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Flashcards in Demyelination and dementia Deck (60):
1

What is demyelination?

Preferential damage to the myelin sheath
Relative preservation of the axons

2

What is the function of oligodendrocytes?

Locally confining neuronal depolarisation
Protecting axons
Forming nodes of ranvier

3

What are examples of primary demyelinating disorders?

MS
Acute disseminated encephalomyelitis
Acute haemorrhagic leukoencephalitis

4

What are examples of secondary demyelinating disorders?

Viral: PML
Metabolic: central pontine myelinolysis
Toxic: CO, organic solvents, cyanide

5

What is MS?

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

6

What is required for the clinical diagnosis of MS?

Two distinct neurological deficits occurring at different times
A neurological deficit implicating one neuro-anatomical site and a MRI appreciated deficit at another neuro-anatomical site
Multiple distinct CNS lesions on MRI

7

What are tests that can be run in MS to support the diagnosis?

Visual evoked potentials; evidence of slowed conduction
IgG oligoclonal bands in CSF

8

What are the clinical features of MS?

Optic neuritis
Spinal cord lesions; motor or sensory deficit in trunk and limbs, spasticity, bladder dysfunction
Brain stem lesion: CN sign, ataxia, nystagmus, INO

9

Whatare the different types of MS?

Acute or insidious
Relapsing and remitting

10

What does MS look like morphologically?

White matter disease
Cut surface shows plaques

11

What are plaques in MS?

Well circumscribed, well demarcated
Irregular shaped areas
Glassy, translucent appearance
Vary from small to large
Non-anatomical distribution

12

What are frequently affected locations in MS?

Adjacent to lateral ventricles
Corpus callosum
Optic nerves and chiasm
Brainstem
Ascending and descending fibre tracts
Cerebellum
Spinal cord

13

What will active plaques show?

Perivascular inflammatory cells
Microglia
Ongoing demyelination

14

What will inactive plaques show?

Gliosis
Little remaining myelinated axons
Oligodendrocytes and axons reduced in number

15

Where are acute lesions commonly found?

Surrounding white matter

16

Where are chronic lesions commonly found?

Around lateral ventricles

17

What are the environmental factors of MS?

Assoc with latitude
Relationship with vit D deficiency
EBV viral trigger

18

What are the genetic risk factors for MS?

HLA DRB1

19

Why is MS classified as an immune mediated disease?

Lymphocytic infiltration in histology
Oligoclonal IgG bands in CSF
Genetic linkage to HLA DRb1

20

What are degenerative diseases of the cerebral cortex?

Alzheimer's
Pick Disease
CJD

21

What are degenerative diseases of the basal ganglia and brain stem?

PD
Progressive supranuclear palsy
Multiple system atrophy
Huntington's disease

22

What are degenerative diseases of the spinocerebellar system?

Friedreich Ataxia

23

What are degenerative diseases of the motor neurons?

MND

24

What is the pathogenesis of degenerative diseases?

Simple neuronal atrophy and subsequent gliosis

25

What is dementia?

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

26

What are the primary dementias?

Alzheimer's
Lewy body
Pick's disease
Huntington's

27

What are the secondary dementias?

Vascular dementia
Infection; HIV, syphilis
Tauma, metabolic
Alcohol
B1
Paraneoplastic syndromes
SOL
Chronic hydrocephalus

28

What is the commonest dementia?

Alzheimer's

29

What genes are implicated in alzheimer's?

Amyloid precursor protein (APP) - chromosome 21
Presenilin 1 - chromosome 14
Presenilin 2 - chromosome 1

30

What are the clinical features of alzheimer's disease?

Insidious impairment of higher intellectual function with alterations in mood and behaviour
Later: progressive disorientation, memory loss and aphasia

31

What can be seen macroscopically in alzheimer's disease?

Cortical atrophy in frontal, temporal and parietal lobes
Widening of sulci and narrowing of gyri
Hydrocephalus ex vacuo

32

What areas of the brain tend to be spared in alzheimer's disease?

Occipital
Brainstem
Cererbellum

33

What are the microscopic features of alzheimer's disease?

Extensive neuronal loss with assoc astrocyte proliferation
Neurofibrillary tangles
Neuritic plaques

34

What are neurofibrillary tangles?

TAU protein, assoc with microtubules
Intracytoplasmotic

35

Where can neurofibrillary tangles be found?

Hippocampus and temporal lobes

36

Are neurofibrilary tangles a good indicator of disease severity?

No

37

What are neuritic plaques?

A-beta amyloid plaques

38

Where can neuritic plaques be found?

Surrounding astrocytes and microglia

39

How is A-beta amyloid produced?

Cleavage of amyloid precursor protein

40

What will amyloid stain with?

Congo red

41

What is the impact of amyloid angiopathy in the brain?

Serum leaking
Oedema
Local hypoxia

42

What is lewy body dementia?

Progressive dementia along with hallucinations and fluctuating levels of attention and cognition
PARKINSONISM

43

Is memory affected at the start of lewy body dementia?

No

44

What are the classical features of parkinson's?

Loss of facial expression
Stooping
Shuffling
Bradykinesia
Stiffness
Pill rolling tumour

45

What can cause parkinsonism?

Idiopatic PD
Lewy body dementia
Drugs; phenothiazines
Trauma; dementia pugilistica
Multi-system atrophy
Progressive supranuclear palsy
Cortio-basal degeneration

46

What is the pathogenesis of parkinson's?

Loss of dopaminergic neurons in the substantia nigra

47

What is seen macroscopically in lewy body dementia?

Pallor in substantia nigra where the pigmented dopaminergic neurones should run

48

What is seen microscopically in lewy-body dementia?

Loss of pigmented neurones
Reactive gliosis
Microglial accumulation
Aggregates of alpha-synuclein and ubiquitin

49

What are the classical clinical features of huntington's disease?

Emotional
Cognitive
Motor disturbance; chorea

50

What is the inheritance of huntington's disease?

Chromosome 4
CAG repeats
Shows genetic anticipation

51

What is seen macroscopically in huntington's disease?

Atrophy of striatum
Frontal and parietal atrophy occurs later

52

What is seen microscopically in huntington's disease?

Simple neuronal atrophy of striatal neurones
Pronounced astrocytic gliosis

53

What is Pick's disease (frontotemporal dementia)?

Progressive dementia commencing in middle life characterised by changes in character and social deterioration leading onto impairment of intellect, memory and language

54

What are the symptoms of frontotemporal dementia?

Personality and behavioural change
Speech and communication problems
Changes in eating habits
Reduced attention span

55

What can be seen macroscopically in frontotemporal dementia?

Extreme atrophy of cerebral cortex in frontal and later in temporal lobes

56

What is seen microscopically in frontotemporal dementia?

Neuronal loss and gliosis
Pick's cells (swollen neurones)
Intracytoplasmic filamentous inclusions known as Pick's bodies

57

What is multi-infarct dementia?

Disorder involving a deterioration in mental function due to cumulative damage to the brain through hypoxia or anoxia as a result of multiple blood clots within the blood vessels supplying the brain

58

Who is most likely affected by vascular dementia?

Men after age of 60
Middle-aged hypertensives

59

How can alzheimer's and MID be differentiated?

Abrupt onset
Stepwise progression
History of hypertension or stroke
Evidence of stroke seen on CT or MRI

60

What is the morphological appearance of MID?

Large vessel infarcts
Atheroma of large cerebral arteries
Lacunar infarcts; related to longstanding hypertension and arteriosclerosis of small vessels