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M2M Exam 3 wk 2 > MS vignette > Flashcards

MS vignette Flashcards

1
Q

MS stats

A

> 400,000 americans
80% of MS patients between 16-46
female to male risk: 2.4:1

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2
Q

MS outcomes if untreated:

A

50% require cane or more support within 10 yrs
30% wheelchair or bed bound
avg. lifespan decreased by 5 yrs

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3
Q

___ is the leading cause of disability in young women and 2nd of young men

A

MS

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4
Q

potential triggers for MS

A
  1. infectious agent
  2. genetic predisposition
  3. environmental factors

all lead to an abnormal immunologic response, leading to MS

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5
Q

inflammatory processes occurring early in MS leads to

A

demyelination and axonal loss

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6
Q

immuniopathogenesis

A
  1. CNS damage (demyelination, transection, neuronal loss)

2. CNS repair (remyelination)

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7
Q

immune respinse in MS invloves

A

many cells , like B cell, macrophage, neurtophil, T cells,

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8
Q

brain lesions form an

A

oval chap around veins coming off the ventricles because demyelination occurs around the veins

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9
Q

dawson’s fingers

A

the lesion orientation in an outward array around the veins of the brain

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10
Q

The open ring sign

A

Active BBB disruption
Passage of inflammatory cells in to the CNS 5–10x more frequent than relapses Predictive of relapses, but lessens in SPMS Window 2-8 wk; mean 3 wk

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11
Q

Common MS symptoms

A
  1. fatigue
  2. walking impairment
  3. spacity
  4. cognitive impairment
  5. bladder dysfunction
  6. pain
  7. mood instability
  8. sexual dysfunction
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12
Q

MS walking impairment: Gait description:

A
  1. ataxic
  2. spastic
  3. paretic
  4. foot drop
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13
Q

MS walking impairment: disabling impact:

A
  1. negatively impacts work productivity, employability and income
  2. impairs activities of daily living, like deriving
  3. significantly affects quality of life
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14
Q

Factors involved in walking impairment

A
  1. muscle weakness
  2. spasticity
  3. loss of balance
  4. sensory deficit
  5. fatigue
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15
Q

Assessing walking impairment:

A
  1. timed 35- foot walk
  2. 500 meter walk
  3. 6 minute walk
  4. assess posture
  5. assess use of a device
  6. asses overuse of joint compensating
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16
Q

MS : Evoked potentials

A
  1. Prolonged Conduction Velocity = Demyelination
  2. Can measure conduction multiple ways
    a. Visual stimulation
    b. Brainstem stimulation, auditory pathways
    c. Somatosensory system stimulation
  3. Main use is to define a lesion as “demyelinating”, or identify a “second lesion” if MRI is negative
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17
Q

Prolonged Conduction Velocity =

A

Demyelination

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18
Q

affect of lesions in the brain on:
amplitude:
duration:

A

May see slowing, decreased amplitude, prolonged duration, or even total conduction block of potential

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19
Q

demyelination produces proliferation of

A

sodium channels along the axon

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20
Q

sodium channel blockade causes

A
  1. with increased sodium entry into cell, the slowing of nerve conduction
  2. ultimately there may be a reversal of sodium calcium exchanger –> calcium influx
    - – this produces calcium mediated nerve injury
  3. sodium channel blockers phenytoin and flecainide preserves the axons in EAE
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21
Q

Drugs to help manage walking impairment

A

dalfampridine

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22
Q

dalfalmpridine indication

A

to improve walking speed in patients 
 with MS”

This is not a disease-modifying therapy”

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23
Q

dalfalmpridine mechanism

A

K+ channel blockade

enhances conduction of AP in demyelinated axons through inhibition of K+ channels

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24
Q

dalfalmpridine appropriate candidates:

A
  1. Contraindicated in patients with history of seizures or moderate to
    severe renal impairment”
  2. Monitor patients with history of multiple urinary tract infections”
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25
Q

MS is a

A

inflammatory demyelination disease

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26
Q

MS is a common CNS disease causing

A

disability and multiple neurological problems in patients

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27
Q

MS causes a decrease in

A

speed of conduction in nerves

28
Q

MS results in

A

many lesion in the CNS (brain and spine)

29
Q

Some MS treatments can also

A

increase the speed of conduction on the nerves

30
Q

Conduction of an action potential is initiated with a

A

stimulus that depolarizes the membrane of a nerve cell.

31
Q

This depolarization causes voltage-gated Na+ channels to _____.

A

open

32
Q

A threshold voltage is reached when

A

enough voltage-gated Na+ channels have opened, so that sodium and potassium currents across the cell membrane are exactly equal and opposite (Na+ is entering the cell at the same rate that K+ is leaving the cell.)

33
Q

As the depolarized membrane opens more voltage-gated Na+ channels, the balance between the sodium and potassium currents is tipped in the direction of

A

ENa and an action potential is fired.

34
Q

The maximum voltage of the action potential is reached when the, ______.
The cell then begins to repolarize as the voltage-gated _______.

A

voltage-gated Na+ channels close

K+ channels open and K+ leaves the cell

35
Q

The action potential is conducted along

A

a nerve as current (Na+ inside the cell) moves down the length of an axon from the initial action potential.

36
Q

This propagated positive charge causes

A

depolarization in a neighboring region of the membrane and an action potential is again fired.

This process repeats, propagating the action potential down the length of an axon in either direction.

37
Q

Myelin is an important component in______.

A

propagating action potentials

38
Q

Myelin increases the _______, thereby increasing ______.

A

resistance and capacitance of cell membranes

conduction speed

39
Q

Myelin wraps nerve axons, leaving only intermittent uncovered axonal regions: _____.

A

the nodes of Ranvier

40
Q

The action potential is propagated from _______, due to the ability of myelin to ______

A

node to node very quickly and without loss of current

insulate the internodal regions of the axon.

41
Q

Multiple sclerosis occurs when _______.

A

T-cells cross the blood-brain barrier and become trapped in the brain

42
Q

The T-cells recognize myelin as an _____.

A

antigen

43
Q

This recognition initiates a series of events in which

A

T-cells, B-cells, microglia and macrophages proliferate and are directed to the CNS.

44
Q

The immune response leads to

A

inflammation, demyelination and axonal degradation.

45
Q

Demyelination of axons causes inefficiency in an axon’s ability to

A

propagate signals to the rest of the body.

46
Q

Electrode studies of the effects of MS on conduction have shown that demyelination causes

A

longer conduction periods, decreased amplitudes of action potentials and/or total conduction block.

47
Q

Drugs aimed at alleviating the symptoms of MS include

A

sodium channel blockades and dalfampridine.

48
Q

Sodium channel blockades work by

A

blocking some of the sodium channels that are exposed as a result of demyelination.

49
Q

As sodium builds up, the cell’s Ca2+/Na+ exchanger ______, and____ enters the cell.

A

reverses direction

Ca2+

50
Q

Calcium buildup in the axon leads to

A

degeneration.

51
Q

Sodium channel blockades, such as Phenytoin and Flecainide have been shown to limit

A

calcium-mediated axonal degeneration.

52
Q

Normally, myelin insulates these sodium to prevent

A

excess sodium from entering the axon.

53
Q

An increase in sodium channels causes

A

sodium to buildup in the cell, as the Na+/K+ pump is not able to efficiently remove the excess sodium.

54
Q

Dalfampridine has been shown to improve the:

A

walking speed of MS patients

55
Q

Dalfampridine blocks______ in neurons, which leads to a _______.

A

K+ channels

prolonged action potential and increased conduction

56
Q

In Phase III clinical trials, Dalfampridine was shown to improve walking speed by

A

25% (compared to a 5% improvement in the placebo group).

57
Q

MS incidence pattern

A

related to migration patters

58
Q

___ is a risk for MS

A

smoking

59
Q

early on, MS is

A

asymptomatic

60
Q

if you have demyelation, speed of transmission is

A

decreased

61
Q

when speed of transmission is decreased, latency is

A

increased

62
Q

A typical action potential begins at the ______

A

axon hillock

63
Q

During the relapsing-remitting phase, the disease is characterized by

A

frequent inflammation, demyelination, axonal transection, and remyelination.

64
Q

Immunopathogenesis of MS is the result of 3 components of the disease.

A
  1. Inflammatory activity
  2. Possible remyelination or regeneration
  3. Axonal destruction
65
Q

In MS, blood brain barrier is _____.

A

leaky

M2M Exam 3 wk 2 (11 decks)

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