Raised ICP Pathology Flashcards
What is normal ICP?
5-13mmHg
What is normal number of lymphocytes in CSF?
<4 cells/ml
What is the normal protein in CSF?
<0.4g/l
What is normal glucose in the CSF
> 2.2mmol/l
What are hte causes of hydrocephalus?
obstruction of CSF eg inflammation, pus and tumours; decreased resoption of CSF- post SAH or meningitis; overproduction of CSF- rare- tumours of choroid plexus
How is hydrocephalus classified?
non-communicating adn communicating hydrocephalus
What is non-communicating hydrocephalus?
obstruction to flow of CSF occurs within ventricular system
What is communicating hydrocephalus?
obstruction to flow of CSF outside of ventricular system eg in subarachnoid space or arachnoid granulations
What happens to the brain with hydrocephalus?
expansion of hte ventricles; flattening of the dyrae; fullness of the sulci and riased ICP
What is hydrocephalus ex vacuo?
dilation of the ventricular system and a compensatory increase in CSF volume secondary to loss of brain parenchyma
What is a subfalcine hernation?
unilateral or asymmetric expansion of cerebral hemisphere displaces the cingulate gyrus under the falx cerebri
What happens in a tentorial hernation?
medial aspect of temporal lobe (hippocampus) herniates over the tentorium cerebelli
What is tonsillar herniation?
displacement of cerebellar tonsila through the foramen magnum
What is the consequences of tonsillar hernation?
brainstem compression and vital respiratory centresi nthe medulla
What is a consequence of tentorial herniation?
compression ipsilateral CNIII and its parasympathetic fibres
What is a consequence of subfalcine hernation?
compression of the anterior cerebral artery and weakness and /or sensory loss in leg
What are the features of an ICP induced headache?
worse on lying down; coughing; sneezing and straining
Where do tumours o the brain in children arise?
mostly below the tentorium cerebelli
Where do CNS tumours in adults tend to arise?
above the tentorium cerebelli
What are hte most common origins of brain metastates?
breast; bronchus; kidney; thryoid; colon and melanoma
What is the most common priamry malignant intracranial tumour in adults and children?
astrocytoma
what is the second most common malignant primary intracranila tumour in children?
medulloblastoma
hwat is the most common primary benign intracranial tumour in adults?
meningioma
What is the most common benign intracranial tumour in children?
craniophayrngioma
What type of astrocytoma do only children get?
grade 1 pilocytic astroctyoma
What do tumour cells relase that leads to neoangiogenesis?
VEFG secretion
Where are medulloblastomas found?
midline of the cerebellum
What is the treatment for medulloblastoma
is very radiosensitive- radiotherpay
What do medulloblastomas look like histopathologically?
undifferentiated embryonic/fetal cells
What tends to cause single abscesses?
local extension or direct implantation- tend to occur adjacent to source
what causes multiple brain abscesses?
haematogenous spread
Where can abscesses locally ectend from?
chronic otitis media; mastoiditis; paranasla sinusitis
How does e.coli appear on gram stain?
gram ive rods
How does h.influenzae appear on gram stain?
gram negative cocco-baciili
How does neisterria meningitides appear on gram stain?
gram negative diplococci
How does strep. pneumoniae appear on gram stain?
gram +ve cocci in chains
How does listeria monocytogenes appear on gram stain?
gram +ve rods
What happens with high veolcity head injury?
cavitation occurs- small bubbles appearing at low pressure
How are non-missile injuries caused?
sudden acceleration and/or deceleration
What are primary injuries to the brain?
shear injury to axons and contusions due to compressive strain, cavitation or surface lacerations of brain parenchyma
What is a linear skull #?
striaght sharp # line, that may cross sutures(diastatic #)
WHat is a compound skull #?
associated with full thickness scalp lacs
What does a linear # increase the chance of?
a haematoma being present
What are coup and contracoup injuries?
coup injury occurs at point of impact whereas contracoup occur diametrically opposite the point of impact
Are coup or contracoup injuries usually worse?
contracoup
What is the most importnant type of brain damage due to blunt injury?
diffuse axonal injury
what is diffuse axonal injury?
widespread disruption of axons due to shear strains tearing axons at the immediate time of acceleration/deceleration
Wher does diffuse axonal injury most commonly happen?
in central structures due to cerebral hemispheres moving a different rates relative to each other when exposed to forces
Waht is the pathological hallmark of diffuse axonal injury?
axonal bulbing and blebbing of the truncated axons
What is a burst lobe?
a gross contusion that involves disruption of much of the frontal and temporal lobes and is associated iwth a significant degree of haemorrhage
Why are the elderly more at risk of subdural haemorrhage?
age related strophy of hte brain puts more pressure on the briding veins and brain is more mobile in cranium meaning higher chance of rupture of one of these bridging veins
What are the chronic subdural haemorrhages composed of?
liquefied blood/yellow-tinged fluid separated from inner surface of dura mater and underlying brain by a neomembrane (granulation tissue and mature collagen)
