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Flashcards in Demyelination and Dementia Deck (60)
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1

what is demyelination

preferential damage to the myelin sheath with relative preservation of axons

2

what is the role of myelination

Locally confining neuronal depolarisation
Protecting axons
Forming nodes of Ranvier (precipitate rapid saltatory conduction)

3

what cell myelinates

oligodendrocytes

4

what does myelin damage cause

disrupts neuronal conduction

5

what are the acute causes of demyelination

-MS
-acute disseminates encephalomyelitis
-acute haemorrhagic leukoencephalitis

6

what are the secondary causes of demyelination

viral
-progressive mulitofcal leukoencephalopathy
metabolic insults
-central pontine myelinosis
toxic
-CO, organic solvents, cyanide

7

what is the epidemology of MS

1/1000
F:M 2:1
peak incidence 20-30yrs
association with latitude

8

what is MS

auto immune demyelinating disorder characterised by distinct episodes of neurological deficits, separated in time and which correspond to spatially separated foci of neurological injury

9

what is needed for a clinical diagnosis of MS

Two distinct neurological defects occurring at different times
A neurological defect implicating one neuro‐anatomical site, and a MRI appreciated defect at another neuro‐anatomical site
Multiple distinct (usually white matter) CNS lesions on MRI

Also supportive
Visual evoked potentials (evidence of slowed conduction)
IgG oligoclonal bands in CSF

10

what is seen on MRI in MS

areas of hyperintensity - plaques

11

what are the clinical features of MS

presentation typically with a focal neurological deficit
-optic neuritis (unilateral vision loss painful)
-spinal cord lesions (motor/ sensory deficit in trunk and limbs , spasticity, bladder dysfunction)
-brain stem lesions (CN nerve signs, ataxia, nystagmus, internuclear ophthalmoplegia)

acute/ insidious onset
relapsing and remitting / progressive

12

what type of matter does MS principally affect

white matter (axons)
cut surface of brain shows plaques, surface (grey) is normal

13

what do MS plaques look like

well circumscribed, well demarcated, irregular shaped, glassy
non anatomical and non symmetrical distribution

14

where in CNS typically gets plaques in MS

adjacent to lateral ventricles
corpus callosum
optic nerves and chiasm
brainstem
ascending and descending tracts
cerebellum
spinal cord

15

what is the histology of an active MS plaque

perivascular inflammatory cells
recruitment of microglia
ongoing demyelination

are yellow/ brown with ill defined edge

16

what is the histology of inactive plaques

gliosis
little remaining myelinating axons
oligodendrocytes and axons both reduced in numbers

grey/ brown well demarcated lesions, typically around lateral ventricles

17

what are shadow plaques in MS

reflects a degree of myelination

18

what are the risk factors for MS

lattitude
vit D deficiency
viral trigger? (EBV)
genetics- familial, HLA DRB1

19

what is the immune pathogenesis of MS

t cells
- TH1 cells – IFN‐g activating macrophages
-TH17 cells – recruiting and activating damaging leukocytes
- lymphocytic infiltration

humeral factors
-oligoclonal IgG bands on CSF

20

why is MS classed as an immune mediated disease

Lymphocytic infiltration in histology
Oligoclonal IgG bands in CSF
Genetic linkage to HLA DRB1

21

what are the degenerative diseases of the cerebral cortex

alzheimers disease
pick disease
CJD (prion disease)

22

what are the main degenerative diseases of the basal ganglia and brain stem

parkinsons, huntingtons

23

what is a degenerative diseases of the spinocerebellar

spinocerebellar ataxias

24

what are the degenerative diseases of the motor neurones

MND

25

what is the pathology of degenerative diseases

simple neuronal atrophy and subsequent gliosis

26

what is dementia

an acquired and persistent generalised disturbance of higher mental functions in an otherwise fully alert person

27

where do neurodegenerative diseases typically affect

functionally related neuronal groups

28

is dementia part of the normal ageing process

no

29

what are the primary dementias

alzheimers
lewy body
picks disease (fronto-temporal dementia)
huntingtons

30

what are the secondary dementias

other disorders that give rise to dementia:
-multi infarct (vascular)
-infection (HIV/syphilis)
-trauma
-metabolic

drugs and toxins (alcohol)
vit B12 def
paraneoplastic syndromes
intracranial SOL
chronic hydrocephalus