The Eye and Raised ICP Flashcards
What is raised intracranial pressure?
Increased pressure within the cranial cavity = may be chronic or acute
What causes raised intracranial pressure?
An increased pressure in the fluid surrounding the brain or an increase in pressure within the brain itself
What are some pathologies that may cause raised intracranial pressure?
Brain tumour, head injury, hydrocephalus, stroke, meningitis
What can raised intracranial pressure ultimately cause?
Damage to the brain or spinal cord = damages tissue, shifts tissues, leads to herniation, constricts blood vessels
What is the Monro-Kellie hypothesis?
The cranial compartment is inelastic and the volume inside the cranium is fixed
What do patients with raised intracranial pressure often present with?
Visual problems = transient blurred vision, double vision, loss of vision, papilloedema, pupillary change
What are the optic nerves (CN II)?
CNS tracts = not actually nerves in the traditional sense
What covers the optic nerves?
Meninges = dura, arachnoid, pia
What is the subarachnoid space?
Space between the arachnoid and pia = filled with CSF
Where is raised ICP transmitted along in order to compress the optic nerve?
Transmitted along the subarachnoid space in the optic nerve sheath
What structures are usually compressed alongside the optic nerves?
The central retinal artery and vein
What may happen to the optic discs due to raised intracranial pressure?
May swell or bulge (papilloedema)
What are the visual symptoms associated with a disturbance to CN II?
Transient visual obstruction, transient flicking, blurred vision, constriction of visual field, decreased colour perception
How may CN III be damaged by raised intracranial pressure?
Compression or tentorial herniation
What may occur if CN III is disturbed?
Paralysis of somatic motor innervation = 4 extra-ocular muscles and eyelid
Paralysis of parasympathetic innervation = sphincter of pupil
