Nerve Palsies

Question 1

Abduction issues are often as a result of an issue with which muscle and which nerve?

Answer 1

Lateral rectus

Abducens nerve

Question 2

For which reasons may the abducens nerve fail to fucntion correctly?

Answer 2

1. Microvascular causes
2. Raised ICP
3. Tumour
4. Congenital

Question 3

Why does raised ICP cause the abducens nerve to often fail?

Answer 3

It is compressed onto the petrous tip of the temporal bone

Question 4

How will a fourth nerve palsy present?

Answer 4

Reduced depression in adduction

Question 5

With which nerve palsy will a head tilt often be seen and why?

Answer 5

Trochlear

Attempted correction of double vision

Question 6

What are the causes for a 4th nerve palsy?

Answer 6

1. Congenital (most common)
2. Microvascular
3. Tumour
4. Trauma

Question 7

How does a 3rd nerve palsy present?

Answer 7

Eye down and out

Question 8

What are the causes for a 3rd nerve palsy?

Answer 8

1. Microvascular
2. Tumour
3. Aneurysm (often life threatening)
4. Multiple sclerosis
5. Congenital

Question 9

Which vessel is often affected by aneurysm in a 3rd nerve palsy?

Answer 9

Posterior communicating artery

Question 10

The following clinical signs are indicative of what?

1. Pain in the back of the head
2. Large pupil
3. Ptosis

Answer 10

Posterior communicating artery aneurysm

(causing a third nerve palsy)

Question 11

What causes homonymous hemionopia?

Answer 11

Damage to temporal nerve fibres from one eye and nasal fibres from the other eye

(this happens after the optic chiasm)

Question 12

What can can cause optic nerve defects?

Answer 12

1. Ischaemic optic neuropathy
2. Optic neuritis
3. Tumours

Question 13

What is internuclear ophthalmoplegia?

Answer 13

The affected eye cannot abduct

The other eye abducts but with nystagmus

Question 14

What can cause internuclear ophthalmoplegia?

Answer 14

1. MS
2. Vascular causes
3. Many others

Question 15

How quickly is vision lost with optic neuritis?

Answer 15

Gradually

Question 16

What may be the cause for an visual field defect originating at the optic chiasm?

Answer 16

1. Pituitary tumour
2. Craniopharyngioma
3. Meningioma

Question 17

Which type of defect will a optic chiasm problem induce?

Answer 17

Bi-temporal field defect

Question 18

What are the main causes for visual field defects originating in the optic tracts and radiations?

Answer 18

1. Tumours
2. Demyelination
3. Vascular abnormalities

Question 19

Which type of visual field defects are associated with the optic tracts and radiations?

Answer 19

Homonomous defects

(sometimes quadrantanopia)

Question 20

What are the main causes for a visual field defect originating in the occipital cortex?

Answer 20

1. Vascular disease
2. Demyelination

Question 21

How do visual field defects originating in the occipital cortex differ from those which originate in the optic tract/radiations?

Answer 21

Macula is spared