are mentally retarded
- Near normal strength of upper limbs
- Hypotonia
- Brisk reflexes
 Associated with:
• lethargy, lack of alertness, poor feeding
• Mental retardation
• poor Moro’s reflex, and seizures during the neonatal period.
2. Infantile Botulism
- Acute onset descending weakness,
- cranial neuropathies, ptosis,
- unreactive pupils, dysphagia
- Isolation of organism from stool
- Presence of toxin in the stool
C/P:
Investigations:
 Forster sign:
Vertical suspension while held under the arm → flex legs at the hip.

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3. Spinal Muscle Atrophy type 1 (SMA 1)
“Werdnig-Hoffman disease”
•AR trait • AD or XR in few cases
- Degenerative disease of motor units beginning in the fetus and progressing into
infancy; denervation of muscle and atrophy
-Deletion in SMN gene on chromosome 5q13  degeneration of AHCs in spinal cord &
motor nuclei in the lower brainstem  progressive muscle weakness and atrophy.
* SMA 1 presents in early infancy with:
1) Thin muscle mass, Progressive hypotonia, generalized weakness;
Infant is flaccid, has little movement & poor head control, No independent sitting
2) Absent DTRs
3) Fasciculations of the tongue (13)
4) Contractures in 10-20%.
5) Feeding difficulty: Child is alert, poor feeding and cry
6) Respiratory insufficiency
7) Normal Intelligence, cognition & facial expressions; Typically appear brighter than
others of same age
 Molecular genetics: deletion in SMN gene → Simplest, most effective diagnosis
 EMG—fibrillation potential and other signs of denervation
 Muscle biopsy: shows neurogenic type of atrophy “perinatal denervation”
Death occurs by 2-4 years of age
AGE OF ONSET MODE OF
INHERITANCE
C/P PROGRESSION
SMA TYPE I Before birth to 6 months AR - Generalized muscle
weakness
- No independent sitting
- Progress rapidly
- Death usually by
age 2
SMA TYPE II 6 to 18 months AR - muscle weakness
- BUT many sit
independently
- Variable
- Most survive to
2nd
or 3rd
decade
SMA TYPE III Childhood to
adolescence
AR - Some muscle weakness
- BUT most ambulate
independently
- Slow Progression
- Normal lifespan
Definition:
Pathology:
C/P:
Investigations:
Prognosis:

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4. Myasthenia gravis
- It is an autoimmune disorder.
- Commonest cause is antibody to post synaptic acetylcholine receptors
Clinical feature frequency
Feeding/swallowing difficulties 100 %
Generalized weakness 70 %
Respiratory difficulty 66 %
Weak cry / facial weakness 60 %
Mechanical ventilation 30 %
Eye movements abnormalities 10 %
Reflexes Present
Arthrogryposis, pulmonary hypoplasia Rare
1) Congenital 2) Transient neonatal
- Not autoimmune
- It may be familial (AR) with reduced
number of Ach receptors
- Rare
- Familial disorder is permanent.
- In infant born to myasthenic mother
(10-20% affected mothers)
- Appearing within few hours: 3 days after
birth.
- After antibodies wane, they are normal and
have no risk for disease
* Characterized by:
- Generalized muscle weakness
- marked hypotonia
- poor feeding
- pooling of oral secretions
- feeble cry
Treatable (Cholinesterase inhibitors) Good response to Cholinesterase inhibitors
C/P:
Types

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5. Metabolic Myopathies
Mitochondrial - Biopsy Shows: Ragged red fibers
- lactic acidosis
- HSM
- systemic symptoms
Glycogen storage - Liver disease
- GSD type II “Pompe disease” or “acid maltase deficiency”;
1. profound hypotonia with progressive muscle weakness
2. Cardiomegaly
3. Macroglossia “large Tongue “
Lipid Metabolism - Hypoglycemia with low ketones
- Coma
- high NH3
• Regular physiotherapy → prevent contractures.
• Occupational therapy →facilitate daily activities .
• Annual orthopedic review is required to monitor for scoliosis and to exclude hip
dislocation/subluxation.
• Vigorous treatment of respiratory infections is indicated.
• Annual flu vaccination is necessary.
• Feeding intervention by nasogastric tube or gastrostomy For the undernourished child.
• Maintenance of ideal weight as excessive weight gain will exacerbate existing weakness.
• Children with neuromuscular disorders deserve special attention when it comes to anesthesia;
 The anesthetist should be forewarned about the possibility of an underlying muscle disease
( even if the child has very mild or non-existing symptoms)
 Muscle relaxants should only be used if essential
because of their more profound and prolonged effect in myopathic children.
• A family history of muscle disease or mild hyperkalemia may be of importance.
MANAGEMENT
PRINCIPLES OF MANAGEMENT:

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( Mainly supportive , physiotherapy )
• They require a multidisciplinary team approach with the involvement of several specialties
including: ”pediatrics, neurology, genetics, orthopedics, physiotherapy, and occupational therapy “
• Physiotherapy is mainly preventative to avoid contractures and wasting
(But will NOT increase muscle tone).
• Counseling the families about potentially preventable disorders is very important
• Consanguinity needs to be strongly discouraged to prevent inherited causes in our region.
Treatment:
Question
During the health supervision visit for a 6-week-old boy, his father expresses concern that his son
“doesn’t look like” his other children.
Growth parameters are normal except for a head circumference of 35.5 cm (<5th percentile).
On PE, you note that the infant does not appear to fixate or track your face visually. There is a “slip
through” on vertical suspension and “draping over” on horizontal suspension. DTRs are brisk. Moro
reflex is present and brisk.
* Of the following, the MOST likely cause of this infants hypotonia is:
a) AHC disease
b) Congenital brain malformation
c) Congenital myasthenic syndrome
d) Congenital myopathy
e) Spinal cord disease
Answer
B. Congenital brain malformation
- Hypotonia +
- Localize! UMN vs. LMN signs
- Take into account growth parameters, especially head circumference & features such as
tracking
* Regarding other choices:
A. anterior horn cell disease – wouldn't cause microcephaly or increased reflexes
C. Congenital myasthenic syndrome – wouldn't cause microcephaly or brisk reflexes
D. Congenital myopathy – no microcephaly or poor visual tracking
E. Spinal cord disease – wouldn't cause microcephaly or poor visual tracking