CRANIAL NERVE FUNCTION TESTS

Question 1

WHAT IS ANOSMIA

Answer 1

loss of smell due to a neurological lesion

Question 2

testing function of olfactory nerve

Answer 2

eyes closed, the subject is asked to sniff substances through each nostril in turn and name the odours - coffee , vanilla

Question 3

optic and oculomotor nerve tests

Answer 3

test for visual acuity , check visual fields and inspect optic discs , inspect size and shape of pupil and compare , test pupillary reactions to light

Question 4

occulomotor trochlear and abducens

Answer 4

subject sitting upright , head held by examiner , subject asked to follow examiners finger .
movement of eyes along horizontal plane - > medial and lateral rectus muscles

movement of eyes along vertical planes - looking outwards - superior and inf rectus muscles

movement of eyes along vertical planes - looking inwards - superior and inferior oblique muscles

Question 5

during exam of occulomotor trochlear and abducens note what

Answer 5

Note for any strabismus (squint), ptosis, nystagmus, deviation of the
eye and ask the patient if they have diplopia (double vision )

Question 6

testing function of CN V

Answer 6

cutaneous sensation can be tested in appropriate areas of the face.
jaw muscles can be tested by asking subject to clench teeth and palpating the contracting masseter and temporalis muscles .
jaw jerk reflexes .
pterygoids -> if subject opens their mouth against resistance and there is unilateral weakness , jaw will deviate to one side

Question 7

test functions of CN V and VI

Answer 7

wisp of cotton wool is applied to cornea , results in blinking of both eyes
sensory limb is opthalmic division . motor response is a contraction of orbicularis oculi , recieves its motor innervation form VII

Question 8

testing function of vestibulocochlear - hearing

Answer 8

ƒ Each ear is tested separately
ƒ Vibrating tuning fork is held close to the external auditory
meatus and its base is then pressed gently against the mastoid
bone Æ subject is asked which of these two stimuli is loudest
ƒ Fork is left applied to the mastoid bone until the vibrations are
no longer heard and the fork is the held against the ear Æ
subject is asked if note can still be heard
ƒ For a normal subject, air conduction > bone conduction
ƒ If this is not the case may be due to infection of middle ear
ƒ Weber’s test Æ tuning fork is placed in centre of forehead and
subject is asked which side is louder
ƒ Both equally (normal), left (right sensironeural impairment) and
right (left sensironeural impairment)

Question 9

vestibulo-occuloreflexes

Answer 9

ƒ Reflex movements of the eyes consequent upon rotation of a
subject in a rotating chair
ƒ Horizontal nystagmus (rotate as per normal) -> eyes move
horizontally
ƒ Vertical nystagmus (head bend and tilt to one side) -> eyes
move vertically
ƒ Rotational nystagmus (head bent) -> eyes swing upwards from
left to right
ƒ Ask subject to observe the pictures on the slowly rotating drum
and observe eye movements -> optokinetic nystagmus
(normally observed by looking at objects moving across field of
vision)

Question 10

testing glossopharyngeal and vagus nerves

Answer 10

tests are not very impressive esp in normal subject

- subject has no huskiness , dysphonia, dysphagia and palate moves symmetrically when the subject says AHHHHH

Question 11

accessory nerve function test

Answer 11

subject should be able to lift shoulders against resistance , strenght of trapezius muscle

Question 12

hypoglossal function test

Answer 12

when subject is asked to protrude tongue and it will deviate to weaker side

Question 13

what compartment is the most easily displaced in the brain when there is raised ICP

Answer 13

the CSF
Can be dis-placed from the ventricles and cerebral subarachnoid space into the spinal subarachnoid space.
it can also undergo increased absorption or decreased production

Question 14

what is the Monro-kellie hypothesis

Answer 14

Normally, a reciprocal relationship exist among the three intracranial
volumes such that the ICP is maintained within normal limits.
Because these volumes are practically incompressible, a change in one
component must be balanced by an almost equal and opposite effect
in one or both of the remaining components

Question 15

clinical effects of raised ICP

Answer 15

headache -> worse in the morning and when stooping or bending
vomiting -> acute rise in ICP
papilloedema -> swelling of the optic disc and retina resulting in disc haemorrhages

Question 16

what is brain herniation

Answer 16

consequence of increased ICP
brain is protected by the skull and two supporting septa (falx cerebri and tentorium cerebelli)
brain herniation represents a displacement of brain tissue under the falx cerbri or through tentorial notch or incisuria of the tentorium cerebelli
area of high pressure ,moving contents to low pressure

Question 17

brain herniation is divided into two categories

Answer 17

supratentorial

infratentorial

Question 18

causes of hypoxic brain damage

Answer 18

extracranial blood loss -> common in association with severe head injury

uncontrolled seizures -> further source of secondary insults following head injury due to increased metabolic rate associated with head seizures and the respiratory impairment that comes with them

Question 19

acute management of head injury

Answer 19

ƒ Airways and cervical spine control
ƒ Breathing and ventilation
ƒ Circulation and haemorrhage control
ƒ Disability and neurological status
ƒ Exposure and environment

Question 20

neural plasticity

Answer 20

recovery of tissue which had been partially but not irreversibly damaged by the injury and adaptation of uninjured tissue to undertake some of the functions previously subserved by tissue which has been irreparably damage

Question 21

Sequelae

Answer 21

pathological condition resulting from a prior disease, injury or
trauma

Question 22

sequelae of head injury

Answer 22

incomplete recovery -> cognitive impairment , hemiparesis 
post traumatic epilepsy 
post traumatic syndrome
chronic subdural haemorrhage 
hydrocephalus

Question 23

what is post traumatic syndrome

Answer 23

complaints of headache , dizziness, malaise
litigation
depression

Question 24

what is punch drunk syndrome

Answer 24

o Consists of cognitive impairment, extrapyramidal and pyramidal signs
o Seen typically in professional boxers

Question 25

Which nerve provides somatosensory innervation to the nasal cavity ?

Answer 25

Trigeminal - ophthalmic and maxillary divisions

Question 26

Which intrinsic eye muscles are innervated by the oculomotor nerve

Answer 26

Sphincter papillae - pupil constriction

Ciliary muscle - accommodation

Question 27

Where do cranial nerves III, IV and VI enter the orbit?

Answer 27

All enter the orbit through the superior orbital fissure

Question 28

Which cranial nerve is involved in the corneal reflex

Answer 28

Trigeminal - sensory afferent ,ophthalmic division

Facial nerve efferent - orbicularis oculi

Question 29

Which gland is innervated by the glossopharyngeal nerve

Answer 29

Parotid gland via the lesser petrosal nerve

Question 30

Which cranial nerves are involved in the gag reflex

Answer 30

Afferent glossopharyngeal nerve

Efferent vagus nerve

Question 31

Deviation of the uvula indicates a weakness of what CN ?

Answer 31

Glossopharyngeal and vagus

Question 32

What is shingles

Answer 32

Reactivation of the chicken pox virus - varicella - zoster virus - which remains dormant in nerve cell ganglia

Question 33

What is Ramsay hunt syndrome?

Answer 33

A particular form of shingles that forms in the geniculate ganglion

Question 34

What is a common cause of jugular foramen compression

Answer 34

Paraganglioma

Question 35

How can CSF be identified

Answer 35

CSF should have glucose in it , but nasal secretions do not; this is neither sensitive nor specific - beta 2 transferrin level only found in CSF
HALO SIGN on tissue of blood stained fluid

Question 36

What is nystagmus

Answer 36

Abnormal eye movements

Question 37

What can lead to oculomotor nerve palsy ?

Answer 37

Aneurysms of the posterior communicating artery causing a subarachnoid haemorrhage -> presents with severe head ache, dilated pupil, ptosis