Raised intracranial pressure Flashcards
what is raised intracranial pressure
increased pressure within the cranial cavity
what can cause an increase in intracranial pressure
fluid surrounding the brain, due to brain tumour, head injury, hydrocephalus, meningitis, stroke
what 2 organs (kind of) can be damaged by raised intracranial pressure
spinal cord and brain
what factors make up the intracranial volume
brain, blood, CSF, other components
can the cranial cavity expand?
no- thus increase in pressure causes damage to tissues, herniation and constriction of blood vessels
what symptoms do 65-75% of patients present with in ICP
transient blurred vision, double vision, loss of vision, papilloedema, pupillary changes
what is the sing called where patients with hydrocephalus cannot look up
sunset sign
why does vision problems arise with increased intracranial pressure
compression of the optic nerve
what are th optic nerves covered in?
meninges
what are the 3 layers of the meninges
dura, arachnoid and pia
what is the space called between arachnoid and pia
sub- arachnoid space
what is enclosed between the dura layers?
dural venous sinuses
what cranial nerve supplies the dura mater?
CN V
what is contained within the subarachnoid space?
blood vessels and CSF
what does the pia layer attach on to
brain + vessels/ nerves
what does the subarachnoid space surround?
brain and spinal cord
where is CSF produced within the brain?
choroid plexus of the ventricles
where is the CSF reabsorbed after being made in the choroid plexus of the ventricles
dural venous sinuses via arachnoid granulations
what procedure can be used to access the sub arachnoid space
lumbar puncture at L3/4 or L4/5
what does the cerebral aqueduct do
connects the 3rd and 4th ventricles in the midline
where is the 4th ventricle
between the cerebellum and the pons
where is the 3rd ventricle?
in the midline within the diencephalon
what are the laterals and 3rd ventricles connected by
foramen of Munro
what 2 things does the CSF drain into
central canal and subarachnoid cisterns
what is the circulation of CSF in 8 steps
1- made in the choroid plexus in lateral and 3rd ventricles
2- then drain into right and left lateral ventricles
3- then the 3rd ventricle
then the cerebral aqueduct
4th ventricle
6- pass into central canal or subarachnoid cisterns/ space
7- then reabsorbed from subarachnoid space through arachnoid granulations
8- drain into dural venous sinuses
what 3 things will be compressed in the eye due to ICP
optic nerve, central artery and vein of retina
how could the oculomotor nerve be damaged
compression and tectorial herniation
what 4 muscles does the oculomotor nerve supply
medial recuts, superior rectus, inferior rectus, inferior oblique
is oculomotor nerve sympathetic or parasympathetic
parasympathetic (3,7,9,10)
if paralysis of oculomotor nerve, will the pupil be dilated or constricted?
dilated
so if oculomotor nerve is damaged, what eye position would the eye rest in
down and out (lateral rectus and superior oblique)
what muscle would cause ptosis
levator palpebrae superioris
what nerve would be damaged in paralysis of superior oblique
trochlear
what eye position can the eye not be in when superior oblique paralysis is present
inferomedial
what would you get in trochlear nerve palsy when trying to look down?
diplopia
