Q11

Describe the pathological mechanisms which cause cerebral oedema.

PROMPT: If specific examples used – can you describe the difference between vasogenic & cytoxic oedema?

  • Vasogenic
    • BBB disruption
    • INcreased vascular permeability
    • Fluid shift intravascular to intercellular spaces of brain
    • May be generalised or localised (inflammation or neoplasm)
  • Cytotoxic
    • Increased intracellular fluid due to neuronal, glial, or endothelial injury
      • Ie: generalised hypoxic/ischaemic insult of metabolic damage
    • Interstitial or ependymal oedema around (lateral) ventricles due to the high pressure of hydrocephalus

Pass Criteria:

  • Bold to pass or basic understanding of two mechanisms

What are the morphological findings of generalised cerebral oedema.
Prompt: What would be the CT findings?

  • Flattened gyri
  • Narrowing of sulci
  • Compression of ventricles and/or basal cisterns
  • Herniation

Pass Criteria:

  • 3 out of 4 to pass

Describe the major herniation locations associated with raised intracranial pressure.

  • Subfalcine herniation
    • Asymmetric expansion of cerebrum displaces the cingulate gyrus under the falx cerebri
  • Transtentorial or uncal herniation
    • Medial aspect of the temporal lobe is compressed against the free margin of the tentorium
  • Tonsillar herniation
    • Displacement of the cerebellar tonsils through the foramen magnum

Pass Criteria:

  • 2 of 3 bold plus correct description

Q12

Q12B Neuro Path

What is the major abnormality shown on this CT?

  • Right sided subdural with midline shift

Pass Criteria:

  • Side subdural

Q12A Neuro PathologyA Case courtesy of Dr Andrew Dixon, Radiopaedia.org, rID: 36677

Which type of vessels have been damaged to produce the subdural blood seen on this CT?

  • Subdural blood come from damage to bridging veins between the brain and the venous sinuses (displacement of the brain with in trauma can tear the veins at the point where they penetrate the dura to enter the sinuses) –> blood between the dura and the archnoid

Pass Criteria:

  • Bridgning veins

Which groups of patients are most at risk for SDH and why?

  • Elderly
    • Veins stretched and more movement due to brain atrophy
  • Infants
    • Thin walled bridging veins

Pass Criteria:

  • Bold to pass

How does an extradural haematoma occur?

  • Extradural haematoma occurs with rupture of a meningeal artery
  • Usually associated with a skull fracture
  • Leads to accumulation of arterial blood between the dura and the skull

Pass Criteria:

  • Meningeal (often middle) artery

Define & describe diffuse axonal injury?

  • Axonal microscopic injury
  • Axonal swelling and focal haemorrahagic lesions
  • Believe to damage the integrity of the axon at the node of Ranvier  –> alterations in axoplasmic flow
  • Commonly found with “coma” but no cerebral contusions

Pass Criteria:

  • Microscopic damage to deep brain white matter

Q13

What are the main pathological processes causing ischaemic stroke?
Give examples for each category.

  • Thrombotic occlusion
    • Atherosclerosis is the most common
  • Embolism
    • AMI
    • Mural thrombus
    • Valvular heart disease
    • AF
    • Vascular surgery
    • Fat embolism
    • Endocarditis
  • Inflammatory
    • Infectious vasculitis
    • Autoimmune vasculitis
    • Primary angiitis of the CNS

Pass Criteria:

  • Bold to pass and at least 2 causes of embolism plus one other (either embolic or inflammatory)

What are the distinguishing pathological features of haemorrhagic and non-haemorrhagic ischaemic cerebral infarcts?
Prompt: Why does haemorrhagic change occur in ischaemic stroke?

  • Haemorrhagic (red)
    • Multiple, sometimes confluent, petechial haemorrhages typically associated with embolic events
    • Thought to be secondary to reperfusion either via collaterals or dissolution of materials
    • Greater risk if anticoagulated
  • Non-haemorrhagic (pale)
    • Usually associated with thrombosis

Pass Criteria:

  • Bold causes and concepts to pass.

How are these pathological processes important in relation to stroke thrombolysis?

  • Complications higher with embolic/haemorrhagic CVAs
  • Trying to reverse injury in ischaemic penumbra
  • In non-haemorrhagic CVA little macroscopic change can be seen within the first 6 hours
  • Earlier treatment leads to better outcome and less haemorrhagic risk.

Pass Criteria:

  • Reversible ischaemic penumbra (term or concept) to pass.

 

 


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