Neuropathology Flashcards
name three types of glial cells and their function
1) astrocytes - metabolic control (hug around blood vessels and contact neurons) 2) oligodendrocytes - structure and clasp around axons In the CNS and myelinated them 3) ependyma - line fluid compartments (equiv of epithelium) 4) microglia - monocyte lineage population
what are the components of SCALP?
Skin and Connective tissue Apneurosis Loose connective tissue Periosteum
which layer of the meninges covers the brain is continues into the spinal cord?
dura mater
what is the normal volume of CSF in the brain and how much is made per 24 hours?
- normal volume is 150ml 450ml is made per 24 hours
what connects the lateral ventricles and third ventricle?
inter ventricular foramen
what connects the 3rd to the 4th ventricle?
the cerebral aqueduct
where does the fourth ventricle connect to in the spinal column?
the central canal
how is CSF produced by the choroid plexus?
through ultrafiltration of blood
what are arachnoid granulations and what do they do?
arachnid granulations are outpocketings of the arachnoid into the dura - resorption of fluid back into the venous system (superior saggital sinus)
what condition arises when CSF circulation goes wrong?
hydrocephalus
what is the mechanism of hydrocephalus? (4)
- impaired resorption at arachnoid granulations - continous production by the choroid plexus - no drainage into venous system - therefore increase in ICP
what structural abnormality may cause hydrocephalus
shrinking of brain tissue eg in dementia
what is i) communicating ii) non communicating hydrocephalus?
I) communicating = whole system affected ii) non communicating = isolated problem
what causes a raised ICP? give three examples of this
raised ICP can be caused by space occupying lesions - neoplasm, haemorrhage and abscess
what is the main consequence of raised ICP?
herniation
what type of herniation is caused by i) brain pulled under faux cerebri ii) brain pulled through tentorium cerebelli iii) brain pulled through foramen magnum
i) subfalcine ii) transtentorial/central iii) tonsillar/cerebellar
what type of herniations are a,b,c?
a) through falx cerebri
b) through tentorium cerebelli
c) through foramen magnum
give three examples of parenchymal injuries
1) contusion (bruising)
2) laceration (penetration or tearing)
3) diffuse axonal injury
what causes a diffuse axonal injury? is this structural or functional?
caused by impact forces that makes the whole axonal network stop working
- functional injury
what happens when:
i) a moving head hits a stationary object
ii) stationary head hits a moving object
i) coup and contrecoup
ii) just coup
what mechanism in the head allows coup and contrecoup to occur?
the ability of the brain to move in the skull
where in the head do
i) veins
ii) arteries
run?
i) veins run under the dura
ii) arteries run between the skull and dura
how much force does it take to sever an artery that runs between the skull and the dura?
a lot
what type of haemmorhage will be caused by something hitting the side of the head?
an extradural/epidural haemmorhage
what artery may be lacerated in an extradural haemmorhage? what foramen does this artery exit the skull?
middle meningeal
exits the skull through foramen spinosum
For subdural haemmorhage
i) what level of trauma will cause this
ii) which structures may be implicated?
iii) what population of people are most vulnerable to this?
i) minor trauma
ii) bridging veins (under pressure due to brain atrophy)
iii) elderly
what is the principal cause of a subarachnoid haemmorhage? and what artery is this most commonly in?
principal cause is rupture of a berry aneurysm in the circle of wilis
most commonly in the anterior cerebral artery
is the dura still attached to the skull in
i) extradural haematoma
ii) subdural haematoma
i) no - dura is peeled off the skull
ii) yes - dura is still attached to the skull
what is the principle cause of intracerebral haemmorhage?
hypertension
what type of haemmorhage is this?
extradural
what type of haemmorhage is this?
subdural
- characteristic change in brain shape
what type of haemmorhage has caused this?
subarachnoid
what type of haemmorhage has caused this? and what is it principally associated with?
intracerebral which is associated with hypertension
what is cerebral oedema?
explain the i) vasogenic and ii) cytotoxic causes
cerebral oedema is swelling of the brain itself
i) vasogenic changes are increased vascular permeability of blood vessels so more fluid and blood gets into the brain matter
ii) cytotoxic changes are neuronal, glial or endothelial cell change which attracts more oedema and increases ICP
what % of cardiac output and O2 goes to the brain?
15% CO and 20% O2
is it more important to maintain blood flow or oxygen to the brain?
blood flow
In haemmoehagic infarction in emboli how are toxic metabolites stopped from building up but there is still a haemmoehagic lesion?
collateral circulation can maintain some flow
- this stops build up of toxic metab
- not enough to maintain cells so there is a haemmorhagic lesion
what haemmorhagic infarction is thrombosis and what does this result in?
blood supply is completely cut off
- results in a bloodless infarct which causes necrosis and tissue cell death
what type of infarction is bloodless? what is the characteristic appearnce of the tissue?
what causes this?
ischaemic infarction
characteristic appearance is liquefied tissue
caused by irreversible hypoxia or ischaemia
What five things are typically seen in a ischaemic infarction?
1) red neurons on histol due to necrosis
2) pynkosis of nuclei (small and dark)
3) shrinkage of cell body
4) loss of nucleoli
5) intense eosinophilia of cytoplasm
what type of infarction are these cells seen in?
ischaemic infarction
what % of brain neoplasms are primary?
75%
what % of malignant childhood tumours are located in the CNS?
20%
give three examples of a glioma
astrocytoma, oligodendroma, glioblastoma
what are tumours of the meninges called? are they malignant or benign?
meningiomas are benign
what type of neoplasm is this?
meningioma
what type of neoplasm is this?
glioblastoma
what type of cells are seen in acute meningitis? what else may be seen covering the brain
lots of neutrophils and may also see pus covering brain
which type of infective agent can cause meningitis?
any eg viral, fungal, malaria, lyme disease
what infective thing often occurs in relation to a penetrative traumatic brain injury?
abscess
what condition is characterised by the whole brain being inflammed and has a viral cause eg HSV, CMV and HIV?
encephalitis
