CLINICAL Cranial Nerve Examination

Question 1

Different classification of nystagmus and their causes?

Answer 1

Nystagmus can be:
 Physiological - (as when looking out of a moving train window)
 Peripheral - due to abnormalities of vestibular system, the eighth nerve or nucleus
 Central - due to abnormalities of central vestibular connections or the cerebellum
 Retinal – due to damage to retina and a resultant inability to fix on an image

Question 2

Depression is most effective when the eye is turned ________-

Answer 2

Depression is most effective when the eye is turned medially.

Question 3

Elevation is most effective when the eye is turned ________.

Answer 3

Elevation is most effective when the eye is turned medially.

Question 4

Lateral rectus _____ the eye. (CN VI)
Medial ______ adducts the eye.
Superior rectus and inferior oblique ______ the eyes.
_______ rectus and superior oblique depress the eyes. Superior oblique innervated by CN __.

Answer 4

Lateral rectus abducts the eye. (CN VI)
Medial rectus adducts the eye.
Superior rectus and inferior oblique elevate the eyes. Inferior rectus and superior oblique depress the eyes. Superior oblique innervated by CN IV.

Question 5

Argyll Robertson pupil

Answer 5

Pupils are small, irregular, non-reactive to light and constrict when focused on a near object
“They both accommodate, but don’t react”, and both are associated with neurosyphilis.
Associated with: DM, alcoholism, Tonic phase of Holme’s Adie

Question 6

What is the direction and consensual reflex?

Answer 6

Direct Reflex
Bring a torch light in from the side of the eye that you are testing and shine the light in one eye. Look for the reaction in that eye (pupillary constriction).

Consensual Reflex
Look for the reaction in the other eye.
Repeat the process in the other eye and look at the direct and consensual responses.

Question 7

What is the presentation of a myotonic pupil?

Answer 7

The affected pupil is dilated, unresponsive to light and constricts very slowly to near vision. (See section 9 below) It is benign and may be bilateral. When associated with absent tendon reflexes it is called Holmes–Adie syndrome.

Question 8

What is the medial longitudinal fasciculus?

Answer 8

The medial longitudinal fasciculus contains fibers that connect the abducens nucleus to the contralateral oculomotor nucleus to perform horizontal conjugate lateral gaze.

Question 9

What is enophthalmos?

Answer 9

Recession of the eyeball into the orbit. It is caused by a degeneration and shrinking of the orbital fat, a tumour, an injury to the orbit or to shortening of the extraocular muscles following excessive resections.

Question 10

What is anosmia?

Answer 10

Loss of sense of smell (although still responds to pungent, irritant odours e.g. ammonia)

Question 11

Oculomotor (CN III) supplies levator palpebrae and all the muscles of the eye with the exception of ……

Answer 11

Oculomotor (CN III) supplies levator palpebrae and all the muscles of the eye with the exception of superior oblique (CN IV) and lateral rectus (CN VI).

Question 12

Clinical sign in CN III of ocular paresis?

Answer 12

Ptosis, eye deviated laterally and slightly downwards, pupil may be dilated and unresponsive.

Question 13

Clinical sign in CN IV of ocular paresis?

Answer 13

Impaired depression of the fully adducted eye, head may be tilted to the opposite side to avoid diplopia when reading or looking down to walk downstairs.

Question 14

Clinical sign in CN VI of ocular paresis?

Answer 14

Impaired abduction

Question 15

Jaw jerk reflex?

Answer 15

The jaw jerk
The afferent limb of this brainstem reflex is mediated through proprioception endings within the muscles of mastication. These endings are stimulated when the muscles are stretched when hit. These proprioceptive fibres travel in the trigeminal nerve to the mesencephalic nucleus in the midbrain. Fibres then project to the pons to the motor nucleus of V lying in the upper pons. This motor nucleus supplies the motor root of CN V. The efferent limb arises from this nucleus and travels in the mandibular division of the trigeminal back to the muscles of mastication.

Question 16

Abnormalities in jaw jerk reflex?

Answer 16

The normal response is reflex closing of the mouth due to contraction of masseter and temporalis muscles. The reflex is often absent or minimal and an absent reflex is not significant.

Pathologically brisk when
there are bilateral upper motor neurone lesions affecting the corticobulbar pathways. E.g.: infarcts in the internal capsules.
Note: (Bulb is another name for the medulla.)

Question 17

Differentiation of upper and lower motor neurone lesions of facial nerve (CN VII) in facial
asymmetry.

Answer 17

There is a BILATERSL supply from both cortices to both facial motor nuclei in the pons for control of the FOREHEAD (frontalis).

But only a UNILATERAL crossed supply to the area of the nucleus that controls the muscles of the LOWER part of the face. (e.g. buccinator and orbicularis oris.)

Question 18

What is Bell’s palsy? When does it present?

Answer 18

Bell’s palsy is used to describe swelling of the facial nerve in the facial canal.

Presents in:
LMN lesions
Hyperacusis as stapedius muscle may also be affected. (Its function is to dampen the ossicular chain and so if affected, sounds may be echoing and distorted.)

Question 19

In stroke presentation…

Answer 19

UPN lesion so can wrinkle forehead bilaterally due to dual innervation.

Question 20

What is Ramsay Hunt syndrome?

Answer 20

Ramsay Hunt syndrome describes a lower motor neurone lesion of the CN VII where there is herpes zoster infection of the geniculate ganglion. There are usually associated vesicular eruptions in the external auditory canal.

Question 21

What is the Webber test?

Answer 21

 Place a vibrating 512Hz tuning fork in the midline of the forehead and ask where the patient hears the sound the loudest.
 If the hearing is normal, or hearing loss is symmetrical, the patient will hear the sound the same in both ears.
 If the patient has a conductive problem in one ear the patient will hear it loudest in that ear (the affected ear) because the outside sounds are not interfering with it.
 If hearing is reduced by sensorineural deafness the noise will be loudest in the good ear.

Question 22

What is Rinne test?

Answer 22

 Place the tuning fork over the mastoid process (of the temporal bone) and then about 1cm from the external auditory meatus (where it should be heard louder) and ask the patient which is louder.
 If AC>BC = Rinné positive = normal. There is no conductive deafness.
 In air conductive deafness BC>AC (Rinné negative), bone conduction is better than air
conduction.
 In sensorineural deafness both bone and air conduction are impaired, but maintaining the
relative difference of AC > BC, and the Rinné is positive.
 However, when one ear has no hearing at all, or when a patient has a very severe
unilateral sensorineural deafness, the Rinné test may be negative. The sound is being conducted through the skull bones to the opposite ‘good’ ear – This is called a false Rinné negative test. BC > AC

Question 23

What are the CN VIOI tests?

Answer 23

1. Webber test

2. Rinne test

Question 24

Test for vertigo patients?

Answer 24

The Hallpike Manoeuvre is a procedure that is performed if a patient complains of vertigo

Question 25

Afferent and efferents in gag reflex?

Answer 25

Afferent: CN IX

Efferent CN X

Question 26

Afferent and efferents in cough reflex?

Answer 26

Afferent: CN V2 to the Chief sensory nucleus of V
Efferent: CN X and IX

Question 27

Parotid parasympathetic secretions are a function of ______________.

Answer 27

Parotid parasympathetic secretions are a function of glossopharyngeal.

Question 28

CN XI innervates which muscles?

Answer 28

SCM

Trapezius