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Neuroscience BB Exam 1 > Section 6 - Embryology > Flashcards

Section 6 - Embryology Flashcards

1
Q

Anencephaly (brain not formed) results from:

A

Anterior neuropore defect

Meninges and skull may also be absent; defects can extend from lamina terminalis to foramen magnum - always fatal.

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2
Q

What is an encephalocele?

A

Herniation of intracranial contents through the cranium (cranium bifidum)

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3
Q

Define meningocele.

A

Cyst structure containing meninges

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4
Q

Define meningoencephalocele.

A

Cyst structure containing meninges plus brain.

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5
Q

Define meningohydroencephalocele.

A

Cyst structure contains meninges, brain, and part of ventricular system.

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6
Q

What are dysraphic effects?

A

Congenital malformations associated with defective neurulation. Can be prevented with folic acid prior to pregnancy.

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7
Q

What is Arnold-Chiari sydrome?

A

Cerebellar herniation into foramen magnum - there are two types.

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8
Q

Chiari I malformation:

A

Congenital herniation of the cerebellar vermis through foramen magnum –> pressure on medulla and cervical spinal cord

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9
Q

Chiari II malformation (Arnold-Chiari deformity):

A

Similar defect to Chiari I, but with additional myelomeningocele (herniation of meninges, CSF, spinal cord through unclosed posterior neuropore)

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10
Q

Chiari I is associated with:

A

Syringomyelia and syringobulbia

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11
Q

What is syringomyelia?

A

cavitation of the spinal cord

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12
Q

What is syringobulbia?

A

cavitation of the medulla

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13
Q

What is exencephaly?

A

Cephalic disorder wherein the brain is located outside of the skull

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14
Q

What is meroencephaly?

A

Rare form of anencephaly characterized by malformed cranial bones and median cranial defect through which protrudes a cerebrovasculosa

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15
Q

What is microcephaly?

A

Circumference of the head is more than three standard deviations smaller than average - caused by abnormal growth of brain

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16
Q

Neural tube defects (dysraphic effect) are associated with inadequate ______; treat with ______

A 
Folic acid (shoutout to Dr. Forney)
Closure of spinal defects and ventricular shunts
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17
Q

What is myeloschisis?

A

Defect in the closure of the posterior neuropore - involves failure of vertebral arch to form completely to cover spina cord (spina bifida)

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18
Q

Define spina bifida occulta.

A

Neuroectoderm exposed on the lower back from incomplete posterior neuropore fusion; results in a tuft of hair and the skin covering the defect.

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19
Q

Define spinal bifida aperta.

A

Incomplete neuropore fusion, and there is an inadequate closure over the vertebral defect (patent aperture)

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20
Q

Define spina bifida cystica.

A

Meningocele: herniation of the meninges and CSF through the unclosed posterior neuropore
Meningomyelocele: herniation of meninges, CSF, and spinal cord (usually cauda equina) through unclose posterior neuropore.

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21
Q

What are some complications of spinal bifida cystica, with meningomyelocele?

A

May be unable to move lower limbs, perceive pain sensation. Often also have hydrocephalus, Arnold-Chiari malformation.

22
Q

What is septooptic dysplasia (or de Morsier syndrome)?

A

Dysgenesis of diencephalon, hypoplasia of optic n. and hypothalamus-pituitary, and midline structural defects

23
Q

de Morsier syndrome (septic optic dysplasia) causes:

A

Congenital blindness, hypothyroidism, diabetes insipidus, hypoadrenocorticism

24
Q

What is myelodysplasia?

A

Malformation of part of the neural tube formed by secondary neurulation (typically covered by skin); site may have unusual pigmentation, hair, telangiectases (large superficial capillaries), or prominent dimple

25
What is tethered cord syndrome?
Conus medullaris and filum terminale are abnormally fixed to defective vertebral column, leading to weakness, sensory loss, and asymmetric growth of legs and feel, and bowel/bladder control issues
26
What is caudal regression syndrome?
Infants born to mothers with diabetes mellitus - affects development of embryonic structures of the caudal region (like spinal cord)
27
The acronym TORCH is good for remembering causes of defects from infectious diseases during gestation. What does it stand for?
``` Toxoplasmosis Other agents (syphilis) Rubella Cytomegalovirus Herpes simplex virus (also, HIV) ```
28
What are some defects associated with infectious diseases during gestation?
Cataracts, retinitis/blindness, deafness, cerebral calcifications, cerebral atrophy, and microcephaly
29
What is a spinal dermal sinus?
Appears as a dimple of sinus close to midline with opening of 1-2 mm; potential pathway for infection (meningitis or abscess)
30
What is heterotopia?
Disrupted migration of neurons from the ventricular surface of the cortex. Band heterotopia seen in severe cases - gray and white matter in banding pattern.
31
List some characteristics of heterotopia.
- Cell layers of cortex thickened - Large ventricles - Abnormal gyri and sulci patterns - Can associate with epilepsy and development disorders
32
What is schizencephaly?
Condition with unilateral or bilateral clefts in cerebral hemispheres. Results from profound failure of cell migration or lack of blood during development.
33
Closed lip schizencephaly:
Thin slit in hemisphere with communication between ventricle and surface of brain
34
Open lip schizencephaly:
Large defect with substantial brain loss producing large open channels between ventricular cavity and subarachnoid space
35
What are porencephalic cysts?
Cystic lesions from tissue destruction
36
What is the Dandy-Walker Malformation?
Absence/atresia of foramina of Magendi/Luschka. Leads to hypoplasia of cerebellar vermis, cystic dilation of fourth ventricle, and often hydrocephalus; macrocephaly, ataxia, developmental delay
37
What is Joubert syndrome?
Similar to Dandy-Walker, but without cystic dilation of fourth ventricle **Absence / underdevelopment of cerebellar vermis**
38
What is lissencephaly?
Failure of gyri to form within the cerebral cortex --> smooth surface. Often have retractable epilepsy.
39
What is pachygyria?
Unusually large gyri formation.
40
What is microgyria?
Unusually small gyri
41
What is holoprosencephaly?
Prosencephalon fails to undergo cleavage; most common defect of forebrain and face - associated with abnormal Shh signaling
42
What are some environmental causes of holoprosencephaly?
Maternal diabetes, alcohol, cyclopamine (retinoic acid)
43
What are some defects association with holoprosencephaly?
- Craniofacial abnormalities (cyclopia) - Motor deficits - Feeding and swallowing problems - Endocrine issues - Seizures - Developmental delay - Mental retardation - Hypotelorism (unusally close set eyes) - Rudimentary nasal structure (probiscus)
44
Alobar holoprosencephaly:
No lobes develop; large single forebrain ventricle, thalamus poorly developed, and corpus callosum, longitudinal fissure, falx cerebri, olfactory structures missing
45
Semilobar holoprosencephaly:
Some separation of forebrain into two lobes and partial development of falx cerebri, primitive lobes and gyri and rudimentary lateral and third ventricles can be present
46
What is Hirschsprung's disease?
Congenital megacolon; excess ECM molecules present in colon due to abnormal migration of neural crest-derived cells. Neurons forming enteric ganglia fail to migrate to lower bowel --> to motor signal to move bowels
47
What is familial dysautonomia?
Aberrant development of neural crest derivatives. - Sensory symptoms: impaired pain/temp. perception - Autonomic symptoms: cardiovascular instability, GI dysfxn
48
Mutant Shh gene lead to the "triple threat":
- Loss of notochordal induction --> holoprosencephaly - Medulloblastoma - tumor at cerebellopontine angle - Basal cell carcinoma
49
What is Mobius syndrome?
Defect from developmental sequence of rhombomeres. Several developmental defects: - Aplasia of abducens and facial motor nuclei (6 and 7) - Weakness of muscles innervated by oculomotor and trochlear nerves (3 and 4) - Atrophy/weakness of tongue and mm. of mastication (12 and V3) - Skeletal defects of face/body
50
What is amblyopia?
Input from one eye dysfunction during critical period at disadvantage b/c they compete for synaptic space --> "good" eye has exclusive access and "bad" eye is ignored --> functional blindness
51
What is pontocerebellar hypoplasia?
Atrophy of pons/cerebellum --> hypotonia, poor feeding, growth retardation, profound mental retardation
52
What factors can affect myelination?
- Neurodegenerative diseases - Many amino acids/organic acid metabolism abnormalities (PKU) - Inadequate nutrition

Neuroscience BB Exam 1 (10 decks)

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