Developmental Disorders of CNS (Bonthius) Flashcards
from which germ layer are the CNS and skin derived?
ectoderm
during neurulation, what does the neural tube become? what does the neural plate become?
neural tube - CNS
neural plate - PNS and DRG
what is the difference between a meningocele and an encephalocele?
meningocele = meninges and CSF bulge through improperly closed vertebral column or skull
encephalocele = sac like protrusion of the meninges + brain through improperly closed skull
What condition results from complete failure of the telencephalon to subdivide into two halves:
A. Hemi-megalencephaly
B. Telencephaly
C. Holoprosencephaly
D. Septo-optic dysplasia
E. Fetal alcohol syndrome
C.
Holoprosencephaly is characterized by CP, seizures, and intellectual disability.
(Just for your knowledge: the term ‘mental retardation’ has finally been abolished in the new DSM-5. Hooray!)
This is a mild form of holoprosencephaly, in which an interhemispheric fissure develops but midline structures do not form (no septum pellucidum), or form abnormally (pituitary gland and optic chiasm)
septo-optic dysplasia
*seizures, endocrine and vision problems
where do neuroblasts undergo mitosis in the brain?
in the ventricular zone (often on the lateral edges)
this condition is due to interference of neuronal mitosis, and results in physical features such as indistinct philtrum, thin upper lip border, and a low nasal bridge
these are features of fetal alcohol syndrome; gross finding is microencephaly
Hemi-megalencephaly occurs when 1/2 of the brain produces too many neuron cells. This leads to what kind of symptoms and where are they localized?
cerebral paulsy on the contralateral 1/2 of the body
Which of the following statements regarding neuronal migration is FALSE?
A. The cerebral cortex is formed “inside out” with the 1st wave of cells taking up residence in the 6th layer of the cortex
B. Neurons crawl along radial glia, whose processes extend from the ventricles to the pial surface.
C. Pachygyria and polymicrogyria are both conditions that result from improper neuronal migration
D. The main MRI finding in lissencephaly is clumps of gray matter, ofteh at the lateral surface of the lateral ventricle
D. This is the main finding in cortical heterotopia. Nodules formed by neuronal cells that did not migrate lead to abnormal clusters of cells that make connections with other cells in the cortex (may cause epilepsy)
The major finding in lissencephaly is lack of gyri and sulci, resulting in a “smooth brain” appearance. Causes CP, seizures, and intellectual disability.
The patient with the MRI finding below is suffering from what condition which may result in epilepsy and motor deficits:
schizencephaly; note the clefts of gray matter replacing the typical white matter in an otherwise normally developing brain
a dynamic, actin-supported extension of a developing neurite seeking its synaptic target is known as a what?
growth cone
Which of these is NOT a cue that influences the direction of the axonal growth cone?
A. Na+ gradients
B. Long-range diffusible molecules
C. Short-range surface molecules
D. Voltage gradients
E. Growth factors
A. It is the calcium gradient that influences the axonal growth cone.
these rudiments denote white matter fibers normally destined to cross the corpus callosum in patients with agenesis of the corpus callosum, leading to widely spaced lateral ventricles.
Probst bundles
an inherited disorder characterized by the accumulation of sulfatides in cells, leading to progressive destruction of white matter throughout the nervous system; this causes deterioration of intellectual functions and motor skills
Metachromatic leukodystrophy
Which of the following is NOT part of the postnatal developoment of the human brain?
A. Increased size of neurons
B. Increased number of neurons
C. Increased number of glia
D. Production of myelin
E. Development of synapses
B.
