Glossary in Congenital Malformations

NeuroLearn NeuroHelp Malformations @ General Syndromes

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General:

#X-linked hydrocephalus:

·         Clinical features: Mental retardation (particularly failure in language development) that is disproportionately severe in reference to the hydrocephalus, moderate hydrocephalus, flexed adducted thumbs, spastic paraplegia.

·         Genetics: X-linked recessive. It is due to different mutations of the L1-CAM gene on Xq28. The abnormal cell adhesion molecules probably contribute to abnormal migration of the cells in brain stem. The same mutations can be seen in X-linked spastic paraplegia without hydrocephalus (SPG1) or so called MASA syndrome (mental retardation, aphasia, shuffling gait, adduction of the lower limbs). It is probably a variant of Bickers-Adams sybndrome.

·         CNS pathology: Absence or hypoplasia of corticospinal tract and medullary pyramids are almost invariable. Stenosis of aqueduct, agenesis of corpus callosum and septum pellucidumm, fusion of thalami, and polygyria.

#X-linked lissencephaly:

·         Genetics: The gene has been localized to Xq22.3-q23 and encodes a protein named doublecortin (DCX). This gene is related to X-linked lissencephaly and subcortical band heterotopia.

·         Clinical features: similar to other cases with classic type I lissencephaly syndrome such as Miller-Dieker syndrome.

·         Gross pathology: The spectrum varies from diffuse agyria to frontal agyria with posteria pachygyria to diffuse pachygyria. They all tend to be more severe in frontal areas (in contrast to Miller-Dieker syndrome).

·         Histology: similar, if not identical, to Miller-Dieker syndrome.

#X-linked nodular ventricular heterotopia: 

·        Nodular heterotopia occurs commonly. Heterotopic grey matter can be seen in anywhere within the brain but most the ventricular surface is the most common site. There is a female predominance. It may consist of a single nodule of gray matter at the ventricular surface or a row of nodules at the ventricular wall creating an irregular ventricular surface. They may not be well demarcated in the myelinating white matter in fetus and infants. These nodules are frequently positive for synaptophysin.

·         Bilateral periventricular nodular heterotopia may be related to a gene on Xq28. Pathologically, there are bilateral and symmetric subependymal (periventricular) heterotopia. Clinically, most patients have normal intelligence and epilepsy with multiple seizures types that may or may not be difficult to control. Asymptomatic individuals may be seen. Male patients are more severely affected but female patients are more common.

 

Syndromes and Sequences:  Head

NeuroLearn NeuroHelp Malformations General Syndromes For Comment: KarMing-Fung@ouhsc.edu