Neuropathology - trauma, infection, demyelination and neurodegenerative diseases

Question 1

What are the causes of primary and secondary neurological events in head injury?

Answer 1

Primary changes are neural and vascular

Secondary changes are ischaemia, oedema and infection

Question 2

What are the types of neural damage in head injury?

Answer 2

Can be confusional, at the surface of the brain.

This can either by focal or contre-coup (most commonly in the frontal and temporal lobes)

Question 3

What are the complications of confusional damage?

Answer 3

• intra-cerebral haemorrhage, causing a burst lobe

- post-traumatic epilepsy

Question 4

When does diffuse-axonal injury occur?

Answer 4

• when there has been a high velocity acceleration-deccelration event with torsion
• the mechanism by which this occurs is called mechanoporation, in which the sudden movement of the brain stretches axonal membranes and scripts ionic transport

Question 5

What features are pathonmnemonic of brain injury and are visible after 24hrs?

Answer 5

• axonal bulbs

Question 6

What kind of vascular damage leads to death?

Answer 6

• diffuse

Question 7

Why does ischaemia occur in brain injury?

Answer 7

• damaged brain is more sensitive to hypoxia and hypercarbia
• there is often associated hypoxia due to chest injury or airway compromise, reduce circulation and infarction to damaged arteries

Question 8

What 2 factors are raised ICP in head injury due to ?

Answer 8

• cerebral oedema as a reaction to haematoma, rapid deceleration, or a problem with perfusion
• mass effect of haematoma

Question 9

What are the risk factors for infection in head injury?

Answer 9

• depressed fractures
• fractures of the base of skull, air sinuses, middle ear
• MEninigits, cerebral abscess

Question 10

What is the cause of neurodegeneration in most cases?

Answer 10

Protein aggregation is common ,due to a failure of folding at tertiary level, leading to the accumulation of insoluble intracellular and extracellular fibrils

Question 11

What are the reversible causes of dementia?

Answer 11

• tumours, autoimmune limbic encephalitis, thyroid disease, metabolic disease and B12 deficiency

Question 12

What are the main causes of dementia?

Answer 12

Vascular, infective

Alzheimers, then vascular then Lewy body, then frontotemporal

Question 13

What are the pathogenesis of Alzheimer’s disease?

Answer 13

• causes cerebral atrophy (mainly of the frontal and temporal lobes), alongside reduced dendritic branching, neurofibrillary tangled, neuritic plaques, amyloid angiopathy, reduced cholinergic input to the cortex due to basal nuclear damage
• largely the pathogenesis surrounds amyloid formation

Question 14

What are the risk factors for alzheimers?

Answer 14

• age, head injury, educational status
• anti-inflammatory drugs appears to be preventative
• some genetic factors all affecting the processing of Bamyloid precursor protein BAPP
• Alipoprotein E is also associated with BAPP processing,, and leads to an 8 fold increase in risk

Question 15

Lewy bodies contain

Answer 15

alpha synuclein

Question 16

What is parkinson’s disease?

What is Lewy Body dementia?

Answer 16

• PD is ude to loss of pigmented cells in the substantia nigra, reducing the dopaminergic input to the basal ganglia
• LB dementia is often associated with PD, and patients will have visual hallucinations with relative memory preservation

Question 17

What is vascular dementia due to?

Answer 17

• multiple infarcts causing bilateral grey matter lesion

- this is due to small vessel disaee associated with HTN and vasculitis

Question 18

What are the trinucleotide repeat disorders?

Answer 18

• due to an expansion of three base pairs
• ## two main forms

Question 19

What is the difference between the repeat being an intron and an exon in tricucleotide repeat disorders?

Answer 19

• if repeat is an exon, it leads to AD disease, e.g. Huntington’s, this causes progressive dementia and choreofrm movements
• if the repeat is an intron, it leads to AR disease e.g. Friedereich’s ataxia

Question 20

What is motor neurone disease

Answer 20

• causes primar lateral sclerosis of the upper motor neurone and progressive muscular atrophy due to lower motor neurone disease
• this is due to ubiquination of motor neurones, resulting in axonal loss and no sensory involvement

Question 21

What are the causes of raised ICP?

Answer 21

• cerebral oedema
• focal expanding mass
• cerebral oedema

Question 22

What are the 3 important herniations within the brain?

Answer 22

Subfalcine herniation = movement of the cingulate gyros off