Cranial Nerves III, IV, VI clinical correlations

Question 1

ipsilateral ptosis

Answer 1

III drooping of upper eyelid due to paralysis of levator palpebrae superioris muscle

(upper eyelid levitate palpate superior)

Question 2

lateral strabismus

Answer 2

III ipsilateral eye fixed in a down and lateral position - due to unopposed ipsilateral superior oblique and lateral rectus muscles respectively.

down and out against superior oblique and lateral rectus

Question 3

diplopia

Answer 3

III double vision due to lateral strabismus

di means double, due to strabismus

Question 4

ipsilateral proptosis

Answer 4

III bug-eye due to relaxation of four of six extraocular eye mm.

four out of six extraordinary props

Question 5

ipsilateral mydriasis

Answer 5

III dilation of pupil due to paralyzed sphincter pupillae muscle and unopposed dilator pupillae m (sympathetic innervation from superior cervical ganglion)

rise big sphincter pupillae does not work dilator pupillae unopposed

Question 6

ipsilateral loss of accommodation

Answer 6

III inability to focus on close objects - due to paralysis of ciliary m. leading to permanently flat lens set for distant viewing

permanent flat lens, ciliary muscle, close

Question 7

ipsilateral loss of pupillary light reflex

Answer 7

III ipsilateral sphincter pupillae muscle is paralyzed

paralyzed pupil sphincter

Question 8

entire paralysis or paresis of one-half of ipsilateral face is caused by

Answer 8

a peripheral lesion of the primary root of CN VII

Question 9

Hyperacusis

Answer 9

sensitivity to lound sounds - paralysis or paresis of ipsilateral stapedius muscle

Question 10

Peripheral paralysis, or total involvement of ipsilateral half of face such as Bell palsy caused by

Answer 10

Lesion on facial nerve before it synapses onto facial nucleus.

Question 11

Central paralysis (central seven, upper half of face spared) caused by

Answer 11

lesion on facial nerve after it synapses onto facial nucleus

Question 12

Corneal Reflex testing

Answer 12

a wisp of cotton touched to ipsilateral cornea should elicit a corneal reflex and both eyes should shut - damage to CN VII is a loss of the efferent limb of reflex

Question 13

what can cause symptoms of dry mouth?

Answer 13

chorda tympani nerve, submandibular ganglion or postganglionic fibers may have been damaged

Question 14

What can cause dry eye?

Answer 14

greater petrosal nerve, nerve of the pterygoid canal, pterygopalatine ganglion or postganglionic fibers in lacrimal nerve have been damaged

Question 15

where must a lesion on CN VII be in order to cause flaccid paralysis of face (Bell’s palsy), loss of corneal reflex but no parasympathetic symptoms or loss of taste?

Answer 15

at or distal to the stylomastoid foramen

Question 16

A lesion on CN VII distal to geniculate ganglion but proximal to exit of nerve to stapedius m and the chorda tympani will cause what symptoms?

Answer 16

decreased salivation and taste
flaccid paralysis of half of face
hyperacusis
loss of the corneal reflex all ipsilateral but sparing of lacrimation, mucous production as greater petrosal nerve is spared.

Question 17

You have a patient who is suffering from Bell’s palsy. He has decreased mucous production in ipsilateral nasal and oral cavities. He is suffering from decreased lacrimation by ipsilateral lacrimal gland and decreased salivation from ipsilateral submandibular and sublingual glands. There is some loss of cutaneous innervation from ipsilateral pinna and external auditory canal. He is experiencing decreased taste sensation from ipsilateral anterior 2/3rds of tongue. There is loss of corneal reflex and hypercusis. Where is lesion?

Answer 17

proximal to geniculate ganglion and origin of greater petrosal nerve

Question 18

what will elicit a gag response?

Answer 18

touching the walls of the pharynx; glossopharyngeal nerve and vagus nerve

Question 19

What could cause damage to glossopharyngeal nerve?

Answer 19

could be damaged with vagus nerve at jugular foramen.

Question 20

What are the consequences of damage to ipsilateral glossopharyngeal nerve?

Answer 20

loss of taste, gag reflex and glossopharyngeal neuralgia

Question 21

glossopharyngeal neuralgia

Answer 21

idiopathic attacks of severe pain in sensory territories

Question 22

What causes Vernet syndrome? What are its symptoms?

Answer 22

a. lesion at or just inside the foramen
b. loss of taste and general sensation from ipsilateral half of pharyngeal tongue (posterior 1/3rd)
- accessory nerve CN XI involved, paresis on ipsilateral sternocleidomastoid and trapezius muscles
- Vagus nerve CN X - leads to loss of sensation in the larynx and pharynx and dysarthria and dysphagia due to paralysis of ipsilateral vocal fold and intrinsic laryngeal muscles

Question 23

What causes Collet-Sicard syndrome? What are its symptoms?

Answer 23

a. lesion just distal to foramen, hypoglossal nerve may be involved
b. paresis in the ipsilateral half of the tongue

Question 24

What causes retropharyngeal syndrome or Villaret syndrome? What are its symptoms?

Answer 24

a. damage to CNs IX, X, XI and XII plus ipsilateral Horner syndrome symptoms resulting from damage to the superior cervical ganglion

Question 25

How do we test vagus nerve function?

Answer 25

with glosopharyngeal using gag reflex observe soft palate while patient says "ah". palate should elevate symmetrically. if damaged, uvula will deviate to undamaged side.

Question 26

What would damage to the root of the vagus nerve result in?

Answer 26

dysphagia and dysarthria

Question 27

dysphagia

Answer 27

dificulty in swallowing due to flaccid paralysis of ipsilateral pharyngeal and laryngeal muscles

Question 28

dysarthria

Answer 28

weakness in vocalization due to flaccid paralysis of ipsilateral vocalis and other laryngeal muscles - may also be seen in patients whose recurrent laryngeal nerve has been damaged during thyroid surgery.