Dementia & Degeneration Flashcards

1
Q

Which diseases are characterised by central degeneration?

A
  • Alzheimer’s - Multiple Sclerosis - Parkinson’s - Huntington’s
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2
Q

Which diseases are characterised by peripheral degeneration?

A

-Diabetic Neuropathy -Motorneuron disease -ALS -Guillain Barre Sydrome

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3
Q

Name 3 types of neurodegeneration

A

-Wallerian -Axonal -Myelin

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4
Q

Describe Wallerian degeneration

A
  • Distal degeneration of axon and myelin, generally trauma induced. -Rupture - cuts transmission completely
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5
Q

Describe Axonal degeneration

A

-Dying back of the axon proximal to cell body -Some regeneration is possible -progressive

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6
Q

Describe myelin degeneration

A

-Loss of oligodendroglial (central)/Schwann (peripheral) cells affecting conduction velocity -Seen in MS (central) -Seen in Guillain Barre (peripheral)

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7
Q

Name 2 causes of Wallerian Degeneration

A

-Head trauma (shaken baby syndrome, diffuse axonal injury) -Nerve compression

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8
Q

Why is regeneration more likely in the periphery rather than central nervous system?

A

-Schwann cells in the periphery are better than oligodendroglial cells at releasing growth factors

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9
Q

What are the 3 classifications of Wallerian degeneration?

A
  1. Neuropraxia 2. Axonotmesis 3. Neurotmesis
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10
Q

What are amyloid plaques?

A

-Aggregations of misfolded/fragmented proteins -Caused by changes in phosphorylation or protein folding -Lead to increased Beta sheet formation

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11
Q

What are beta-amyloid plaques associated with?

A

Alzheimers disease

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12
Q

what are alpha-synuclein associated with

A

Parkinson’s disease

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13
Q

What are prion proteins associated with?

A

CJD

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14
Q

What are Tau proteins?

A

Maintain the structural composition of microtubules, allowing transport through the neuron.

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15
Q

What are neurofibrillary Tangles?

A
  • Hyperphosphorylation of tau proteins leads to misfolding -misfolding causes breakdown of tubules, B-sheet and fibril formation -Fibrils aggregate to form tangles. -This occurs OUTSIDE the cell
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16
Q

What are inclusions?

A

-Intracellular protein aggregations including LEWY BODIES and PICK CELLS -Generally alpha-synuclein -Inclusions are INTRACELLULAR

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17
Q

How does diabetic neuropathy present and what is it caused by?

A

Presentation: Pain, ulcers, tingling, poor balance Caused by: microvascular disease, activated PKC, polyols (secondary to high glucose)

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18
Q

How does Motor Neuron Disease (MND) present?

A
  • UMN and LMN features -Bulbar or pseudobulbar features -muscle weakness and atrophy -no sensory signs, bladder involvement or ocular involvement
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19
Q

What is MND caused by?

A

-Degeneration of the motor pathways, affecting outflow from the anterior horn cells

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20
Q

What is Guillain-Barre Syndrome?

A
  • Autoimmune reaction triggered by preceding viral/bacterial infection -Rapid onset weakness and tingling that spreads through the body. Normally starts in the feet/legs and spreads upwards -Demyelinating disorder -Treated with IV immunoglobulins and plasmapheresis
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21
Q

What is Multiple Sclerosis?

A

-Primary inflammatory, autoimmune disease causing CNS demyelination (oligodendroglial cells)

22
Q

How does multiple sclerosis present?

A

-Neuropathy -Blindness -Weakness -Numbness Diagnosis is based on demonstration of multiple levels of CNS involvement and CSF sample immunoglobulin bands. MRI: Plaques of products of inflammation accumulate in demyelinated areas, seen as flares in white matter regions of CNS on

23
Q

What are the different types of MS?

A

-Benign = No disability, return to normal between attacks, least impact on quality of life - Relapsing-Remitting = Episode + slight deterioration which becomes new baseline = most common - Secondary Progressive = no new disability between attacks, followed by steady increase in disability - Primary progressive = Steady increase in disability without attacks - worst case and the fastest decline

24
Q

What would be seen in Histology for a patient with Parkinson’s Disease?

A

-Loss of Dopamine neurons in substantia nigra -Presence of Lewy Bodies -Raised alpha-synuclein/parkin levels -Also get inclusions

25
What are the characteristics of Huntington's disease?
- Choreiform movements - Character alteration - Psychotic behaviour - Presentation between 20-50yrs
26
What causes Huntington's disease?
- Genetic - Autosomal dominant - Loss of GABA neurons - Loss of cholinergic function - Astrocytosis -Loss of substance P
27
What pathologies would be seen in the brain of a Huntington's disease patient?
- Loss of caudate nucleus - Expansion of sulci - Ex vacuo dilatation (Brain produces more CSF to compensate for degeneration, in order to still support the brain) = ventricles get bigger
28
What causes Creutzfeld-Jakob disease? Presentation?
- Prion protein alteration from PrPc to PrPs - Genetic component - Transmissable Presentation: Behaviour + personality changes, then coordination and myoclonic twitches, incontinence and gradually motor symptoms get worse. - Visbile amyloid plaques and vacuolisation give spongiform appearance
29
What is a prion?
- Proteinaceous infectious particle - Normal function is presynaptic transport and cell signalling, like alpha-synuclein - Confirmation changes lead to formation of B-sheets and fibrils
30
Explain the presentation of Variant Creutzfeld-Jakob Disease or "Mad Cow disease"
- Cerebellar presentation (ataxias, stammers, slurred speech) - Cerebellar spongiform - Plaques in cerebral and cerebellar regions - Psychiatric symptoms - PrP in GI tract Notifiable disease! - Local teams + National CJD surveillance unit + National Prion clinic
31
What is dementia?
A progressive global deterioration in: - Cognition - Memory - Orientation - Concentration - Speech - Behaviour - Personality Deterioration must be sufficient to affect work, social function or relationships It is common, about 1 in 100 people over 60 years old have dementia
32
Name the 4 broad causes of dementia
- Neurodegenerative - Cerebrovascular - Infection - Normal Pressure Hydrocephalus
33
Give examples of neurodegenerative conditions which may lead to dementia
Alzheimer's disease Huntington's disease Parkinson's disease Pick's disease Progressive supranuclear palsy Frontal lobe dementia Dementia with lewy bodies
34
Give examples of cerebrovascular causes of dementia
Multi-infarct dementia Binswanger's dementia
35
Give examples of infection causing dementia
Prion dementias - CJD/ variant CJD AIDs dementia complex Viral Encephalitis
36
Give examples of acute dementia causes (weeks)
Infective e.g. encephalitis Paraneoplastic
37
Give examples of subacute (months) dementia?
Thiamine deficiency e.g. Wernicke's Creutzfeld-Jakob (variant CJD quicker) Inflammatory e.g. vasculitis, sarcoidosis
38
Give examples of chronic (years) dementia?
Alzheimer's Pick's disease Multi-infarct dementia Huntington's disease
39
How do we test for dementia?
History from patient and family/friend/carer Cognitive tests Bloods (rule out other causes): FBC, ESR, CRP, B12, LFT, Ca2+, TFT, VDRL/TPHA (rule out syphilis as stomping gait due to dorsal column loss) Neuroimaging - CT/MRI/fMRI For rapidly progressing dementia, may need CSF sample
40
Which types of dementia are subcortical?
Normal pressure hydrocephalus Parkinson's disease (BG) Huntington's disease (BG)
41
Which types of dementia are cortical?
Frontotemporal dementia Creutzfeld-Jakob disease Alzeheimer's disease
42
name some subcortical features of dementia
Apathetic Forgetful & slow impaired visuospatial ability depression of mood
43
Name some cortical features of dementia
Dysphasia Agnosia Apraxia
44
Which types of dementia show subcortical and cortical features?
Lewy Body dementia Multi-infarct dementia
45
What is the commonest cause of dementia? (62%)
Alzheimer's Disease
46
Describe the stages of Alzheimer's disease
**Mild cognitive impairment:** * Impairment of episodic memory (hippocampus degeneration) * Anterograde memory loss **Mild-Moderate dementia:** * poor short-term and longer term memory * poor semantic memory with poor naming ability * loss of general knowledge * visuo-spatial defects * apathy, irritability, low mood **Advanced dementia:** * global intellectual loss with aphasia, amnesia, apraxia * Disintegration of personality * Myoclonus and extrapyramidal motor signs
47
What can be seen on imaging an adult with Alzheimer's disease? How is it truly diagnosed?
* early imaging normal * Later see neocortical/hippocampal atrophy and medial temporal lobe atrophy * Functional imaging shows hypometabolism in the posterior cingulate and bilateral parieto-temporal regions Only confirmed 100% post mortem by histology: * Plaques * Neurofibrillary tangles * Cerebral atrophy- hippocampal/temporal/cortical * Ex-vacuo dilatation Normal cause of death is pneumonia
48
Describe Vascular dementia
* Second most common of dementias (17%) * Stroke-related * Step-wise deterioration due to multiple successive events --\> multi-infarct dementia * Pyramidal signs are common Where there are lots of damaged areas over time e.g. TIAs
49
Describe Dementia with Lewy Bodies
* Linked to Alzheimer's and Parkinson's * Lewy bodies: protein deposits - alpha-synuclein * Dopamine & Acetylcholine neurons lose (as in Parkinsons) * Characteristics are parkonsonisms, visual hallucinations and fluctuations in cognition Differentiate via DAT scan which is hard on the patient so not often worth it as can easily be distinguished from history, symptoms and exam
50
Treatments for mild to moderate dementia
**Cholinesterase inhibitors: Donepezil, galantamine, rivastigmine** *Prevents breakdown of acetylcholine, most affected neurotransmitter system in Alzheimer's disease)* ***Glutamate receptor (NMDA) antagonist: memantine*** *May alter disease progression by interfering with glutamate mediated cell death - modest effect (Amantadine and Talampanel also used in Parkinson's)*