Cranial nerve examination

Cranial Nerve Examination

Irfan Ziad MD UCDdrkupe.blogspot.com

CN2 :Optic

CN1 :Olfactory

CN3 :Oculomotor

CN4 :Trochlear

CN5: Trigeminal

CN6 :Abducens

CN7 :Facial

CN8: Vestibulocochlear

CN9: Glossoparyngeal

CN10: Vagus

CN11: Accessory

CN12: Hypoglossal

midbrain

pons

medulla

Anterior aspect of midbrain

Dorsal aspect of midbrain

InspectionPosition the patient sitting over the edge of the bed

Look for : Scars (eg. craniotomy), pupil equality, facial asymmetry, ptosis, proptosis, neurofibromas

Hi, my name is _____. Can I examine you?

CN 1CN 1Olfactory Nerve

CN I

Have you ever noticed any change in sense and

smell?

You ask the patient “Have you ever noticed any change in sense and smell?”If the answer is NO, proceed to the next CN

SmellCN 1CN 1Olfactory Nerve

CN I

If the answer is YES, Test: occlude one nostril, close eyes, identify smell (mint, coffee)

Anosmia- loss of the sense of smell (eg. flu, nasal polyps)Lesion- nose, cribiform plate of the eythmoid bone, base of skull- eg meningioma, early sign of parkinson.

SmellCN 1CN 1Olfactory Nerve

CN I

Can you tell me what smell is this?

Optic canal

CN 2CN 2 Optic NerveCN II

Ask patient do they have any difficulty with their vision.

“Can you see the clock on the wall?”“Can you read the newspaper?”

Ask the pt whether she’s myopic (nearsighted) or hyperopic(farsighted)

Visual Acuity

Can you see the clock on

the wall?


Snellen chart is hold at arm-length

A portable Snellen’s chart will enable you to perform a more formal testA patient who is having visual problems should be asked to count fingers held up in front of each eye in turn, and if this is not possible then perception of hand movement should be assessed. Failing this, light perception only may be present

Visual AcuityCN 2CN 2 Optic NerveCN II

Test acuity with her glasses on. Pinhole if

she forgets her glasses

Confrontation test: ask the pt to look into your eyes while you place our index finger just outside the outer limits of your temporal fields. Move the fingers in turn and then together.

“Point to the moving finger”

In visual inattention (parietal lobe lesions) the patient will only point to one finger when you move both simultaneously.

Point to the moving finger

Visual FieldCN 2CN 2 Optic NerveCN II

Test her peripheral field on each eye separately.

“Can you see the whole of my face?”Can you see the whole of

my face?

Visual FieldCN 2CN 2 Optic NerveCN II

Keep looking at my nose, tell me when you see my finger

moves

Visual Field

Test her left temporal vision against your right temporal vision by moving your wagging finger from the periphery towards the centre

“Tell me when you see my finger moves”

The temporal field should be tested in the horizontal plane and in the upper and lower temporal quadrants.Change hands and repeat on the nasal side


Bitemporal hemianopia: causes: optic chiasm lesion, pituitary tumour, craniopharyngioma

Right optic nerve lesion

Left Homonymous hemianopia

Left Superior Quadrantanopia

Left Inferior Quadrantanopia

Left homonymous scotoma

2a 2b

2b

1

2

3

4

2+2a

5

6

7

2a+2b Binasal hemianopia: Very rare

Left Homonymous hemianopia with macular sparing

Visual Field

Level of lesions


Arcuate scotoma- moderate glaucoma

Unilateral defect found with arterial occlusion, branch retinal

vein thrombosis and inferior retinal detachment

Central scotoma- macular degeneration or

macular oedema

Lesions at the level of the retinaThese affect one eye only

Visual Field

CN IICN 2CN 2 Optic Nerve

Tell the pt to look at the tip of your nose. Move the red-headed pin from the temporal periphery through the central field to the nasal periphery, asking the patient

“tell me when the red pin disappears, and reappears.”

“tell me when the red pin disappears

and reappears.”

The blind spot enlarges with papilloedema e.g. raised intracranial pressure with brain tumour. Demyelination of the optic nerve in multiple sclerosis can cause loss of central vision

Blind SpotCN 2CN 2 Optic NerveCN II

This is affected in colour blindness and optic neuritis (loss red colour first).


Colour Vision

Test is done with an Ishihara plate

FundoscopyTurn on, set diopters to zero, focus on specific distance, look for red reflex, adjust if pt wear glass, look for blood vessels, follow, look at optic disc- clear or blurred?

- Hypertensive, diabetic, papillodema, optic neuropathy, pigmentation (mithocondrial disorder, retinotitis pigmentosa)


CN 3,4.6CN 3,4.6 Oculomotor, Trochlear, Abducens Nerve

Extraocular movements

CN III, IV, VI

From oculomotor nucleus

Pupillary light reflex

Direct and Consensual: Put your hand in between the patient’s eyes.With a pocket torch shine the light from the side. Do a swinging-light test.

Normally, the pupil into which the light is shone constricts rapidly (Direct light reflex)Simultaneously the other pupil constricts in the same way, (Consensual light reflex)Repeat this procedure on the other side

RAPD (Relative Afferent Pupillary Defect) previous optic neuritis)- swinging light test- damaged nerve dilate in response to lightCauses: eg previous optic neuritis

CN 3CN 3 Oculomotor Nerve

CN III

Accommodation reflex

“Look at that mark on the wall, now look at my finger”

“Look at that mark on the wall, now look

at my finger”

Examine the pupils for size, shape, equality and regularity

PERRLA : Pupils Equal, Round, Reactive to Light and Accommodation

PathologyUnilateral dilated pupil- drugs- cocaine, eye drops (mydriatic)- 3rd nerve palsy- any associated ptosis, strabismus- Holes-Adie pupil- pupil reacts sluggishly, associated with syphilis-Absent light reflex with an intact accommodation reflex occurs in Argyll Robertson pupil in neurosyphilis

CN 3CN 3 Oculomotor Nerve

CN III

Assess for eye movement, diplopia [double vision] and nystagmus

Ask the patient to look laterally left and right, continue moving the finger to complete H pattern.Tell the patient to inform you if they see double images [diplopia]

Diplopia is an early sign of ocular muscle weakness

Without moving your head, follow the pin with your eye. Tell me if you

see double

Extraocular movementsCN 3,4.6CN 3,4.6 Oculomotor, Trochlear, Abducens Nerve


SR SR

IRIR

IO

MRLR LR

SO

LR – Lateral RectusMR – Medial RectusSR- Superior RectusIR- Inferior RectusIO- Inferior ObliqueSO- Superior Oblique

CN IV supplies SOCN VI supplies LRCN III supplies all others + levator palpebrae superioris (which elevates the superior eyelids)


Complete ptosisEye down and outDilated pupil which is not responsive to light and accommodation.

Double vision going down stairs or reading booksAsk patient to turn the eye in and then to look down- may cause vertical hypertropia (pic)

Failure of lateral movementNystagmus.

3rd nerve palsy 4th nerve palsy 6th nerve palsy


NystagmusThe direction of nystagmus is defined as that of the fast [correcting] movement

Vestibular lesion – nystagmus away from the side of the lesionCerebellar lesion – nystagmus to the side of the lesion

Internuclear ophthalmoplegia Abducting eye has greater nystagmus than the adducting eye. Problems btw nuclear, 3rd n 6th connected by medial longitudinal fasciculus (MLF) - MS


CN 5CN 5 Trigeminal NerveCN V

Sensory branch

Ophthalmic (V1)

Maxillary (V2)

Mandibular (V3)

Motor Muscle of mastication

Masseter

Temporalis

Medial pterygoid

Lateral pterygoid

Tensor veli palatini

mylohyoid

Anterior belly of digastric

Tensor tympani

Others

All involved in biting, chewing, swallowing except for tensor tympani which acts to dampen sound produced from chewing

Masseter

Temporalis

Trigeminal Nerve

Test for soft touch using cotton wool - sternum first, close eyesin the 3 divisions of the nerveV1- ophthalmic- forehead up to the top of the headV2- maxillaryV3- mandibular (up to angle of the jaw)

The patient should be instructed to say “yes” each time the touch of the cotton wool is felt. Do not stroke the skin touch it.Test for pain using sharp object.Ask patient does it feel sharp or dull

Causes of sensory problems- MS- MS plaque in the brainstem in young people- Sjogren- dry eyes, dry mouth-Trigeminal neuralgia- older people

Facial Sensory

Say “yes” if you feel this


Ask the pt to look up and away, touch the corneal. Reflex blinking of both eyes is a normal response.

PathologyBell’s palsy- unable to blink due to damage to the efferent limb (CNVII)CNV forms the afferent limb

Corneal Reflex

I’m going to gently touch your eye with a cotton bud.


Inspect for wasting of the temporal and masseter musclesAsk patient to clench their teeth and palpate for contraction of the temporal and masseter muscles

Motor

Can you grit your teeth, please?


Ask patient to open their mouth and hold it open while the examiner attempts to force it shut [pterygoid muscles].

A unilateral weakness of the motor division causes the jaw to deviate towards the weak side.If weakness is suspected patients should be asked to move the jaw laterally against resistance. The jaw can be moved towards the affected muscle but cannot move towards the normal side.

Motor

Open up your mouth and hold it for me


Ask the pt to open her mouth fully, and close halfway, , place index finger on her chin and tap with a patella hammer, if jaw jerk is highly exaggerated.

Help to distinguish btw pseudobulbar palsy (UMN lesion of lower cranial nerve 9, 10,11,12) and a bulbar palsy (LMN lesion of lower cranial nerve 9,10,11,12)

The Jaw Jerk

I’m going to gently tap your jaw


CN 7CN 7 Facial NerveCN VII

Facial canal (tortuous course)

Internal auditory meatus

Geniculate ganglion

Stylomastoid foramen

Temporal

Zygomatic

Buccal

Mandibular

Cervical

Major facial branches

Inside SkullOutside skull

Other

Posterior auricular nerve

Posterior belly of Digastric

Stylohyoid muscle

Stapedius

Frontalis, orbicularis oculi

Z1: Eye & around orbitZ2: Mid face & smile

Buccinator, upper lip

Lower lip, orbicularis oris

Platisma

controls scalp muscles around the ear

3. SENSORY

2. PARASYMPATHETIC

Greater petrosal to Lacrimal gland, sphenoid sinus, frontal sinus, frontal sinus, maxillary sinus, eithmoid sinus, nasal cavity,

The facial nerve has four components:

1. BRANCHIAL MOTOR

4. TASTE

From facial nerve nucleus

Small contribution to external acoustic meatus

Palate via greater petrosalAnt 2/3 tongue via chorda tympani

From Nevus Intermedius

Petrous temporal bone

Ask the patient to shut the eyes tightlyObserve and try to force open each eye.

If a lower motor neuron lesion is detected [weakness on one side of face], check for ear and palatal vesicles of herpes zoster of the geniculate ganglion – the Ramsay Hunt syndrome

Motor

Shut your eyes tightly and don’t let me open them


Ask patient to look up and wrinkle her forehead. Feel for muscle strength by pushing down on forehead.

This movement is preserved on the side of an upper motor neurone lesion [a lesion which occurs above the level of the brainstem nucleus], because of bilateral supranuclear innervation giving some compensation to the upper face which is not the case in LMN lesion (Bells palsy/Ramsay Hunt- Herpes Zoster)

The remaining muscles of facial expression are usually affected on the side of an UMN lesion.In a LMN lesion all muscles of facial expression are affected on the side of the lesion.

Motor

Wrinkle your forehead for me please


Ask the patient to show their teeth

Compare the nasolabial grooves which are smooth on the weak side.

Left upper motor neuron seventh nerve lesion leads to drooping of the corner of the mouth, flattened nasolabial fold, and sparing of the forehead on the left side**

Motor

Show me your teeth


Ask the patient blow out her cheeks

Motor

Blow out your cheeks



Upper Motor Neurone Lower Motor Neurone

Pathway Rt motor cortex-corona-radiata-internal capsule-brainstem (midbrain-pons-medula)-crosses- anterior horn cell-

Anterior horn cell, intervertebral foramen, lumbar sacral(lower limb)/brachial plexus(upperl imb plexus, runs in peripheral nerve- stop at NMJ

Presentation increased tone, reflex, clonus, upgoing(extensor) plantar

- wasting, fasciculation, lose of tone, reflex, flexor plantar

Cerebrovascular accidentstroke! most common

Intracranial tumourCervical spine injury

Motor neuron diseasePeripheral nerve neuropathy

Diabetic neuropathy?Poliomyelitis

anterior horn cell affectedSpinal cord injury

with nerve root compression

CN 8CN 8 Vestibulo-Cochlear NerveCN VIII

Cochlear division- HearingFrom organ to Corti in cochleaHair cells to cell bodies in spiral ganglion (in modiolus)To 2 cochlear nuclei (ventral & dorsal)

Vestibular division – BalanceFrom semicircular canals, utricle & sacculeCell bodies in vestibular ganglion in outer part of internal acoustic meatusTo 4 vestibular nuclei (medial, lateral, superior, inferior)

Any problem with hearing? Hearing aids?Mask- cover the tragus of the ear and whisper a number, ask pt to repeat

If deafness is suspected perform Rinne’s test and Weber’s test

Hearing+Balance

I’m going to whisper a number. I want you to

repeat it.


Rinne’s Test

Rinne- base of tuning fork on the mastoid process,

“tell me when it stops”, then bring it to the ear,

“Can hear it? “

With nerve deafness the note is audible at the external meatus, as air and bone conduction are reduced equally, so that air conduction is better as is normal. This is termed Rinne-positive.With conduction [middle ear] deafness no note is audible at the external meatus. This is termed Rinne-negative.

Can you hear it?


Weber’s Test

A vibrating tuning fork is placed on the centre of the forehead. Normally the sound is heard in the centre of the forehead. With nerve deafness the sound is transmitted to the normal ear. With conduction deafness the sound is heard louder in the abnormal ear.

Patients with defective hearing should be referred for audiometry. This measures the degree of hearing loss at different sound frequencies.

Can you hear it?


CN 9CN 9 Glossopharyngeal NerveCN IX

CN 10CN 10 Vagus NerveCN X

CN 9, 10CN 9, 10 Glossopharyngeal and Vagus NerveCN IX, X

Uvula + Gag Reflex

UvulaGet the patient to open their mouth and inspect the palate with a torch. Note any displacement of the uvula. Ask the patient to say ‘Ah’. If the uvula is drawn to one side this indicates a unilateral tenth nerve palsy. The uvula is pulled towards the normal side.Now test gently for the gag reflex

Ninth is the sensory componentTenth is the motor component

Gag ReflexTouch the back of the pharynx on each side with a spatula. Ask the patient if the touch of the spatula is felt each time. Normally there is reflex contraction of the soft palate.

The ninth nerve supplies taste from the posterior two-thirds of the tongue this is not routinely tested for.

CN 9, 10CN 9, 10 Glossopharyngeal and Vagus NerveCN IX, X

Open your mouth and say “ah”

CN 12CN 12 Hypoglossal NerveCN XII

Its nucleus receive Corticonuclear fibers from both cerebral hemispheres, but the cells supplying the genioglossus muscle receives corticonuclear fibers only from the opposite cerebral hemisphere It supplies1. All the intrinsic muscles of the tongue2. Styloglossus3. Hyoglossus4. Genioglossus5. Doesn’t supply Palatoglossus – Supplied by the vagus Function is to control the movement of the tongue In the upper part, the Hypoglossal nerve is supplied by the C1 fibers

CN 12CN 12 Hypoglossal NerveCN XII

Motor Nerve of Tongue

Observe the tongue at rest- wasting? on one side? fasciculation?Stick out tongue straight- deviate to one side?Tongue deviate to the side of a lesion of CNXII

Wiggle tongue side-to-side - (coordination)altered in cerebellar disorder

Wiggle your tongue side-to-side

Cranial Root Spinal Root

Receives corticonuclear fibers from both cerebral hemispheres

It joins the spinal root & leaves the skull through jugular foramen

Then the roots separate again, cranial root joins the vagus

Situated in the anterior grey column of the spinal cord in the upper 5 cervical segments

Nerve fibers emerge from the spinal cord & form a nerve trunk that ascends into the skull through the foramen magnumSpinal part joins the cranial part & pas through the jugular foramenThen they separate again

Supply the muscles of:Soft palate (Except tensor veli palatini)Pharynx (Except stylopharyngeus)Larynx (Except cricothyroid)

Supplies the SCM muscle & trapezius muscle

CN 11CN 11 Accessory NerveCN XI

Trapezius

Ask the patient to shrug their shoulders and feel the bulk of the trapezius muscles and attempt to push the shoulders down.


Shrug your shoulder, push up against my

hand

Sternocleidomastoid

Ask the patient to turn their head against resistance and feel the bulk of the sternomastoids. Feel for the sternomastoid on the side opposite to the turned head. There will be weakness on turning the head away from the side of a muscle whose strength is impaired.

(Optional)Test neck flexors if suspect myasthenia gravis, MND- “put chin on chest, I’ll put my hand onto

your forehead, push up against my hand”


Turn your head against my hand

Thank You

Education

Cranial nerve examination