Characterized by postaxial polydactyly and central
nervous system malformation (encephalocele, severe hydrocephalus), large
polycystic kidneys, and liver failure (fibrosis). Other clinical features
include microcephaly, abnormality of the larynx and tongue, severe
mandibular micrognatism, obesity, and cleft lip/ palate. Associated abnormalities
include oral clefting and genital anomalies. Pulmonary hypoplasia is the
leading cause of death.
Meckel Syndrome; Gruber Syndrome; Dysencephalia
Genetic disorder characterized mainly by encephalocele,
polydactyly, and polycystic kidneys, but with a wide phenotypic variation.
Worldwide incidence of Meckel-Gruber syndrome varies from 1:13,250-140,000
live births. There is a predilection for the Finnish population, in whom the
birth incidence is 1:9000. More than 200 cases have been described in the
Autosomal recessive; a gene has been
identified on chromosome 17q21-q24.
It has been suggested that a failure of mesodermal
induction causes MKS. The induction cascades of early morphogenesis involve
numerous growth factors, homeobox genes, and paired domain genes.
Some authors consider that the minimal diagnostic
criteria for the syndrome consist of cystic dysplasia of the kidney,
fibrotic changes of the liver, and occipital encephalocele. Thus histologic
studies are needed to confirm the diagnosis. Clinical features are highly
variable among patients.
The main features are central nervous system malformations consisting
usually of occipital encephalocele (with holoprosencephaly, agenesis of
corpus callosum and/or hydrocephalus); seizures; postaxial polydactyly always involving the hand
and occasionally the feet and polycystic kidneys; other urologic anomalies include absent or hypoplastic ureters or
bladder. Often the liver shows cystic changes with duct proliferation and
fibrosis. Other anomalies include microcephaly, microphthalmia or
anophthalmia, cleft lip and/or palate, genital anomalies, lung hypoplasia,
and congenital heart disease such as atrial septal defect (ASD), ventricular septal defect (VSD),
coarctation of the aorta, and patent ductus arteriosus (PDA). Patients also present a
typical “Meckel appearance” with micrognathia, flat nose, hypertelorism, a
sloping forehead, wide mouth with full lips, low-set ears, and short neck.
A complete medical history must
be obtained. Assess the neurological system, especially for seizures and the
presence of encephalocele and raised intracranial pressure. The renal function
must be evaluated. Because of the facial anomalies, the airway must be
carefully examined. Finally, the cardiac system needs a thorough examination because
of the high incidence of congenital heart defects. An ECG and echocardiogram must
be obtained. Medications should be continued until the morning of surgery.
It is highly improbable that children
with Meckel syndrome will come to the operating room. If they do, remember
that all the main systems, such as the heart, liver, kidneys, and lungs, may
be involved, so these children can be very unstable. Also, they present many
features, such as micrognathia, short neck, and occipital encephalocele that
can render intubation difficult.
Implications are related to decreased
renal and liver function in the setting of neonatal anesthesia.