Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PBL SEM 3 > CASE 1 - spina bifida > Flashcards

CASE 1 - spina bifida Flashcards

1
Q

how does the neural tube develop?

A

neurulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

describe neurulation

A
  • notochord forms in the middle of the mesoderm — under where the primitive streak was , mesoderm cells differentiate into the notochord
  • notochord sends inductive signals to the overlying ectoderm to form a thickening in the ectoderm = neural plate
  • neural plate is widest at cranial end
  • laterally the edges thicken to form the neural folds
  • neural folds develop towards each other to eventually form the neural groove, ultimately fusing as the neural tube
  • the brain develops at the cranial end and the remainder gives rise to the spinal cord
  • at the end of the tube are the anterior + posterior neurospores which close in the middle and end of the 4th week respectively (25th and 27th day)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is vital for the closing of the anterior and posterior neurospores?

A

folic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

failure of closure of anterior neurospore = ____?

A

anencephaly — brainstem forms but the upper part of the brain doesn’t develop — not compatible with extra-uterine survival

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

failure of closure of posterior neurospore = ______?

A

spina bifida

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

after closure of the anterior neurospore, what does the head end of the neural tube form?

A

3 primary vesicles:

1) prosencephalon (forebrain)
2) mesencephalon (midbrain)
3) rhombencephalon (hindbrain)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

due to insufficient space, the tube in the cranial end is forced to bend, forming what?

A

cervical and cephalic flexures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what do the 3 primary vesicles become by the 5th week?

A

5 secondary vesicles
- telencephalon
- diencephalon
- mesencephalon
- metencephalon
- myelencephalon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what does the lumen of the neural tube become?

A

the central canal of the spinal cord and the ventricular system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what are 2 NTDs of the brain?

A
  1. anencephaly = the total or partial absence of the upper part of the brain, the bones make up the top of the skull, and the skin that would cover these parts. very severe (death). failure of closure of anterior neuropore
  2. encephalocele = an opening in the skull bones that exposes part of the brain or the tissues that covers it
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

name a NTD of the spinal cord

A

spina bifida = failure of closure of posterior neurospore

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are the types of SB?

A

> OPEN — neural tissue exposed (not covered by skin)
- spina bifida occulta
- meningocele
- myelomeningocele

> CLOSED — neural tissue not exposed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is a NTD of both the brain and spinal cord?

A

craniorachischisis — incompatible with life, entire brain and spina cord are exposed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

folic acid roles

A

= a B vitamin
- essential for a wide range of normal bodily functions including DNA synthesis/repair, cell division and neurodevelopment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

where is folate supply from at the start of embryogenesis?

A

yolk sac

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are the international recommendations of folic acid in terms of pregnancy?

A

400ug/day 3 months before pregnancy and 3 months into pregnancy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

folic acid supplements can prevent up to what % of NTDs?

A

70%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is an indicator of a serious loss of folate availability to the brain?

A

fluid accumulation due to drainage insufficiency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

when does the neural tube normally close?

A

28th day

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

SB = 1/____ globally?

A

1/500

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

describe spina bifida occulta

A
  • occulta means hidden
  • mildest and most common type
  • there is a small gap in one or more bones in the spine — many people don’t even know they have it
  • tuft of hair
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what does a tuft of hair indicate?

A

that CSF is leaking from the neural tube and stimulating hair follicles to form hairs — tells us exactly where the tube defect is

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

describe myelomeningocele

A
  • open spina bifida
  • most severe type
  • spinal canal is open along several vertebrae in the lower or middle back
  • the membranes and spinal nerves push through this opening at birth, forming a sac on the baby’s back — typically exposes tissue and nerves
  • makes baby prone to life-threatening infections and may also cause paralysis and bladder and bowel dysfunction (because the nerves that supply the bowel and bladder come from the lowest level of the spinal cord)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

describe meningocele

A
  • rare type
  • characterised by a sac of CSF bulging throguh an opening in the spine
  • no nerves affected
  • spinal cord not in fluid sac
  • babies born with it have some minor problems functioning, including those affecting the bladder and bowels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what happens do the ventricles in SB?

A

ventriculomegaly as the CSF is formed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

why does CSF go into the opening in the spine in SB?

A

due to the opening in the neural tube, there is not enough pressure for the CSF to leave the 4th ventricle so it goes down the spinal canal and protrudes out into the opening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what are risk factors for NTD?

A
  • nutritional status
  • obesity and diabetes
  • no folic acid supplementation and/or fortification during and before pregnancy
  • environmental toxicants
  • genetic predisposition among ethnic groups
  • some medications such as anti-seizure meds (eg. valproic acid) when taken during pregnancy — interfere with body’s ability to use folate and folic acid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

complications of spinal bifida

A
  • walking and mobility problems — the nerves that control the leg muscles dont work properly below the area of the defect
  • bowel and bladder problems
  • hydrocephalus (myelomeningocele) — 50%
  • shunt malfunction — shunts put in brain to treat hydrocephalus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what is chiari malformation type II?

A
  • problem in myelomeningocele
  • cerebellum and brainstem tissue extend into the foramen magnum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what is the lemon sign?

A
  • noted on antenatal imaging
  • indentation of frontal bone
  • classically seen as a sign of chiari II malformation
  • can only be seen before 24 weeks
  • due to decrease in intrapspinal pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

spina bifida treatment?

A
  • most serious types of SB cannot be cured
  • some may require catheterisation and help training to learn to manage bladder and bowel functions
  • surgery to repair spine postnatally (cannot repair nerve damage)
  • shunt to treat hydrocephalus
  • open lesion — antibiotics to treat infection
  • decompression surgery — help remove pressure on brain
  • post natal surgery within 48 hours
  • surgery in utero (weeks 23-27) = high risk, only done in 3 places in UK
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what is between the dura mater and arachnoid mater?

A

sub dural space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

what is between arachnoid mater and pia mater?

A

subarachnoid space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

what is in the subarachnoid space?

A
  • CSF
  • all cerebral arteries and veins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

what is meningitis?

A

infection of meninges

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

what is between the periosteum and meningeal layers of the dura mater?

A

dural venous sinuses — venous drainage, drain into IJV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

vascular supply of dura mater?

A

has its own vascular supply from middle meningeal artery and vein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

what do dural reflections do?

A
  • compartmentalise the cranial cavity
  • hold brain in place
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

what dural reflection houses:
a) superior and inferior sagittal sinuses
b) occipital sinus
c) anterior and posterior intercavernous sinuses

A

a) falx cerebri

b) falx cerebelli

c) diaphragma selllae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

vascular supply of arachnoid mater?

A

avascular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

what is the relationship between arachnoid mater and sulci + gyri?

A

does not extend into sulci — brides over one gyrus to the next

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

innervation of arachnoid mater?

A

no innervation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

what do arachnoid granulations do?

A

CSF diffuses through the lining of arachnoid granulations into the dural venous issues — their function is to enable the continuous drainage of the CSF from the subarachnoid into the vascular system

44
Q

what is the function of pia mater?

A

to physically separate the neural tissue from the blood vessels in the subarachnoid space

45
Q

what does each vessel that enters the brain carry with it?

A

a sleeve of pia mater — pia mater fairly adheres to the surface of the brain and spinal cord, each sulcus contains blood vessels which lie just outside the pia

46
Q

what is pia mater made of?

A

connective tissue and has many tiny blood vessels

47
Q

what is breech position?

A

positioned feet or bottom first in the uterus

48
Q

when do most babies turn to the head first position?

A

week 36

49
Q

why are babies with spina bifida more likely to be in breech position?

A

reduced leg movements — legs not strong enough to move around into correct position

50
Q

risk factors for breech position

A
  • prematurity
  • uterine abnormalities
  • maternal smoking
  • maternal diabetes
  • too much or too little amniotic fluid
  • multiple pregnancy
  • foetal malformation (eg. hydrocephalus)

many babies with myelomeningocele (severe type of SB) tend to be breech

51
Q

what is depakote?

A
  • anti-seizure medication in epileptic people >10y
  • also used in adults to prevent migraines or to treat manic episodes related to bipolar disorder
52
Q

how does depakote work?

A
  • works by increasing the amount of gamma-aminobutyric acid (GABA) in the brain
  • GABA is a chemical neurotransmitter naturally produced by the body
  • GABA is an inhibitory neurotransmitter — it attaches to a GABA receptor and decreases activity in the nervous system
  • hence by increasing this pathway, there is a calming effect, helping with feelings of anxiety, stress and fear

it is also a FOLATE ANTAGONIST

53
Q

GABA levels in people with seizure disorders, movement disorders (eg. Parkinson’s), ADHD, anxiety, panic and mood disorders?

A

levels may be lower

54
Q

how does sodium valproate interfere with folate?

A
  • it is a folate antagonist
  • it interferes with folate transport and metabolism by inhibiting glutamate formyl transferase, an enzyme mediating the pathway that produces folinic acid
55
Q

side effects of depakote?

A
  • upset stomach
  • headache
  • sleepiness/drowsiness
  • muscle weakness
  • causes suicidal thoughts in a small % of people
  • tremors
56
Q

depakote and pregnancy?

A
  • must not be on depakote while pregnant
  • must be on effective brith control while using depakote
  • it makes SB 30x more likely
  • impaired folate metabolism contributes to congenital risks, including NTDs

Valproate should not be used in female children and women of childbearing potential unless other treatments are ineffective or not tolerated — valproic pregnancy prevention program

57
Q

what is gillick competence?

A

> established in 1983
allows a child, if they past the gillick test, to medical treatment without their parents knowing or given permission
gillick test : in order to assess an under 16’s capacity to provide informed consent, they must pass this test. to pass, they must demonstrate sufficient understanding and knowledge of the treatment and the processes it involves, awareness of the benefits and risks, as well as the alternative options
if not found competent, then parental permission must be obtained

58
Q

what are the fraser guidelines?

A

> guidelines build on the gillick competency test
guidelines relate specifically to the issue of contraceptive advice for under 16s
they state a doctor can give contraceptive advice and treatment without parental consent, provided the doctor is satisfied:

1That the young person will understand the professional’s advice
2The young person cannot be persuaded to inform their parents
3The young person is likely to begin, or to continue having, sexual intercourse with or without contraceptive treatment
4That unless the young person receives contraceptive treatment, their physical or mental health (or both) are likely to suffer
5That the young person’s best interests require them to receive contraceptive advice or treatment with or without parental consent

> the guidelines have been applied more broadly to include other related treatments, including abortion

59
Q

at what age are you legally assumed capacity?

A

16

60
Q

what is bipolar disorder?

A

used to be known as manic-depression

  • a severe and enduring mental disorder in which sufferers usually experience recurrent periods of sustained depressed mood and hopelessness (major depressive episodes) and periods of abnormally elated mood with increased energy (known as manic episodes, or – when less severe – hypomanic episodes)
61
Q

what do each of the 5 secondary vesicles become?

A

telencephalon — cerebral cortex and basal nuclei (and caudate and putamen)
diencephalon — retina of the eye, thalamus, hypothalamus (and subthalamic nucleus and globus pallidus)
mesencephalon — midbrain, sup + inf colliculus (and substantia nigra)
metencephalon — pons, cerebellum
myelencephalon — medulla

62
Q

what produces all the peripheral NS?

A

neural crest cells

63
Q

what does sunken eyes indicate?

A

pressure on the oculomotor nerve

64
Q

why does hydrocephalus accompany nearly 50% of SB cases?

A

due to chiari malformation blocking CSF exit from the ventricles

65
Q

what are 4 obvious distinctions between brainstem-spinal cord development and cerebral cortex development?

A
  1. notochord does not control cerebral development
  2. genetics
    - Hox genes for brain and spinal cord
    - Emx and Otx genes for prosencephalon
  3. timing
  4. fluid system changes
66
Q

what stimulates cells to migrate?

A

CSF

67
Q

what are some causes of neurodevelopment defects?

A
  • genetic
  • metabolic/immune disorders (phenylketonuria etc)
  • environment (alcohol, tobacco, nutritional deficiencies)
  • accidents - complications of an infection
68
Q

what leads to formation of the neural plate?

A

gastrulation

69
Q

what is spina bifida detected by?

A

ultrasound

70
Q

what are essential for the patterning of the dorsoventral and anteroposterior axes?

A
  • secreted molecules called morphogens (such as Shh or BMP)
  • hemeotic genes are also required for the setting up of the AP axis
71
Q

prenatal diagnosis of NTDs?

A
  • foetal liver is the main source of a-fetoprotein (AFP) which leaks through the open neural tube defects into the amniotic fluid and then into the maternal blood
  • this abnormal increase in maternal serum AFP is best detected at weeks 16-18
  • maternal serum screening does not detect closed defects and is less sensitive in women taking sodium valproate
  • ultrasound recommended to at risk women and those with a +ve serum AFP screening
  • lemon sign
  • amniocentesis
72
Q

when can anencephaly and SB be detected?

A
  • anencephaly — from 12th week
  • SB — from 16-20 weeks
73
Q

what is a posterior fossa decompression surgery?

A

performed on adults with type 1 and 2 chiari malformations to create more space for the cerebellum and to relieve pressure on the spinal column

74
Q

what is the only type of chiari malformation that can be acquired?

A

type 1

75
Q

what are glia?

A

= the connective tissue of the nervous system, consisting of several different types of cell associated with neurons
- glia are more numerous than neurons in the brain (3:1)
- glia do not participate directly in synaptic interactions and electrical signalling

76
Q

what are some roles of glial cells in the nervous system?

A
77
Q

what are 3 types of glial cells in the mature CNS?

A
  1. astrocytes
  2. oligodendrocytes
  3. microglial cells
78
Q

describe astrocytes

A
  • physical support, repair, K+ metabolism, removal of excess neurotransmitter, maintenance of blood-brain barrier
  • star-like appearance
79
Q

describe oligodendroglia

A
  • myelinate CNS axons
  • these cells are destroyed in MS
  • predominant type of glial cells in white matter
80
Q

descirbe microglia

A
  • CNS phagocytes
  • mesodermal origin
81
Q

what does a mutation in Shh cause?

A

holoprosencephaly

82
Q

what is holoprosencephaly?

A
  • a disorder caused by the failure of the prosencephalon (embryonic forebrain) to sufficiently divide into the double lobes of the cerebral hemispheres
83
Q

what can cause microcephaly?

A

zika virus

84
Q

what is lissencephaly?

A
  • smooth brain (absence of the normal convulsions and microcephaly)
  • failure in cells migrating
85
Q

what do the alar and basal plates in the spinal cord give rise to?

A

alar plate — dorsal horn (sensory)

basal plate — ventral horn (motor)

86
Q

what is received by neurons as a signal for migration through the disabled-1 signalling pathway?

A

reelin

87
Q

what secretes reelin?

A

CR cells in marginal zone

88
Q

what stops reelin output from CR cells?

A

BDNF

89
Q

The needle in a lumbar puncture is usually inserted between the L3 and L4 (or L4 and L5) vertebrae. The spinous process of L4 is determined by a plane that transects the highest points of the iliac crests.

what is the name of this plane?

A

supracristal plane

90
Q
A
91
Q

the ectoderm sends and receives signals of what?

A

BMP4

92
Q

what is the neural plate derived from?

A

ectoderm

93
Q

what is the notochord derived from?

A

mesoderm

94
Q

what direction does the neural tube fuse in?

A

centrally, spreading outward

95
Q

on what date does the anterior neurospore close?

A

25

96
Q

what are the alar and basal plate separated by?

A

sulcus limtians

97
Q

during apical constriction, the neural plate cells change shape into what?

A

pyramidal

98
Q

what patterns the ventral neural tube?

A

Shh

99
Q

what does Shh bind to? this binding results in the activation of what? which rests in the Gli complex releasing what?

A
  • binds to patched
  • results in activation of smoothened
  • results in the Gli complex releasing Gli activator
100
Q

the highest levels of Shh cause what?

A

floor plate differentiation

101
Q

what is the name given to the condition in whcih the cerebral hemispheres are missing and instead filled with sacs of CSF?

A

hydrancephaly

102
Q

what is folate aka?

A

vitamin B9

103
Q

which type of chairi malformation involves the extension of the cerebellar tonsils into the foramen magnum, without involving the brain stem?

A

type 1

104
Q

which type of chiari malformation involves the herniation of the cerebellum and brain stem through the foramen magnum and into the spinal cord?

A

type 3

105
Q

which type of chiari malformation involves an incomplete or underdeveloped cerebellum?

A

type 4

106
Q

which type of chiari malformation involves the extension of both cerebellar and brainstem tissue into the foramen magnum?

A

type 2

107
Q

whcih type of chairi malformatuon is known as “classic CM”?

A

type 2

PBL SEM 3 (49 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions