Raised ICP

Question 1

what is raised ICP

Answer 1

increase in pressure within the cranial cavity caused by an increased pressure in fluid surrounding the brain or increase in pressure within the brain itself. Can be acute or chronic.

Question 2

What is the monro-kellie hypothesis

Answer 2

Pressure volume relationship that aims to keep a dynamic equilibrium. ie the intracranial volume in adults in 1700- 1400 brain tissue, 150 CSF and 150 blood so a decrease in any should be compensated with an inc in another

Question 3

what is CN II

Answer 3

An extension of the brain covered in meninges- optic nerve

Question 4

what are the meninges

Answer 4

Protective covering of the brain and spinal cord- dura mater, arachnoid mater and pia mater

Question 5

What is the dura mater? Features and innervation.

Answer 5

Outermost layer of the meninges- directly underneath the bones of the skull and vertebral column. thick and tough. contains a dural venous sinuses- responsible for the venous vasculature of the cranium and drains into internal jugular veins.
Innervated by trigeminal nerve (V1, V2 and V3)
Vasculature: middle meningeal artery and nerve

Question 6

What is the arachnoid mater?

Answer 6

middle layer directly underneath the arachnoid dura mater. It is avascular and has no innervation- consists of sheets of connective tissue.

Question 7

What is the subarachnoid space

Answer 7

Underneath the arachnoid layer there is a space filled with CSF to cushion the brain. there are small projections of arachnoid mater into the dura mater called arachnoid granulations that allow CSF to re-enter circulation via the dural venous sinuses

Question 8

What is the Pia mater

Answer 8

Underneath the sub arachnoid space and thin. It is tightly adhered to the brain and spinal cord and follows the contours of gyri and fissures. HIghly vascularised.

Question 9

What is the tentorial notch

Answer 9

allows the passage of brainstem

Question 10

What is the flex cerebri

Answer 10

descends vertically in the human brain between cerebral hemispheres. its a double fold of dura mater through the inter hemispheric fissure.

Question 11

What is the tentorium cerebelli

Answer 11

Dura mater that is perpendicular to the flex cerebri (ie its in the axial plane) and divides it into superior and inferior compartments.

Question 12

What are the ventricles in the brain lined with?

Answer 12

ependymal cells which form a choroid plexus and produce CSF

Question 13

What are the ventricles derived from?

Answer 13

Lumen of the neural tube

Question 14

How many ventricles are there and what are they called?

Answer 14

4:
right and left lateral ventricles
3rd ventricle
4th ventrcile

Question 15

Lateral ventricles structure

Answer 15

right and left lateral ventricles
They have horns which project into the temporal, occipital and frontal lobes.
volume of lateral ventricle increases with age

Question 16

What connects the lateral and 3rd ventricle

Answer 16

foramen of monro/ interventricular foramina

Question 17

Location of the 3rd ventricle

Answer 17

between the right and left thalamus- midline in the diencephalon

Question 18

what connects the 3rd and 4th ventricles

Answer 18

Cerebral aqueduct

Question 19

Location of the 4th ventricle

Answer 19

in the brainstem @the junction between the pons and medulla oblangata

Question 20

How is CSF drained from the brain

Answer 20

Draingae occurs in the subarachnoid space. Arachnoid granualtions project into the dura mater allowing CSF to drain into the dural venous sinuses and then into the Internal jugular veins

Question 21

How does CSF drain from the 4th ventricle

Answer 21

via the apertures: 1 median aperture and 2 lateral aperture

Question 22

Effects of raised ICP on the optic nerve

Answer 22

will compress the optic nerve in the subarachnoid space (also will compress the central artery and vein of the retina). can lead to a bulging or swollen optic disc (papillodema) and visual symptoms.

Question 23

What do the parasympathetic fibres of CNIII innervate?

Answer 23

Sphincter pupillae fibres and ciliary msucles of the eye

Question 24

What are the effects of compression of CNIII

Answer 24

paralysis of somatic motor innervation: extraocular muscles

paralysis of parasympathetic innervation of sphincter pupillae

Question 25

Clinical signs of CNIII injury

Answer 25

• no /slow pupillary light reflexes
• dilated pupil due to unopposed action of dilator pupillae
• ptosis- due to loss of LPS innervation
• postion of eye- looking down and out due to unopposed action of LR and SO

Question 26

3 main causes of oculomotor nerve lesion

Answer 26

• increasing ICP
• aneurysm of posterior cerebral artery
• cavernous sinus infection

Question 27

What are the effects of CN IV damage

Answer 27

paralysis of superior oblique so the IO is unopposed. eye cannot move inferomedially

Question 28

Presentation of CNIV damage

Answer 28

diplopia especially when looking down eg reading or going down stairs
Pateint may develop head tilt

Question 29

Most common cause of CN IV damage

Answer 29

microvascular damage from DM or HT

Question 30

Function of abducens nerve (CN VI)

Answer 30

somatic motor innervation of lateral rectus

Question 31

Presentation of damage to CN VI

Answer 31

medial rotation and diplopia

Question 32

what is the choroid plexus

Answer 32

network of capillaries which filter blood to from CSF