Cerebrovascular disease and Trauma

Question 1

1. What is Cerebral oedema
2. What are the two main types?
3. What is the end result?

Answer 1

1. Excess accumulation of fluid in the brain parenchyma
2. Two main types:

• Vasogenic – disruption of the blood brain barrier
• Cytotoxic – secondary to cellular injury e.g. hypoxia/ischaemia - caused by an insult to the brain

3. Result is raised intracranial pressure - bad

Question 2

How does cerebral oedema form?

Answer 2

• Vasogenic - breakdown in tight junctions, and water moves out into the parenchyma of the brain
• Cytogenic - caused by damage to brain structures - AQP4 channels found on the end feet of astrocytes - become damaged, leak water

Resolve oedema:

• Push fluid back into the CSF and water transporters are reveresed to push water back into the CNS

Question 3

What can be seen on radioimaging that makes you think cerebral oedema?

Answer 3

• Gyri are tightly packed - swollen brain
• Loss of gyral identity - expanded and compressed in a swollen brain

A space occupying lesion causes compression and swelling also

Question 4

Describe normal CSF flow

Answer 4

Hydrocephalus is “water on the brain” and is caused by a disturbance in CSF flow

Ventricular system - within the venticles is the choroid plexus which pumps out CSF, which flows through this system. Very little volume goes down into the central canal. Arachnoid granulations pierce throughout the venous sinus and this allows for CSF reabsorptin

Many foramen moves fluid into the subarachnoid space in order to bathe the brain, and also acts as a protector against impact

Question 5

What are the two types of hydrocephalus?

Answer 5

• Non-communicating - involves obstruction of flow of CSF
• Communicating - involves no obstruction but problems with reasbsorption of CSF into venous sinuses

Question 6

What is normal ICP for a supine adult?

Answer 6

7-15mmHg

Question 7

What are the consequences of raised ICP?

Answer 7

• The skull is an enclosed bony-box and pressure can increase due to oedema, space occupying lesions
• Increased pressure forces brain against unyielding bony wall of skull
• This results in herniation of brain structures where space is available

Question 8

What is the WHO definition of stroke?

Answer 8

•A stroke is a clinical syndrome characterised by rapidly developing clinical symptoms and/or signs of focal, and at times global loss of cerebral function, with symptoms lasting more than 24 hours or leading to death, with no apparent cause other than that of vascular origin (Hatano, 1976)

This includes stroke due to cerebral infarction, primary intracerebral haemorrhage, intraventricular haemorrhage and most cases of subarachnoid haemorrhage

Question 9

Define a TIA

Answer 9

• TIA is a warning stroke that should be taken very seriously
• TIA is caused by a clot; the blockage is temporary
• Most TIAs last less than five minutes; the average is about a minute. Unlike a stroke, when a TIA is over, there is usually no permanent injury to the brain
• 1/3 of those with TIA get significant infarct within 5 years

Question 10

1. What is non-traumatic intra-parenchymal haemorrhage?
2. Most common location?
3. Most common cause?
4. Presentation?

Answer 10

1. Haemorrhage into the substance of the brain - rupture of a small intraparenchymal vessel
2. Most common in basal ganglia
3. Hypertension > 50% of bleeds
4. Presentation with severe headache, rapid loss of consciousness, focal neurological signs

Question 11

1. What are arteriovenous malformations?
2. When and how does it present?
3. What is the treatment?

Answer 11

1. Tangle of abnormal vessels that can occur anywhere within the CNS and have a higher susceptibility to bleed
2. People become symptomatic between 2nd and 5th decade of life. People present with haemorrhage, seizures, headache and focal neurological deficits
3. Surgery, embolization, radiosurgery

Question 12

1. What is a cavernous angioma?
2. How do they present?
3. Treatment?

Answer 12

1. Well-defined malformative lesion composed of closely packed vessels with no parenchyma interposed between vascular spaces Can be found anywhere in the CNS, usually symptomatic after age 50
2. Presents with headache, seizures, focal deficits, haemorrhage - even at low pressures
3. Treatment is surgery

Question 13

1. Where do the majority if berry aneurysms form?
2. What does a ruptured berry aneurysm cause?

Answer 13

1. 80% of berry aneuryms form in the internal carotid artery bifuraction, 20% occur within the vertebro-basilar circulation
2. Rupture of a berry aneurysm causes a sub-archnoid haemorrhage

Question 14

1. Define cerebral infarction
2. Epidemiology
3. Risk factors
4. Define the difference between focal and global cerebral ischaemia

Answer 14

1. Cerebral infarction is tissue death due to ischaemia and is the commonest form of cerebrovascular disease
2. Causes 70-80% of all strokes - most common site is the near carotid bifurcation or in basilar artery. or can be due to emboli (embolic attacks occlude in middle cerebral artery branches most commonly)
3. Cerebral athersclerosis is the most common cause. Other risk factors include hypertension, diabetes and smoking
4. Focal cerebral ischaemia - defined vascular territory

Global cerebral ischaemia - systemic circulation fails

Question 15

Describe the vascular territories of the brain

Answer 15

Question 16

What is the largest cause of death in people under 45?

Answer 16

Trauma

Question 17

What is the difference between missile and non missile head trauma?

Answer 17

Missile = open head injury - dura mater not intact

Non-missile = closed head injury - dura mater intact

Question 18

Define contusion

Answer 18

• Brain in collision with skull
• Surface “bruising”
• If pia mater torn then becomes laceration
• Lateral surfaces of hemispheres, inferior surfaces of frontal and temporal lobes

Question 19

What is a coup and contrecoup injury?

Answer 19

• Coup - injury that occurs with the object
• Contrecoup - injury that occurs on the other side of the impact with an object

Question 20

What is diffuse axonal injury and when does it occur?

Answer 20

• Occurs at moment of injury
• Shear & tensile forces affecting axons
• Commonest cause of coma (when no bleed)
• Midline structures particularly affected e.g. corpus callosum, rostral brainstem and septum pellucidum

Question 21

Describe the complications of fractures

Answer 21

• Fissure fractures often extend into base of skull
• May pass through middle ear or anterior cranial fossa
• Otorrhea or rhinorrhea
• Infection risk