Papilloedema Flashcards
papilloedema vs swollen optic disc?
swollen optic disc = disc swelling secondary to any cause
papilloedema = swollen disc secondary to raised intracranial pressure
what presentation may indicate a raised intracranial pressure?
bilateral optic disc swelling
4 components of optic nerve examination?
visual acuity
pupil exam
visual field assessment
colour vision
the optic nerve is an extension of the brain, what confirms this?
optic nerve is covered by meninges
how does increased intra cranial pressure affect the optic nerve and how?
subarachnoid space around optic nerve is continuous with optic subarachnoid space around brain
increased pressure in subarachnoid space is transmitted to the optic nerve
this causes interruption of axoplasmic flow and venous congestion
= swollen discs
total intracranial pressure is the sum of what 3 components?
brain (80%)
blood (10%)
cerebrospinal fluid (CSF) = 10%
how do the 3 components of intracranial pressure interact?
the sum must remain constant
therefore an increase in one variable will result in a decrease in another etc as the cranium is rigid and cannot expand
potential complications of increase in pressure?
compression of vessels ultimately causing global brain ischaemia/swelling with herniation through foramen magnum, brainstem compression and death
what is auto-regulation?
the inability of the brain to tolerate hypo/hyperperfusion
brain requires constant flow of blood over range of pressures
how can malignant hypertension cause pailloedema?
poorly understood
possibly leakage and ischaemia of arterioles supplying the optic disc which causes swelling/haemorrhage around the disc
do all patients with papilloedema have a space occupying lesion?
no
but disc swelling can be a sign of another serious pathology
so always check blood pressure
name 5 functions of CSF
maintains stable extracellular environment for the brain buoyancy provides mechanical protection waste removal nutrition
where is CSF produced?
mostly in lateral ventricles by choroid plexus
3 general causes of raised intracranial pressure?
obstruction of CSF circulation
overproduction of CSF
inadequate absorption
how can idiopathic intracranial hypertension cause papailloedema?
stenosis of transverse cerebral sinuses
increased abdominal pressure (due to obesity)
possible role of vitamin A
possible microemboli in sagittal sinus blocks CSF absorption
