Neuropathology - trauma, infection, demyelination and neurodegenerative diseases Flashcards
What are the causes of primary and secondary neurological events in head injury?
Primary changes are neural and vascular
Secondary changes are ischaemia, oedema and infection
What are the types of neural damage in head injury?
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)
What are the complications of confusional damage?
- intra-cerebral haemorrhage, causing a burst lobe
- post-traumatic epilepsy
When does diffuse-axonal injury occur?
- 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
What features are pathonmnemonic of brain injury and are visible after 24hrs?
- axonal bulbs
What kind of vascular damage leads to death?
- diffuse
Why does ischaemia occur in brain injury?
- 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
What 2 factors are raised ICP in head injury due to ?
- cerebral oedema as a reaction to haematoma, rapid deceleration, or a problem with perfusion
- mass effect of haematoma
What are the risk factors for infection in head injury?
- depressed fractures
- fractures of the base of skull, air sinuses, middle ear
- MEninigits, cerebral abscess
What is the cause of neurodegeneration in most cases?
Protein aggregation is common ,due to a failure of folding at tertiary level, leading to the accumulation of insoluble intracellular and extracellular fibrils
What are the reversible causes of dementia?
- tumours, autoimmune limbic encephalitis, thyroid disease, metabolic disease and B12 deficiency
What are the main causes of dementia?
Vascular, infective
Alzheimers, then vascular then Lewy body, then frontotemporal
What are the pathogenesis of Alzheimer’s disease?
- 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
What are the risk factors for alzheimers?
- 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
Lewy bodies contain
alpha synuclein
What is parkinson’s disease?
What is Lewy Body dementia?
- 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
What is vascular dementia due to?
- multiple infarcts causing bilateral grey matter lesion
- this is due to small vessel disaee associated with HTN and vasculitis
What are the trinucleotide repeat disorders?
- due to an expansion of three base pairs
- ## two main forms
What is the difference between the repeat being an intron and an exon in tricucleotide repeat disorders?
- 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
What is motor neurone disease
- 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
What are the causes of raised ICP?
- cerebral oedema
- focal expanding mass
- cerebral oedema
What are the 3 important herniations within the brain?
Subfalcine herniation = movement of the cingulate gyros off
