Pathology of Brain Tumours Flashcards
what is contained in the cranium ?
brain meninges dural folds blood CSF
what is the pressure gradient ?
P1 - P2
for examples the arterial pressure and the venous pressure
what does CPP stand for?
cerebral perfusion pressure
what does the CPP reflect?
reflects the pressure gradient to get into the cranium
how do you calculate the CPP?
CPP = MAP - ICP
how do you calculate the cerebral blood flow ?
CBF = CPP/CVR
what mechanism is there that makes sure CBF remains constant as the CPP changes ?
auto regulation
what is cushings triad ?
- decrease in heart rate
- decrease in resp. rate
- increase of BP
when does cushings reflex occur?
cushings reflex is a late reflex which occurs when CBF is low to ensure that CPP is maintained
how does auto regulation maintain CBF?
maintained by changing the diameter of the vessels
when CPP increases what happens to the radius of vessels and why?
CPP increases
the diameters decrease to increase resistance and hence decrease cerebral blood flow to optimum level
when CPP decreases what happens to the radius of vessels and why?
CCP decreases
the diameters increase so the resistance is less and hence the blood flow will increase back to optimum
what shape is the auto regulation graph of CPP and CBF ?
sigmoid graph
under what CPP does the brain start to become ischaemic and loss function ?
<50mmHg
at which CPP does brain oedema occur due to hypertension ?
> 150mmHg
what are four causes of raised ICP?
inflammation
vascular
tumours
hydrocephalus
state some vascular disorders which could cause raised ICP ?
intracranial haemorrhage
brain swelling due to trauma
hypotension due to cardiac arrest
what are the three opening in the brain where herniation can occur?
subfalcine space
tentorial hiatus
foramen magnum
what abouts in the skull does a subfalcine hernia occur?
inferior border of the falx cerebri just superior to the lateral ventricles
what structure sits in the tentorial hiatus ?
the brain stem
when the cerebellum passes through the foramen magnum what is this called?
cerebellar coning
when there is raised ICP, what happens to the CBF and why?
CBF decreases as the pressure gradient outside and inside the skull is less
when the cerebrum herniates inferiorly and medially through the tentorium what is this called?
uncle grooving
what type of hernia is it when the brain pushes through the skull following a fracture ?
transcalvarial
what three tests and investigations can be done to test for loss of function due to a tumour and hence raised ICP?
Glasgow Coma Scale
Pupillary dilation
Localising signs such as weakness in one arm
what cranial nerve is affected when there is a fixed dilated pupil?
Nerve 3 - oculomotor
are brain tumours more common type of tumour in adults or children?
brain tumours is the 2nd most common ground of tumour in children
where abouts in the brain are the majority of brain tumours in adults ?
70% above the tentorium
where abouts in the brain are the majority of brain tumours in children ?
70% below the tentorium
are brain tumours in children more likely to be primary or secondary ?
nearly all are primary in children
what percentage of brain tumours are primary in adults ?
65%
where are the common places secondary brain tumours have spread from ?
breast lung kidney colon melanoma
where are the 7 locations a brain tumour can occur?
glial cells primitive neurorectoderm arachnoidal cell nerve sheath cell pituitary gland lymphoid cell capillary vessels
what is a pituitary gland tumour called ?
adenoma
what are the clinical complications of pituitary gland tumour ?
loss of endocrine function
may extend up to the optic chiasma
what is a tumour os the capillary vessels called?
haemangioblastoma
what are the two types of nerve sheath cell tumours called?
schwannoma
neurofibroma
are schwann cells found in the CNS or PNS ?
PNS
what type of cell in the CNS produces myelin?
oligodendrocyte
what is a tumour of arachnoidal cells called?
meningioma
are medulloblastoma more common in children or adults ?
children
from what cells does medulloblastoma originate from ?
primitive neurorectoderm
what are the four types of glial cell tumours ?
glioblastoma
astrocytoma
oligodendroglioma
ependymoma
what is ischaemic penumbra ?
area of ischaemia around a tumour
what is the clinical significance of ischaemic penumbra ?
the ischaemia around the tumour can be removed to improve function of the brain tissue
what is the function of glial cells?
CNS supporting cells
- providing myelin
- providing a favourable environment for neurones
do glioma spread around the body ?
no stays in the CNS
are glioma encapsulated ?
no they have diffuse edges
what is the prognosis of glioma ?
high grade glioma grow fast and respond poorly to surgery
- survival time = 36 weeks
can people live their entire life with low grade glioma without any complications?
yes
state a treatable complication of low grade glioma ?
epilepsy can be triggered
in which fossa does medulloblastoma usually occur ?
posterior fossa especially in the brain stem
what is the prognosis of medulloblastoma ?
poor prognosis due to deep location and difficult access for surgery
are meningiomas benign or malignant ?
benign
how can meningiomas invade the skull?
via emissionary veins
what is the most common nerve sheath tumour ?
acoustic neuroma
what cranial nerve is affected by an acoustic neuroma ?
CN 7
what is a symptom of acoustic neuroma ?
unilateral deafness
what are two clinical signs that a patient may have a pituitary adenoma ?
acromegaly
giantism
what is the prognosis of CNS lymphoma ?
poor
- often deep and central site
- difficult to biopsy
- difficult to treat due to BBB
do CNS lymphomas spread out of the CNS ?
no
is there any lymph tissue in the brain ?
no
what cell makes up a CNS lymphoma ?
B cell lymphoma
where do capillary haemangioblastomas often occur ?
cerebellar hemispheres
what are the complications of capillary haemangioblastomas ?
may bleed
space occupying
difficult to get to
are secondary tumours mostly malignant or benign?
malignant
what are secondary tumours often surrounded by ?
they are encapsulated surrounded by oedema
are primary and secondary tumour histology similar ?
yes
