Pathology of Brain Tumours

Question 1

How is CSF reabsorbed into the veins?

Answer 1

Via arachnoid granulations

Question 2

What equation describes cerebral perfusion pressure? What does this reflect?

Answer 2

CPP = MAP - ICP

The pressure gradient to get into the cranium

Question 3

What equation describes the cerebral blood flow?

Answer 3

CBF = CPP / CVR

CVR = cerebrovascular resistance

Question 4

What term describes the fluid nature of the relationship between the CPP and CBF?

Answer 4

Autoregulation

Question 5

What is the Cushing reflex?

Answer 5

A late reflex to brainstem ischaemia that results in increased MAP to ensure that the CPP is maintained

Question 6

What is the result of a CPP less than 50mmHg

Answer 6

The brain cannot perfuse adequately with oxygen and nutrients
There is loss of function

Question 7

What is the result of a CPP in excess of 150mmHg?

Answer 7

There is a loss of control of blood flow - ischaemic forced vasodilation
Brain swelling occurs - brain oedema

ICP = MAP - therefore no flow

Question 8

Outline the main causes of raised ICP

Answer 8

Inflammation - meningitis, encephalitis, abscess

Vascular - intracranial haemorrhage, disease or traumatic
- Brain swelling/oedema, traumatic brain injury , physical or physiological e.g. MI

Tumours

Hydrocephalus

Question 9

What is the falx cerebri?

Answer 9

A large, crescent-shaped fold of meningeal layer of dura mater that descends vertically in the longitudinal fissure between the cerebral hemispheres. The falx cerebri attaches anteriorly at the crista galli in proximity to the cribriform plate and to the frontal and ethmoid sinuses. Posteriorly, it is connected with the upper surface of the tentorium cerebelli. Its superior margin is attached at midline to internal surface of skull, as far back as the internal occipital protuberance

Question 10

What is the tentorium cerebelli?

Answer 10

An extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes

Question 11

What are the effects of an intracranial space occupying lesion?

Answer 11

Amount of tissue within the cranium increases and therefore so dos the ICP - CBF is now at risk (CBF = (MAP-ICP)/CVR)
If focal, e.g. tumour or haematoma, can cause internal shift or herniation between the intracranial spaces

Question 12

What are the six forms of brain herniation?

Answer 12

Cingulate
Central
Uncle
Cerebellotonsillar
Upward
Transcalvarial

Question 13

What pathology does the GCS relate to?

Answer 13

Squeeze onto cortex and brainstem

Question 14

What pathology does pupillary dilation indicate?

Answer 14

Sneeze and stretch on CNIII

Question 15

What pathology do localising signs relate to?

Answer 15

Squeeze on decussation of the corticospinal tracts and posterior columns

Question 16

What is the most common site of brian tumours in adults? How does this differ in children?

Answer 16

Adults - 70% above the tentorium

Children - 70% below

Question 17

What proportion of brain tumours in adults and in children are primary?

Answer 17

Adults - 65%

Children - almost all

Question 18

What primary sites do secondary brain tumours most commonly spread to?

Answer 18

Breast, lung, kidney, colon, melanoma

Question 19

What is a meningioma a cancer of?

Answer 19

Arachnoidal cell

Question 20

What is a medulloblastoma a cancer of?

Answer 20

Primitive neurorectoderm

Question 21

What are glioblastomas, astrocytomas (glioma), oligodendrogliomas and ependymomas cancers of?

Answer 21

Glial cells

Question 22

What are ademona cancers of?

Answer 22

Pituitary gland

Question 23

What are schwannoma and neurofibroma cancers of?

Answer 23

Nerve sheath cells

Question 24

Describe the principal of the ischaemic penumbra

Answer 24

This refers to the space surrounding the core area of infraction, tumour or insult to the brain that is affected by local ischaemia but is distal enough to have some other arterial supply, and unlike the ischaemic core, may be salvageable if the ischaemia is resolved

Question 25

Are gliomas able to metastasise outside or the CNS?

Answer 25

No

Question 26

What is unique about medulloblastomas? What age group do they affect in particular?

Answer 26

They are blue. Children

Question 27

Are meningiomas benign or malignant?

Answer 27

‘Benign’ but can display aggressive growth, causing surrounding tissue destruction

Question 28

What is the most common form of nerve sheath tumour? Describe this form of tumour

Answer 28

Acoustic neuroma

Affects vestibulocochlear nerve CNVII
CNVII (facial) can be affected as also runs through IAM

Causes unilateral deafness

Removal technically difficult

Question 29

What cells are most commonly affected by a CNS lymphoma?

Answer 29

B-cells
Tumours are usually large and diffuse
Often deep and central -difficult to resect

Question 30

What makes brain tumours difficult to treat form a pharmacological perspective?

Answer 30

BBB