Glossary in Congenital Malformations
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#Schizencephaly:
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Clinical features:
Extremely variable and correlates with the anatomical anomalies.
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Pathology:
Abnormal division, fissure, or cleft of the brain substance. The lesions may be
symmetrical. In the malformative type of schizencephaly, there is believed to be
a complete agenesis of a portion of the germinative zones and thereby the
cerebral wall at the lesion site, leaving seams of clefts. Schizncephaly, on the
other hand, can be generated by a destructive process that destroy damage the
cerebral mantle. Cases with collapsed clefts are refered to closed-lips
schizencephaly and those with wide open clefts are refered as opened-lips
schizencephaly.
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EMX2 gene:
Some sporadic cases are associated with mutations in this homeobox gene.
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Comment:
This term was first used by Yakovlev and Wadsworth. According to Fride and Rorke,
this term should no longer be used because of the hypothetical destruction of
the germinal zones. In my opinion, this term should be used as a descriptive
term without reference to the pathogenesis and reserved for cleft like lesion of
the brain that has no communication between the subarachnoid space and the
ventricles. Cavitary lesion that has communication between the subarachnoid
space and ventricles (being termed "communicating schizencephaly"),
regardness of whether the communicating channel is wide open or collapsed,
should be classified as porencephaly.
#Septo-optic
dysplasia: see de Moriser Syndrome.
#Sequence: a pattern of cascade anomalies. In some instances,
the constellation of anomalies may be explained by a single, localized
aberration in organogenesis (malformation, disruption, or deformation)leading to
secondary effects in other organs.
#Sirenomelia: (syn. Mermaid syndrome). Incidence is about 1 in
25,000 to 50,000 live birth. The severest form of caudal regression syndrome.
Sirenomelia is the only anomaly invariably associated with a single umbilical
artery. The babies are usually stillborn or die immediately after birth due to
renal agenesis and pulmonary hypoplasia.
#Spina
bifida: this is the defect of the osseous spine. Dorsal
defects are the most common.
·
Spina bifida cystica:
spina bifida with an external saccular protrusion. This term is not used any
more.
·
Spina bifida occulta:
the spinal osseous defect is limited to the posterior neural arches, laminae and
the spines. This term is not used any more.
#Status verrucus deformis: the second cortical layer makes irregular
protrusions into the molecular layer, while the external surface is smooth. Some
consider that this is a transitional stage of development. Others consider
thatis to be a true malformation and is related to polymicrogyria.
#Status verrucus simplex: innumerable uniform, semicicular protrusion at the
cortical surface. Each protrusion was formed by an outward bulge of molecular
and upper cell layers, separated from the next bulge by a sharp indentation.
This is a fixation artifact (e.g., fixing the brain in a bag of gauze).
#Subcortical
band heterotopia: see
"Heterotopic gray matter".
#Syndromes: a constellation of congenital anomalies believed
to be pathologically related, that, in contrast to a sequence, cannot be
explained on the basis of a single, localized, initiating defect or insult.
#Syringobulbia: Cavities situitated in the medulla. Slit-like
cavities usually lie in three locations: most commonly an anteriolateral slit,
usually in the lower half or two third of the medulla, running from the floor of
the 4th ventricle external to the hypoglossal nucleus; extension of the fourth
ventricle along the median raphe for a variable distance; a cavity in between
the pyramid and the inferior olive where it interrupts the emerging fibers of
the hypoglossal nerve.
#Syringomyelia/syringobulbia:
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Clinically:
Syringomyelia usually begins during the second and third decade and is slowly
progressive or the symptoms may increase at first rapidly and then more slowly.
They may cease to progress at any time. Symptoms and signs associated with
cervical syringomyelia/syringobulbia include sensory loss that spreads from the
baci of the head forwards on to the facedue to compression of the descendting
tract of the trigerminal nerve. The hypoglossal nuclei are the first cranial
nuclei to be affected and case bilateral wasting and weakness of the tongue.
Nystagmus and abnormal gaze may also be present.
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Pathology:
Tubular cavitation of the spinal cord extending over many segments. The
syringomyelic cavity is not covered by ependymal cells and is not connected with
the central canal. Communicating synringomyelia is the type that communicates
with the central canal where ependymal lining could be found. The cavity is
usually found to be largest in the cervical region and commonly extends through
the upper thoracic segments for a varying distance.
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Pathogenesis:
Congenital abnormality at the foramen magnum is common; 90% of patients with
idiopathic syringomyelia have a Chiari anormaly. The lumbosacral enlargement is
rarely involved and other mechanisms such as tumor formation may be involved.
#Sequence: a pattern of cascade anomalies. In some instances,
the constellation of anomalies may be explained by a single, localized
aberration in organogenesis (malformation, disruption, or deformation) leading
to secondary effects in other organs.
#Short-rib
polydactyly
syndrome: Chondrodysplasia and extremely bizarre
convolutional pattern of deep clefts and disorganized cerebral mantle. Histologically with excessive and precocious gyral formation
and cortical dysplasia.
#Sturge-Weber
syndrome: Also
known as encephalofacial angiomatosis or encephalotrigerminal angiomatosis.
NeuroLearn NeuroHelp Malformations General Syndromes For Comment: KarMing-Fung@ouhsc.edu