wk 11- neuro Flashcards
list SOLs
-tumours
-haematomas
-oedema
-abscess
-hydrocephalus
-aneurysm`
why are SOLs dangerous?
skull is a closed system, if something is introduced slowly the brain compensates by reducing the amount of CSF, blood and by undergoing atrophy. once this hits a limit or if something is introduced fast, intracranial pressure rises and the brain harniates
causes of brain atrophy
-senile atrophy (escalated by alcohol, smoking, drugs and vascular diseases)
-SOL, Space occupying lesion that accumulates slowly
what is the determining factor for brain atrophy or herniation?
the speed of accumulation
what is the most common malignant tumour of the CNS?
in children- astrocytoma (2nd most common overall)
in adults- approx 50% are metastatic cancers usually carcinomas or melanomas, and the other 50% are glioblastoma
what occurs in the brain tissue surrounding the tumour and are these cellular changes reversible?
they cause secondary oedema and raise intracranial pressure
cellular change- brain atrophy through apoptosis because it is a slow process and permanent tissue
not reversible (permanent)
if theres necrosis and bleeding within a tumour what can occur?
leads to increase in intracranial pressure and may cause a fatal herniation
what are the pros of high/low mitotic rate
high- fast growing tumour responds better to treatment (side effects of treatment hwoever)
slow- longer life (doesnt respond as well to treatment)
what intracranial pathology might be expected from a case of trauma to the head?
Epidural, subdural, subarachnoid haematoma, intracerebral haemorrhage, cerebral contusion and
laceration, coup-contrecoup injury, diffuse brain (axonal) injury, concussion.
epidural haemorrhage
-rupture of dural arteries and the middle meningeal artery is often involved following trauma to the temporal area of skull
-high arterial pressure results in rapid accumulation of blood between the skull and dura
-rapid surgical intervention is required because of the intracranial pressure increasing which could cause herniation/death
subdural haematoma
-tearing (caused by displacement of the skull) of the bridging veins between the dura mater and arachnoid layers
-elderly people and those with atrophied brains are at greater risk because the brain is able to shift more
-slow process with vague symptoms up to 2 days after the event
subarachnoid haematomas
-trauma causing an arterial hemorrhage from a congenital aneurysm (or could also be systemic hypertension and rupture of an acquired aneurysm)
-rapid rise in ICP due to the rapidly accumulating haematoma
what is a stroke?
necrosis occurring in the brain from ischaemia or haemorrhage resulting in altered brain function
explain the chronic conditions that atherosclerosis of the carotid and cerebral arteries can cause
chronic
-reduced blood supply to the brain accelerating senile atrophy (apoptosis)
-the loss of functional tissue can cause vascular dementia
-increased risk of subdural haematomas bc more CSF produced so can shift in the skull more.
-transient occlusion of the vessel causing transient ischaemia attack (mini stroke)
explain the acute conditions that atherosclerosis of the carotid and cerebral arteries can cause
-increased risk of thrombus fromation due to tubulent blood flow and localised hypercoagulability
-thrombus could increase in size and lead to ischameic stroke
-embolus leading to an ischaemic stroke
-embolus causing oedema and rise in ICP can cause a haemorrhagic stroke
-thrombus- ischaemic stroke
-embolus- ischaemic stroke or haemorrhagic stroke
-aneurysm- haemorrhagic stroke which can lead to herniation of the brain + death
list 4 ways the brain and meninges may become infected
- trauma/surgery
- through blood
3.extension from local sites (ears, eyes, etc) - via the peripheral nervous system
what is the anatomical difference between encephalitis and meningitis?
E- brain tissue
M- within the meningeal layers
how does VIRAL meningitis differ in terms of CSF indicators and prognosis?
-CSF has normal glucose
-contains lymphocytes
-slight increase in proteins
-intracellular
how does BACTERIAL meningities differ
-CSF is often purelent, cloudy or turbid
-increased protein
-reduced or absent glucoses
-neutrophils present
-extracellular
-must be treated aggressively with antibiotics
what does an acute bacterial infection result in?
may result in increased intracranial pressure and herniation of the brain causing death.
also can form abscess or switch to chronic inflammation
what does acute atherosclerosis cause in carotid /cerebral arteries
thrombus, embolus- ischaemic stroke, aneurysm rupture or haemorrhagic stroke
what does chronic cause
atrophy/ transient ischaemic attacks- vasuclar dementia, increased risk of subdural haematoma
exam response for acute
Swelling & bleeding within the atherosclerotic lesion can obstruct the artery leading to ischaemia (loss
of blood supply). In addition, atherosclerosis predisposes towards the development of a thrombus
(blood clot attached to the wall of a vessel), an embolus (anything undissolved travelling in the blood
but in this case a piece of thrombus) & an aneurysm (localized abnormal dilatation of a section arterial
wall). A thrombus or embolus in the cerebral or carotid arteries can lead to an ischaemic stroke (an area
or necrosis or infarct caused by a loss of blood supply). This is an example of an acute injury & one that
will lead to an inflammatory response, which in this closed system could lead to an increase in ICP. A
ruptured aneurysm in a cerebral artery leads to a haemorrhagic stroke & a fast accumulating
subarachnoid or intracerebral haematoma, which can lead to a rapid rise in ICP predisposing towards
herniation & death. This is another example of an acute injury i.e. something that occurs abruptly
exam response for chronic
atherosclerosis, even without causing stroke can lead to a reduction in perfusion of the
brain which can result in atrophy (tissue shrinks due to cells dying through apoptosis). Depending on
the regions of the brain affected this can result in vascular dementia or other neurological deficits.
In addition, as the brain atrophies there is increased production of CSF to keep the pressure within the
skull constant. But this increases the risk of the brain moving excessively within the skull leading to
tearing of the bridging veins causing a subdural haematoma
haemtoma involving the arteries accumulates
rapidly
haematoma involving the veins accumulates
slowly
