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Complete Trisomy 8 occurs in 0.8% of spontaneous
pregnancy losses. Mosaic trisomy 8 is a well-known syndrome characterized by
severe mental retardation, craniofacial dysmorphism, skeletal anomalies,
complex congenital heart defect, and kidney malformations.
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Mosaicism is less common than what is often
referred to as “full” trisomy. A mosaic exists when a person presents with
trisomic cells in their body, but in the presence of normal chromosomic
cells. The genetic error occurs during the division of cells after
fertilization. Trisomy 8 is rarely observed at birth.
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Clinically evocated; patients with trisomy 8 mosaicism
present with moderate mental retardation, multiple skeletal anomalies,
urogenital malformations, congenital heart defects, deep palmar and plantar
furrows, distinct facial dysmorphism, and agenesis of the corpus callosum.
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Clinical features involve head and face (simian
crease seizures; expressionless facies; micrognathia; prominent forehead; large
dysplastic ears; microphthalmia; strabismus; hypertelorism; corneal opacity;
cataract, heterochromia; everted lips; highly arched or cleft palate and
stretched) and skeleton (short neck; thin, elongated trunk; pectus carinatum;
camptodactyly; clinodactyly; short metacarpal and metatarsal bones; absent
or dysplastic patellae; multiple joint contractures; coxa valga; abnormal
diaphyses and epiphyses of radial, femoral, and humeral bone;
kyphoscoliosis, hemivertebrae; fusion of vertebrae; spina bifida; broad
dorsal ribs). Abdominal and pelvic organs (hydronephrosis, ureteral reflux, cryptorchidism,
malrotation or absence of gallbladder, jejunal duplication, gastric sarcoma)
and thoracic organs (cardiac septal defects and great vessel anomalies) can present
malformations. Deep palmar and plantar furrows are frequent.
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Evaluate cardiac function (clinical,
echocardiography, ECG) and renal function (echography, urea, creatinine,
electrolytes).
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Careful intraoperative positioning
should be done (vertebral anomalies, joint contractures). Direct
laryngoscopy and tracheal intubation can be difficult because of short neck
and microretrognathia. Spontaneous respiration must be maintained at all times because face-mask
fit may be difficult, and failure to intubate the trachea highly possible. The availability of
a laryngeal mask airway and/or fiberoptic equipments is highly recommended. Venous access
can be difficult because of limb anomalies. Perimedullar anesthesia is often
contraindicated or difficult because of vertebral and spine anomalies.
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Consider anesthetic drug interaction
with antiepileptic medications. Prophylactic antibiotics should be as
indicated in case of cardiac defect. Preserve spontaneous ventilation before
intubation is performed. Avoid anesthetic drugs with marked cardiovascular
effect.
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Trisomy 8p: Duplication 8p with craniofacial defects,
brevicollis with redundant skin folds, and mental retardation. High,
prominent forehead; wide face in infancy; fleshy, everted lower lip; long
and poorly defined philtrum with marked macrostomia and gingival
hypertrophy; low nasal bridge and antevertebral nostrils; hyperextensibility
of the finger joints; and hypoplastic nails. Cardiac malformations (33%
of patients) are reported. Agenesis of the corpus callosum with severe
epilepsy, spina ...