Glossary in Congenital Malformations
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#Encephalocele: Herniated protrusion of brain substance through a
congenital or traumatic opening of the skull. Congenital encephalocele, like
anencephaly, is usually associated with hypoplastic lungs and often with other
internal anomalies. About 80-90% are occipital encephalocele. The next common is
parietal encephalocele. Basal and frontoethmoidal encephaloceles are rare.
#Ependymal canal in basal
frontal area: during development, the ventricles extends into
the olfactory bulb. As development proceeds, the olfactory rescess close up.
Residual ependymal canals corresponding to the residual olfactory recess can be
seen in the anterior ventral frontal areas. They are surrounded by a layer of
supependymal primitive neuroepithelial cells. They should not be mistaken as
malformation.
#Ethmocephaly: this is morphologically closely related to
cyclopia, but neither the eyes nor the orbits are fused. The nose is absent or
represented by a proboscis. The forehead is narrow and there is no metopic
suture. The nasal bones, maxillae, nasal septum and turinates are missing; the
lacrimal and palatine bones are united. The olfactory nerves and olfactory lobes
are not developed, but rudiments may be found. The optic nerve originates singly
but may be forked at the dura. The forebrain is represented by an elongated thin
vesicle that leaves the mesencephalon uncovered.
#Exencephaly: Lemire et al., retained the term "exencephaly"
for embryos or experimental animal models where it describes protrusion of the
brain prior to its degeneration". Rarely seen in human due to the rapid
necrosis of brain tissue exposed to amniotic fluid, leading to anencephaly.
Exencephaly is now being demonstrated antenatally in human by ultrasound.
#Ectomesodermal syndromes: a consortium of syndromes characterized by a
combination of malformation of the CNS, tumor of the CNS, systemic neoplastic
and non-neoplastic manifestations. The blood vessels, eyes and skin are most
frequently involved. They are often familial and autosomal dominant.
#Epidermal nevus syndrome
(linear sebaceous nevus syndrome of Jadasshon):
This is an ectomesodermal syndrome. Cerebral malformations include
hemimacrocephaly, hemigegalencephaly, ventriculomegly, cerebellar agenesis,
leptomeningeal hemangioma, hamartoma, arachnoid cyst overlying dysgenetic
cortex, porencephaly, heteretopias, agyria with dilated ventricle, optic nerve
hypoplasia, neuronal migration defect. There is also an increased incidence of
astrocytoma. Skin lesion include pigmented skin lesions, vascular skin lesions,
scalp defects, skeletal anomalies. There is also basal cell carcinoma,
syringocystadenoma papilliferum, and squamous cell carcinoma.
NeuroLearn NeuroHelp Malformations General Syndromes For Comment: KarMing-Fung@ouhsc.edu