CNS

Question 1

How does atrial fibrillation cause stroke?

Answer 1

Atrial fibrillation creates pockets of stasis where thrombi can form in the atria
This can cause cerebral embolism and cerebral infarction (stroke)

Question 2

Types of intracranial haemorrhage

Answer 2

Epidural haemorrhage
Subdural haemorrhage
Subarachnoid haemorrhage
Intracerebral/intraparenchymal haemorrhage

Question 3

Pathogenesis of epidural haemorrhage

Answer 3

Temporal bone fracture
Laceration of MMA, extravasation of high pressure arterial blood
Dura separates from internal surface of skull
Lucid for 2-3h, before losing consciousness due to rapid expansion and raised ICP

Question 4

Pathogenesis of subdural haemorrhage

Answer 4

Tearing of bridging veins within subdural space, causing extravasation of venous blood
Slow progressive neurological deterioration
Dura still attached to internal surface of skull
After 36h, headache and confusion without loss of consciousness

Higher risk in infants due to thin vein walls and in elderly due to brain atrophy and higher brain mobility

Question 5

Pathogenesis of subarachnoid haemorrhage

Answer 5

Berry aneurysm of circle of Willis has thin walls and static blood
Increased BP, traumatic, or spontaneous rupture of the aneurysm causes bleeding into the subarachnoid space

Question 6

Pathogenesis of intracerebral/intraparenchymal haemorrhage

Answer 6

Hypertension damages BV
Increased formation of micro-aneurysms increases the likelihood of rupture and bleeding within the parenchyma
Symptoms are headache, nausea, coma, fever and vomiting

Can lead to death due to:
Brain herniation
Compression of brain stem
Haemorrhage in midbrain and pons
Rupture into ventricular system causing acute hydrocephalus
Rupture into ventricular system causing dissection into brain stem