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A genetic disorder characterized by a severe form of
asymmetric dwarfism with growth retardation, peculiar facies, and frequent
hypoglycemia.
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Silver-Russell Dwarfism; Silver Syndrome; Silver-Russell
Syndrome.
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Rare; more than 150 cases have been described.
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Autosomal recessive. Most cases are sporadic.
No established mendelian or chromosomal basis, with new dominant mutation or
X-linked dominant inheritance possible. Gene map locus at 17q25.
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In 1985, Partington proposed an X-linked inheritance for this syndrome, but
described children with no asymmetry and a pigmentary anomaly quite
different from the café-au-lait spots. This syndrome is sometimes called
Russell-Silver X-linked or Partington syndrome, but should not be confused
with the true Partington syndrome, which is characterized by the association of mental
retardation, X-linked transmission, dystonic movements, ataxia, and
seizures.
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The two main features are low birth weight dwarfism and
lateral asymmetry.
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The first feature is extreme intrauterine growth
retardation with normal head circumference, sometimes referred as
pseudohydrocephalus. The characteristic facial features are craniofacial
disproportion, delayed fontanel closure, triangular facies, turned-down
mouth corners, and micrognathia. Asymmetry of arms and/or legs causes
hemihypertrophy and lateral asymmetry. Fifth finger clinodactyly and
syndactyly of toes are observed. The radiology findings are usually fifth
finger middle or distal phalangeal hypoplasia, ivory epiphyses, second
metacarpal pseudoepiphysis, vertebral abnormalities, absent sacrum, and
absent coccyx. Hypoglycemia at birth and even after is common. Café-au-lait spots,
precocious sexual development, and cryptorchism are frequent. Cardiac defects can be
observed. Gastrointestinal manifestations are now known to be a part of the disease
(gastroesophageal reflux, esophagitis, food aversion, and failure to thrive).
Susceptibility to malignancies is higher. Normal intelligence is the rule with some delay
in the early motor milestones because of the decreased muscle bulk and relatively large
head. The children remain thin with a lack of subcutaneous fat. Therapeutic trials with
growth hormone have not corrected the growth pattern.
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The airway must be carefully assessed
(clinical, radiographs). Search for cardiac defect (clinical, echocardiography).
Evaluate hypoglycemic risk (clinical, history, glucose level). Search for
gastroesophageal reflux (clinical, endoscopy, manometry).
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The potential for difficult direct laryngoscopy and
tracheal intubation is common because of facial malformations.
In case of difficult airway or suspicion of difficulty, it is recommended to
maintain spontaneous ventilation until the trachea is secured and lung ventilation
confirmed. A laryngeal mask airway and fiberoptic equipment must be available.
Pay special attention to the glucose
need because of the easily depleted glycogen storages and severe hypoglycemia
intraoperatively. Preoperative
fasting may be minimal or preoperative glucose infusion realized. Careful
intraoperative positioning is needed because of skeletal malformations. Regional
anesthesia is not contraindicated but can be difficult to realize as a
result of anatomical modifications and may also require intraoperative glucose
monitoring because of the suppression of adrenergic response to surgical
stress that is induced by these techniques. Rapid induction sequence is
needed in cases of gastroesophageal reflux.
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Avoid muscle relaxants ...