Neurological Conditions

Question 1

diagnosis of squint

Answer 1

1. corneal reflection - should fall centrally and symmetrically on corneas
2. cover test

Question 2

cover test and eccentric fixation

Answer 2

the cover test relies on the ability to fixate, so if there is eccentric fixation, the deviating eye will not move to take up fixation

corneal reflection will show malalignment

Question 3

causes of eccentric fixation

Answer 3

foveal vision can be so poor that it is not used for fixation

Question 4

convergent squint

Answer 4

esotropia

• eye is too far in so moves outward

Question 5

who is esotropia seen in

Answer 5

children commonly, can be due to hypermetropia

Question 6

divergent squint

Answer 6

exotropia

occurs in older children and are often intermittent

Question 7

paralytic squint

Answer 7

diplopia is worst on looking in th direction of the pull of the paralysed muscle

often sudden onset

Question 8

monocular diploplia

Answer 8

rare, occurs with cataracts or corneal scars

Question 9

hypertropia

Answer 9

the eye is too high so moves downwards on cover test - vertical diplopia

converse for hypotropia

Question 10

oculomotor palsy

Answer 10

eye looking down and out

ptosis, proptosis (due to reduced recti tone)

fixed pupillary dilation

Question 11

causes of CNIII palsy

Answer 11

microvascular

tumour

ANEURYSM

MS - demyelination

congenital cavernous sinus lesions

superior orbital fissure syndrome

Question 12

what is the classical location of an aneurysm causing oculomotor palsy

Answer 12

posterior communicating artery

Question 13

what are the actions of the superior oblique muscle

Answer 13

intorsion, depression in adduction and weak abduction

Question 14

trochlear nerve palsy

Answer 14

diplopia and the patient may hold their head tilted (ocular torticollis)

the eye looks upwards on adduction, and cannot look in and down

Question 15

bilateral trochlear nerve palsy

• presentation and cause

Answer 15

results in torsion and chin depression (as eyes are looking too far up)

can be cause by blunt head trauma

Question 16

cause of trochlear nerve palsy

Answer 16

microvascular (diabetes - 30%)

CONGENITAL - presents in adulthood due to decompensated ability to overcome vertical deviation

tumour

TRAUMA - 30%

Question 17

abducens nerve palsy

Answer 17

horizontal plane diplopia, worse when looking in the distance (this uses lateral rectus to abduct the eye)

eye is medially deviated and cannot move laterally from the midline

Question 18

causes of CNVI palsy

Answer 18

microvascular

SOL/tumour causing raised ICP (papilledema may be present)

trauma to base of skull

congenital

multiple sclerosis

Question 19

what is the most common cause of CNVI palsy

Answer 19

The nerve leaves the brainstem at the level of the pons and then runs upwards and over the petrous temporal bone. Raised ICP can stretch the nerve and hinder its function causing a CNVI palsy. This is called a false localising sign

Question 20

treatment of CNVI palsy

Answer 20

botulinum toxin can eliminate the need for surgery in selected VI palsies

Question 21

Inter-Nuclear Ophthalmoplegia

Answer 21

• The MLF facilitates conjugate eye movements on lateral gaze.
• Abduction is normal in either eye, whereas adduction is impaired, resulting in dissociation of eye movements
• When each eye is tested independently by covering the other eye, medial rectus function is shown to still be present.
• E.g. when an attempt is made to gaze contralaterally, the affected eye adducts minimally, whilst the unaffected eye abducts with nystagmus (repetitive, uncontrolled movements).

Question 22

what is the main cause of INO

Answer 22

injury/dysfunction in the medial longitduinal fasciciulus

Question 23

how does the patient with INO usually present

Answer 23

dont usually complain of diplopia

Question 24

MLF

Answer 24

found in the brainstem and is a set of crossed fibres formed of both ascending and descending fibres that links CNIII, IV and VI (and CNVIII) to integrate the movements of the eyes, and head

Question 25

what is the likely cause in young patients with bilateral INO

Answer 25

multiple sclerosis - demyelination of nerves in brain and spinal cord

Question 26

what is a possible cause of INO in older patients with one sided lesions

Answer 26

stroke