Raised Intracranial Pressure

Question 1

what is raised intracranial pressure

Answer 1

an increase in pressure in the cranial cavity

Question 2

what are some causes of raised intracranial pressure

Answer 2

head injury
space occupying lesions (tumour, abscess, haemorrhage)
Hydrocephalus
Meningitis

Question 3

what is a consequence of unrelieved raised intracranial pressure

Answer 3

brain damage

Question 4

what are the meninges

Answer 4

3 layers that surround the brain

Question 5

what are the names of the 3 meninges

Answer 5

Dura mater
Arachnoid mater
Pia mater

Question 6

what is the Dura Mater

Answer 6

tough outer meningeal layer

means “tough mother”

Question 7

what are the 2 layers of the Dura Mater

Answer 7

Endosteal layer (lines bone)

Meningeal layer (layer under the endosteal layer surrounding the brain)

Question 8

what is found in-between the endosteal and meningeal layers of the Dura Mater when the separate

Answer 8

blood (forms the dural venous sinuses)

Question 9

what is the arachnoid layer

Answer 9

spidery thin layer - just under the Dura Mater

“spider mother”

Question 10

what is the Pia Mater

Answer 10

single cell layer that completely surrounds the brain matter

“soft mother”

Question 11

what is a clinical sign of raised ICP seen in the eyes

Answer 11

Sunset sign

pressure affects the extra-ocular muscles so the whites of the eyes are visible above the pupil

Question 12

how does CFS drain into the venous system

Answer 12

via the arachnoid villi which penetrate into the dural venous sinuses

Question 13

what is the falx cerebra

Answer 13

a double layer or meninges in the centre of the brain (because they come down from both hemispheres and meet in the middle)

Question 14

what is the horizontal layer of the meninges called

Answer 14

Tentorium cerebri

Question 15

what is the tentorial notch

Answer 15

where the brain stem passes through the meninges (with raised ICP the brain can be pushed down through the tentorial notch and squished)

Question 16

what are the ventricles

Answer 16

spaces between the meninges which are full of CSF

Question 17

How many ventricles are there

Answer 17

4

Lateral 2 ventricles
Third ventricle
Fourth ventricle

Question 18

where is CSF made

Answer 18

choroid plexus

Question 19

where does CSF go to after leaving the choroid plexus

Answer 19

into the lateral ventricles

Question 20

how does the CSF get from the lateral ventricles into the third ventricle

Answer 20

via the inter ventricular foramen

Question 21

how does CSF travel from the third to the fourth ventricle

Answer 21

via the cerebral aqueduct

Question 22

where does the CSF end up

Answer 22

central canal of the spinal cord

Question 23

how is CSF transported to the venous system

Answer 23

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

Question 24

what visual problems arise from raised ICP

Answer 24

Transient blurred vision 
Double vision 
Loss of vision 
Papillodema (optic disc swelling) 
Pupillary changes

Question 25

what covers the optic nerves making them part of the brain

Answer 25

meninges

• dura
• arachoind
• pia

Question 26

Why does raised ICP in the subarachnoid space affect the eye

Answer 26

because the subarachnoid space continues to into the back of the eyeball

Question 27

symptoms of papilloedema

Answer 27

transient visual obscuration 
greying out of vision 
transient flickering 
blurring of vision 
constriction of the visual field 
decreased colour perception

Question 28

how can CNIII be damaged by raised ICP

Answer 28

Compression

tentorial herniation

Question 29

what happens when CNIII is damaged

Answer 29

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

Question 30

what happens when the trochlear nerve is damaged (CNIV)

Answer 30

paralysis of the superior oblique

therefore the superior oblique is unposed and the eye cannot move down and in (so looks up and out)

Question 31

what happens when the abducens nerve is damaged (CN VI)

Answer 31

paralysis of the lateral rectus muscle

eye can’t move laterally leading to medial deviation of the eye