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NSCI 6112: Neuroscience > Myelin Disorders > Flashcards

Myelin Disorders Flashcards

1
Q

Demyelinating Disease is a category of neurologic disease in which destruction of what is the predominant pathologic process?

A

myelin

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2
Q

Where is myelin in the CNS?

A

white matter (tracts of myelinated axons)

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3
Q

Where is myelin in the PNS?

A

peripheral nerves and nerve roots

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4
Q

What is a main cause of demyelinating disease?

A

autoimmunity

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5
Q

There are two main types of demyelinating diseases that occur within the CNS/PNS. What are they?

A

Monophasic vs. Chronic

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6
Q

Acute disseminated encephalomyelitis (ADEM) is a rare kind of inflammation that affects the brain and spinal cord, usually in children. Is ADEM a part of the CNS or PNS? Is it Monophasic or Chronic?

A

CNS; Monophasic

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7
Q

Guillain-Barre syndrome is a rare disorder in which your body’s immune system attacks your nerves. Weakness and tingling in your extremities are usually the first symptoms. These sensations can quickly spread, eventually paralyzing your whole body. Is GB syndrome a part of the CNS or PNS? Is it Monophasic or Chronic?

A

PNS; Monophasic

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8
Q

In MS, resulting nerve damage disrupts communication between the brain and the body. Multiple sclerosis causes many different symptoms, including vision loss, pain, fatigue, and impaired coordination. Is MS a part of the CNS or PNS? Is it Monophasic or Chronic?

A

CNS; Chronic

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9
Q

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a neurological disorder – a condition that targets your body’s nerves. Symptoms aren’t the same for everyone, but you may be tired and have areas of numbness and pain. It can slow your reflexes and make your arms and legs feel weak. Is CIDP a part of the CNS or PNS? Is it Monophasic or Chronic?

A

PNS; Chronic

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10
Q

Demyelination impedes what?

A

saltatory conduction

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11
Q

Demyelination slows or blocks what?

A

signal transmission

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12
Q

Conduction Speed depends on 2 constants which are?

A
  1. Length

2. Time

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13
Q

Length Constant is how far an electrical impulse can travel along an axon without requiring what?

A

active regeneration by ion channels

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14
Q

Length Constant is determined by membrane ____

A

resistance

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15
Q

Time Constant is how quickly the membrane potential changes in response to what?

A

electrical impulse

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16
Q

Time Constant is determined by membrane _______ > resistance

A

capacitance

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17
Q

Resistance is the _____ of the cell membrane to ions. Increased resistance = less _____.

A

Leakiness; leaky

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18
Q

Capacitance is the amount of _____ stored in the cell membrane, which is the cations/anions lined up along the cell membrane. The closer together they are, the more strongly attracted they are to each other = ____ capacitance

A

charge; higher

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19
Q

In autoimmunity, the immune system attacks against self-______

A

antigens

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20
Q

______ breakdown is a fundamental pathologic process in neurologic autoimmune diseases

A

barrier

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21
Q

The CNS’s barrier is the _____, while the PNS’s is the ______.

A

BBB: Blood Brain Barrier
BNB: Blood Nerve Barrier

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22
Q

The BBB is composed of what kind of junctions?

A

Tight

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23
Q

Besides tight junctions, the BBB also is composed of what?

A
  1. Astrocyte end-feel

2. Pericytes

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24
Q

The BNB is composed of what 3 layers?

A
  1. Endoneurium
  2. Perineurium
  3. Epineurium
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25
Q

To reach myelin, the immune system must gain access to which layer of the BNB?

A

The endoneurium

Endoneurial inflammatory infiltrate is a hallmark pathologic finding

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26
Q

The endoneurium surrounds what?

A

the myelinated nerve fiber

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27
Q

The perineurium surrounds what?

A

fascicles (bundle of fibers)

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28
Q

The epineurium surrounds what?

A

the nerve (bundle of fascicles)

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29
Q

The BNB is composed of tight junction-forming _____ within the endoneurium

A

microvessels

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30
Q

The PNS is a ____ environment for myelin regeneration

A

supportive

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31
Q

The CNS is a ____ environment for myelin regeneration

A

prohibitive

32
Q

Schwann Cells are to the _____ as Oligodendrocytes are to the ____

A

PNS; CNS

33
Q

Different cell types means that there are different ____

A

antigens

34
Q

GB Syndrome’s main process of attacking the body is via molecular ____

A

mimicry

35
Q

In GBS, first there is exposure to a pathogen with a component that resembles a _____ cell component.

Next, the immune system sees this as an _____ and creates a defense against it, including antibodies and activated ___cells.

Third, the antibodies later mistake the ____ cells as foreign, even though they are not, and attack them.

This causes ________

A

Schwann

antigen; T

Schwann

Demyelination

36
Q

Acute diarrheal illness commonly linked to GBS is known as

A

Campylobacter jejuni

37
Q

Access to the breakdown of the BNB in GB Syndrome can help to identify if there is what hallmark sign?

A

endoneurial inflammatory infiltrate

38
Q

In GBS, there is _____ demyelination

A

segmental

39
Q

GBS is often preceded by a _____ or ___ infection, which may be mild.

A

respiratory; GI

40
Q

Common subacute (days-weeks) characteristics of these disease mechanisms include infectious or autoimmune ______

A

demyelinating

41
Q

What could antecedent diarrheal illness indicate in a patient suspects of GBS?

A

exposure to Schwann cell-mimicking pathogen

42
Q

An important indicator of GBS is _____ weakness, which may be sub-acutely worsening pain/tingling then weakness in the distal ____ extremities

A

ascending; lower

43
Q

How does ascending weakness occur in GBS?

A
  1. Demyelination causes a conduction block
  2. BNB becomes deficient distally
  3. Subacute presentation due to segmental demyelination and immune-mediated process
44
Q

A major indicator of GBS besides ascending weakness is _____, where muscles do not respond to stimuli. Hyporeflexia also can occur.

A

Areflexia

45
Q

GBS classic clinical presentation can also include cranial nerve deficits, especially CN ___, autonomic _____ and respiratory _____ which can lead to weakness of the respiratory muscles known as restrictive lung disease.

A

VII (7)
dysregulation
failure

46
Q

Supportive care is key for treating GBS, which includes blood pressure monitoring and _____, if necessary

A

intubation

47
Q

MS is defined by the presence of multiple “____” (sclerosis) of the ____ nervous system

A

scars; central

48
Q

MS scars develop during _____ attacks over time

A

episodic

49
Q

In MS, there is disruption in the _____ and __cells are targeted against the CNS’s myelin component

A

BBB; T

50
Q

____ form “glial scars” in damaged after acute attacks known as “MS plaques”

A

astrocytes

51
Q

Chronic plaques are visible with MRI, frequently _____ or juxtacortical

A

periventricular

52
Q

What MRI contrast agent does NOT cross the BBB?

A

Gadolinium

53
Q

Ataxia and dysmetria are _____ deficits (uncoordinated movments)

A

cerebellar

54
Q

What is opthlamoplegia?

A

paralysis or weakness in the eye muscles caused by damage to the medial longitudinal fasciculus; ptosis

55
Q

Inflammation of the optic nerve is known as

A

optic neuritis

56
Q

Why is optic neuritis common with a CNS disease such as MS?

A

because the autoimmune disorder causes the body to attack the myelin sheath surrounding the optic nerve, which leads to swelling and damage

57
Q

The CNS normally _____ reflexes via inhibitory modulation. If the CNS is damaged however, _____ can occur

A

dampens; hyperreflexia

58
Q

What is the main population of MS?

A

young women

59
Q

What is the onset/progression of MS?

A

subacute onset and progression (days)

60
Q

In MS, neurologic deficits localize to multiple parts of the CNS, such as the brain, ____ nerve, brainstem, ____ cord and the _____.

A

optic
spinal
cerebellum

61
Q

MS classically presents with __reflexia

A

hyper

62
Q

MS tends to follow a replapsing/remitting or “____” pattern

A

episodic

63
Q

For acute attacks of MS, what is the immunotherapy treatment?

A

steroids

64
Q

For chronic attacks of MS, what is the immunotherapy treatment?

A

disease modifying drugs

65
Q

What is the prognosis of MS?

A

rarely fatal

chronic cumulative disability can occur, may be severe but most patients do NOT experience substantial disability

66
Q

Which system is better at myelin regeneration, the PNS or the CNS?

A

PNS

67
Q

___ deficits are more likely to recover than deficits from ___ attacks because of the myelin regeneration process in the PNS vs. CNS

A

GBS; MS

68
Q

Decreased _____ and increased ____ leads to ____ length constant and ____ time constant, which leads to an overall drop in ____ speed (length/time)

A 
resistance
capacitance
decreased
increased
conduction
69
Q

How does myelin affect resistance & capacitance?

A

Increases resistance and decreases capacitance

70
Q

Insulation by myelination ____ dissipation of ions across membranes, which is why myelin increases the resistance

A

decreases

71
Q

Myelin ___ the amount of charge stored by membranes by increasing the separation b/w cations and anions, which is why myelin decreases the capacitance

A

decreases

72
Q

Demyelination causes the length constant to ____ and the time constant to ____

A

decrease

increase

73
Q

Demyelination decreases the length constant by ____ the charge dissipation across the membrane

A

increasing

74
Q

Demyelination increases the time constant by changing the membrane potential, making it ____ to respond to sodium channel activation

A

slower

75
Q

Demyelination causes a slower conduction velocity because the length constant ____ and the time constant ___ (length/time)

A

decreases, increases

76
Q

If you see contrast enhancement within an MS lesion on an MRI, what does that tell you?

A

Contrast enhancement indicates BBB breakdown, which is evidence of an acute MS exacerbation

NSCI 6112: Neuroscience (10 decks)

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