Anatomy 6 - Raised ICP

Question 1

What is raised intracranial pressure?

Answer 1

Increase in pressure within the cranial cavity (chronic or acute)e

Question 2

What causes raised ICP?

Answer 2

An increased pressure in fluid surrounding the brain or an increase in pressure within the brain itself e.g. brain tumour, head injury, hydrocephalus, meningitis, stroke

Question 3

What is hydrocephalus?

Answer 3

Increased fluid around the brain

Question 4

Why is ICP such a serious problem?

Answer 4

It can cause damage to the brain and the spinal cord

Question 5

How does the intracranial volume normally fluctuate?

Answer 5

It is normally constant

Question 6

What is the main idea of the Monro-Kellie Hypothesis?

Answer 6

3 things exist within the fixed minions of the skull: blood, CSF and the brain - an increase in any one component must lead to a decrease in one (or both) of the other components, otherwise intracranial pressure will increase

Question 7

In what way can raised ICP damage the brain and spinal cord?

Answer 7

Causes damage to tissues, shifts in tissues, herniation and constriction of blood vessels

Question 8

What kind of visual/ eye problems can increased ICP cause?

Answer 8

Transient blurred vision
Double vision
Loss of vision
Transient flickering
Decreased colour perception
Pupillary changes
Papilloedema (swelling of optic disc due to increased ICP)

Question 9

What is the name of the membranes that line the skull and vertebral canal and enclose the brain and spinal cord?

Answer 9

meninges

Question 10

What are the 3 layers of meninges?

Answer 10

Dura
Arachnoid
Pia

Question 11

Name of the space between the arachnoid and pia?

Answer 11

Sub-arachnoid space

Question 12

What is the toughest layer of the meninges?

Answer 12

Dura mater

Question 13

What provides the sensory supply to dura mater?

Answer 13

CN V

Question 14

What does the dura mater enclose?

Answer 14

The dural venous sinuses

Question 15

What is the name for the projections of arachnoid membrane into the dural sinuses?
What is the purpose of this?

Answer 15

Arachnoid granulations

To allow CSF entrance from the subarachnoid space into the venous system

Question 16

What is contained within the subarachnoid space?

Answer 16

Circulating CSF and blood vessels

Question 17

Describe the appearance of the pia?

Answer 17

Adherent to the brain with vessels and nerves entering or leaving

Question 18

What is the purpose of the subarachnoid space?

Answer 18

Completely surrounds both brain and spinal cord and contains circulating CSF = cushions and protects

Question 19

Where is CSF produced?

Answer 19

In the choroid plexus of the ventricles

Question 20

Where is CSF reabsorbed?

Answer 20

Into the dural venous sinuses via arachnoid granulations

Question 21

At what levels can CSF be drawn during a lumbar puncture?

Answer 21

L3/4 or L4/5 IV disc level

Question 22

At what level does the subarachnoid space end/ close?

Answer 22

S2

Question 23

Name of the sinus within the cranium that can be seen surrounding the brain when it is cut longitudinally in half?

Answer 23

Superior sagittal sinus

Question 24

What ventricle is located within the right cerebral hemisphere?

Answer 24

Right lateral ventricle

Question 25

What ventricle is located in the midline within the diencephalon?

Answer 25

The 3rd ventricle

Question 26

What part of the spinal cord is continuous with the 4th ventricle?

Answer 26

The central canal

Question 27

Where is the 4th ventricle located?

Answer 27

Between the cerebellum and pons

Question 28

What connects the third and 4th ventricles in the midline?

Answer 28

The cerebral aqueduct

Question 29

Where is the choroid plexus located?

Answer 29

Within the lateral and third ventricle

Question 30

How does raised ICP affect the optic nerve?

Answer 30

Raised ICP will be transmitted along the subarachnoid space in the optic nerve sheath compressing the optic nerve and can lead to bulging or swollen optic discs

Question 31

How does raised ICP affect the other structures of the retina (apart from the optic nerve)?

Answer 31

Will also compress the central artery and vein

Question 32

What type of damage is the oculomotor nerve susceptible to?

Answer 32

Compression | Tentorial herniation

Question 33

What effect can damage to the oculomotor nerve have on the eye? (3)

Answer 33

Paralysis of somatic motor innervation Paralysis of parasympathetic innervation of the sphincter of the pupil Ptosis

Question 34

What is the name of the triangular opening in the tentorium cerebelli through which the brainstem extends?

Answer 34

Tentorial notch

Question 35

Name of the 4 folds of dural mater that divides up the cranial cavity?

Answer 35

Falx cerebri Tentorium cerebelli Falx cerebelli Diaphragm sellae

Question 36

What nerve can be damaged if raised ICP causes medial temporal love to herniate through tentorial notch?

Answer 36

Oculomotor nerve

Question 37

What type of damage is the trochlear nerve susceptible to?

Answer 37

Stretching, compression

Question 38

What symptom can damage to the trochlear nerve cause? | Why?

Answer 38

Paralysis of superior oblique muscle = inferior oblique is unopposed -> eye cannot move inferomedially = diplopia when looking down

Question 39

What type of damage is the abducent nerve susceptible to?

Answer 39

Damage by stretching

Question 40

What eye movements cannot occur if the abducent nerve is damage?

Answer 40

Eye cannot move laterally in horizontal plane (due to paralysis of lateral rectus muscle)

Question 41

What is the name of the sign in infants/ children where the eyes appear driven downward, the sclera may be seen between the upper eyelid and iris and part of the pupil may be covered by the lower eyelid? What is this a sign of?

Answer 41

Sunset sign | Hydrocephalus

Question 42

What dural fold is located right down the centre between the 2 hemispheres?

Answer 42

Falx cerebri

Question 43

What dural fold separates the cerebellum from the rest of the brain?

Answer 43

Tentorium cerebelli

Question 44

What dural fold separates the 2 hemispheres of the cerebellum?

Answer 44

Falx cerebelli

Question 45

How many grades of papilloedema are there?

Answer 45

5

Question 46

What does grade I papilloedema look like?

Answer 46

C-shaped halo around the disc

Question 47

What does grade II papilloedema look like?

Answer 47

Circumferential halo with blurred edges

Question 48

What does grade III papilloedema look like?

Answer 48

Vessels on edge of disc disappear

Question 49

What does grade IV papilloedema look like?

Answer 49

loss of major vessels on disc

Question 50

What does grade V papilloedema look like?

Answer 50

Extremely blurry edges of disc with total or partial obscuring of vessels on disc