8.3.1 Neuropathology I Flashcards
What is normal intracranial pressure?
0-10mmHg
What can cause an increase in intracranial pressure?
Cough and straining (toilet) can increase by up to 20mmHg, (transient)
What compensatory mechanisms are there to ensure that normal ICP is maintained?
Reduction in venous blood volume
Reduce CSF volume
Brain atrophy
What are the causes of raised ICP?
- Haematoma/haemorrhages
- Tumours
- Space occupying lesions
- Cerebral oedema
- Infections
What are some effects of raised ICP?
- Destruction of brain tissue around lesion/mass
- Displacement of midline structures
- Brain shifts- internal herniation
- Cerebral oedema
What is the difference between a normal brain and one affected by oedema?
Loss of sulci
Bulging gyri
What are the different types of intracranial herniation?
Subfalcine- herniation under flax cerebri
Transtentorial- medial temporal lobe herniates over tentorium cerebelli
Tonsillar- cerebellum herniates through foramen magnum
What is damaged in a subfalcine herniation?
Ischaemia of medial parts of frontal and parietal lobes and corpus
callosum because compression of the anterior cerebral artery
Anterior cerebral artery supplies midline structures
What happens in a trans-tentorial herniation?
Uncus/medial part of the parahippocampal gyrus
through the tentorial notch:
- Damage to CN 3 (oculomotor nerve) on
ipsilateral (same) side
- Occlusion of the blood flow in posterior cerebral
and superior cerebellar arteries
resulting in ischaemia.
COMMON mode of death (tumours and ICH)
What can a trans-tentorial herniation lead to?
Duret haemorrhage- haemorrhage into brainstem due to brain being pushed downwards which causes the pontine vessel branches to be compressed
What happens in a tonsillar herniation?
Cerebellar tonsils pushed into foramen magnum compressing the brainstem
What are the 4 types of intracranial haemorrhages?
Extradural
Subdural
Subarachnoid
Intraparenchyma (haem strokes)
What causes an extradural haematoma?
Anterior branch of middle meningeal branch ruptured, runs underneath the pterion, thinnest part of the skull
Where does blood accumulate in an extradural haematoma?
Between potenital space between dura mater and skull- Lemon shape
What causes an extradural haemorrhage?
Trauma, skull fractures and scalp bruises
How do extradural haemorrhages present?
Lucid interval, then signs of drowsiness and neurological deficits
Takes >40-50mls to have pressure effects on the brain
What vessel causes a subdural haemorrhage?
Shearing of bridging, blood accumulates between dura mater and arachnoid mater, subdural potential space
How much blood is needed to cause effects in a subdural haemorrhage?
More than 40 ml= pressure effect
80-100mls=fatal raised ICP
What are the important factors which are associated with increased risk of subdural haemorrhages?
Anticoagulant therapy or liver cirrhosis- coagulopathies, due to reduced production of clotting factors
On CT limited to one hemisphere, falx cerebri separates
What vessel is damaged in a subarachnoid haemorrhage?
Shearing of meningeal blood vessels
Circle of willis, causes film of blood over the brain
Label the image and complete the chance of berry aneurysm in each artery
What vessel occlusion can lead to cerebral infarction?
Deep penetrating arteries with no collateral supply e.g. basal ganglia, thalamus etc.
Watershed areas, areas that lie at most distal portion of artery territory
Identify what this and describe the histology
Cerebral ischaemia
Infiltration of infaction by neutrophils at edges of the lesion where there is intact vascular supply
Infarction has macrophages (middle pic)
What does this CT scan show?
Intracerebral and intraventricular haemorrhage
What are arteriovenous malformations?
- Worm-like tangled vascular channels
- M>F 10-30 years
- Affects subarachnoid vessels to brain / vessels in brain
