More week 2

Question 1

What is the Frontal Eye Field?

Answer 1

The cortical area responsible for initiating horizontal and vertical gaze.

Question 2

What is the Paramedial Pontine Reticular Formation?

Answer 2

Brainstem region responsible for control of horizontal eye movements.

Question 3

What is the cause of Parinaud Syndrome?

Answer 3

Compression of dorsal midbrain, pretectum and dorsal region of riMLF; pineal tumor, hydrocephalus

Question 4

Discuss the 2 groups of Abducens nerve neurons

Answer 4

Group 1: innervates lateral rectus of ipsilateral eye

Group 2: Axons cross midline, travel rostrally in MLF, innervate OMN and medial rectus of contralateral eye.

Question 5

What 3 things can cause an imbalance between the left and right FEFs?

Answer 5

1. voluntary
2. Seizure (increased activity)
3. The result of a cortical lesion/insult (decreased activity), results in the eyes being deviated conjugatively TOWARD the side with the lower level of activity.

Question 6

Describe the effects of a right CN6 palsy

Answer 6

Right eye deviated medially; Can’t direct laterally

Question 7

Describe the effects of a right Abducens nucleus lesion.

Answer 7

Left conjugate gaze normal; No right conjugate gaze

Question 8

Describe the effects of a right PPRF lesion?

Answer 8

same as right abducens nucleus

Question 9

Describe the effects of a left MLF lesion.

Answer 9

left conjugate gaze normal, right gaze normal with right eye but not with left eye; lack of drive to left OMN from right abducens nucleus.

Question 10

How do you determine if the lesion is in the MLF and not in the OMN or CN3?

Answer 10

If vergence is normal, then OMN and CN3 on the affected side are normal.

Question 11

Discuss the Vestibulo-Ocular reflex

Answer 11

Eye movement is equal in magnitude but opposite in direction of movement of head; Stabilizes image on retina during head movements.

Question 12

Describe the directional use of the VOR

Answer 12

Left Semicircular canals activated when head turned left, causing eyes to turn rightand vice versa

Question 13

What are the characteristics of damage to the vestibular appartus?

Answer 13

1. Unilateral damage results in spontaneous nystagmus due to imbalance in left vs right SCC activity 2. Eyes drift to affected side due to greater activity in unaffected SCC system 3. At limit, eyes snap back to center, displaying a beat toward the normal side 4. Damage to left vestibular system = right beating nystagmus 5. Damage to right vestibular system = left beating nystagmus

Question 14

Discuss the Oculocephalic Maneuver

Answer 14

If eyes move along with head movement, instead of in opposite direction, brainstem dysfunction is indicated

Question 15

Describe the effects of Relative Afferent Pupillary Defect.

Answer 15

Decreased sensitivity of affected eye to light due to lesion in the retina or optic nerve 2. Direct response of affected eye decreased, but Consensual response of affected eye is normal

Question 16

Describe the actions of the affected eye in a swinging flashlight test (RAPD)

Answer 16

Dilation of the pupil

Question 17

What is Horner’s syndrome? Presentation?

Answer 17

Loss of sympathetic innervation to eye; Anhydrosis, pupil constriction

Question 18

Describe Argyll-Robertson Pupil

Answer 18

1. Pupils are small and irregular
   
   2. Pupil responses to light are less compared to response seen during near response
2. Generally seen during neurosyphilis (tabes dorsalis)