LEC53: Pathology of Cranial Nerves

Question 1

disorders in what part of brain might CNI: olfactory n be involved with?

Answer 1

frontal lobe, because located just under frontal lobe

Question 2

what is most common cause of loss of smell

Answer 2

common cold, not CNI lesion

Question 3

how to test if pt has CNI: olfactory n issue?

Answer 3

make sure pt has clear nasal paths by putting odor under nose - ensure it’s not noxious

Question 4

what & where is this, & what does it cause?

Answer 4

meningioma on CNI: olfactory n

pt has loss of smell on 1 side

Question 5

optic disc

Answer 5

where optic nerve enters globe

Question 6

what does using opthalmoscope allow?

Answer 6

look into eye

look for signs of either:

1) opticatrophy
2) papilodema - swelling of the disc

Question 7

what is papilodema, what does it suggest?

Answer 7

swellings of the optic disc

sign of increased intercranial pressure

Question 8

how to test visual field?

Answer 8

testing CNII: optic n

move fingers to different areas in pt’s visual field; assess what they can see

what they can or cannot see tells where meningioma is

Question 9

which cranial nerves are occulomotor nerves?

Answer 9

CNIII, IV, VI

all move the eye

Question 10

what does CNIII innervate re: eye

Answer 10

all extraoccular muscles EXCEPT lateral rectus, superior oblique

Question 11

what does CNIII do re: pupil?

Answer 11

CNIII involves fibers that constrict pupil

if knock out CNIII, pupil dialates

Question 12

what happens if CNIII knocked out?

Answer 12

1) pupil dialates
2) eye deviates LATERALLY b/c CNIII doesn’t innervate lateral rectus m
3) eye deviates DOWNWARD b/c CNIII doesn’t innervate superior oblique m

Question 13

which structure is CNIII?

Answer 13

CNIII=oculomotor n, #3

Question 14

what might pressure on CNIII indicate?

Answer 14

brain herniation

b/c CNIII located adjacent to TEMPORAL LOBE

if anything pushes temporal lobe, will compress CNIII

Question 15

what is this condition? nerve damaged?

Answer 15

trochlear nerve palsy - head tilted slightly

occurs b/c CNIV is a rotator; if knocked out, get slight head tilt

Question 16

what is this condition?

Answer 16

abducens palsy - knock out of CNVI

pt gets double vision & knock out of lateral rectus m so eye cannot ABduct

can be unilateral or bilateral

Question 17

what is this condition

Answer 17

anducens (CN VI) palsy

Question 18

what optic reflex is associated with CNV, trigeminal n?

Answer 18

corneal reflex

NOT SCLERAL REFLEX

Question 19

what is sensory field of CNV?

Answer 19

Question 20

cause and presentation of trigeminal neuralgia?

Answer 20

like “seizure” of CN V

sudden, severe pain in 1 of divisions of CN V

agonizing pain caused by chewing or slightest stimulation to effected area

Question 21

what does lesion of CN VII cause?

Answer 21

facial nerve palsy

lesion involves ALL muscles of effected side of face

Question 22

what condition is this, what nerve is effected, what is presentation?

Answer 22

facial nerve (CN VII) palsy

1) L eye open wider b/c weakness of eye closure muscles
2) nasal labia fold more prominent on R side
3) if ask pt to show teeth, marked weakness contracting L facial muscles > see magnified asymmetry of eye fissures

Question 23

what is this condition

Answer 23

central (woman) and peripheral (man) bell’s palsy

CN VII facial n is effected

usually 1 side of CN VII effected

Question 24

what is an acoustic neuroma, which CN does it effect?

Answer 24

tumor on CNVIII, vestibulo-cochlear n

Question 25

what is nystagmus, which CN involved?

Answer 25

sudden small movements of eyes

CNVIII

Question 26

how to test auditory capability? which nerve tested?

Answer 26

CNVIII, vestibulocochlear n

make dinging sound near ear

Question 27

which nerves involved with gag reflex?

Answer 27

CN IX, CN X

Question 28

where does this pt have a lesion?

Answer 28

R side of CN IX glossopharyngeal, CN X vagus

uvula deviates to STRONGER side

here deviation is to L side so lesion is R side

Question 29

which muscles does CNXI, accessory, innervate?

Answer 29

1) trapezius
2) sternocleidomastoid

Question 30

drop shoulder is sign of what?

Answer 30

lesion to CNIX, spinal accessory n b/c innervates trapezius

Question 31

what is this, what does it indicate?

Answer 31

scalloping on side of tongue due to atrophy of tongue muscle, innervated by CN XII, hypoglassal n

Question 32

what is effected here?

Answer 32

R side of tongue effected b/c strong side - L - pushes tongue out toward weaker muscle

innervation = CN XII, hypoglossal