Cranial nerve examination

Question 1

CN-1

Answer 1

Olfactory, sensory
Any change in sense of smell

Question 2

CN-2

Answer 2

Optic - sensory
Visual acuity

Question 3

CN-3

Answer 3

Occulomotor - motor
EOM except superior oblique and lateral rectus
Pupillary constriction

Question 4

CN-4

Answer 4

Trochlear - motor
Superior oblique

Question 5

CN-5

Answer 5

Trigeminal - mixed
Sensation to face
Muscles of mastication
Jaw-jerk and corneal reflex

Question 6

CN-6

Answer 6

Abducens - motor
Lateral rectus

Question 7

CN-7

Answer 7

Facial nerve - mixed
Muscles of facial expression, stapedius muscle
Taste - anterior two-thirds of tongue

Question 8

CN-8

Answer 8

Vestibulocochlear - sensory
Balance and hearing

Question 9

CN-9

Answer 9

Glossopharyngeal - mixed
Sensation to pharynx, posterior third of tongue
Motor to stylopharyngeus

Question 10

CN-10

Answer 10

Vagus - mixed
sensation to pharynx and larynx
Muscles of pharynx, larynx and palate

Question 11

CN-11

Answer 11

Accessory - motor
Trapezius, SCM

Question 12

CN-12

Answer 12

Hypoglossal - motor
Muscles of the tongue

Question 13

Corneal reflex

Answer 13

Afferent - CN5
Efferent - CN7

Question 14

Jaw-jerk reflex

Answer 14

Afferent - CN5
Efferent - CN5

Question 15

gag reflex

Answer 15

Afferent - CN9 (glossopharyngeal)
Efferent - CN10 (vagus)(

Question 16

Eye exam process

Answer 16

Visual acuity
Visual fields
Fundoscopy

Pupils - size, reactivity (direct and consensual), RAPD
Movements
Accommodation

Question 17

Causes of RAPD

Answer 17

Optic nerve disease:
Demyelination - Multiple sclerosis, Neuromyelitis optica spectrum disorder, anti-MOG
Ischaemia - including GCA
Compression - orbital tumours, thyroid eye disease
Other optic nerve inflammation: sarcoidosis, SLE, sjogrens

Eye disease:
Retina - ischaemia (retinal artery or vein), retinal detachment,
Other - intra-occular tumour, glaucoma

Question 18

Causes of absent light reflex with preserved accommodation reflex

Answer 18

Midbrain lesion - Argyll Robertson pupil of syphilis
Ciliary ganglion lesion - Adie’s pupil

Question 19

Types of eye movements

Answer 19

Pursuit - following a moving object (cerebellum and brainstem)
Saccadic - rapid movement to fix on an object (frontal lobe, brainstem, cerebellum)
Convergence - midbrain
Vestibulo-occular reflex - compensate for movements of the head to remain fixed on a target (vestibular organs, cerebellar and vestibular nuclei)

Question 20

Six eye muscles

Answer 20

Superior rectus
Lateral rectus
Inferior rectus
Superior oblique
Medial rectus
Inferior oblique

Question 21

Features of third nerve palsy

Answer 21

complete or partial ptosis
down and out eye
dilated pupil, unreactive to direct light and accommodation

Question 22

causes of third nerve palsy

Answer 22

Central causes: brainstem lesions (tumours, demyelination, vascular)
Peripheral causes: compressive lesions (aneurysm, usually posterior communicating artery), tumour, basal meningitis, nasopharyngeal carcinoma, orbital lesions. Ischaemia or infarction, migraine

Question 23

features of fourth nerve lesion

Answer 23

paralysis of the superior oblique muscle (causes weakness of downward movement)

Question 24

causes of fourth nerve lesion

Answer 24

idiopathic or trauma

Question 25

Features of sixth nerve lesion

Answer 25

failure to abduct eye

Question 26

causes of sixth nerve lesion

Answer 26

bilateral lesions - wernicke's encephalopathy, mononeuritis multiplex, raised intracranial pressure unilateral lesions - idiopathic, trauma related, vascular lesion, raised intracranial pressure, diabetes

Question 27

What distinguishes supranuclear palsy from cranial nerve lesions

Answer 27

1. both eyes affected 2. pupils may be fixed 3. Usually no diplopia 4. reflex eye movements are usually intact (flexing / extending the neck)

Question 28

PSP eye findings

Answer 28

loss of vertical gaze then later horizontal gaze associated with extrapyramidal signs, neck rigidity, dementia

Question 29

Localising lesions - unilateral 3, 4, V1 and 6 nerves

Answer 29

cavernous sinus involvement

Question 30

Localising lesions - unilateral 5, 7 and 8 lesions

Answer 30

cerebellopontine angle lesion

Question 31

Localising lesions - unilateral 9, 10 and 11

Answer 31

Jugular foramen lesion

Question 32

Localising lesions - bilateral 10, 11, 12

Answer 32

Bulbar palsy - if lower motor neurone changes are present Pseudobulbar palsy - if upper motor neurone signs present