Floppy infant syndrome
Dr. Kalpana Malla
MD Pediatrics
Manipal Teaching Hospital
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Floppy infant syndrome
Causes
1.CNS-
Perinatal asphyxia, kernicterus, CP(Atonic)
ICH, Down syndrome ,IEM
2.Spinal cord lesions –
Anterior horn cell Ds- Werdnig hoffman spinal
muscular atrophy, poliomyelitis

Causes
3.Myoneural junction –
myasthenia gravis, infantile botulism
4.Muscles –
muscular dystrophies, cong myotonic
dystrophies, cong myopathies, polymyositis

Causes
5.Peripheral nerves –
neuropathies
6.Others –
PEM, rickets, prader-willi syndrome,
Ehler-danlos syndrome, cretinism

Differentiating features according to site
of involvement
Site of involvement extent of weakness
Face arms legs
Central - + +
Anterior horn cell ++++ ++++
Peripheral nerve - +++ +++
Neuromuscular junction +++ +++ +++
Muscle Variable ++ +

Differentiating features according to site
of involvement
Site of involvement Proximal Vs distal weakness
Central ≥
Anterior horn cell ≥
Peripheral nerve <
Neuromuscular junction =
Muscle >

Differentiating features according to site
of involvement
Site of involvement Deep tendon R
Central N or ↑
Anterior horn cell absent
Peripheral nerve ↓↓/absent
Neuromuscular junction Normal
Muscle Decreased but +

Topics
Spinal muscular atrophy –Werdnig hoffman
disease
• Myasthenia gravis

Spinal muscular atrophies
• Degenerative diseases of motor neurons that
begin in fetal life and progress in infancy and
childhood
• AR inheritance, few AD, rare X-linked
• Incidence -1/25000
• 2nd most common NMD after DMD

Classification
• SMA type 1- Werdnig –hoffman disease (severe
infantile)
• SMA type 2 –late infantile slowly progressive
• SMA type 3 – kulenberg –welander disease-
chronic juvenile

Etiology
• Pathologic continuation of a process of
programmed cell death (Apoptosis) that is
normal in embryonic life

Clinical features
• Generalized Severe hypotonia,
• Unable to feed
• Involve tongue face and jaw muscles but extra
ocular muscles and sphincters are spared
• Head lag
• Scarf sign-elbow crosses midline
• Respiratory distress at birth, Frequent respiratory
infections,

Clinical features
Unusual postures – Flaccid posture, frog
legged position
• Movements –muscle appear flabby. Weakness,
thin muscle mass, Decreased resistance to
passive movement of limbs and range of
movement of peripheral joints is increased
• Relative immobility

Clinical features
Absent tendon reflexes
• Delayed motor milestones
• Intelligence –normal
• Heart-not involved
• 2/3rd die by 2 yrs and many in early infancy

Treatment
• No medical treatment
• Supportive –orthopedic care,physiotheray
• Counseling

Myasthenia gravis
• Immune mediated
neuromuscular blockade.
• Blocking Ab produced
against acetyl choline
receptors on postsynaptic
membrane (anti Ach
receptor Abs)-Decreased
number of available Ach
receptors

Nicotinic action of Ach
On skeletal muscles – contracts Skeletal
muscles - ↑ tone and power

MG
• Have been reported in 1st yr of life
• Rare before 10 yrs
• F :M- 5:1
• Ocular muscle first affected – ptosis B/L
• Weak voice,swallowing & chewing difficult-
aspiration of secretions & saliva
• Lack of facial expression

• Inability to blow out cheeks
• Worst cases – muscles of limbs & respiration
are affected
• DTR – usually present

Myasthenia gravis
• Types –
1.Neonatal transient MG
2. Juvenile MG
3. Congenital MG

Neonatal transient MG
• Infants of myasthenic mothers
• Placental transfer of anti Ach Receptor -Abs
C/F:
Resp distress in first few hrs of life till 3 day
Hypotonia, generalized weakness
Weak suck, weak cry,dysphagia,choking and cyanosis
Ptosis
Less spontaneous movements
Resolves in 4 weeks but may persist for months

• Temporary
• Ptosis & paralysis of extraocular muscles are
apparently uncommon in neonatal
myasthenia

Juvenile myasthenia gravis
• After 10 yrs
• Ptosis-most common clinical finding-
it increases progressively as patients
are asked to sustain an upward gaze
for 30-90 sec

P - increases progressively as patients are
asked to sustain an upward gaze for 30-90
sec

Juvenile myasthenia gravis
• Extra ocular muscle weakness
• Diplopia
• Pupillary response –normal
• Dysphagia, dysarthria, facial weakness
• Infancy-feeding difficulties, poor head control

Juvenile myasthenia gravis
• Tendon reflexes may be diminished not lost
• Rapid fatigue of muscles
• Limb weakness-proximal or same on both limbs
• Symptomatic late in the day
• If untreated- progressive –resp muscle
involvement –risk of aspiration
• Prolonged course of remissions & relapses

Congenital MG
Hereditary not related to
maternal MG
Nearly permanent disorder
without spontaneous remission
Do not experience Myasthenia
crisis

Associations
• Occasionally secondary to hypothyroidism
usually Hashimoto thyroiditis
• Rheumatoid arthritis,SLE,Diabetes mellitus
• Thymomas noted in adults is rare in children

Diagnosis
• Edrophonium (Tenslon) test is diagnostic:
0.15-0.2mg/kg IV- marked improvement in
ptosis, and other muscle weaknesspositive is
symptoms improve
• Edrophonium – anticholine esterase,action
similar to neostigmine but transient in its effects

Diagnosis
• Electromyography-more specifically diagnostic
than muscle biopsy-decremental response to
repetitive motor nerve stimuli
• Antibody testing-circulating Ach R-antibody in
serum – positive in 80% cases - most specific

Diagnosis
• Thyroid profile – 10% has associated
hyperthyroidism
• CPK-Normal
• Muscle biopsy – not required

Cholinergic crisis
• Excess dose of anti-cholinesterase during
treatment of MG produce symptoms due to
↑ conc of Ach

Nicotinic action of Ach
1. On autonomic ganglion
- CVS –sympathomimetic - ↑ BP
-GIT- parasympathomimetic – diarrhoea
- Urinary tract parasympathomimetic –
voiding of urine
2.On adrenal medulla - ↑ secretion of
adrenaline 80% & nor – adrenaline20% -
vasoconstriction - ↑ BP

Nicotinic action of Ach
3. On skeletal muscles – contracts Sk muscles -
↑ tone and power
4.On CNS - ↑ cholinergic activity -parkinsonism

Muscarinic action
1.On smooth muscles-contraction except
vascular & sphincter
- miosis ,↓ intraocular press,
- ↑lacrimation, salivary ,gastric ,intestinal
secretion ,sweating
- Bronchospasm
- Diarrhoea voiding of urine
- ↓BP, bradycardia

Treatment
• Mild cases- no treatment
• Cholinesterase-inhibiting drugs-
- pyridostigmine or alternative neostigmine
methyl sulfate - IM or Neostigmine bromide -
oral every 4-6 hrs-4-6weeks

Treatment
Immunosuppressive drugs – to reduce Ab to
acetylcholine receptors
- Prednisolone best - 4 wks then A/D dose for
6-8 months
-azathioprine,cyclosporine,cyclophophamide
have been used
Plasmapheresis ,IVIG- for refractory
cases,during myasthenia crisis

Treatment
Thymectomy –older children
• Avoid exacerbating drugs-
Aminoglycosides, Erythromycin, penicillin,
sulfonamides, fluoroquinolones beta-blockers
procainamide, quinidine, anticonvulsants
steroids, chloroquine, penicillamine

Thank you
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Medical Post [ www.themedicalpost.net ]