CNS Anomalies Softchalk Flashcards
What are neural tube defects?
Neural tube defects are congenital anomalies caused by an abnormal neurulation process. They can be open or covered with skin and are frequently associated with anomalies of vertebral arches and skull.
What is a myelomeningocele? Describe its embryological origin and main clinical presentation. How does it differ from a meningocele?
Myelomeningocele is the most common open NTD. It is a type of spina bifida in which the neural tube and its meninges protrude from the vertebral canal forming a fluid-filled sac.
Clinical Presentation: A fluid filled sac, usually lumbosacral in location. There are long term orthopedic, urologic and neurodevelopmental problems.
It is different than meningocele in that the spinal cord itself does not protrude in meningocele, only the meninges.
What is an encephalocele?
Encephaloceles are skin covered NTDs at the level of the brain in which brain tissue protrudes through the skull.
most common location is occipital
What is a Chiari anomaly? What is the most common type and how does it present clinically? What is the type associated with myelomeningocele? What is the clinical characteristic of type III?
A Chiari anomaly is when part of the cerebellum is located below the foramen magnum. Type 1 is the most common is when the cerebellar tonsils extend into the foramen magnum, without involving the brain stem. This type is often asymptomatic.
Type II is often associated with myelomeningocele.
Type III is when the cerebellum and brain stem protrude, or herniate, through the foramen magnum and into the spinal cord.
What is congenital hydrocephalus? What is the most common cause of congenital hydrocephalus?
Congenital hydrocephalus is a condition in which there is excess CSF in the ventricle system. The most common cause is congenital aqueductal stenosis, which makes it so that the CSF cannot drain into the arachnoid space.
What is Dandy Walker anomaly? What is its embryological cause and the main clinical characteristic?
Dandy Walker involves complete agenesis of the cerebellar vermis and cystic dilation of the fourth ventricle. The dominant clinical feature is hydrocephalus. It is not clear what causes it.
What is lissencephaly? What is its embryological cause and the main clinical characteristic?
Lissencephaly is caused by incomplete neuronal migration to the cerebral cortex. Its main clinical characteristic is a smoothened cerebral surface. It is a combination of pachygyria (broad, thick gyri) and agyria (lack of gyri).
What is anencephaly and what is its embryological cause?
Anencephaly (Cranioschisis) is total dysraphism of the brain, but normal formation of the spinal cord. (Dysraphism = incomplete closure of a raphe, in this case the neural tube.)
Cause = Failure of anterior neuropore to close
[These infants don’t have a functional forebrain and are unconscious. Most do not survive more than a few hours after birth}
What is spina bifida occulta? What are clinical findings suggestive for spinal bifida occulta?
Skin-covered neural tube defects. (occulta means the defect is hidden.) The defect is caused by failure of the posterior neuropore to close.
Clinical presentation: Some marker on mid-sacral skin–tuft of hair, pigmented nevus (mole), angioma (wine-colored birth mark), lipoma, or dimple.
What is a tethered cord? What are the main clinical findings suggestive of tethered cord?
Tethered spinal cord = lower end of spinal cord is attached in a lower than normal position. The filum terminale is short and thick.
Clinical presentation: Bladder/bowel dysfunction, motor or sensory abnormalities in the legs (e.g. toe walking), loss of muscle mass, and bony deformities of the feet.
What is holoprosencephaly and what is its embryological cause? What are the main clinical findings in holoprosencephaly?
Holoprosencephaly (HPS) results from incomplete separation of the cerebral hemispheres and is usually associated with facial abnormalities that can range from minor to extremely devastating.
Cause: Cells in median plane of embryonic disc are destroyed during the 3rd week
Clinical presentation: Wide range of birth defects, including facial malformations, eyes abnormally close together (hypotelorism) or fused (cyclopia), nose can be lacking, etc.
What is the embryological cause and the clinical presentation of the agenesis of corpus callosum?
Agenesis of corpus callosum = partial or complete abscence of the corpus callosum, the main neocortical commissure of the cerebral hemispheres.
Clinical presentation: Often seizures and mental deficiency. Agensis of corpus callosum is associated with more than 50 different human congenital syndromes. It could also be asymptomatic.
Type 2 Arnold-Chaira
asociated lumbar myelomeningocele, hydrocephalus
Type 3 Arnold Chairi
tonsils, cerebellum, brain stem through magnum
associated with encephalocele
MALFORMATION
Closed NTD
Spina bifida occulta
failure of posterior neuropore to close
tuft of hair, pigmented nevus, angioma, kipoma, dimple
nueral arch formation, possibly not neural tube problems
tethered cord
