Raised Intracranial Pressure Flashcards
what is raised intracranial pressure
an increase in pressure in the cranial cavity
what are some causes of raised intracranial pressure
head injury
space occupying lesions (tumour, abscess, haemorrhage)
Hydrocephalus
Meningitis
what is a consequence of unrelieved raised intracranial pressure
brain damage
what are the meninges
3 layers that surround the brain
what are the names of the 3 meninges
Dura mater
Arachnoid mater
Pia mater
what is the Dura Mater
tough outer meningeal layer
means “tough mother”
what are the 2 layers of the Dura Mater
Endosteal layer (lines bone)
Meningeal layer (layer under the endosteal layer surrounding the brain)
what is found in-between the endosteal and meningeal layers of the Dura Mater when the separate
blood (forms the dural venous sinuses)
what is the arachnoid layer
spidery thin layer - just under the Dura Mater
“spider mother”
what is the Pia Mater
single cell layer that completely surrounds the brain matter
“soft mother”
what is a clinical sign of raised ICP seen in the eyes
Sunset sign
pressure affects the extra-ocular muscles so the whites of the eyes are visible above the pupil
how does CFS drain into the venous system
via the arachnoid villi which penetrate into the dural venous sinuses
what is the falx cerebra
a double layer or meninges in the centre of the brain (because they come down from both hemispheres and meet in the middle)
what is the horizontal layer of the meninges called
Tentorium cerebri
what is the tentorial notch
where the brain stem passes through the meninges (with raised ICP the brain can be pushed down through the tentorial notch and squished)
what are the ventricles
spaces between the meninges which are full of CSF
How many ventricles are there
4
Lateral 2 ventricles
Third ventricle
Fourth ventricle
where is CSF made
choroid plexus
where does CSF go to after leaving the choroid plexus
into the lateral ventricles
how does the CSF get from the lateral ventricles into the third ventricle
via the inter ventricular foramen
how does CSF travel from the third to the fourth ventricle
via the cerebral aqueduct
where does the CSF end up
central canal of the spinal cord
how is CSF transported to the venous system
from the fourth ventricles, to the two lateral aperture, into the subarachnoid space then into the arachnoid villi and up into the superior sagittal sinus
what visual problems arise from raised ICP
Transient blurred vision Double vision Loss of vision Papillodema (optic disc swelling) Pupillary changes
what covers the optic nerves making them part of the brain
meninges
- dura
- arachoind
- pia
Why does raised ICP in the subarachnoid space affect the eye
because the subarachnoid space continues to into the back of the eyeball
symptoms of papilloedema
transient visual obscuration greying out of vision transient flickering blurring of vision constriction of the visual field decreased colour perception
how can CNIII be damaged by raised ICP
Compression
tentorial herniation
what happens when CNIII is damaged
paralysis of most of the extra-ocular muscles
paralysis of the constructor papillae
eye will look ‘down and out’’ as the lateral rectus and the superior oblique will still work
what happens when the trochlear nerve is damaged (CNIV)
paralysis of the superior oblique
therefore the superior oblique is unposed and the eye cannot move down and in (so looks up and out)
what happens when the abducens nerve is damaged (CN VI)
paralysis of the lateral rectus muscle
eye can’t move laterally leading to medial deviation of the eye
