continuation of cranial nerve exam

12/1/2011 © Clinical Skills Resource Centre, University of Liverpool, UK 1

Examining the cranial nerves

I Olfactory

II Optic

III Oculomotor

IV Trochlear

V Trigeminal

VI Abducens

VII Facial

VIIIAcoustic (auditory & vestibular)

IX Glossopharyngeal

X Vagus

XI Accessory

XII Hypoglossal


1st (Olfactory) nerve

Responsible for the sense of smell

Sense of smell may be lost as a result of

trauma

infection

ageing

Smell is an important component of the

appreciation of taste (which may be the principal

complaint of a patient)

Crude bedside test may be to identify the odour of

coffee or fresh orange


1st (Olfactory) nerve- formal test

One nostril at a time - occlude the other

Use several test smells.

Ask patient to sniff and signal detection

Prompt response needed, else spreads to other

side

Few can identify the classic test smells

Exclude misinterpretation / malingering

Ammonia - detected through nasal pain fibres

Should still taste sugar, salt, vinegar, quinine


The 2nd (Optic) nerve

Various tests are possible which depend to

some extent (though not exclusively) on the

integrity of the optic nerve(s)

These include

Ophthalmoscopy (See separate study guide)

pupillary reflexes

visual acuity

visual fields


The pupils - Inspection

Size and shape

Regularity in outline and equality of both

sides

Defects in iris

Foreign bodies in anterior chamber

Obvious cataract


Pupillary light reflexes

Ask patient to look at a distant object.

Swing light beam in from behind onto one eye, or

switch on from in front. Ensure abrupt stimulus.

Shield other eye effectively.

Direct response- constriction of pupil to light shone

into that eye.

Consensual response - constriction of pupil to light

shone in opposite eye.


Pupillary light reflexes 2

Shield the non-examined eye

Move light beam abruptly in

from the side, or switch on from

the front

Direct reflex - ipsilateral pupil

constricts

Consensual reflex -

contralateral pupil constricts

Direct

Consensual


Pupillary accommodation reflex

Ask patient to fix on a distant object and then

to focus on finger held about 10 cms from

face. Keep target high or eyelids will obscure

the pupil.

The eyes should converge

The pupils should constrict equally


Accommodation

The person fixes on

a distant object

The person is then

asked to look at a

close object - their

eyes converge and

pupils constrict

Documenting P.E.R.L.A.

The acronym P.E.R.L.A. is used to both help remind us

what tests we should do and for documentation purposes.

Pupils

Equal and

Reactive to Light and

Accommodation

When documenting, it is permissible to write PERLA this

signifies that it was checked and is ok.

If there was a problem then you should document in full

what the problem is.



Visual acuity testing

A series of different sized

letters on the chart

Viewed at 6 metres (half

sized charts are viewed at 3

metres)

Under each line is a number

that represents in metres

the distance from which that

size letter would be visible

in someone with normal

eyesight


Visual acuity test results

The result of the test is recorded as the distance from which the patient was positioned (in metres) over the smallest set of letters that can be read on a chart

6/6 (capable of reading letters expected to be visible at 6 metres whilst looking from a distance of 6 meters)

6/60 (only capable of reading letters expected to be visible at 60 metres at 6 metres)

For general examination purposes, if the patient wears glass’s they can be kept on but their lens prescription should be documented

Small

numbers

above

letters

indicate

the

distance at

which a

person

with

normal

vision can

identify

them


Visual acuity measurement

Ask the patient to cover each eye in turn and determine the smallest

print size that can be read

Record separately for each eye e.g. R = 6/6 L = 6/5.

For short-sighted patients glasses should be worn, but if not available

reading through a pin-hole will help to compensate.

For patient unable to read the 60 print size, move them nearer to the

chart (e.g. 3 metres) and record acuity as 3/xx.

For patients unable to read the chart as close as 1 metre record acuity

as:

For children and illiterate patients there are charts showing shapes

rather than letters

CF = Count fingers (Hold hand 0.5 of a metre from the patient )

HM = Hand movement

PL = Perceives light

NPL = No perception of light


Visual field testing

The “bedside” test: face the

patient at a distance of

about 1 metre. Keep

patient’s visual background

uncluttered, with light

behind patient

To test the right eye

Close or cover your right

eye. Say “cover your left

eye and look at my left

eye”. This matches the

visual fields.

Fig 1

Fig 2


Visual field testing 2

Ensure patient doesn’t look away

from your eye

Keeping in a plane midway

between you and the patient,

bring a white pin head from the

extreme of vision (arm’s length)

in towards pupil. Test each

quadrant using diagonal track

bisecting the quadrant. Establish

rough boundary then define with

slower target movements (see

Fig. 1-4)

Fig 3

Fig 4


Visual field testing 3

Ask the patient to indicate when they first appreciate

the white ball entering their visual field

Compare this to your own detection

Produce a more detailed “map” of a defect by

increasing the number of spokes used

The field is limited superiorly by the supra-orbital ridge

and medially by the nose

Any defect should be assessed formally


The blind spot = optic disc

Align patients visual horizontal with yours. Close (eg)your right eye. Tell patient “cover your left eye, and gaze at my left eye”.

Use a red pinhead (approx 1cm diameter). Check patient can see target when aligned with pupil.

Move target slowly, horizontally and laterally from pupil, ask the patient to signal when it disappears and reappears.

Sit approx. 1 metre apart, fix gaze on

each other’s open eye (right to left). Move

the pin slowly across the axis of fixation.

The red pin will disappear when it

coincides with the optic disc.

Left RightTemporalTemporal

Nasal

A B

CD E

F

A

B

C

D

E

Light from images in the temporal region stimulates

the nasal fibres of the retina and visa versa.

left

eye

Optic nerve

Optic chiasm

Optic radiation

F

Optical

cortex

nose

right

eye


Eye movements (3rd, 4th & 6th)

The arrows indicate the direction of movement of the eyes and

not necessarily the position of the muscles.

Medial Lateral

Up

Down

Superior Rectus III

Left eye

Inferior Rectus IIISuperior Oblique IV

Inferior oblique III

Medial

Rectus

III

Lateral

Rectus

VI

Muscle nerve links

A way to remember which muscle is controlled

by which nerve is LR 6 SO4 EE 3

LR 6 Lateral rectus muscle is controlled by

6th nerve. Abducens.

SO4 Superior oblique muscle is controlled

by 4th nerve. Trochlear.

EE 3 Everything else is controlled by the

3rd nerve. Oculomotor



Rectus Muscles

© 2002 Sinauer Associates


Testing eye movements

Hold a pen or similar object 50 cm from the patient in the midline and on a level with the patient’s eyes

Lateral gaze - vertical target Up / down gaze - horizontal target

Ask patient to follow object (“with your eyes”), keeping head still, and to report any double vision

Move the object slowly

side to side

up and down centrally, then at extremes of lateral gaze

stay in binocular range


Eye movements

Observe

range of movement

smoothness and speed

whether conjugate (moving together)

nystagmus (see 8th nerve for details)

If obvious dysconjugate eye movements

Is there double vision?

If present, establish muscle(s) affected

If not, test for latent squint


Diplopia – which eye and muscle?

If patient reports diplopia remember:

False image is from the affected eye

Outer image is the false one

Double vision is maximal in the direction of gaze of

the affected muscle


Diplopia – which eye and muscle?

For each direction of gaze with diplopia

establish position where images are widest apart

cover each eye in turn and confirm binocular diplopia

(present only with both eyes looking).

cover one eye and if outer image disappears that eye

and the muscle turning it that way are the abnormal

ones.

cross-check by covering the other eye. Inner image

should disappear.


3rd (Oculomotor) nerve palsy

RestingPtosis

On lifting ptosis,

the eye deviated

laterally and

downwards

Affected eye (left)

In complete palsy, pupil dilated and unreactive


4th (Trochlear) nerve palsy

Resting

Looking to right and

downwards

Affected eye (left)


6th (Abducens) nerve palsy

Resting position

Look to L

On command to look to the left the affected eye (LEFT) does not

move

Affected eye


The cover test for latent squint

Ask the patient to look with both eyes at examiner’s right eye

Cover patient’s left eye, then uncover left eye and rapidly cover right eye

Observe to see if left eye corrects to fix on examiner’s eye

Repeat for patient’s right eye

R L

Example above:

left latent squint


The 5th (Trigeminal) nerve

The trigeminal nerve supplies

Sensory divisions

Ophthalmic (V1)

Maxillary (V2)

Mandibular (V3)

Motor

Muscles of mastication


Sensory branches of 5th nerve

Ophthalmic

Maxillary

Mandibular

Test light touch with

cotton wool

For pain use sharp

end of a neuro tip

Use the blunt end to

act as a discriminator

if the patient is

unable to readily

sense pain

Compare sides


Sensation - trigeminal nerve

Motor - facial nerve

Twist a wisp of cotton wool to a

point.

Ask the patient to look up and in

Touch the lateral cornea

Both eyes should blink

Be careful to touch the peripheral

cornea and not the conjunctiva

Avoid the central cornea.

Don’t drag the cotton across the

cornea

Corneal reflex

Unlikely to work on people who

wear contact lenses


Testing 5th nerve motor function

Place your fingers on muscles first. Ask patient to clench teeth and you feel masseter and temporalis contracting.

Ask patient to open mouth to left, and stop you trying to push the open jaw back to midline. Repeat for right side. Testing power of lateral and medial pterygoids.

Jaw jerk

ask the patient to open their mouth slightly

place a finger on the chin

percuss the finger

observe and feel jaw movementTesting the jaw reflex


The 7th (Facial) nerve

The facial nerve supplies

Muscles of facial expression

Stapedius muscle in the ear

Taste to the anterior 2/3rds of the tongue

Parasympathetic nerves to the lacrimal gland

LMN lesions affect all facial muscles on that side (final common pathway).

Unilateral UMN lesions spare the forehead (bilateral cortical representation).


Tests of facial nerve function

Ask person to

Show their teeth

Purse lips

Blow out cheeks

Close eyes tightly

Open eyes as wide as they can


Tests of facial nerve power

With eyes tightly shut

attempt to gently pull the eyelids apart

With eyebrows raised

attempt to pull eyebrows downwards

With lips pursed tightly

attempt to pull lips apart

With cheeks blown out

press against the cheek to assess strength


The 8th (Acoustic) nerve

The 8th nerve has two functions

Auditory (hearing)

Vestibular (balance)


Tests of auditory function

Test each ear, one at a time

Block the opposite ear

Use a watch or rubbing

fingers together (in a quiet

environment), judge how far

away the sound can be

detected

If impaired in either ear

perform Rinne’s and Weber’s

test


Rinne’s test 1a

Use a 512 Hz tuning fork,

set it vibrating by gently

tapping on your knee

Place on mastoid process

(bone conduction)

Ask the person to tell you

when they can no longer

“hear” the sound


Rinne’s test 1b

Then place fork in front

of ear directly over the

auditory meatus (air

conduction)

Ask the patient again if

they can hear the

sound (normally louder

as air conduction is

better than bone

conduction)


Interpretation of Rinnes (method 1)

In a normal hearing the sound will be heard better when the tuning fork is placed in front of the ear

In conductive deafness (the sounds cannot conduct from the external to the inner ear) the sound will not be heard when the tuning fork is placed in front of the ear

In partial sensorineural deafness (due to damage to the cochlea, auditory nerve or auditory centres of the brain) the sound may be heard when the tuning fork is placed in front of the ear (but at a higher pitch normal hearing).

In complete sensorineural deafness no sound will be heard when the tuning for is placed in either position. (although there are exceptions to this)


Rinne’s 2

Alternatively

Place base of tuning fork

on mastoid process

Confirm it can be heard

Then immediately place

prongs in front of external

auditory meatus

Ask patient which is louder

- “behind the ear or in

front?


Interpretation of Rinnes (method 2)

In normal hearing the sound is loudest when the

tuning fork is placed in front of the ear

In conductive deafness the sound is loudest on the

mastoid process

In partial sensorineural deafness the sound is

loudest when the tuning fork is placed in front of the

ear (but at a higher pitch than in normal hearing).

In complete sensorineural deafness no sound will

be heard at the mastoid process or in front of the

ear.


Weber’s test

Hold the base of the

512 Hz tuning fork on

the vertex of the

patient’s head.

Ask which ear seems

to hear it louder.


Interpretation of Webers

In normal hearing the sound is equal in both

ears

In conductive deafness then the sound will

be loudest in the affected ear (as all external

sound is removed and effected ear picks up

the vibrating sound more acutely)

In sensorineural deafness all sounds are

diminished or absent.


Interpreting hearing tests

(an overview)

Interpretation of Rinne and Weber tests

Normal Conductive deafness

Partial sensorineural deafness

Weber Equal in both Deaf ear > good ear

Good ear > deaf ear

Rinne Air conduction > bone

Bone conduction > air

Air conduction > bone

Loss of hearing may be conductive (transmission of sound to the nerves

of hearing fails)

Sensorineural deafness reflects disorders of the nerve tissues)


Vestibular function of the 8th nerve

Gait

Ask patient to walk heel to toe

Gait veers to the affected side and is

unsteady

Usually worse with eyes shut


Nystagmus

Involuntary rhythmic eye movements

Peripheral or central vestibular, or cerebellum

Tested during eye movement assessment

Look in central position

Look during up, down and lateral movement

Hold the target steady at the limit of binocular

vision in each direction

Care: Normal people may have a few jerks at extreme lateral

gaze, especially if the target is outside the field of binocular

vision - ensure it is visible to both eyes.


Nystagmus types

May be rotary or linear

Jerk - slow drift of eye position in one

direction with a fast correction in the opposite

direction.

Nystagmus direction is that of fast phase

Pendular – oscillations roughly equal in both

directions


Points to note if nystagmus present

Eye position and gaze direction when nystagmus occurs

Direction of the fast movement and plane - horizontal,

vertical, rotatory

Is the abducting eye affected more than the adducting?

Does it occurs in other directions of gaze?

Typical description: linear nystagmus, fast phase to the left,

in both eyes on left lateral gaze.


Hallpike’s test

Examiner supports head

Hallpike’s

test

Used in testing for positional vertigo

Sit person up in a position so that when (s)he lies down, the head will extend over the end of couch

Turn the head to one side, ask person to look over the shoulder to that side.

Lie the patient back quickly, so that head extends and is supported by the examiner

Ensure continues to look over shoulder (now towards floor)

Ask about sensation of vertigo. Observe for nystagmus in direction of gaze, whether it fatigues with repeating the test.

Repeat for other side


Hallpike’s test interpretation

No vertigo, no nystagmus - normal

Vertigo plus nystagmus Central (brainstem) vestibular

non-fatigable

persists indefinitely during test posture

Repeatable indefinitely

Peripheral vestibular

Delayed-onset rotatory nystagmus

Fatigues

wears off in < 4 minutes

Repeat test less intense, shorter duration features


9th (Glossopharyngeal) nerve

Sensory

posterior 1/3rd of tongue, the pharynx and

middle ear

Motor

stylopharyngeus

Autonomic

parotid salivary gland

afferents from carotid baroreceptors


Testing the 9th nerve (sensory)

Gag reflex (not routinely done); test both sides

Afferent – glossopharyngeal; efferent – vagus (10th)

touch pharyngeal wall behind the pillars of the fauces

ask if patient can feel it, and observe any gag

no feeling or gag may mean ipsilateral 9th nerve dysfunction.

deviation of uvula one way indicates weakness on the other side = UMN / LMN lesion of vagus, 10th nerve –not 9th

Uvula moves on saying “Ahh” but not on gag isolated 9th nerve palsy (rare)


The 10th (Vagus) nerve

Sensory

tympanic membrane, external auditory canal, external ear

Motor

muscles of palate, pharynx and larynx

Autonomic

parasympathetic supply to and from thorax and abdomen


Testing the 10th nerve

Look at the uvula (use tongue depressor if

necessary)

Ask patient to say “Ahh”

Deviation to one side indicates weakness on

the other side (muscle normally “pulls”)

upper or lower motor neurone lesion

Does not move on saying “Ahh” or gag

bilateral palatal muscle paresis


11th (Accessory) nerve

Purely motor

Each cerebral hemisphere supplies

the ipsilateral sternomastoid muscle

the contralateral trapezius muscle

Therefore, a lesion on one side can give rise

to signs on both sides



Sternomastoid

Ask patient to turn their head to one side. Stabilise

patient with shoulder counterpressure. Then put your

hand against patient’s chin and cheek and ask patient to

resist your rotating their head back to midline. Watch the

opposite sternomastoid contract, and test its power.

Trapezius

Ask the patient to shrug shoulders, push down against

movement. Do one side at a time.



Inspect both

sternomastoid and

trapezius muscles for

wasting and fasciculation

Upward shrug

of shoulders -

test of trapezius

Turning head - test

of contralateral

sternomastoid

Weakness of

sternomastoid and

trapezius on the same side

- ipsilateral peripheral

accessory nerve lesion

Weakness of

sternomastoid and

contralateral trapezius -

upper motor neurone

lesion on the side of the

sternomastoid


12th (Hypoglossal) nerve

Motor: intrinsic muscles of the tongue


Open mouth. Examine tongue at rest inside mouth.

Fasciculation and / or wasting (atrophy)

LMN lesion (one side = nerve, both usually = bulbar palsy).

Put out tongue

Deviation to one side indicates weakness on that side (tongue muscle “pushes”).

Fasciculation during active movement is normal.

Waggle tongue (demonstrate to patient)

Normal smooth bulk, poor movement control, usually bilateral

UMN lesion (“pseudobulbar” palsy).

To test power: patient pushes tongue against cheek and examiner presses against skin - repeat for the other side.

continuation of cranial nerve exam

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