Cranial Nerve Disorders Flashcards
What Cranial nerve(s) would be affected by a midbrain lesion?
Oculomotor Bilaterally
What Cranial nerve(s) would be affected by a lesion in the Sup Orbital fissure?
Oculomotor
Trochlear
Abducens
Opthalmic (V1)
What Cranial nerve(s) would be affected by a lesion in the Pontomedullary junction?
VI/VII/VIII
What Cranial nerve(s) would be affected by a lesion at the cerebellopontine angle?
Trigeminal & Vestibulocochlear
Describe some lesions that could damage a cranial nerve?
ISchaemia or tumour within the brain
Meningitis or SAH whilst crossing the subarachnoid space
Skull tumours outside the cranium
Name a condition that can cause optic neuritis?
MS
What are the symptoms of optic neuritis?
- Monocular visual loss
- Pain on eye movement
- Reduced visual acuity & Colour vision
- Papilloedema
What could cause a dilated pupil?
Naturally:
- Youth
- Dim lighting
- Anxiety or Excitement
Unnaturally:
- Mydriatic eye drops
- Amphetamines/cocaine
- third nerve palsy
- Brain death
What could cause a constricted pupil?
Naturally:
- Old Age
- Bright Light
Unnaturally:
- Miotic Eye Drops
- Opiates
- Horners Syndrome (comes with anhydrosis and ptosis)
Define horner’s Syndrome
Something cutting off or compressing the sympathetic innervation to the eye and face (unilateral)
Can be intracranial lesions at the point where the sympathetic fibres leave thalamus and enter brainstem or in spinal cord or after they leave the spinal cord (e.g. pancoast tumour)
It causes:
- Miosis (Constricted pupil)
- Anhydrosis
- Ptosis
What type of cranial nerve palsies can cause eye movement disorders?
- Isolated nerve palsy to III, IV or VI
- Any combination of the above
- Supranuclear gaze palsy
- Nystagmus (VIII)
What is a supranuclear gaze palsy?
An inability to look in a particular direction due to impairment in the cerebrum (Above the cranial nerve nuclei)
What could cause an Isolated III nerve palsy?
Microvascular conditions like diabetes or hypertension could cause a painless, pupil sparing III palsy
Compressive conditions like raised ICP or a Post. Comm. Art. Aneurysm could cause a a painful III palsy with a dilated pupil
What could cause an isolated VI nerve Palsy?
- Idiopathic
- Diabetes
- Meningitis
- Raised ICP
What are the common causes of pathological nystagmus?
- Congenital (may never notice visual problems)
- Visual impairment
- Vestibular problems
- Brainstem disease (Affecting VIII)
- Cerebellar Disease
- Alcohol
- Toxic Med