Chapter 18: CNS (Clinical Correlates)

Pheochromocytomas

are rare tumors involving chromaffin cells that result in excessive production and release of epinephrine and norepinephrine

Congenital megacolon [Hirschsprung disease]

results from a failure of parasympathetic ganglia to form in the wall of a part or all of the colon and rectum because the neural crest cells fail to migrate.

RET gene

Hirschsprung disease are caused by mutations in the what gene?

tyrosine kinase receptor

RET gene codes for what?

GLIAL CELL-DERIVED NEUROTROPHIC GROWTH FACTOR

The ligand for the receptor that is secreted by mesenchyme cells through which crest cells migrate.

Holoprosencephaly [HPE]

refers to a spectrum of abnormalities in which a loss of midline structures results in malformations of the brain and face.

single telencephalic vesicle [alobar HPE]

In severe cases of HPE, the lateral ventricles merge into a what?

SHH

the gene that regulates establishment of the ventral midline in the CNS

Smith-Lemli-Opitz syndrome

what does defective cholesterol biosynthesis lead to?

Smith—Lemli—Opitz

is an autosomal recessive condition due to abnormalities in 7-dehydrocholesterol reductase

Schizencephaly

is a rare disorder in which large clefts occur in the cerebral hemispheres

meningoceles

meningoenceph aloceles

meningohydroencephaloceles

Ossification defects in bones of the skull can result to what?

Exencephaly

caused by failure of the cephalic part of the neural tube to close

anencephaly

this defect occurs when the vault of the skull does not form, leaving the malformed brain exposed.

craniorachischisis

closure defect of the neural tube extends caudally into the spinal cord

polyhydramnios.

Because anencephalic fetuses lack a swallowing reflex, the last 2 months of pregnancy are characterized by what?

Hydrocephalus

is characterized by an ab normal accumulation of CSF within the ventricular system.

aqueduct of Sylvius [aqueductal stenosis]

hydrocephalus in the newborn is due to an obstruction of the what?

Microcephaly

describes a cranial vault that is smaller than normal

maternal alcohol abuse

what is the leading cause of intellectual disability

corpus callosum

is partially or completely absent without much functional disturbance.

pharyngeal hypophysis

a small portion of Rathke pouch persists in the roof of the pharynx as a what

Craniopharyngiomas

arise from remnants of Rathke pouch and cause hydrocephalus and pituitary dysfunction

Spina bifida

is a general term for NTDs affecting the spinal region

Spina bifida occulta

is a defect in the vertebral arches that is covered by skin and normally does not involve underlying neural tissue

meningocele

this type of spina bifida has only fluid-filled meninges protruding through the defect

myelomeningocele

this type of spina bifida has the neural tissue included in the sac

rachischisis

this type of spina bifida has the neural fold not elevate but remain as a flattened mass of neural tissue

Arnold-Chiari malformation

herniation of part of the cerebellum into the foramen magnum

folic acid [400 pig/day]

what is consumed to prevent spina bifida?

autism spectrum disorder [ASD]

aside from spina bifida, folic acid can also prevent what?