Revised Floppy Infant

8/3/2019 Revised Floppy Infant

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Floppy Infant

Fares Kokash,MD


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DefinitionDefinition Floppiness is a term

used to describebabies who havemarked muscle

hypotonia.


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The focus of this talk is primarily on the

diagnostic aspects, although we have notmentioned therapeutic aspects, these

.


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AssessmentAssessment

Perinatal risk factors:

Birth trauma Birth anoxia Deliver com lications

Low APGAR scores (tone, reflexes and respiratory effort) Onset of the hypotonia Short umbilical cord (poor fetal movement or immobility) Abnormal fetal presentation (breech)


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Clinical presentation of muscleClinical presentation of musclehypotonia and weaknesshypotonia and weakness

Posture of full abduction and externalrotation of the legs as well as a flaccidextension of the arms.

When traction is delivered to the arms,there is a prominent head lag.

The presence of a typical myopathicfacies and paucity of facial expressionare common in hypotonic infants

Low-pitched cry / progressively weaker

cry, readily distinguished from thevigorous cry of a normal infant.

Paucity of antigravity movements


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Differential DiagnosisDifferential Diagnosis: Upper Motor Neuron Causes Chromosomal

Turner's Syndrome

Down's Syndrome Prader-Willi Syndrome

Infection Sepsis Meningitis Encephalitis

Metabolic

Differential Diagnosis: Lower Motor Neuron Causes Brainstem or spine

Spinal muscular atrophy (Anterior Horn

Cell Disorder) Infection Poliomyelitis Coxsackie Virus

Neuromuscular Junction Congenital Myasthenia Gravis Myasthenic syndrome

Hypocalcemia Hyponatremia Hypermagnesemia Hypoglycemia Hypothyroidism Aminoaciduria Gangliosidoses Hepatic Encephalopathy or Reye's

Syndrome Toxin Drug Intoxication (e.g. Alcohol, Narcotic) Heavy metal poisoning Organophosphate Poisoning Anticholinergic exposure

Perinatal trauma Perinatal asphyxia (HIE)

Hemorrhage

Botulism

Neyve: -Guillain Barre Syndrome

Muscle Muscular Dystrophy Congenital Myopathy Inflammatory Myopathy

Other

Tick Paralysis Benign congenital hypotonia


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Localization of hypotonia and weaknessLocalization of hypotonia and weakness

The neurological examination directs the clinician inlocalizing the site of the lesion to the

Central (UMN)

Peripheral lower motor unit (LMN) Neuromuscular junction muscles


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UMN LMN

DTRs increased Decreased orabsent

Muscle tone increased decreased

Muscle atrophy non +

Fasciculation non +


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Clinical characteristics of muscleClinical characteristics of musclehypotonia and weaknesshypotonia and weakness

Central hypotonia

Weakness is uncommon except in the acute stages,and usually it is axial weakness

obtundation and depressed level of consciousness

Hyperreflexia


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Infants with severe CNS abnormalities develop signs of hypotonia inaddition to

impairment in level of consciousness feeding difficulties seizures apneas

a norma pos ur ng

abnormalities of ocular movements and of brain stem reflexes


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Disorders of LMN

The presence of profound weakness as well ashypo/areflexia


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neuromuscular disease

combination of weakness in the antigravity limb

muscles and hypo/areflexia together

Involvement of bulbar and occulomotor muscles


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Such a clear distinction, however, may not always bepossible and the features may overlap in conditionswhere the pathology affects both the CNS andperipheral nerve (PelizaeusMerzbacher disease,leukod stro hies

The presence of characteristic patterns of regionalweakness may favor certain etiologies


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Additional clinical clues to differential diagnosisAdditional clinical clues to differential diagnosis

A high arched palate is often noted in infants with neuromusculardisorders

the tongue may be large in storage disorders (acid maltase/Pompedisease)

the presence of tongue fasciculation suggests anterior horn cellinvolvement and denervation

Visceral enlargement (suggests storage disorders)

inverted nipples (congenital disorders of glycosylation)


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Ptosis, external ophthalmoplegia (myasthenic syndromes)

Cataracts, renal cysts, pigmentary retinopathy (peroxisomal

Lens dislocation (sulfite oxidase/molybdenum cofactor

deficiency)


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Arthrogryposis: the presence of severe weakness in early fetal

development, which immobilizes joints, resulting in contractures. Thiscan be a feature encountered in both neurogenic and myopathicdisorders.

eurogen c sor ers are assoc a e w a g er nc ence o o er

congenital anomalies

Myopathic features are less likely to be associated with other defects.


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Laboratory investigationsLaboratory investigations Appropriate and cost effective use of laboratory investigations

to establish a specific etiologic diagnosis is always desirable.

The history and physical assessment will point out the possibleetiology and the indications for relevant diagnostic tests.


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Evaluation of central CNS disorders

Brain MRI

EEG

Genetic tests

Infection screen CSF neurotransmitters


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Evaluation of motor unit disorders

DNA-based testing

Edrophonium chloride Electrodiagnosis

NCS

Repetitive stimulation

Muscle biopsy

Nerve biopsy

Serum CK


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Laboratory investigationsLaboratory investigations We suggest a systematic approach based on the tests currently

utilized in the evaluation of infants with hypotonia:

infants with pure hypotonia of central or peripheral origin


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infants with pure hypotonia of central or peripheral origin


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infants with hypotonia and multisystem features (hypotoniaplus)


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Etiological considerations Central Nervous System:1. Chromosomal disorders2. Metabolic inborn errors3. Structural CNS malformations

1. congenital malformations (lissencephaly, holoprosencephaly)

2. acquired disorders (birth trauma, hypoxic ischemic encephalopathy)

Periphral Nervous System Motor neuron disorders:1. SMA

Disorders of eri heral nerves:1. Peripheral neuropathies

Disorders of the neuromuscular junction:1. Myathenia Syndromes:congenital,transient2. Infantile botulism3. Neonatal hypermagnesemia

Disorders with prominent muscle involvement:1. Congenital myopathies2. Congenital muscular dystrophies3. Metabolic myopathies4. Congenital myotonic dystrophy


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Chromosomal abnormalities


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Metabolic disorders presenting with severe hypotonia in infancyMetabolic disorders presenting with severe hypotonia in infancy


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Structural CNS malformations/encephalopathies

This category includes:

congenital malformations of the nervous system(lissencephaly, holoprosencephaly)

In the majority of instances in this group of disorders,ypo on a s rare y e so e ea ure a presen a on o er

features such as seizures, craniofacial dysmorphisms)

acquired disorders (birth trauma, hypoxic ischemic

encephalopathy) that are associated with profoundhypotonia in the neonatal period.


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Disorders with prominent muscle involvement:1. Congenital myopathies2. Congenital muscular dystrophies

3. Metabolic myopathies4. Congenital myotonic dystrophy


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Disorders affecting motor neuron and peripheral nervesDisorders affecting motor neuron and peripheral nerves


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Motor neuron disordersMotor neuron disorders Spinal muscular atrophy (WerdnigHoffman disease):

is AR disorder involving the degeneration of the anterior horn cells

hypotonic and weak, at birth or soon after poverty of spontaneous movements abnormal posture typical for a floppy infant

tongue fasciculation and absent deep tendon reflexes, mild contracturesand decreased fetal movements before birth

the weakness usually involves the bulbar and respiratory muscles,causing significant respiratory distress and infants develop pneumoniaand respiratory failure.

The diagnosis is often clinical EMG usually shows spontaneous fibrillation potentials at rest Muscle biopsy shows grouped neurogenic atrophy and evidence of

presence of hypertrophic type I myofibres (rennervation) DNA based molecular diagnostic tests


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3. Metabolic myopathies4. Congenital myotonic dystrophy


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Disorders of the neuromuscular junctionDisorders of the neuromuscular junction

The following disorders affecting the neuromuscular junction can beconsidered in the differential diagnoses of the floppy infant:

congenital myasthenic syndromes

Transient myasthenic syndrome

Hypermagnesemia of the newborn

Infantile botulism


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myasthenia syndromemyasthenia syndrome Infants presenting with the myasthenia

syndrome share several features including: hypotonia

facial diplegia

ptosis feeding difficulties

apnea

respiratory difficulties generalized weakness

progressively weakening cry


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Congenital myasthenic syndromeCongenital myasthenic syndrome


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Transient myasthenic syndrome

The disorder occurs in infants born to mothers with myastheniagravis.

The acetylcholine receptor (AchR) antibody that causes MG crossesthe placenta and exerts a blocking effect that is responsible for theinterference with neuromuscular transmission.

The symptoms caused are temporary and recovers in about 6 weeks.


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Hypermagnesemia of the newborn

Elevated magnesium levels can be encountered inthe newborn following treatment of maternal eclampsia with magnesium sulfate or

use of magnesium antacids in the newborn

Clinically: encephalopathic infant with hypotonia,depressed deep tendon reflexes, abdominaldistension due to ileus and irregularities of cardiacrhythm.

Elevated magnesium levels result in impairedneuromuscular transmission.


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Infantile botulism

usually occurs within 6 weeks to 1 year after birth

usually in situations where the infant has been fed honeycontaminated with spores of the C. botulinum.

The first s m tom is usuall consti ation. Later, listlessness, ptosis, facial weakness, decreased eye movements

and feeding difficulties, and progression to respiratory failure occur.

rapid repetitive stimulation : presence of small amplitude motorpotentials and an incremental response noted to is pathognomonic.

Stool study may also be helpful in confirmation, but the results areusually delayed.


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3. Metabolic myopathies4. Congenital myotonic dystrophy5. Endocrine myopathies


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Musculardystrophies

Congenitalmyopathies

Course progressive

non-progressive

wasting progressive

CK significantlyelevated

normal orslightly elevated


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Muscular dystrophies


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Congenital myopathiesCongenital myopathies


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ConclusionsConclusions The practicing clinician faced with the challenge of

making a diagnosis in a floppy infant needs to be aware

of the various etiologies availability of specific diagnostic tests the role of supportive investigations

in order to facilitate this process in a speedy and costeffective way.


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ConclusionsConclusions A detailed history and physical examination can help

sort the issue of isolated hypotonia, from the

hypotonic/dysmorphic infant with multisystemmanifestations.


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ConclusionsConclusions The floppy infant poses a chronic neurological problem

demanding multidisciplinary skills and support for both

diagnosis and management.


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ConclusionsConclusions Establishing a specific diagnosis in each case is

important

anticipated outcome for the condition genetic counselling (parents and family members).

Revised Floppy Infant

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