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Flashcards in 14. Other Deck (13):

What type of hypersensitivity response is MS?

Chronic inflammatory autoimmune (T4HS) demyelinating disease of CNS.


Explain how neuronal axons become demyelinated in MS.

i. T cells cross the BBB and are activated by myelin... release inflammatory cytokines (IL-1, IL-6, TNFa, INFy) that:
- vasodilate BBB vessels
- attract B cells and macrophages
- directly damage oligodendrocytes

ii. B cells produce antibodies that opsonise myelin... macrophage engulfement of oligodendrocytes

iii. Loss of myelin... plaques (scar tissue) form on axons... slows or blocks transmission of APs


Why does MS worsen over time?

Early in disease, regulatory T cells reduce inflammatory/immune attack... oligodendrocytes heal... remyelination.

Over time, decreased oligodendrocytes... irreversible damage.


What are the 4 different types of MS?

1. Relapsing-remitting (most common): periods of exacerbation when new symptoms appear, separated by periods of normal function. Overall decline as exacerbations may not fully return to baseline function.

2. Secondary progressive: start with RRMS but then progress to steady worsening of symptoms over time.

3. Primary progressive: steady worsening of symptoms over time, without periods of relapse and remission

4. Progressive-relapsing: steady worsening of symptoms, overlaid with acute relapses.


How might vision be affected in MS?

1. Demyelination of optic nerve... optic neuritis (acute, sometimes painful, reduction or loss of vision in 1 eye)

2. Demyelination of eye mov. neurones (CN III, IV and VI)...
- nystagmus
- double vision
- lateral rectus weakness


How might hearing and balance be affected in MS?

1. Demyelination of vestibulocochlear nerve...
- deafness
- unsteadiness

2. Acute brainstem demyelination...
- severe positional vertigo
- vomiting
- ataxia
- headache


What cognitive and psychological symptoms might a P with MS present with?

1. decreased auditory and visual attention
2. memory loss (increases as disease progresses)
3. depression


What sensory symptoms might a P with MS experience?

1. non-specific numbness and tingling
2. loss of thermal and pain sensation (spinothalamic tract demyelination)
3. tightness, burning, twisting and pulling sensations (cervical cord posterior column demyelination)


What motor signs and symptoms might a P with MS experience?

1. Signs and symptoms of UMN lesion:
- hypertonia, joint rigidity and hyperreflexia (spaciticity)
- muscle spasms
- up-going plantar reflexes

2. Signs and symptoms of cerebellar lesion:
- wide-based gait
- poor coordination of upper and lower extremity movements


What kind of autonomic system disturbance might a P with MS experience?

1. bladder symptoms:
- frequency and urgency
- +/- incontinence (loss of inhibition of bladder emptying reflex) OR impaired bladder emptying

2. impotence

3. loss of thermoregulation: excess sweating, pyrexia or hypothermia


What is a brain arteriovenous malformation? Which pathologies can it predispose to?

AVM = abnormal connection of arteries directly into veins, forming a nidus of tangled BVs, instead of passing via capillaries. Results in a high pressure shunt (loss of dampening effect of capillaries) which:
1. stretches and dilates vessels of nidus... compression of surrounding tissue and capillaries... tissue ischaemia
2. weakens walls of artery... aneurysm formation... rupture... subarachnoid haemorrhage


What is a prion?

Prion: naturally occuring protein with unclear function (triggers myelin repair in Schwann cells? maintains long-term memory? maintain self-renewal in bone marrow?)

Exists in 2 forms: normal and disease-causing - can act as infectious agent, responsible for various encephalopathies


How do prions cause CJD?

i. Presence of mutated prion protein (sporadic, inherited or ingested) induces conformational change in surrounding prions (chain reaction)...
ii. prions aggregate causing neuronal cell death...
iii. amyloid plaque formation and overall brain atrophy (predominantly grey matter)