The Eye & Raised Intracranial Pressure Flashcards
What is a raised ICP caused by and give examples.
Caused by an increased pressure in fluid surrounding the brain or an increase in pressure within the brain itself.
Examples: Brain tumour Head injury Hydrocephalus Meningitis Stroke
The intracranial volume is….
CONSTANT
List 5 symptoms a patient with raised ICP can experience.
Transient blurred vision
Double vision
Loss of vision (increased pressure can compress the artery or the optic nerve)
Papilloedema (swelling of the optic disc)
Pupillary changes
List the layers of the meninges.
Dura
Arachnoid
Pia
The space between the arachnoid and the pia is known as? and contains what?
The subarachnoid space which contains cerebrospinal fluid (CSF).
What are the meninges?
Protective coverings of the brain and spinal cord.
Describe the dura mater.
Toughest layer
Sensory supply from CN V
Encloses dural venous sinuses
Describe the arachnoid mater.
Arachnoid granulations
Describe the subarachnoid space.
Contains circulating CSF and blood vessels
Completely surrounds the brain and spinal cord
Is continous
Cushions and protects
If vessels in the subarachnoid space rupture, you can get a what?
Subdural haematoma
Describe the pia
Adheres to brain (and vessels and nerves entering or leaving)
Where is CSF produced?
Where is it reabsorbed?
In the choroid plexus of the ventricles.
Reabsorbed into the dural venous sinuses via the arachnoid granulations.
Where is a lumbar puncture done?
L3/4 or L4/5
Describe the circulation of CSF.
Secreted by the choroid plexus from the right and left lateral ventricles and some in the 3rd ventricle
It then moves via the cerebral aqueduct into the 4th ventricle
and then moves mainly into the subarachnoid space of the brain and spinal cord but some passes into the central canal
It is then reabsorbed from the subarachnoid space via the arachoid granulations
And moves into the dural venous sinuses
What is papilloedema?
Bulging or swollen optic discs
Where does the oculomotor nerve come off of?
The Midbrain
In what 4 ways is the oculomotor nerve susceptible to damage?
Compression
Tentorial herniation
Paralysis of parasympathetic innervation sphincter of pupil
Lose/slowness of pupillary light reflex,
The oculomotor nerve divides the cranial cavity into which 2 major regions?
Falx cerebri
Tentorium cerebelli
Where does the trochlear nerve come off of?
The back of the midbrain
Paralysis of the superior oblique muscle means the patient cannot look in which direction?
Down and out
The abducent nerve comes off of where?
The pons-medullary junction
Paralysis of the lateral rectus means what?
The eye cannot move laterally in the horizontal plane meaning there will be medial deviation of the eye
