approach to a floppy infant

APPROACH TO A FLOPPY
INFANT
ANIL KUMAR K M
2nd YEAR M.D STUDENT
DEPT. OF PEDIATRICS
GOA MEDICAL COLLEGE

AGENDA
• What is tone, how its maintained, anatomy and physiology, how its elicited
• Causes of hypotonia and the pathological classification
• How to differentiate causes of hypotonia based on clinical scenarios, how to come
to a definitive diagnosis and principles of management
• Briefly about the common causes of hypotonic infant with case scenarios
• Take home messages

TONE
• Tone is the resistance to stretch
• Clinicians tests 2 kinds of tone: phasic and postural
• Phasic :
• Is the rapid contraction of the muscle in response to high intensity stretch
• Tested by tendon reflex
• Postural :
• Is the prolonged contraction of antigravity muscles in response to low intensity
stretch of gravity

CONTROL OF MUSCLE TONE
CONTROL OF
MUSCLE TONE
SUPRASPINAL MOTOR UNIT

SUPRASPINAL/ SUPRASEGMENTAL
Vestibular
nuclei
Corticospinal
corticobulbar
Rubrospinal
Reticulospinal

MOTOR UNIT OR SPINAL CONTROL
OF TONE

SUPRAPRINAL
• EXCITATORY*
• INHIBITORY*
GAMMA MOTOR
NURONS ON AHC
INTRA FUSAL FIBRES IN
MUSCLE SPINDLE
STIMULATES SENSORY
ENDINGS IN
MUSCLE[Ia,Ib,II]
STIMULATES ALPHA
MOTOR NEURONS IN
AHC
ESTABLISHING THE
PROPER MUSCLE TONE
MECHANISM OF
MUSCLE TONE
*INHIBITORY
CORTICOSPINAL
CORTICORETICULAR’
DORSAL(LATERAL)RETICULOSPINA
L
*EXCITATORY
MEDIAL(VENTRAL)RETICULOSPINA
L
VESTIBULOSPINAL
SHERRINGTONS STRETCH
REFLEX( MYOTACTIC REFLEX)

ASSESSMENT OF TONE
• INSPECTION
• Observe the spontaneous posture of the child in bed
• Floppy infant – frog like position(abduction at hip and flexion at knee)
• PALPATION
• Feel the muscle
• Normal muscle rubbery
• Hypotonic muscles feel flabby and soft

• MOVEMENT AT JOINT
• Freely moving joints suggests hypotonia
• Examine tone in all 4 limbs; look for asymmetry
• In infants see for truncal tone
• RAG DOLL PHENOMENON
• Shake the limb to and fro and observe the movement at the distal joint
• If hypotonia, the ease of movement at the distal limb will be increased
• The distal limb will be wobbling around like a rag doll

TONE ASSESSMENT IN INFANTS
• The range of motion in infants can be quantified by using Amiel-Tison angles
• Pre requsites for assessing the angles:
• Infant should be calm and not crying
• Note the angles and compares with the angle norms
• Should not use excessive force
• Head should be in the midline or else can lead to assymetry

ANGLES AND THEIR NORMAL
VALUES(AMIEL-TISON)
ADDUCTOR ANGLE POPLITEAL ANGLE
0- 3 MONTHS – 40°- 80°
4- 6 MONTHS – 70 – 110
7-9 MONTHS – 100 – 140
10 – 12 MONTHS – 140 - 170
0- 3 MONTHS – 80 - 100
4- 6 MONTHS – 90 -120
7-9 MONTHS – 110-160
10 – 12 MONTHS – 150-170

ANGLES AND THEIR NORMAL
VALUES(AMIEL-TISON)
DORSIFLEXION ANGLE SCARF SIGN
0- 3 MONTHS
4- 6 MONTHS
7-9 MONTHS 60- 70
degree
10 – 12 MONTHS
0- 3 MONTHS – DOESN’T REACH MIDLINE
4 – 6 MONTHS – REACHES MIDLINE
7 – 9 MONTHS – CROSSES MIDLINE
10 – 12 MONTHS – REACHES OPP. SHOULDER

OTHER MANEUVERS
VENTRAL SUSPENSION
SHOULDER SUSPENSION
PULL TO SIT

HYPOTONIA
• Hypotonia is characterized by reduced resistance to passive range of motion
• Hypotonia is caused by lesions affecting anywhere in the nervous system- brain,
brain stem, spinal cord, peripheral nerves, neuromuscular junction and muscle.

CAUSES OF FLOPPY
INFANT BASED ON
ANATOMICAL
LOCATION OF THE
PATHOLOGY

CAUSES OF FLOPPY INFANT
PARALYTIC
• Heriditary spinomuscular dystrophy
• Congenital myopathies
• Structural myopathies
• Metabolic
• Congenital myotonic dystrophy
• Congenital muscular dystrophy
• Neuropathies
• Neonatal myasthenia
NON PARALYTIC
• CNS(hypotonic CP, birth trauma, IVH)
• Chromosomal – downs syndrome
• Metabolic – hypothy., RTA, Rickets
• Connective tissue diseases(Ehler
dandros syndrome,Marfans)
• Prader-willi syndrome
• Nutitional (PEM)
• Benign congenital hypotonia

CAUSES OF FLOPPY NEONATES
WELL NEONATE
• Spinal muscular atrophy
• Spinal cord transection
• Myasthenia gravis
• Congenital myopathy
SICK NEONATE
• IVH
• Neonatal sepsis
• Birth asphyxia
• CNS infection
• Prader willi syndrome
• Organic acidurias
• Urea cycle defects
• Peroxismal disorders
• Maternal medications(diazepam,
MgSO4)

RELEVANT POINTS IN HISTORY
• Clinical suspicion of possibility of a floppy baby arises with the following symptoms :
• Mother feels that baby is slipping from hands
• Less limb movements
• Delayed motor development
• Frequent falls

OBSTETRIC HISTORY
• Helps in identifying the cause and timing of onset
• Maternal disease as in myotonic dystrophy
• Maternal exposure to toxins or infections suggests
a central cause
• Information of fetal movements in utero, fetal presentation
• amount of amniotic fluid
• Low Apgar scores suggests floppiness from birth
• Breech delivery or abnormal positions may suggest a cervical spinal cord trauma

FAMILY HISTORY
• Any consanguinity [ autosomal recessive condn like muscular dystrophies ]
• Any affected parents or sibling
• Any stillbirths or childhood deaths in the family(metabolic or muscle disease)
• Family history of developmental delay(chromosomal abnormality)
• Family history of delayed motor milestones(congenital myopathy)

HISTORY SINCE DELIVERY
• Age at onset
• Respiratory effort
• h/o feeding difficulties(s/o neuromuscular junction disorder) worse with
repetition
• h/o repeated episodes of pneumonia

HISTORY SINCE DELIVERY
• Level of alertness, spontaneous activity
• Character of cry
• Severity of progression of the symptoms
• A term infant who is born healthy and develops floppiness after 12 to 24
hours suggests in born errors of metabolism

DIAGNOSTIC CLUES
Respiratory problems
• Spinal muscular atrophy
• Myotonic dystrophy
• Myotubular myopathy
• Nemaline myopathy
Feeding difficulties
• SMA
• Myotonic dystrophy
• Nemaline myopathy
• Myasthenia gravis(neonatal)
• Prader- willi syndrome

DEVELOPMENTAL HISTORY
• Motor delay with normal social and language development decreases the
likelihood of brain pathology
• Loss of milestones suggests neurodegenerative diseases

GENERAL EXAMINATION
• Lack of spontaneous movement
• With frog like posture
• full abduction of the legs
• arms flexed
at the elbow with hands by the side of the head
• Or arms by the side of body

GENERAL EXAMINATION
• Pectus excavatum – indicates long standing weakness of chest wall muscles
• Hip dislocation/ multiple contractures/ dislocated hips suggests
hypotonia in utero possible etiology being:
• Quality of cry
• High pitched/ unusual sounding cry – CNS pathology
• A weak cry – diaphragmatic weakness
• Fatiguable cry – congenital myasthenic syndrome

DYSMORPHIC FEATURES
• Cerebrohepatorenal syndrome( zellwegwer syndrome )
• Chromosomal aberration
• Neonatal adrenoleukodystrophy

DYSMORPHIC FEATURES
• Cerebrohepatorenal syndrome( zellwegwer syndrome )
• Chromosomal aberration ( downs syndrome )
• Neonatal adrenoleukodystrophy

CNS EXAMINATION
• Higher functions
• Normal intellectual development suggests a possible defect in motor unit
• Mental retardation is found in myopathies, muscular dystrophies , metabolic diseases,
mitochondrial myopathies, cerebral palsy and downs syndrome
• Cranial nerves
PTOSIS FACIAL WEAKNESS
Myotubular myopathy Cong myotonic dystrophy
Mitochondrial myopathy Myotubular myopathy
Myotonic dystrophy Cong muscular dystrophy
Congenital musc dystrophy
Myasthenia gravis

INVESTIGATIONS
• Rule out sepsis : CBC, (blood culture, urine culture, CSF culture and analysis )
• Measurement of serum electrolytes : calcium, magnesium
• Liver function tests
• Thyroid functions
• TORCH titres
• Karyopyte – dysmorphism
• Genetic studies – for imprinting defects and for specific mutational analysis

• CSF examination :
• Evaluation for elevation of protein concentration to rule out polyneropathies
• Nerve conduction studies :
• Median , ulnar and peroneal nerves are usually studied
• Normal study rules out an abnormality between dorsal root ganglion and distal sensory
nerve
• Depressed in disorders of depressed myelination and failure of myelination
• Less severely depressed in disorders of axons
• Anterior horn cell, NMJ, and muscle disorders usually have a normal study

• If there is multisystem involvement in : inborn errors of metabolism to be ruled out
• Presence of acidosis - plasma amino acids and urine organic acids (amino
acidopathies and organic acidemias)
• Serum lactate in disorders of carbohydrate metabolism and mitochondrial disease
• Pyruvate and ammonia in urea cycle defects
• Acylcarnitine profile in organic academia, FAO
• Very long chain fatty acids and plasmalogens (peroxismal disorders)

• CREATINE KINASE
• Highly sensitive test, is a useful indicator of muscle disease
• CK will be high in children with Duchenne Muscular Dystrophy and in congenital
muscular dystrophy
• Not elevated in diseases of anterior horn cells, peripheral nerve and
neuromuscular junctions
• But in certain muscular diseases like neonatal muscular dystrophy and
congenital myopathies it may be with in normal limits
• Normally elevated in the first 24 hours in infants born by vaginal delivery

• MUSCLE BIOPSY
• Single most definitive diagnostic procedure in the evaluation of an infant with a disorder
of motor unit
• The definition of specific diagnosis provides important information for
(1) determination of prognosis;
(2)genetic counseling; and
(3) institution of specific therapy ,if available, and appropriate supportive therapy.

CONGENITAL MYOTONIC DYSTROPHY MYASTHENIA GRAVIS

• Radiological investigations
• MRI
• To delineate structural malformations, neuronal migration defects
• Abnormal signals in basal ganglia(mitochondrial abnormalities) or brain stem defects
(Joubert syndrome)
• Deep white matter changes (Lowe s syndrome)
• Abnormalities in corpus callosum (Smith-Lemili Opitz syndrome)
• Heterotropias (congenital muscular dystrophy)
• MR spectroscopy also revealing for metabolic disease

ABSENT CORPUS CALLOSUM IN
AICARDI SYNDROME
DIFFUSE DEMYELINATION IN INFANT
WITH KRABBES DISEASE

Evolving white matter
abnormality in congenital
muscular dystrophy

• GENETIC ANALYSIS
• Recent studies available such as FISH and DNA studies like restriction fragments,
PCR, sequencing, etc help us in providing specific diagnosis
• The genetic locus of spinal muscular atrophy has been mapped to chromosome
5q, transmitted predominantly by autosomal recessive pattern
• Chr. 5 has 2 genes SMN(survival motor neuron) gene and NAIP gene
• SMN gene deletion more specific seen in 98% of cases
• Recently genes have been identified for CMD, nemaline myopathy, central core
disease, myotubular myopathy, etc

HIE/cerebral palsy
Cerebral malform
Infection
Metabolic
Toxin exposure
CT/MRI
EEG
INFECTION SCREEN
METABOLIC SCREEN
Central hypotonia
SPINE : SMA
NERVE AND NEURO MUSC
JN. : myasthenia gravis,
infantile botulism,GBS
MUSCLE : muscular
dystrophy, myotonic
dystrophy
OTHERS : tick paralysis,
benign cong hypotonia
EMG
CREATINE KINASE ASSAY
NERVE CONDUCTION
MUSCLE BIOPSY
PERIPHERAL HYPOTONIA
Turners syndrome
Downs syndrome
Prader willi syndrome
Trisomy 18, 13
Genetic studies
Karyotyping
FISH
Methylation studies

MANAGEMENT
• Most have a progressive course and treatment is mainly supportive
• AIMS :
• Provide life support : feeding support, intubation and mechanical ventilation
• Prevent and relieve contractures : physiotherapy, casts and surgical management
• Prevent and treat infections(pneumonia)

PRINCIPLES OF MX
• Physiotherapy : strtches 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 of invasive or non invasive
ventilation and / or tracheostomy

MX
• Feeding : nasogastric feeding , caloric supplementation and gastrostomy
• Management of GERD : medical or fundoplication
• Orthopedic intervention in established or evolving contractures
• Encouragement of overall devpt and stimulation of learning
• Prevention ( influenza and pneumococcal vaccination ) and prompt treatment of
respiratory infection

MX
• Specific treatment of cause :
• Gabapentin , riluzole , caspase inhibitors, valproic acid in SMA
• Prednisolone for CIDP, Inflammatory myopathies
• High protein diet in Pompe’s disease
• L- carnitine replacement in carnitine deficiency
• GENETIC COUNSELLING
• Psychological support and counselling of parents

Oromotor
stimulation
Gadgets for oromotor
stimulation
Early stimulation Jaw strengthening exercises

Splints and mobilization
techniques
Truncal exercises

CASE SCENARIO - 1
• A five-month-old infant girl was brought to her family physician with complaints that she was
unable to raise her upper body when lying prone.
• she had made no attempts to roll over, rarely moved her legs. She laughed and interacted
with those around her and became excited at the sight of food.
• She breastfed well and no feeding difficulties.
• She often squealed and seemed to respond to her name. No loss of milestones was
reported.
• She had been born at 38 weeks by spontaneous vaginal delivery with no prenatal or
postnatal concerns. At three months, she had been hospitalized for respiratory syncytial
virus-positive bronchiolitis.
• The family history was unremarkable and there was no consanguinity.

• On examination, the infant looked well, with no dysmorphic features. Height, weight and
head circumference were between the 75th and 90th percentiles.
• She had a strong cry and no fasciculations of the tongue were noted.
• Respiratory, cardiovascular and abdominal examinations were normal.
• Cranial nerves were normal, including extraocular movements. She had marked hypotonia
on horizontal and vertical suspension.
• She had a weak grasp and was unable to reach forward. Primitive reflexes were absent. Deep
tendon reflexes could not be elicited

DIAGNOSIS
• SPINOMUSCULAR ATROPHY
• POINTS IN FAVOUR:
• First, the infant’s social and communication skills were age-appropriate
• hypotonia was associated primarily with marked gross motor delay.
• unremarkable pregnancy and early postnatal course.
• Absent reflexes with decreased strength
• The absence of ptosis, early severe feeding difficulties and extraocular muscle weakness
suggests that problems in the neuromuscular junction are unlikely and increases the
likelihood of motor neuron disease

SPINOMUSCULAR ATROPHY
• The SMAs are a group of diseases characterized by a progressive loss of spinal
anterior horn cells, leading to muscular denervation, atrophy and weakness.
• It is the second most common hereditary neuromuscular disease, with a carrier
frequency of one in 50 to one in 80 and an incidence of one in 10,000 to one in
25,000.
• The most common forms of SMA are transmitted by autosomal recessive
inheritance, with the gene defect localized to the motor neuron survival gene (SMN
gene) on chromosome 5q.

SMA TYPE I
• SMA type 1, also known as Werdnig-Hoffman disease, is the acute, infantile form of the disease,
with symptoms within the first six months of life.
• Patients with SMA type 1 usually die by two years of age .
• Children with SMA type 1 normal during the first months of life, with subsequent development
of dramatic hypotonia, proximal muscle weakness and absent deep tendon reflexes.
• The disease is not associated with sensory loss or intellectual impairment.
• extraocular movements are spared and muscles of facial expression. fasciculations of the tongue
and fingers may be noted.
• With disease progression, feeding and swallowing are compromised, and death usually results
from aspiration and respiratory insufficiency.

Tongue fasciculations
ECG showing base line fasciculations arising from intercostal
muscles in SMA

• Treatment of SMA type 1 is supportive.
• Disease is generally described as rapidly progressive, the course may be quite
variable.
• Counselling, respiratory care, physiotherapy, occupational therapy and other
necessary supports should be made available.

• SMA type 2 has intermediate severity, often following a more chronic course.
Patients may be able to sit unassisted, are generally unable to stand or walk without
assistance, but may survive well into adolescence or young adulthood.
• SMA type 3, Kugelberg-Welander disease, generally manifests after 18 months of
age and follows a slower disease progression, with survival into adulthood.
• SMA type 4, adult SMA with onset >30 yrs

NEW THERAPEUTIC TARGETS AND
STRATEGIES
CATEGORY TARGETS THERAPEUTIC AGENT
SMN UPREGULATION HISTONE DEACETYLAE
INHIBITION
VALPROIC ACID, SODIUM
BUTYRATE
REDUCE METHYLATION
DEPENDENT SILENCING
ROMIDEPSIN
MODULATE SMN
TRANSLATION
TC007
STAT 5 PATHWAY PROLACTIN
NEUROPROTECTIVE
AGENTS
NMDA RECEPTOR NMDA AGONISTS
BETA 2 ADR AGONISTS EXON 7 INCLUSION ALBUTEROL, SALBUTAMOL
MYOSTATIN
ANTAGONISTS
SKELETAL MUSCLE FOLLISTATIN

CASE SCENARIO II
• HISTORY
• The patient was the second son of 4 children born to unrelated Caucasian. No previous
abortions no significant family history. The pregnancy was uneventful, but the mother recalls
very little intrauterine activity.
• Delivery was full term, with a breech presentation.
• there were no obvious abnormalities of appearance, weight (about 2700 g), or head size at
birth. However, the child failed to cry, became blue, and was kept in an incubator for three
weeks.

• He was floppy and weak and, being unable to suck, he was fed with a dropper for six
months.
• There were no spontaneous limb movements until 15 months (when he raised his
hand to bright objects). All his milestones were delayed; he did not talk before 3y,
and walked only at 4y.
• He became obese from the age of 5 years. His milk teeth were discoloured on
eruption and rapidly decayed. He is moderately retarded and from the age of seven
and is going to a special school.

• Examination.
• On examination he had the facial dysmorphism, with almond eyes and a fish
shaped mouth. His teeth were carious.
• He was very obese with brawny oedema of the legs. He had a severe
kyphoscoliosis, and diminutive hands and feet, but his proportions were normal.
His testes were not palpable and the scrotum was rudimentary. He was mentally
retarded

DIAGNOSIS
• PRADER – WILLI SYNDROME
• CLUES TO DIAGNOSIS
• Diminshed fetal movements
• Perinatal asphyxia
• Infantile hypotonia
• No spontaneous movements till 15 months
• Feeding difficulties
• Delayed milestones in all domains
• Mental retardation
• Characteristic phenotypical features for pin pointing the diagosis

CASE SCENARIO III
• A 4 month old Caucasian male presented to casualty with a 9 day history of
constipation and 6 day history of decreased feeding
• The child also appeared weak and not able to hold the head by himself
• Weak cry and was minimally interactive to surroundings
• Developmentally normal, Past history, family history uneventful
• Vital signs were normal , no dysmorphisms
• Had hypoactive bowel sounds
• Weak gag reflex, no evident ptosis
• With generalized hypotonia
• Chid was transferred to picu and required mechanical ventilation

• INFANTILE BOTULISM ( most probable )
• Points in favour
• Hypotonia with weakness
• Cranial nerve involvement
• Symptoms of constipation, lethargy and decreased feeding
• No evident ptosis
• No history of diarrhea, fever or respiratory tract infection
• No significant past history, family history , obstetric history or history of developmental
delay

DIAGNOSIS
• Myasthenia gravis
• EMG : decremental response
• Response to acetyl choline esterase inhibitors
• Anti – AChR antibodies
• Infantile botulism
• Isolation of clostridium botulinum in stool culture
• Presence of toxin in stool
• Acquired GBS
• Nerve conduction study : velocities greatly reduced
• Albumino cytological dissociation in CSF

TAKE HOME MESSAGES
• Hypotonic infants can present as a diagnostic challenge in a pediatricians clinic
• Careful history and clinical examination can lead to the diagnosis in 50% of the cases
• Blood investigations including Creatinine kinase levels, Radiological investigations, EMG, nerve
conduction studies , and specific tests including newer genetic analysis can lead us to specific
diagnosis
• Treament for most of the disease is supportive with clinical trials going on for specific
therapies for diseases like SMA
• Genetic counselling and parent education comprises an important aspect of management

REFERENCES
J.J Volpe, Neurology of the new born. 5th ed.: saunders; 2011.
Kleigman S,Sg. Nelson textbook of periatrics. first south asian edition ed.: elsevier; 2015.
Suraj G. Recent advances in pediatrics; 2011.
Veena K. PRACTICAL PEDIATRIC NEUROLOGY. 2nd ed.: arya; 2011.
Piyush G. CLINICAL METHODS IN PEDIATRICS. 3rd ed.: CBS; 2015.
Jan MM. THE HYPOTONIC INFANT CLINICAL APPROACH. Journal of pediatric neurology.
2007 november; 5.
John.B B. The evaluation of the hypotonic infant. Seminars in Pediatric neurology. 2007.

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