Pathology Flashcards
What are common causes of acute neuronal injury?
Hypoxia
Ischaemia
What is the descriptive term used for neurones affected by acute neuronal injury?
Red Neurones
How soon after the acute injury do “Red Neurones” appear?
12-24 hours
On examination what do the neurones post injury look like?
Shrinking and angulation of nuclei
Loss of nucleolus
Red cytoplasm
Eosinophilia
How do axons appear post injury?
Swelling of the cell body and nucleolus.
Degeneration of axon and myelin sheath distal to the injury.
Chronic Degeneratie neuronal atrophy appears how?
Shrunken small dark nuclei
Reactive Gliosis
How do oligodendrocytes react to injury?
Loss of myelin sheath
Conduction is reduced
Axons are exposed to injury
What are oligodendrocytes susceptible to?
Oxidative stress e.g hypoxia
Astrocytes undergoing scar formation and repair can be described as undergoing what?
Gliosis
How does early gliosis appear?
Hyperplasia
Hypertrophy
Nucleus enlargement
How does late gliosis appear?
Translucent nuclei
Shrunken and dark lying within a dense mass
What are ependymal cells susceptible to?
Limited reaction to injury
Usual site of tumour formation or infection
Microglia
CNS Macrophage
How do microglia appear on inspection?
Form aggregate around area of necrotic or damaged tissue.
M2 - Microglia
Anti inflammatory phagocytic cells - More Acute
M1 - Microglia
Pro Inflammatory more chronic
List some common causes of Hypoxia.
Cerebral Ischaemia Infarct Haemorrhage Trauma Cardiac Arrest
What proportion of the bodies intake of oxygen is used by the brain?
20%
By how many times can cerebral blood flow increase to match the demand before supplies of ATP are used up?
2x
What s excitotoxicity?
Energy Failure- Hypoxia or hypoglycaemia
What is the Pathophysiology behind excitoxicity?
Neuronal depolarisation and re-uptake of transmitters inhibited.
Glutamate is released and builds up.
Glutamate storm
Ca2+ build-up proteases activated.
Mitochondria dysfunction and oxidative stress.
List the types of oedema affecting the brain.
Cytotoxic
Ionic
Vasogenic
Haemorrhagic Conversion
Causes of Cytotoxic oedema
Intoxication
Severe hypothermia
Causes of Ionic oedema
Hyponatraemia
Excess water intake
Causes of Vasogenic oedema.
Breakdown in the BBB
Trauma Tumour Inflammation
How does a breakdown in the BBB result in vasogenic oedema?
Plasma proteins and insoluble proteins able to cross, water follows via osmosis.
Global Cerebral ischaemia is due to.
Generalised reduction in blood flow - Hypovolaemic shock cardiac arrest
Focal Cerebral Ischaemia is due to.
Vascular obstruction
Which areas are most susceptible to ischaemia?
Neocortex
Hippocampus
Zones between two arterial territories.
A cerebral thrombosis is most likely to occur where?
Middle cerebral artery
A cerebral emboli is most likely to occur from where?
Internal carotid or aortic arch.
List some risk factors for Cerebral infarction.
Atheroma Hypertension Obesity Diabetes Mellitus Smoking Septal Defects
0-12 hours post infarct what is to be seen?
Little is visible
12-24 hours post infarct what is to be seen?
Paleness
Softening
Swollen Tissues - oedema
Red neurones
24-48 hours post infarct what is to be seen?
Recruitment of neutrophils
Haemorrhagic conversion
Activation of microglia
What is Haemorrhagic conversion.
Post infarct the blood vessels can break down leading to leakage.
2-14 days post infarct what is to be seen?
M1 Microglia predominant
Reactive Gliosis
Several Months post infarct what is to be seen?
Cavitation
Liquifaction
Gliotic scar
A middle cerebellar artery infarct would present with…
Contralateral face and arm weakness
Anterior Cerebelar infarct would present with…
Weakness and sensory loss in contralateral leg
A verterbro basilar artery infarct would present with…
Vertigo
Ataxia
Dysarthia
Dysphasia
Charcott-Bouchard
Micro-aneurysm linked to chronic hypertension
Charcott- Bouchard are most likely to be found in….
Basillar arteries
Hypertension is strongly linked to this form of infarct.
Lacunar
What are lacunar infarcts?
Occlusion of small penetrating vessels.
What region of the brain is commonly affected by lacunar infarcts?
Basal Ganglia
How does someone with hypertensive encephalopathy present?
Headache Confusion Fits Coma Behavioural changes
What would the brain of someone with hypertensive encephalitis appear like.
Global and cerebral oedema
Tentorial Herniation
Necrosis
Give some risk factors for intracerebral haemorrhage.
Hypertension Amyloid deposits Diabetes Cocaine Vasculitis
List some common vascular malformations.
Arteriovenus Malformation
Cavernous Angiomas
Venous Angioma
Capillary Telangectaisia
What do AVM look like?
Abnormal tortuous vesels
Shunting high pressure blood straight into the venous system.
Pathologically what do AVM vessels look like.
Hypertrophy of smooth muscle in vessels
Loss of compliance
Why do AVM carry the highest risk of intracerebral haemorrhage?
High pressure blood with weaker fragile walls.
What is the commonest cause of Subarachnoid haemorrhage?
Rupture of berry aneurysms
Where do berry aneurysm usually appear?
Bifurcations within the circle of willis
At what size do berry aneurysms carry the biggest risk of bleeding?
6-10mm
At what size does the risk of rupture for berry aneurysms decrease?
> 25mm
What is the cause of symptoms in a large berry aneurysm ?
Mass effect e.g compression
