Disorders of cranial nerves

Question 1

REVISION: what are the 12 cranial nerves

Answer 1

olfactory
optic
oculomotor
trochlear
trigeminal
abducens
facial
vestibulocochlear
glossopharyngeal
vagus
accessory
hypoglossal

Question 2

what are the 4 broad functions pf cranial nerves

Answer 2

special senses
ordinary sensation
control of muscle activity
autonomic functions

Question 3

what cranial nerves control special senses

Answer 3

Olfaction (I)

Vision (II)

Taste (VII, IX and X)

Hearing - and balance (VIII)

Question 4

what cranial nerves control ordinary sensation

Answer 4

Mainly the Vth (trigeminal nerve)

the ear from the VIIth (facial) and IXth (glossopharyneal) nerves

Question 5

what cranial nerves control muscle activity

Answer 5

Eye muscles – III (oculomotor), IV (trochlear) and VI (abducence) (LR6,SO4, rest 3)

Muscles of mastication – V (trigeminal)

Muscles of facial expression – VII (facial)

Muscles of larynx and pharynx – mainly X (vagus)

Sternomastoid and trapezius muscles - XI (accessory)

Question 6

what cranial nerves control autonomic functions (parasympathetic)

Answer 6

Pupillary constriction – III (oculomotor)

Lacrimation – VII (facial)

Salivation – submandibular and sublingual glands – VII (facial)

Salivation – parotid gland - IX (glossopharyngeal)

Vagal (X) input to organs in thorax and abdomen

Question 7

how do you test CNI

Answer 7

smell

unilateral or bilateral

Question 8

how do you test CNII

Answer 8

visual acuity
visual fields
pupillary reactions
fundoscopy
colour vision

Question 9

how do you test CNIII, IV and VI

Answer 9

ptosis
pupil of equal size
pupillary reactions
eye movements - vertical and horizontal

Question 10

how do you test CNV

Answer 10

sensation in ophthalmic, maxillary and mandicular divisions

power in the muscles of mastication

corneal reflex

jaw jerk

Question 11

how do you test CNVII

Answer 11

muscles of facial expression

corneal reflex

taste

Question 12

how do you test CNVIII

Answer 12

hearin
rinnies and webers tests

vestibular function - DIx-hallpike manoevre

untenbergers test - walk in place with eyes closed

Question 13

how do you test CNIX and X

Answer 13

movement of the palate
gag reflex
quality of speech
quality of cough

Question 14

how do you test CNXI

Answer 14

head turning and shoulder shrugging

sternomastoid and trapezius function

Question 15

how do you test CNXII

Answer 15

appearance, movement and power of tongue

Question 16

what CN are the afferent and efferent for the pupillary laugh reaction

Answer 16

afferent – II

efferent – III

Question 17

what CN are the afferent and efferent for the corneal reflex

Answer 17

afferent – V

efferent – VII

Question 18

what CN are the afferent and efferent for the jaw jerk reflex

Answer 18

afferent and efferent – V

Question 19

what CN are the afferent and efferent for the gag reflex

Answer 19

afferent – IX

efferent - X

Question 20

what CN nuclei are in the midbrain

Answer 20

III

IV

Question 21

what CN nuclei are in the pons

Answer 21

V

Question 22

what CN nuclei are in the ponto-medullary junction

Answer 22

VI
VII
VIII

Question 23

what CN nuclei are in the medulla

Answer 23

IX
X
XI
XII

Question 24

what might unusual combinations of cranial nerve signs indicate

Answer 24

chronic or malignant meningitis

Question 25

what might pure motor signs indicate

Answer 25

myasthenia gravis

Question 26

how might cranial nerves be damaged within the brain

Answer 26

ischaemia | tumour

Question 27

how might cranial nerve be damaged crossing the subarachnoid space

Answer 27

meningitis

Question 28

how might cranial nerves be damaged outside of the skull

Answer 28

base of skull tumours | eg arising in the nasopharynx

Question 29

what is optic neuritis and how does it present

Answer 29

demyelination within the optic nerve monocular visual loss pain on eye movement reduced visual acuity reduced colour vision optic disc may be swollen often associated with multiple sclerosis

Question 30

what nervous systems control pupillary responses

Answer 30

contraction - parasympathetic dilation - sympathetic

Question 31

what does loss of parasympathetic input to the pupil cause

Answer 31

fixed, dilated pupil from e.g. third nerve palsy

Question 32

what does loss of sympathetic input to the pupil cause

Answer 32

constricted pupil

Question 33

what are causes of dilated pupils

Answer 33

Youth Dim lighting Anxiety, excitement “Mydriatic” eye drops Amphetamine, cocaine overdose Third nerve palsy Brain death

Question 34

what are causes of small pupils

Answer 34

Old age Bright light “Miotic” eye drops Opiate overdose Horner’s Syndrome

Question 35

give examples of some eye movement disorders

Answer 35

isolated third nerve palsy isolated fourth nerve palsy isolated sixth nerve palsy supranuclear gaze palsy - inability to look in a particular direction nystagmus

Question 36

what are the causes and presentation of third nerve palsy

Answer 36

microvascular - diabetes, hypertension - painless, pupil spared compressive - PComA aneurysm, raised ICP - painful, pupil affected

Question 37

what are the causes of sixth nerve palsy

Answer 37

idiopathic diabetes meningitis raised intracranial pressure

Question 38

what are the causes of nystagmus

Answer 38

Congenital Serious visual impairment Peripheral vestibular problem Central vestibular / brainstem disease Cerebellar disease Toxins (medication and alcohol)

Question 39

what is trigeminal neuralgia and what causes it

Answer 39

Paroxysmal attacks of lancinating pain Triggers Middle age and older Caused by vascular loop - compression fifth nerve in the posterior fossa

Question 40

what is the treatment of trigeminal neuralgia

Answer 40

carbamazepine surgical options if medication resistant

Question 41

what is bells palsy

Answer 41

idiopathic facial nerve palsy

Question 42

how does bells palsy present

Answer 42

Unilateral facial weakness Lower motor neurone type Often preceded by pain behind ear Eye closure affected Risk of corneal damage

Question 43

how is bells palsy treated

Answer 43

steroids

Question 44

what causes UMN facial paralysis

Answer 44

stroke | tumour

Question 45

what causes LMN facial paralysis

Answer 45

Bells palsy Lyme disease sarcoid

Question 46

how does vestibular neuritis present

Answer 46

sudden onset disabling vertigo vomiting gradual recovery uncertain cause - viral?

Question 47

what is dysarthria

Answer 47

disordered articulation, slurring of speech

Question 48

what is dysphagia

Answer 48

difficulty swallowing

Question 49

what is pseudobulbar palsy

Answer 49

bilateral UMN lesion eg vascular lesions in both internal capsules

Question 50

how does pseudo bulbar palsy present

Answer 50

- dysarthria - dysphonia - dysphagia - spastic, immobile tongue - brisk jaw jerk - brisk gag reflex

Question 51

what is bulbar palsy and how does it present

Answer 51

bilateral LMN lesion affecting IX-XII eg MND, polio, tumours, vascular, lesions of the medulla, syphilis

Question 52

how does bulbar palsy present

Answer 52

- wasted, fasciculating tongue - dysarthria - dysphonia - dysphagia BEWARE OF FEEDING THESE PATIENTS