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Flashcards in Neuropathology 2 Deck (131)
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1
Q

What do oligodendrocytes do?

A

Insultate axons
Locally confine neuronal depolarisation
Protect axons
Form nodes of Ranvier

2
Q

What do nodes of ranvier precipitate?

A

Rapid saltatory conduction

3
Q

What does damage to oligodendrocytes do?

A

Damaged neuronal conduction

4
Q

What is demyelination?

A

Preferential damage to the myelin sheath, with relative preservation of axons

5
Q

Demyelinating disorders can be either?

A

Primary or secondary

6
Q

Name 3 primary demyelinating disorders.

A
  • Multiple Sclerosis.
  • Acute disseminated encephalomyelitis. (post-infectious AI disorder, mild, self-limiting, kids)
  • Acute haemorrhagic leukoencephalitis. (post-infectious AI disorder, rapidly fatal, adults)
7
Q

Outline 3 secondary demyelinating disorders.

A
  • Viral – progressive multifocal leukoencephalopathy (PML).
  • Metabolic – central pontine myelinosis.
  • Toxic – CO, organic solvents, cyanide.
8
Q

What is the most common demyelinating disease?

A

MS

9
Q

What is the female to male ratio in MS?

A

2:1

10
Q

What is the peak age incidence in MS?

A

20-30 years old

11
Q

What does MS have a well known association with?

A

Latitude

12
Q

What is MS defined as?

A

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

13
Q

For a clinical diagnosis of MS, what is needed?

A
  • 2 distinct neurological defects occurring at different times
  • A neurological defecting implicating one neuro-anatomical site, and a MRI-appreciated defect at another neuro-anatomical site
  • Multiple distinct (usually white matter) CNS lesions on MRI
14
Q

What also supports a diagnosis of MS?

A
  • Visual evoked potentials (evidence of slowed conduction)

* IgG oligoclonal bands in CSF

15
Q

What would be seen in the CSF of a patient with MS?

A

IgG oligoclonal bands

16
Q

Where is presentation of MS usually?

A

Within a focal neurological deficit

17
Q

Give an example of a focal neurological deficit.

A

Optic nerve lesions - optic neuritis

- unilateral visual impairment

18
Q

Onset of MS is?

A

Acute OR Insidious

19
Q

Describe the complications of a spinal cord lesion.

A
  • motor or sensory deficit in trunk and limbs.
  • spasticity.
  • bladder dysfunction
20
Q

Describe the complications of a brain stem lesion.

A
  • cranial nerve signs.
  • ataxia.
  • nystagmus.
  • internuclear ophthalmoplegia.
21
Q

Describe the course of MS.

A

Can be relapsing and remitting, later becoming progressive

22
Q

In areas corresponding to white matter, what does demyelination show up as on an MRI?

A

Hyperintense regions on T2 weighted MRI scans

23
Q

What is MS a disease of?

A

WHITE matter

24
Q

Therefore, how does the external surface of the brain appear?

A

NORMAL

25
Q

What does the cut surfaces of the brain in MS show?

A

Plaques

26
Q

Describe the appearance of plaques in MS.

A

Well circumscribed, well-demarcated.
Irregularly shaped areas.
Glassy, almost translucent appearance.
Vary from small to large lesions.

27
Q

What is the distribution of plaques in MS like?

A

Non-anatomical

28
Q

List areas which are frequently affected by plaques.

A
  • Adjacent to lateral ventricles
  • Corpus callosum
  • Optic nerves and chasm
  • Brainstem
  • Descending and ascending fibre tracts
  • Cerebellum
  • Spinal cord
29
Q

Describe the histology of active plaques.

A
  • Perivascular inflammatory cells

* Ongoing demyelination

30
Q

Describe the histology of inactive plaques.

A
  • Gliosis
  • Little remaining myelinated axons
  • Oligodendrocytes and axons reduced in numbers
31
Q

What may ‘shadow’ plaques represent?

A

A degree of RE-myelination

32
Q

What do shadow plaques demonstrate at the edge of lesions?

A

Thinned out myelin sheaths

33
Q

What do shadow plaques result in?

A

Less well defined lesions

34
Q

Macroscopically, how do active plaques appear?

A

Demyelinating plaques are yellow/brown, with an ill-defined edge which blends into surrounding white matter

35
Q

Describe the macroscopic appearance of inactive plaques.

A
  • Well-demarcated grey/brown lesions in white matter

* Classically situated around lateral ventricles

36
Q

What environmental factors may MS be associated with?

A
  • Latitude
  • Vit D deficiency - lack of sun
  • Viral trigger remains hypothesised (ie. EBV)
37
Q

What does MS have a genetic linkage to?

A

HLA DRB1

IL-2 and IL-7

38
Q

Outline how MS is an immune-mediated disease.

A
  • Lymphocytic infiltration in histology
  • Oligoclonal IgG bands in CSF
  • Genetic linkage to HLA DRB1
  • T cell factors
39
Q

What therapy reduces relapses and frequency of demyelinating disorders?

A

Anti- B cel

40
Q

Give examples of degenerate disorders affecting the cerebral cortex.

A

Alzheimer’s Disease
Pick Disease
CJD

41
Q

Give examples degenerate disorders affecting the basal ganglia and brainstem.

A

Parkinson Disease
Progressive Supranuclear Palsy
Multiple System Atrophy
Huntington Disease

42
Q

Give examples of degenerate disorders affecting spinocerbellar areas

A

Spinocerebellar ataxias (ie. Friedereich Ataxia).

43
Q

Give examples of degenerate disorders affecting motor neurones

A

MND

44
Q

What are degenerate disorders characterised by?

A

Simple neuronal atrophy, and subsequent gliosis

45
Q

What is dementia?

A

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

46
Q

What are neurodegenerative disorders characterised by?

A
  • Progressive loss of neurons.

* Typically affecting functionally related neuronal groups.

47
Q

Name the 4 primary dementias.

A
  • Alzheimer’s disease
  • Lewy body dementia
  • Pick’s disease (fronto-temporal dementia)
  • Huntington’s disease
48
Q

What are secondary dementias?

A

Disorders that give rise to dementia

49
Q

What is the most common subtype of dementia?

A

Alzheimers

50
Q

What is the 2nd most common subtype of dementia?

A

Vascular dementia

51
Q

List causes of multi-infarct (vascular) dementia.

A
Infection (HIV, syphilis)
Trauma
Metabolic
Drugs and toxins (alcohol)
Vitamin deficiencies (Vitamin B1)
Paraneoplastic syndromes
Intracranial space occupying lesions
Chronic hydrocephalus
52
Q

What is the female to male ratio of Alzheimers?

A

2:1

53
Q

Why does Alzheimers most commonly arise?

A

Usually sporadic

54
Q

What genes may be found in Alzheimers?

A
  • Amyloid precursor protein (APP)

* Presenilin 1 + 2.

55
Q

What is there an increased incidence of Alzheimers in?

A

Trisomy 21 - amyloid precursor protein

56
Q

Describe clinically, what Alzheimers is like at the beginning?

A

Insidious impairment of higher intellectual function with alterations in mood and behaviour

57
Q

What happens later in Alzheimers? What does this indicate?

A

Progressive disorientation, memory loss, aphasia

SEVERE CORTICAL DYSFUNCTION

58
Q

How does death in Alzheimers usually occur?

A

Due to secondary cause e.g pneumonia

59
Q

What happens to the size of the brain in Alzheimers?

A

DECREASES - due to cortical atrophy

60
Q

What areas of the brain are most commonly affected by atrophy in Alzheimers?

A

Frontal, temporal and parietal lobe atrophy

61
Q

What happens to sulci in Alzheimers?

A

They become wider

62
Q

What happens to gyri in Alzheimers?

A

They become more narrow

63
Q

How is the ventricular system in Alzheimers affected?

A

There is compensatory dilatation of the ventricles, and secondary hydrocephalus ex vacuo

64
Q

What areas are normal/spared in Alzheimers?

A

The occipital lobe, brainstem and cerebellum

65
Q

What are the 4 main microscopic features of Alzheimers?

A
  • Extensive neuronal loss, with associated astrocyte proliferation - simple neuronal atrophy and gliosis
  • Neurofibrillary tangles
  • Neuritic plaques
  • Amyloid angiopathy
66
Q

Where in the brain are Neurofibrillary Tangles found?

A

In the hippocampus and temporal lobe

67
Q

Are neurofibrillary tangles extra or intracytoplasmic?

A

Intracytoplasmic

68
Q

What, associated with microtubules, is seen in Alzheimers and other degenerate diseases?

A

Tau protein

69
Q

What are Aß amyloid plaques also called?

A

Neuritic plaques

70
Q

What do Aß amyloid plaques surround?

A

Astrocytes and microglia

71
Q

What is Aß amyloid the central element of?

A

Neuritic plaques

72
Q

What is Aß produced by?

A

Cleavage of amyloid precursor protein (APP)

73
Q

What is trisomy 21 associated with the early onset of?

A

Alzheimers

74
Q

What is trisomy 21 associated with?

A

Amyloid precursor protein (APP) is on chromosome 21

75
Q

What mutations are implicated in familial Alzheimers?

A
  • Point mutations in APP
  • Presenilin 1
  • Presenilin 2
76
Q

What chromosome is the gene for Presenilin i) 1 ii) 2 located on?

A

i) 14

ii) 1

77
Q

What is the commonest familial cause of Alzheimer’s? What does this do?

A

Apolipoprotein E e4 allele – dysregulates APP

78
Q

What are thought to be the main toxic lesions in Alzheimers?

A

Abeta Oligomers

79
Q

What are neuritic plaques composed of?

A

Amyloid, formed from oligomerisation of Ab oligomers

80
Q

What do Ab oligomers promote?

A

Hyper-phosphorylation and mis-localisation of TAU

81
Q

What does the mislocation of TAU appear to do?

A

Enhance the excitotoxicity affect of Abeta oligomers

82
Q

What do fibrillary tangles arise due to?

A

Abnormal organisation of the cytoskeleton; hyperphosphorylated TAU protein is insoluble in vivo

83
Q

What lesion does Alzheimers demonstrate?

A

Cerebral amyloid angiopathy

84
Q

What is the amyloid that accumulates in cerebral amyloid angiopathy in Alzheimers?

A

Ab, which accumulates in the wall of arterioles

85
Q

What colour does amyloid stain?

A

Congo red

86
Q

What is the effect of the accumulation of Ab?

A

Stiffens and thickens vessel walls, disrupting the BBB

87
Q

What does Stiffens and thickens vessel walls, disrupting the BBB lead to?

A
  • Serum leaking
  • Oedema
  • Local hypoxia
88
Q

What accumulated extracellular in amyloid angiopathy?

A

Eosinophils

89
Q

What does Ab form?

A

Polymerised beta sheets

90
Q

What does Ab form?

A

Polymerised beta pleated sheets

91
Q

Name important features of Lewy Body dementia.

A
  • Progressive dementia.
  • Hallucinations.
  • Fluctuating levels of attention/cognition.
  • Fluctuation in severity on a day-to-day basis.
  • Features of Parkinsonism are present at onset, or emerge shortly after.
92
Q

Lewy body dementia can show an overlap with Parkinson’s. What are the differences?

A
  • Characterised by fluctuating cognitive dysfunction, including attention.
  • MEMORY is affected LATER in the course of the disease
93
Q

What are the clinical features of Parkinson’s?

A
  • Loss of facial expression. (hypomimia)
  • Stooping.
  • Shuffling gait.
  • Slow initiation of movements.
  • Stiffness and pin rolling tremor.
94
Q

What is hypomimia?

A

Loss of facial expressions

95
Q

Most cases of Parkinson’s are ______

A

IDIOPATHIC

96
Q

What is the pathology of lewy body dementia?

A

Degeneration of the substantia nigra

97
Q

In what condition can you also see degeneration of the substantia nigra?

A

Parksinson’s

98
Q

Macroscopically, what is seen in lewy body dementia?

A

Pallor in the substantia nigra, where pigmented dopaminergic neurones run

99
Q

You get MORE cortical lewy bodies in Dementia

A

FALSE - LESS

100
Q

What are the microscopic features of lewy body Dementia?

A
  • Loss of pigmented neurones.
  • Reactive gliosis and microglial accumulation.
  • Remaining neurones may show Lewy bodies:
  • “Single / multiple intracytoplasmic, eosinophillic, round to elongated bodies that have a dense core and a surrounding pale halo”
  • Aggregates of a-synuclein and ubiquitin
101
Q

What is Huntington’s disease?

A

A relentlessly progressive neuropsychiatric disorder

102
Q

When does onset of Huntington’s occur?

A

Most commonly between the ages of 35-50, but can occur at any time.

103
Q

What is the triad of clinical features in Huntington’s?

A

A triad of emotional, cognitive and motor disturbance

104
Q

What are the symptoms of Chorea?

A
  • Chorea (dance-like movements).
  • Myoclonus.
  • Clumsiness.
  • Slurred speech.
  • Depression.
  • Irritability.
  • Apathy.
105
Q

When do people with Huntington’s develop dementia?

A

Later on in the course of the disease

106
Q

What is the inheritance pattern on Huntington’s?

A

Autosomal dominant

107
Q

What chromosome is the Huntington’s gene on?

A

4p

108
Q

Genetically, when does Huntington’s occur?

A

CAG repeats …. CAG CAG CAG CAG
<28 = normal
>35 = Huntington’s

109
Q

Describe the macroscopical pathology of Huntington’s.

A
  • Atrophy of basal ganglia: caudate nucleus, putamen.

* Cortical atrophy occurs later

110
Q

Describe the microscopic pathology of Huntington’s.

A
  • Simple neuronal atrophy of striatal neurones of the basal ganglia.
  • Pronounced astrocytic gliosis.
111
Q

What is Pick’s disease also known as?

A

Fronto-temporal dementia

112
Q

What is Pick’s disease?

A

A progressive dementia, commencing in middle life (usually between 50 and 60 years) characterised by progressive changes in character and social deterioration leading to impairment of intellect, memory and language

113
Q

What are the symptoms of Pick’s disease?

A

Sx related to frontal and temporal lobes:

  • Personality and behaviour change.
  • Speech and communication problems.
  • Change in eating habits.
  • Reduced attention span
114
Q

Picks disease is a ______ ________ illness

A

RAPIDLY, PROGRESSIVE

115
Q

How long does Pick’s disease last?

A

Between 2 to 10 years.

- the mean length of illness is ~ 7 years

116
Q

What happens to the frontal and temporal lobes in Pick’s disease?

A

EXTREME atrophy - frontal lobe first then temporal

117
Q

What does the weight of the brain end up being in Pick’s disease?

A

<1kg

118
Q

What are the histological hallmarks of Pick’s?

A
  • Pick’s cells – swollen neurones.

* Intracytoplasmic filamentous inclusions, known as Pick’s bodies.

119
Q

What is vascular dementia?

A

Disorder involving a deterioration in mental functioning due to cumulative damage to the brain through hypoxia or anoxia (lack of oxygen) as a result of multiple blood clots within the blood vessels supplying the brain.

120
Q

What is vascular dementia also called?

A

Multi-infarct dementia

121
Q

What do successive, multiple, cerebral infarctions cause?

A

Increasingly larger areas of cell death and damage

122
Q

What happens when a significant area of the brain is damaged?

A

Dementia results

123
Q

Who is vascular dementia more common in?

A

MEN

124
Q

Who gets vascular dementia?

A

Commonly after the age of 60

AND MIDDLE AGED HYPERTENSIVES

125
Q

Sufferers of vascular dementia are aware of their mental defects, what can therefore happen?

A

Depression and anxiety

126
Q

What is vascular dementia difficult to distinguish from?

A

Alzheimer’s

127
Q

What clues help to diagnose vascular dementia from Alzheimer’s?

A
  • Abrupt onset.
  • Stepwise progression.
  • Hx of hypertension or stroke.
  • Evidence of stroke will be seen on CT or MRI.
128
Q

Steadily progressing deterioration is?

A

Alzheimer’s

129
Q

Step-wise deterioration, due to episodic vascular induced brain infarction is?

A

Vascular dementia

130
Q

What provokes thromboembolism in vascular dementia?

A

Atheroma of large cerebral arteries

131
Q

What would be seen in MID?

A

Large vessel infarcts