Education purpose

1. BY – DR NILANJANA GHOSH

2. Outlines
 Definitions and basic physiology
 Differences between central and peripheral causes of
hypotonia.
 Evaluation of hypotonia in infants.
 Management options

3. Relevant terminologies and definitions
 Tone: is the baseline resistance of muscle to stretch.
 Phasic tone: The rapid contraction in response to a
high –intensity stretch, as in tendon reflex response.
 Postural tone: It is the prolonged contraction of
antigravity muscles in response to the low- intensity
stretch of gravity.

4.  Hypotonia- reduced resistance to ta passive
movements around a joint
 Weakness is reduction in the maximum power that
can be generated
 Floppy infants exhibit poor control of movements,
delayed motor skills, alteration in postural control,
increased range of motion.
 Weak infants always have hypotonia but
hypotonic infants may not have weakness.

5. How muscle tone is maintained?
Cerebral cortex
Cerebellum
Basal ganglia
Vestibular nuclei
Cerebral cortex
Cerebellum
γ motor discharge of spinal cord
Bulbo reticular facilitatory area in
pons
Bulbo reticular area in medulla

6. γ motor discharge of spinal cord
Stretching of muscle spindle
Activation of α motor neuron
Partial contraction of muscle
How muscle tone is maintained?

7. The maintenance of normal tone requires
intact central and peripheral nervous
system. Hence hypotonia is a common
symptoms of neurological dysfunction and
occurs in diseases of the brain, spinal cord,
nerves and muscles.

8. The term- Floppy Infant
 Indicates multiple disorders with various degree of hypotonia
(axial, appendicular or both).
 Supraspinal conditions(brain, brainstem, cervical spinal junction)-
Central hypotonia
 Segmental conditions(anterior horn cell, peripheral nerve, neuromuscular
junction, muscle)-Motor unit hypotonia/peripheral hypotonia
 Vast differential diagnosis-ranging from benign condition with good prognosis to life
threatening condition incompatible with life.

9. A systematic approach to a child who
has hypotonia,paying attention to the
history and clinical examination, is the
paramount to localizing the problem to
a specific region of the nervous system.

10. Mainly two approaches
(1) Based on neuro-
anatomical localization i.e
Central or Peripheral
nervous system
involvement.
(2) To determine whether
or not the hypotonia is
associated with weakness.

11. CENTRAL HYPOTONIA PERIPHERAL HYPOTONIA
 Central causes account for 60%
to 80% of hypotonia cases
 Abnormalities of other brain
functions.
 Global developmental delay.
 Axial hypotonia>
appendicular hypotonia.
 Dysmorphic features:
microcephaly.
 Fisting of hands.
 Normal or brisk tendon
reflex.
 Scissoring on vertical
suspension.
 peripheral causes occur in 15% to
30%.
 Alert, normal cognition
 Motor delay.
 Hypotonia with profound
limbs weakness(axial
hypotonia=appendicular
hypotonia)
 Hyporeflexia or areflexia.
 Reduced or absent antigravity
movement.
 Fasciculation.
 Muscle atrophy or
pseudohypertrophy.
 Respiratory and feeding
impairment.

12. Causes of Central hypotonia
 Brain malformations :
 Chromosomal disorders- Down syndrome,
Praderwilli syndrome.
 Genetic disorders- Familial dysautonomia, Lowe
syndrome.
 Endocrine disorders- hypothyroidism
 Metabolic- rickets, renal tubular acidosis

13.  IEM- aminoaciduria, organic aciduria,
mucopolysaccharidoses,
 glycogen storage disorder, fatty acid oxidation defect
etc
 Cerebral insult- Hypoxic ischemic encephalopathy,
intracranial hemorrhage, Hypoglycemia.
 Cerebellar disorder- Joubert syndrome, Ponto-
cerebellar hypoplasia.
 Paroxysmal disorder- neonatal
adrenoleukodystrophy, Zellweger syndrome.

14. Causes of peripheral hypotonia
Anterior horn cell disorders- Spinal muscular
atrophy.
Congenital neuropathy- Hereditary motor-
sensory neuropathy, congenital hypo
myelinating neuropathy, Charcot Marie tooth
disease.
Neuromuscular junction disorders-
Transient neonatal myasthenia, congenital
myasthenic syndrome, infantile botulism,
magnesium toxicity, aminoglycoside toxicity
Myopathies- Congenital myopathy, Nemaline
myopathy, central core disease, myotubular
myopathy,
Muscular dystrophies- Walker- Warburg,
Fukuyama, muscles- eye-brain disease,merosin
positive CMD, early infantile
facioscapulohumeral dystrophy.

15. APPROACH
 Presenting complaints:
 Age of presentation
 Onset(sudden or gradual)
 Course(progressive, static or fluctuating)
 Muscles weakness distribution(proximal –myopathy or
distal –neuropathy)

16. Antenatal history
 Decreased fetal movement
 Polyhydramnios
 Drug exposure
 Breech presentation
 Prolonged labour

17. Postnatal history
 Birth asphyxia
 Weak cry
 Respiratory distress, prolonged ventilatory support
 Feeding difficulties
 Convulsion
 Honey consumption
 Joint dislocation

18.  History of consanguinity
 Family history
 Developmental history(isolated motor or motor and
cognitive)
 Anthropometry: head circumference, weight

19. Salient points in history
 Any significant family history-affected parents or
siblings,consanguinity,stillbirths,childhood deaths
 Maternal disease- myotonic dystrophy
 Pregnancy and delivery history- drug or teratogen exposure,
decreased fetal movements, abnormal presentations,
polyhydramnios/oligohydramnios, Apgar score, resuscitation requirements.
 History since delivery
 Respiratory effort
 Ability to feed
 Level of alertness
 Level of spontaneous activity
 Character of cry

20. EXAMINATION
 Dysmorphic features
 Anterior fontanel
 Eyes: cataract(Lowe syndrome)
 Eye lid drop
 Tongue fasciculation
 Genitalia hypogonadism
 Limbs examination

21. Neurologic examination
 Detailed neurologic assessment- tone, strength and
reflexes
 Assessment of tone- begin by examining posture and
movement. A floppy infant often lies with limbs
abducted and extended.

22. Evaluation of hypotonia
Observation of position at rest,
Palpation of muscles,
Passive movements
Further evaluation of
hypotonia by Amiel
Tison method and
18o degree flip
merhod.

23. Amiel-Tison method
Age
(months)
Adductor
angle
Popliteal
angle
Dorsiflexion
angle
Scarf sign
0-3 40˚-80˚ 80˚-100˚ 60˚-70˚ Elbow does not cross
midline
4-6 70˚-110˚ 90˚-120˚ 60˚-70˚ Elbow crosses
midline
7-9 110˚-140˚ 110˚-160˚ 60˚-70˚ Elbow goes beyond
axillary line
10-12 140˚-180˚ 150˚-170˚ 60˚-70˚ -----

24. 180 degree flip method
A supine infant is pulled to sit, held vertical, held in
ventral suspension and finally put in prone position,
completing 180 degree flip.
Supine- assess any preferred position, like external
rotation of lower limb indicating weakness of floppiness
on that side. Floppy baby may have frog like posture.

25. Traction response
The presence of more than minimal head lag and failure to
counter traction by flexion of the limbs in the term newborn is
abnormal and indicate hypotonia.

26.  Sitting- assess sitting ability(with or without
support),rounded or straight back etc.

27. Vertical suspension
The examiner places both the hands in the infant’s
axillae and without grasping the thorax, lifts up.
Normal response- Head erect in the mid line with
flexion at the knee.hip and ankle joints.
Hypotonic infant-
suspends vertically,
head falls forward, legs
dangle and the infant
may slip through
examiner’s hand.

28. Horizontal suspension
Baby suspended in the prone position with
the examiner’s palm underneath the chest
Normal infant- keeps the head erect,
maintains the back straight and flexes the
elbow,hip,knee and ankle joints.
Hypotonia-
infants drape
over the
examiner’s hand
legs hanging
limply

29.  Prone- place the child prone in bed and look for any
arching.

30. Deep tendon reflexes(DTRs)
 DTRs often normal/hyperactive in central conditions.
 DTRs- normal/decreased/absent in peripheral
disorders.

31. Other pertinent findings
 Decreased resistance to flexion and extension of the
extremities.
 Exaggerated hip abduction and ankle dorsiflection
 Oral-motor dysfunction
 Poor respiratory efforts
 Gastro esophageal reflux
 Note the distribution of weakness. Ex. Face is spared
versus the trunk and extremities.

32. Variable Central
injury
Central
developm
ental
Anterior
horn cell
Periphera
l nerve
NM
junction
Muscle
Strength Normal or slight
weakness
Normal or slight
weakness
weakness weakness weakness weakness
DTRs Normal/increase
d
normal decreased decreased Normal/decreas
ed
Decreased to
absent
Babinski’s sign +/- +/- absent absent
Infantile reflex persistent Persistent/absen
t
absent absent absent absent
Muscle
fasciculation
absent absent prominent absent absent absent
Muscle mass Normal/disuse
atrophy
Normal/disuse
atrophy
Prominent
atrophy(proxima
l)
Distal atrophy Normal/decreas
ed
Proximal
atrophy:
increased or
decreased
pseudo
hypertrophy
Sensation normal normal normal Increased
/decreased
normal normal
Localization of disorder producing hypotonia

33. Anterior horn cell disease versus NM
junction disorder
 Usually spares extra ocular muscles, while diseases of
the neuromuscular junction may be characterized by
ptosis and extra ocular muscles weakness.

34. Clues to central hypotonia
 Dysmorphic features : Trisomy-21,Prader-willi syndrome, DiGeorge
syndrome.
 Depressed level of consciousness or lethargy
 Abnormal eye movement or inability to track visually
 Early onset seizure.
 Apnea
 Exaggerated irregular breathing patterns ..
Joubert syndrome
 Predominant axial weakness
 Normal strength with hypotonia
 Scissoring on vertical suspension- Cerebral palsy
 Fisting of the hands
 Hyperactive or normal reflexes
 Malformation of other organs

35. Characteristics of peripheral causes of
hypotonia
 Alert infant and appropriate response to surroundings
 Normal sleep-wake patterns
 Associated with profound weakness
 Hypotonia and hyporeflexia/ areflexia
 Other features- muscle atrophy, presence of
respiratory and feeding impairment.

36. Clues to anterior horn cell disorders(Infantile
form of spinal muscular atrophy)
Hypotonia
Generalized weakness
Absent reflexes
Feeding difficulties
Fasciculation of tongue
Alert face
Profound distal weakness

37. Clues to specific diagnosis
 Hepatosplenomegaly-storage disorder, congenital
infections.
 Hepatomegaly,retinitis pigmentosa-neonatal
adrenoleukodystrophy.
 Renal cyst, high forehead, wide fontanel's- Zellweger’s
syndrome.
 Congenital cataracts,glucoma-oculocerebrorenal
syndrome.
 Abnormal odor- metabolic disorder.
 Hyperpigmentation,undescended testis- Prader willi

38. Peripheral causes
 Diagnosis mainly by history and clinical examination
 Molecular genetics-CTG repeats, deletions in SMN gene
 Nerve conduction studies and muscle biopsy(Depending
on clinical situation, may be delayed until around 6
months of age as neonatal results are difficult to interpret)
 Creatine kinase-elevated in muscular dystrophy but not
in spinal muscular atrophy or many other myopathies
 Specific DNA testing-for myotonic dystrophy and for spinal
muscular atrophy(SMN gene)
 Electrophysiological studies- shows abnormalities in
nerves , myopathies and disorders of NM junction.