Third, Fourth, and Sixth Nerve Palsies (F)

Question 1

What is the cranial nerve with the longest intracranial course? 1. Thinnest cranial nerve? 2

Answer 1

1. CN IV

2. CN IV

Question 2

What are the common abnormal patterns in aberrant regeneration?

Answer 2

1. lid elevation during adduction or depression of the eye

2. depression and miosis of a pupil unreactive to light during adduction

Question 3

What is the rule of pupil in a third nerve palsy?

Answer 3

pupil-sparing III palsy is of ischemic nature and can be observed if it is a complete III nerve palsy

Question 4

What is the pathway of the CN VI?

Answer 4

1. Exit brainstem at pontomedullary junction
2. Travel over petrous apex of temporal bone
3. In the cavernous sinus: inferior to CN III,IV and adjacent to carotid artery
4. Through superior orbital fissure to ipsilateral lateral rectus

Question 5

Where are the signs of a Weber syndrome lesion? 1. Where is the location of the lesion? 2

Answer 5

1. CN III palsy, contralateral hemiplegia

2. corticospinal tracts or cerebral peduncle

Question 6

Where does the third nerve anatomically split into superior and inferior portions?

Answer 6

anterior portion of the cavernous sinus

Question 7

What is a condition with a medial inferior pontine lesion that results in ipsilateral CN VI palsy with contralateral hemiplegia from disruption at corticospinal tract?

Answer 7

Millard-Gubler syndrome

Question 8

What are the two types of aberrant regeneration (and what do each indicate)?

Answer 8

1. primary (absence of CN III palsy and may be first sign of expanding lesion in or around cavernous sinus)
2. secondary (following CN III palsy that is from trauma or compression but NOT ischemic)

Question 9

What does pupil involvement in a third nerve palsy indicate?

Answer 9

indicates compression from arteries as opposed to ischemia (inner nerve)

Question 10

What is a compression against the tentorial edge of CN III by the uncal portion of the temporal lobe called? 1. What will probably accompany this? 2

Answer 10

1. cerebral herniation

2. altered mental status or unconsciousness

Question 11

What is the pathway of the CN IV?

Answer 11

1. emerges from dorsal aspect of brainstem posterior to inferior colliculi
2. decussates completely in superior medullary velum (roof of fourth ventricle)
3. travels in cavernous sinus along lateral wall, inferior to III
4. through superior orbital fissure
5. innervates the SO contralateral to the IV nucleus

Question 12

Where are the signs of a Nothnagel syndrome lesion? 1. Where is the location of the lesion? 2

Answer 12

1. CN III palsy, ipsilateral ataxia

2. brachium conjunctivum

Question 13

What does the nucleus of CN IV innervate?

Answer 13

contralateral superior oblique

Question 14

Where are the signs of a Benedikt syndrome lesion? 1. Where is the location of the lesion? 2

Answer 14

1. CN III palsy, contralateral ataxia and involuntary movements
2. red nucleus

Question 15

What is the CN VI lesion that is a pontine lesion (dorsal) that results in ipsilateral horizontal gaze palsy and facial nerve palsy with contralateral hemiparesis and hemisensory loss (hearing, taste)?

Answer 15

Foville syndrome

Question 16

What is a condition with a complete bilateral paralysis of CN VI and VII resulting in strabismus, deafness, and facial diplegia (mask-like faces)?

Answer 16

Moebius syndrome