Neurological Conditions Flashcards
Name cranial nerve VI
Abducens
What muscle does CN VI supply?
Lateral rectus muscle
How will patients with a CN VI palsy present?
Unable to abduct their eye properly and it will turn inwards in primary position
What causes a CN VI palsy?
> 50 years old - microvascular pathology
<50 years old - increased ICP, tumour, congenital, demyelination
Why is CN VI susceptible to compression?
It travels over the petrous apex of the temporal bone right next to the brain
Name cranial nerve IV
Trochlear
What muscle does the trochlear nerve supply?
Superior oblique
How will a patient with a CN IV palsy present?
Abnormality on depression in adduction and eyes will lie at the wrong angle (weak incyclo-torsion)
How will patients compensate for the weak incyclo-torsion?
Tilt their head
What causes a CN IV palsy?
Most common - congenital
Microvascular, tumour, closed head trauma
Why is CN IV susceptible to damage?
It is long and thin
Name cranial nerve III
Oculomotor
How will patients with a CN III palsy present?
Down and out ocular position with a dilated pupil and ptosis
What can cause a CN III palsy?
Aneurysm, tumour, microvascular pathology, MS, congenital
What is the significance of a dilated pupil in suspected CN III palsy?
If the pupil is involved this signifies peripheral compression on the nerve and more serious pathology. If pupil is normal then microvascular pathology is most likely.
Describe internuclear ophthalmoplegia
The eyes have to work together, CN III and CN VI connect at the medial longitudinal fasciculus, pathology leads to eye problems
What are the signs of internuclear ophthalmoplegia?
Failed ipsilateral adduction with a nystagmus in the other eye
What can cause internuclear ophthalmoplegia?
MS, vasculopathy, tumour
Describe supranuclear ophthalmoplegia
Inputs from higher brain centres send signals to the eyes telling them how to respond to stimuli this can be disrupted by a stroke or demyelination
Describe optic neuritis
Progressive unilateral visual loss with pain behind the eye (on movement) due to inflammation of the nerve
What are the symptoms of optic neuritis?
Blurred vision, colour desaturation, central scotoma, pain on eye movement
What disease is associated with optic neuritis?
MS
How long does optic neuritis take to clear up?
2 weeks
What follow optic neuritis?
Atrophy
What usually causes optic neuropathy?
Depends on age but usually ischaemia by CVD
Describe altitude defect
Superior and inferior halves of the optic head have different blood supplies so in ischaemia only one half of the visual field may be impacted
What can cause disruption to the optic chiasm?
Pituitary tumour, craniopharyngioma, meningioma
How do optic chiasm pathologies present?
Bitemporal hemianopia
What causes optic tracts and radiations pathology?
Tumours, demyelination, vascular anomalies
How do optic tract/radiation pathologies present?
Homonomous, no macular sparing, incongruous quadrantanopia
What causes occipital cortex pathology?
Stroke or demyelination
How do occipital cortex pathologies present?
Homonomous, macular sparring congruous
