One of the Most discussed topic in every residency

1. An Approach to a
Floppy Infant
Dr Suit Kumar Shrestha
MD-Pediatrics,
1st Year Resident
IOM, TUTH
Medchrome.com
OVERVIEW of Content
Anatomical Review
Introduction
Etiologies
Clinical Evaluation
Investigations
Management
Summary

2. What is Tone?
 Muscle tone is the resistance offered by a muscle against stretch in
resting condition due to state of partial contraction of the extrafusal
fibers resulting from asynchronous discharge of the motor neurons.
 Types-
1. Passive tone
2. Active tone
Structures responsible-
 Muscle
 Muscle Spindle (Receptor)
 Group I and II sensory fibers
 Spinal Cord ( Center)
 Alpha and Gamma Motor Neurons ( Nerve paths)
 Supraspinal Control ( Brainstem, Cerebellum, Corex, RF )

3. Mechanism
 The myotactic reflex is the basis of normal tone in a muscle.
 Muscle tone is maintained at the peripheral level by the
participation of the fusimotor system: pathways involving the
muscle spindles that promote muscle contraction in response to
stretch
 And the inverse myotactic reflex involving the golgi tendon
organ that provides a braking mechanism to the contraction of
muscle.
 A lesion interrupting the stretch reflexes at any level in the lower
motor neuron (LMN) will result in a loss of muscle tone and
stretch reflexes i.e. flaccidity .

4.  The output of gamma motor neurons to the muscle spindle is
influenced by supraspinal influences  predominantly inhibitory.
 Thus lesions affecting the UMN  reduction of these inhibitory
influences  increase in excitatory output of the gamma motor
neurons to the muscle spindle
 In early infancy, contrary to expected increase in muscle tone,
the response to an upper motor neuron lesion in the early
stages is flaccidity and loss of muscle tone .
 This pattern- hypotonia is associated with preserved or
hyperactive reflexes later evolves into spasticity.
 Clinical distinction between an UMN and LMN lesion provides a
rationale for investigations based on the localization of lesion in
the pathway of motor control (central vs. peripheral hypotonia)

5.  Hypotonia is characterized by reduced resistance
to passive range of motion in joints versus
weakness, which is a reduction in the maximum
muscle power that can be generated.
(Dubowitz, 1985; Crawford, 1992; Martin, 2005)
 Weak infants always have hypotonia, but hypotonia may exist
without weakness.
 A hypotonic newborn should be considered
septic until proven otherwise

6. Introduction “Floppy Infant”
o A well-recognized entity
o An organized approach is essential for Evaluation
o Problems like frequent infections, feeding problems,
ptosis, ophthalmoplegia and dislocated hips.
 The word ‘floppy’ can be used to mean:
◦ decrease in muscle tone (hypotonia)
◦ decrease in muscle power (weakness)
◦ ligamentous laxity and increased range of joint mobility.
 But strictly speaking - hypotonia.
 Floppy infant refers to those children presenting with
generalized hypotonia, most often arising out of an insult
incurred during fetal or neonatal period.

7. Useful indicators of weakness are:
 Ability to cough and clear airway secretions (‘cough
test’)- Apply pressure to the trachea and wait for a single
cough that clears secretions. If more than one cough is needed
to clear secretions, this is indicative of weakness.
 Poor swallowing ability as indicated by drooling and
oropharyngeal pooling of secretions.
 The character of the cry — infants with consistent
respiratory weakness have a weak cry.
 Paradoxical breathing pattern — intercostal muscles
paralysed with intact diaphragm.

8. Causes of Floppy Infant Syndrome
Neurology Chapter of IAP
Central nervous system –
 Perinatal asphyxia
 Neonatal encephalopathy
 Kernicterus,
 Cerebral palsy (atonic type)
 Intracranial hemorrhage
 Chromosomal anomalies- Down syndrome
 Inborn errors of metabolism e.g., aminocidurias,
mucopolysaccharidosis and cerebral lipidosis.
.

9. Causes…
Spinal cord lesions
 Anterior horn cell disease – Werdnig Hoffman spinal
muscular atrophy, SMA II and III, Myelopathies.
 Poliomyelitis
Peripheral nervous
 Acute polyneuropathy
 Familial dysautonomia
 Congenital sensory neuropathy.
Myoneural junction
 Neonatal myasthenia gravis
 Infantile botulism
 Following antibiotic therapy

10. Causes of Floppy Infant Syndrome (Contd.)
Neurology Chapter of IAP
Muscles
 Muscular dystrophies,
 Congenital myotonic dystrophies,
 Congenital myopathies (including central core disease and
nemalin myopathy),
 Polymyositis,
 Glycogen storage disease (pompe’s), and
 Arthrogryposis multiplex congenital.
Miscellaneous
 Protein energy malnutrition, rickets,
 Prader willi syndrome,
 Malabsorption syndromes,
 Ehler-danlos syndrome,
 Cutis laxa, cretinism.

11. The Floppy Infant : Evaluation of Hypotonia
DOI: 10.1542/pir.30-9-e66
Pediatrics in Review 2009;30;e66
Dawn E. Peredo and Mark C. Hannibal
Causes of Hypotonia Percentage (n=277)
HIE 19%
Chromosomal /Genetic Syndromes
Down syndrome 13%
Prader-Willi syndrome 5%
31%
Brain Anomalies 13%
Myopathies 5%
Congenital Myotonic Dystrophy 4%
Metabolic disorders 3%
Benign Neonatal Hypotonia 3%
Spinomuscular Arophy 2%
Muscular Dystrophy 2%
Others 5%
Unknown 13%

12. Approach to a Floppy Infant
History
 Presenting Complaints:
◦ Decreased Tone
◦ Difficulty sucking, chewing; Weak cry
◦ Decreased movement
◦ Delayed motor milestones
◦ Complications of muscle weakness:
 Recurrent respiratory infections, Respiratory difficulty
 Age of Onset: The onset -important to distinguish between
congenital and aquired aetiologies. Eg
◦ SMA Type I -: < 6 months;
◦ SMA Type II : 3mo- 15 mon
◦ SMA Type III : at or after 12 mon
◦ Neonatal myasthenia – soon after birth;
◦ Juvenile myasthenia - >6 mo

13. History:
 Sudden onset: IVH in Premature infants
 Course- progressive,static or fluctuating
 Distribution of weakness:
◦ Proximal (Unable to stand from sitting) – Myopathies
◦ Distal (Unable to hold things) – Neuropathy
 Associated Atrophy of muscles:
◦ Myopathies,
◦ neuropathies
 Muscle pain:
◦ Acute polyneuropathies,
◦ myositis,
◦ Metabolic disease,
◦ Ischemic myopathies

14. History:
 Joint deformities
◦ Arthrogryposis
 Zellweger Syndrome,
 Chromosomal disorder
 Congenital Muscular dystrophy,
 Myotonic dystrophy,
 Transitory Neonatal myasthenia
 Congenital dislocation of hip- frequent finding
 CNS causes:
◦ Seizures , Abnormal movement,
◦ Mental retardation/Learning disabilities, ataxia
◦ Poor state of alertness
◦ Lack of response to visual and auditory stimuli
◦ Dysmorphic features

15.  Dysmorphic Features:
◦ Cerebral dysgenesis,
◦ Zellweger syndrome,
◦ Prader-Willi Syndrome
◦ Fiber type Disproportion myopathies,
◦ Neonatal myotonic Dystrophies
 Severity:
◦ Respiratory difficulty (Involvement of respiratory
muscles)
◦ Apnea, Aspiration (Gag reflex lost)
 H/o Fatigue on continuous sucking – Myasthenia
 H/o Constipation – Botulism
 H/o easy bruising, poor wound healing – Ehler-
Danlos

16. Relevant History:
The pre-, peri- and postnatal history is important.
Enquire about the
quality and quantity of fetal movements,
breech presentation
and the presence of either poly or oligohydramnios.
Neonatal seizures and an encephalopathic state ( Central)
Documentation of birth trauma, birth anoxia, delivery complications,
low cord pH and Apgar scores are crucial as HIE remains an
important cause.
H/O consanguinity and identify other affected family members in
order to reach a definitive diagnosis, using a detailed family pedigree
to assist future genetic counselling

17.  Development h/o:
◦ Delayed milestones
 Family h/o:
 A family history of neuromuscular abnormalities may be
informative because many disorders are inherited.
 Examples of familial neuromuscular diseases include
 congenital myotonic dystrophy,
 spinal muscular atrophy,
 metabolic disorders (e.g., mitochondrial disease, acid
maltase deficiency, defects of creatine synthesis).

18. Examination:
Detection of Hypotonia:
 Main Features:
◦ Bizarre or Unusual postures
◦ Decreased resistance of joints to passive movement
◦ Increase in range of movement of joints
◦ Decreased Spontaneous movements

19. Clinical signs in a floppy infant
1. ‘frog-leg’ posture- generally implies reduced spontaneous
movement, with the legs fully abducted and arms lying
beside the body either extended or flexed
2. Significant head lag on traction or pull-to-sit manoeuvre
and excessively rounded back when sitting (>33 weeks)
3. Rag-doll posture on ventral suspension
4. Vertical suspension test – feeling of ‘slipping through the
hands’ when the infant is held under the arms
5. Various associated examination findings such as flat
occiput or congenital dislocation of the hips, arthrogryposis.

20. Appearance of the Floppy Infant:
 Supine position:
◦ Paucity of spontaneous
movement
◦ Fully abducted at hip
joint
◦ Thighs externally
rotated (Frog-leg
posture)
◦ Arms extended or flexed
at elbow with hands
beside the head
Traction response
Head lag when pulled
to sit
Normally, Flexion at
the elbow, knee and
ankle (To counter
traction)
4wks: Head in plane of
body momentarily
20 wks: No head lag

21. Examination:
 Sitting Posture:
◦ Head falls forward
◦ Trunk control poor
◦ Unable to sit
unsupported
 Vertical suspension:
◦ Hold at axilla
◦ Head falls forward
◦ Legs dangle or
scissoring (Normally
flex)
◦ Tendency to slip
through one’s hands
Horizontal suspension:
Normally, head erect,
back straight, limbs
flexed
Hypotonic – head and
legs hang limply, Rag
doll
Prone:
Unable to lift head and
trunk

22. Examination:
 Palpation of muscles: Flabby
 Adductor angle: Angle between
thighs when hips maximally
abducted with extension at knees
 Popliteal angle: Hips flexed onto
abdomen by holding at the knees
 Dorsiflexion angle of the foot: By
gentle pressure on the sole
 Heel to ear manoeuvre: Both
extended legs lifted towards the
ears without lifting the pelvis
 Scarf sign: Flexed at elbow and
pulled across the chest by holding
at the hand and wrist
Adductor
angle

24. Diagnostic approach
 The initial approach to a floppy infant
is to determine whether the problem
is of central or peripheral origin.
 This is of crucial importance when
forming a plan for diagnostic
investigation.

25. Differentiating clinically

26. Floppy Strong Floppy Weak

27. Differentiating Features of a Floppy Infant
according to Site of Involvement
Site of
involvement
Extent of weakness Proximal vs.
distal
weakness
Face Arms Legs
Central - + + > or =
Anterior horn cell + ++++ ++++ > or =
Peripheral nerve - +++ +++ <
Neuromuscular
junction
+++ +++ +++ =
Muscle Variable ++ + >

28. Differentiating Features of a Floppy Infant
according to Site of Involvement (Contd.)
Site of
involvement
Deep tendon
reflexes EMG
Muscle
biopsy
Central Normal or
increased
Normal Normal
Anterior horn cell Absent Fasciculation /
fibrillation
Denervation
pattern
Peripheral nerve Decreased Fibrillation Denervation
pattern
Neuromuscular
junction
Normal Decremental /
incremental
Normal
Muscle Decreased Short duration small
amplitude potential
Characteristic

29. A distinct pattern of weakness
• Axial weakness is a significant feature in central hypotonia.
• Generalised weakness with sparing of the diaphragm, facial
muscles, pelvis and sphincters suggests anterior horn cell
involvement.
• With myasthenic syndromes, the bulbar and oculomotor
muscles exhibit a greater degree of involvement.
• Progressive proximal symmetrical weakness suggests a
dystrophinopathy. Signs of proximal weakness in the older
infant include a lordotic posture, Trendelenburg gait and Gower
sign.
• A striking distribution of weakness of the face, upper arms and
shoulders suggests fascioscapulohumeralmuscular dystrophy.
• Distal muscle groups are predominantly affected with peripheral
neuropathies.

30. Clues to etiology

31. Clues to Etiology

32. Clues to Etiology

33. Clinical features - Hypotonia of central origin
 Social and cognitive impairment in addition to motor delay
 Dysmorphic features implying a syndrome or other organ
malformations sometimes implying a syndrome
 Fisting of hands
 Normal or brisk tendon reflexes
 Features of pseudobulbar palsy, brisk jaw jerk, crossed
adductor response or scissoring on vertical suspension
 Features that may suggest an underlying spinal
dysraphism
 History suggestive of hypoxic-ischaemic encephalopathy,
birth trauma or symptomatic hypoglycaemia
 Seizures

34. Indicators of peripheral hypotonia
 Delay in motor milestones with relative normality of social
and cognitive development
 Family history of neuromuscular disorders/maternal myotonia
 Reduced or absent spontaneous antigravity movements,
reduced or absent deep tendon jerks and increased range of
joint mobility
 Frog-leg posture or ‘jug-handle’ posture of arms in
association with marked paucity of spontaneous movement
 Myopathic facies (open mouth with tented upper lip, poor lip
seal when sucking, lack of facial expression, ptosis and
restricted ocular movements)
 Muscle fasciculation- rare but diagnostic
 Other corroborative evidence including muscle atrophy,
muscle hypertrophy and absent or depressed deep
tendonreflexes

35. Investigations:
I. Motor Unit disorder:
 Serum Creatine Kinase: Prior to EMG or Biopsy
◦ ↑↑ in rapidly progressive myopathies
◦ Maybe normal in Fiber type Disproportion
myopathies and some metabolic myopathies
◦ May ↑ in rapidly progressive neuronopathies (SMA)
 EMG:
◦ Myopathies – Brief, small amplitude, Polyphasic
potentials (BSAPPs)
 Muscular Dystrophies, Myotonic Dystrophies
◦ Neuropathies- Denervation potentials at rest
(Fibrillations, Fasciculations, Sharp waves) and Motor
unit potentials large in size, prolonged and polyphasic

36. Inv:
 Nerve Conduction Test:
◦ Demyelinating Conditions – Slower velocity
◦ Helps localise site of traumatic nerve injury
◦ Repetitive nerve stimulation:
 Increase in size of motor unit potentials – Infantile
botulism
 Decremental response - Myasthenia Gravis
• Muscle Biopsy:
immunohistochemical staining and electron microscopy
– The method of choice for differentiating myopathies and
muscular dystrophies
– more invasive
– If biopsy shows specific abnormalites, could be an
essential part of the diagnostic evaluation in the newborn to
guide subsequent DNA molecular diagnostic studies

37.  Nerve Biopsy: Sural nerve
◦ Demyelination
◦ Multifocal endoneurial edema, Mononuclear
infiltrates – CIDP
◦ Metabolic products
 Tensilon Test:
◦ Edrophonium 0.15mg/kg sc in neonates,
response in 10 mins
◦ 0.2mg/kg iv in infants, response in 1 min
 Serum Acetylcholine receptor Protein Antibody
 Stool – Clostridium botulinum

38. Inv:
 CSF examination:
◦ Increased protein (Albumino-cytological
Dissociation) – GBS, Congenital hypomyelinating
neuropathy
 ECG:
◦ For associated Cardiomyopathy
◦ Acid maltase deficiency: Short PR, High QRS in
all leads
 Chest X-Ray:
◦ Pneumonia
◦ CHF: Acid maltase deficiency, Carnitine
deficiency

39. Investigations - CNS causes of
Hypotonia:
 CT Scan of head/MRI:
◦ Intraventricular/parenchymal hemorrhage
◦ CNS malformations
◦ Ischemic changes
 EEG: Epileptiform activities
 Chromosome analysis: Trisomy 21- Down’s,
Chromosome 15 translocation – Prader Willi
 X-Ray/MRI of Spine
 OTHERS-
◦ TFT
◦ TORCH
◦ Investigations for liver, renal involvement
Look
for
Sepsis
Looks
Like
Sepsis
without
Sepsis

40. Investigations in cases where a central
cause for hypotonia is suspected
Investigations of peripheral
hypotonia
 Serum electrolytes, including
ca,phosphate, serum ALP, venous
blood gas, TFT
 Plasma copper/ ceruloplasmin assay
(as screening test for Menkes
syndrome)
 Chromosomal analysis (trisomy),
testing for Prader-Willi
syndrome(15q11–13)
 Plasma amino acids and urine organic
acids, Urine mucopolysaccharide
screen (GAG)
 Molecular/biochemical diagnosis of
pro-collagen disorders
 Very long chain fatty acids
 Medical genetics opinion
 Ophthalmology opinion
 Brain imaging (CT/MRI)
 Creatinine kinase
 Lactate
 EMG /NCS/repetitive nerve
stimulation test
 M uscle biopsy (histology,
immunohistochemistry, electron
microscopy, respiratory chain
enzyme analysis)
 Genetic testing (SMN gene
deletion present in 95% of cases
of spinal muscular atrophy type 1,
myotonic dystrophy, congenital
myasthenic syndromes)
 Nerve biopsy (rarely)
 Tensilon test

41. USEFUL EMG FEATURES IN PERIPHERAL HYPOTONIA
 EMG /NCS studies may distinguish between neurogenic,
myopathic and myasthenic aetiologies for hypotonia
 Neurogenic – large amplitude action potentials, reduced
interference pattern, increased internal instability
 Myopathic – small amplitude action potentials with increased
interference pattern
 Myotonic – increased insertional activity
 Myasthenic – abnormal repetitive and single fibre studies

42. Diagnostic Yield
 Method of Diagnosis % Successfully
 Diagnosed
 History and Physical Examination (Step 1) 50%
◦ Family history, Pregnancy and delivery
◦ Clinical and neurologic examination
 Imaging Study (CT or MRI/MRS) (Step 2) 13%
 Clinical Genetic Evaluation (Step 3) 9%
 Genetic Testing (Step 4) 6%
◦ Karyotype, FISH, CGH
 Biochemical Evaluation (Step 5) 6%
◦ Amino acids, organic acids, peroxisomes,
◦ carnitine, CDG test
 Neuromuscular Testing (Step 6) 6%
◦ CK, EMG, NCV, DNA for SMA and CMD, muscle biopsy
 Follow-up Testing 7%
◦ Some tests repeated/Further tests
Adapted from Paro-Panjan D, Neubauer D. Congenital hypotonia: is there an algorithm? J
Child Neurol. 2004;19:439–44

43. Management:
 Most have no cure and have a progressive
course
 Aim:
◦ Provide Life support: Intubation and mechanical
ventilation, Feeding support
◦ Prevent and relieve contractures- Physiotherapy,
Casts, Surgical management
◦ Prevent and treat Infections (Pneumonia)

44. Principles of management
 Physiotherapy - stretches aimed at prevention of
contractures
 Occupational therapy - appliances, improvement of
posture and function, facilitating activities of daily
living
 Prevention and correction of scoliosis
 Evaluation and treatment of associated cardiac
dysfunction
 Respiratory support - assessment of requirement for
invasive or non-invasive ventilation and/or
tracheostomy

45. Cont… management.
 Feeding - nasogastric feeding, caloric
supplementation,gastrostomy
 Management of gastro-oesophageal reflux -
medical or fundoplication
 Orthopaedic intervention in setting of established
or evolving joint contractures
 Encouragement of overall development and
stimulation of learning
 Prevention (influenza and pneumococcal
vaccination) and prompt treatment of respiratory
infections

46. Mx-
 Specific Treatment of Cause:
◦ Gabapentin, Riluzole, Caspase inhibitors in SMA
◦ Prednisolone for CIDP, Inflammatory Myopathies
◦ High Protein diet in Pompe’s
◦ L-carnitine replacement in carnitine deficiency
 Genetic Counseling
 Psychological support, Counselling of
parents

47. Recent developments
 Recent advances in genetics have uncovered new
conditions causing hypotonia and weakness such
as congenital myasthenic syndromes and spinal
muscular atrophy variants
 Advances in immunohistochemistry, electron
microscopy and genetics have led to a more
specific diagnosis of myopathies
 Some of these advances have allowed for specific
therapeutic interventions, e.g. use of
acetylcholinesterase inhibitors in some congenital
myasthenic syndromes

48. Neurology Chapter of IAP
Common causes of floppy infant
Cerebral Palsy
Many hypotonic children due to causes in central
nervous system are mentally retarded.
In atonic or hypotonic cerebral palsy, reflexes are
brisk in spite of generalized flaccidity.
Floppy infant due to cerebral causes is associated
with lethargy, poor feeding, and lack of alertness, poor
Moro’s reflex, and seizures during the neonatal
period.

49. Neurology Chapter of IAP
Werdnig Hoffman disease
It is characterized by marked hypotonia, sluggish fetal
movement, and fasciculation of tongue.
The child is alert.
Feeding behaviour and cry are poor.
Deep tendon reflexes are absent.
Muscle biopsy shows neurogenic type of atrophy or
that the muscle spindles are atrophied in groups.
Disease is inherited as an autosomal may be
available. Death occurs by 2-4 years of age.

50. Neurology Chapter of IAP
Myasthenia gravis
Occurs in about 12 percent of the babies born to mothers wih MG.
Characterized by marked hypotonia, pooling of oral secretions, poor
feeding, feeble cry and generalized muscle weakness appearing within 2-3
days after the birth. Baby is alert.
Facial weakness manifests by mask-like facies, open mouth and staring
look. External opthalmoplegia and ptosis are rare. Deep tendon reflexes
are normal.
The prognosis is substantiated by improvement in the muscle functions
following intramuscular injection of edrophonium chloride 1 mg or
neostigmine methyl sulfate 0.1 mg. the condition lasts for 3 to 4 weeks. The
child is treated with neostigmine methyl sulphate 0.1 to 0.5 mg IM 10
minutes before each feel for 1 or 2 days followed by neostigmine bromide, 1
to 4 mg orally half an hour before each feed.

51. Neurology Chapter of IAP
Congenital myopathies
These are rare inherited disorders resulting in a
benign congenital hypotonia, with generally good
outlook for normal life span.
Nemaline myopathy is the most common variant.
Other disorders of this group include the central core
disease, myotubular myopathy and congenital fiber
type disproportion.

52. Neurology Chapter of IAP
Others
In polyneuritis there is symmetrical weakness of the limbs
with sensory changes.
The diagnosis of Pompe’s disease is suspected when the
child has macroglossia, cardiomegaly and generalized
hypotonia.
Babies with prader-willi syndrome are mentally retarded and
obese; deep tendon reflexes are diminished. Diabetes
mellitus occurs later in life. Testes may be undescended.
Ehlers-danlos syndrome is characterized by hyperelasticity
of the skin, hyperflexibility of joints and extreme, fragility of
skin. Wound healing is delayed and there are freely
movable subcutaneous nodules. In cutis laxa, the child has
loose skin hanging in baggy folds.

53. references
 Nelson Text Book of Pediatrics 18th Edition
 Essential Pediatrics- OP Ghai 6th Edition
 The Floppy Infant : Evaluation of Hypotonia-Pediatrics in
Review 2009;30;e66 Dawn E. Peredo and Mark C. Hannibal
 The floppy infant: contribution of genetic and metabolic
disorders- Asuri N. Prasada,*, Chitra Prasad- Received 4
October 2002; received in revised form 29 January 2003;
accepted 19 March 2003
 IAP Neurology
 Evaluation of the floppy infant Vasantha Gowda ,Jeremy
Parr, Sandeep Jayawant Neurology Symposium
 From Volpe J: Neurology of the Newborn, 4th ed.
Philadelphia, WB Saunders, 2001, p 645