Histo: Cerebrovascular disease and Trauma

Question 1

What are the two types of cerebral oedema?

Answer 1

• Vasogenic - due to disruption of blood-brain barrier
• Cytotoxic - secondary to cellular injury (e.g. hypoxia, ischaemia). This is usually due to damage to astrocyte end feet - which maintain BBB

Leads to raised ICP

Question 2

Which water transporting molecule is found in the brain?

Answer 2

Aquaporin 4

Question 3

What radiological appearance is characteristic of cerebral oedema?

Answer 3

Loss of gyri

Question 4

Describe the passage of CSF through the brain.

Answer 4

• The choroid plexus (mainly found in the lateral ventricles) pumps out CSF
• It passes from the lateral ventricles, through the interventricular foramina and into the 3rd ventricle
• It then goes down the cerebral aqueduct into the 4th ventricle
• It then flows down into the medulla and down the spinal cord in the central canal of the spinal cord
• Most of the CSF will leave the 4th ventricle and enter the subarachnoid space
• CSF will circulate around the subarachnoid space and will drain via arachnoid granulations into the superior sagittal sinus (and hence back into the systemic venous circulation)

Question 5

What constitutes the floor and the roof of the 4th ventricle?

Answer 5

Floor = pons

Roof = cerebellum

Question 6

Name and describe the two types of hydrocephalus.

Answer 6

• Non-communicating - caused by obstruction of CSF flow (usually in the cerebral aqueduct)
• Communicating - caused by reduced reabsorption of CSF into the venous sinuses (this could be caused by infection e.g. meningitis)

treatment is shunt to peritoneal cavity

Question 7

What is the normal range for ICP?

Answer 7

7 - 15 mmHg

Question 8

Name and describe the three sites of brain herniation.

Answer 8

• Subfalcine - the cortex is pushed under the falx cerebri (rare)
• Transtentorial (uncal) - the posterior cranial fossa is covered by the tentorium cerebelli which has a rigid opening for the brainstem. Supratentorial pressure can result in herniation of the medial temporal lobe over the rigid end of the opening of the tentorium cerebelli
• Tonsillar - herniation of the cerebellar tonsils through the foramen magnum (this can put pressure on the medulla and kill)

Dura and skull are inflexible

Question 9

Define stroke.

Answer 9

A clinical syndrome characterised by rapidly developing clinical symptoms and/or signs of focal or global loss of cerebral function with symptoms lasting > 24 hours or leading to death with no apparent cause other than that of vascular origin

Question 10

Which diseases are encompassed by the term ‘stroke’?

Answer 10

• Cerebral infarction
• Primary intracerebral haemorrhage
• Intraventricular haemorrhage
• Subarachnoid haemorrhage (most of the time)

Question 11

Which diseases are excluded by this definition of ‘stroke’?

Answer 11

• Subdural and epidural haemorrhage
• Infarction due to infection or tumour

Question 12

What is a TIA?

Answer 12

Same definition as stroke but resolving within 24 hours

NOTE: TIA is an important predictor of future infarct (1/3 people with TIA will have a significant infarct within 5 years)

Question 13

What is non-traumatic intraparenchymal haemorrhage?

Answer 13

Haemorrhage into the substance of the brain (parenchyma) due to rupture of small intraparenchymal vessels

Question 14

Where do non-traumatic intraparenchymal haermorrhages tend to occur most frequently?

Answer 14

Basal ganglia

NOTE: hypertension is implicated in > 50% of bleeds

Question 15

What is an arteriovenous malformation?

Answer 15

• A malformation where blood bypasses quickly from artery to vein without going through a normal capillary network
• They can occur anywhere in the CNS and they can rupture
• As they occur under high pressure, they tend to cause massive bleeds

Question 16

How are arteriovenous malformations treated?

Answer 16

• Surgery
• Embolisation
• Radiosurgery

Question 17

Define cavernous angioma.

Answer 17

• Well-defined malformative lesion composed of closely-packed vessels with no parenchyma interposed between vascular spaces
• NOTE: it is similar to an arteriovenous malformation but there is no brain substance wrapped up amongst the vessels
• NOTE: these tend to bleed at lower pressure causing recurrent small bleeds

Question 18

Describe the appearance of cavernous angiomas on MRI.

Answer 18

Shows target sign

Question 19

What causes subarachnoid haemorrhages?

Answer 19

Rupture of a berry aneurysm

NOTE: berry aneurysms are congenital

blood can move freely in sub-arachnoid space - low pressure

Question 20

Where are berry aneurysms typically found?

Answer 20

• 80% at the internal carotid bifurcation
• 20% within the vertebro-basillar circulation
• NOTE: highest risk of rupture if diameter of 6-10 mm

30% of patients have multiple aneurysms

Question 21

Management of berry aneurysm

Answer 21

endovascular coiling - minimally invasive

clipping - surgical (rare)

Question 22

What is the most common cause of cerebral infarctions?

Answer 22

Cerebral atherosclerosis

Question 23

Where is atherosclerosis most commonly found within the cerebral vasculature?

Answer 23

• Carotid bifurcation
• Basilar artery

Question 24

Which part of the cerebral vascular tends to be affected by infarcts resulting from emboli?

Answer 24

Middle cerebral artery branches

Question 25

List some differences between infarctions and haemorrhagic strokes.

Answer 25

Infarction

• Tissue necrosis
• Rarely haemorrhagic
• Permanent damage in the affected area
• No recovery

Haemorrhage

• Dissection of parenchyma
• Fewer macrophages
• Limited tissue damage
• Partial recovery

Question 26

What is the biggest cause of death in people < 45 years?

Answer 26

Traumatic brain injury

Question 27

Describe how traumatic brain injury can be classified.

Answer 27

• Non-missile and missile (e.g. shrapnel)
• Acceleration and deceleration (e.g. RTA, includes rotational)
• Focal or diffuse

Question 28

What are the consequences of base of skull fractures?

Answer 28

• The fracture may pass through the middle ear or anterior cranial fossa
• It can cause otorrhoea or rhinorrhoea - CSF leakage
• Increased risk of infection - through paranasal sinuses

NOTE: battle sign and raccoon eyes are manifestations of basal skull fractures

Question 29

With regards to brain injury, what is a laceration?

Answer 29

Bruising of the brain that causes rupture of the pia mater

Question 30

What is the term used to describe reboud injury to the opposite side of the brain?

Answer 30

Contrecoup injury

can be worse than the actual injury area

Question 31

What is diffuse axonal injury?

Answer 31

• Occurs at the moment of injury
• Shear and tensile forces causes damage to the axons
• This is the most common non-bleed related cause of coma
• Midline structure are particularly affect (e.g. corpus callosum)
• Some people suffer cognitive and behavioural changes further down the line

Question 32

With regards to brain injury, what is a contusion

Answer 32

brain in collison with skull - surface bruising

Occurs where the brain is close to skull