Lecture 33: Clinical Neuro-Opthalmology

Question 1

How are your visual fields represented in the retina? In the cortex?

Answer 1

Right visual field is seen contralaterally
Right visual field is seen in left V1, and v. versa
Superior visual field is represented inferiorly in V1
Cortex = retina in representation

Question 2

What is the optic radiation? What is its path?

Answer 2

AKA Geniculo-calcarine tract AKA geniculostriate pathway
The relay between LGN and Striate cortex
In its pathway, it splits into two two parts on each side of the cortex
-fibers from inferior retina (superior eye field) must pass MEYERS LOOP in the TEMPORAL LOBE
-fibers from superior retina (inferior eye field) must travel through parietal lobe to the occipital lobe

Question 3

What happens when you lesion the temporal lobe?

Answer 3

You can potentially lesion Meyers loop and cause a defect in the superior eye field (pie in the sky defect or quadrantanopia)

Question 4

What is Macula vision?

Answer 4

Definition: where light focuses

takes up 50 percent of occipital lobe even though it is only 5-10%

Question 5

What clinical symptoms would you get with a left inferior branch of retinal artery occlusion?

Answer 5

Inability to see out of your LEFT superior temporal/nasal hemifields
This is because there is no blood going to your INFERIOR retina…which gets light coming from your SUPERIOR visual field

Question 6

What symptom do you get with a left optic nerve tumor?

Answer 6

You get left (ipsilateral) complete blindness.

Blindness is unilateral because your optic nerve is anterior to your optic chiasm and only carries nerves from one eye

Question 7

What is the most common cause of bitemporal hemianopsia

Answer 7

Pituitary adenoma!

Question 8

What are the symptoms of pituitary adenoma?

Answer 8

David and Goliath Motherfucker
Goliath was too Big (due to the tumor)
No peripheral vision so couldn’t see David (Bitemporal hemianopia, or the temporal hemifields are fucked bilaterally)
Goliath got killed with a simple hit to the head because tumor makes herniation possible?

Question 9

What is Bitemporal hemianopia?

Answer 9

Can’t see shit from BOTH temporal hemifields

Question 10

What happens when you lesion the optic chiasm?

Answer 10

You get bilateral vision deficits in the nasal hemifields

Because nasal hemifields are the only ones that cross

Question 11

What happens when you lesion the right optic tract?

Answer 11

You get homonymous anopsia…no vision on the temporal hemifield of RIGHT eye and no vision on the nasal hemifield of the LEFT eye
This is because temporal hemifield nerves run ipsilateral while nasal hemifield run contralateral

Question 12

What happens if you lesion the right optic radiations (inferior and superior branches)?

Answer 12

You get a left homonymous hemianopia (you can’t see from the same side on both eyes…nasal and temporal)
Cause: brain tumor
Same symptoms as a right optic tract lesion

Question 13

What is homonymous hemianopia?

Answer 13

One temporal hemifield deficit on one side and one nasal hemifield deficit on the other side
(Can’t see out on the same side of the visual field for both eyes)

Question 14

What happens when you damage right meyer’s loop of temporal lobe with temporal lobectomy?

Answer 14

Left (contralateral) UPPER quandrantopsia (because it is the upper left quadrant)
Caused by mesotemporal sclerosis which requires emporal lobectomy

Question 15

What is homonynous quandrantopsia?

Answer 15

Same quadrant of the visual field (e.g. upper left quadrant) is blinded on both sides

Question 16

What happens to a patient with a left posterior cerebral artery stroke?

Answer 16

You get a right (contralateral) homonymous hemianopia with macular sparing

Question 17

When you see macular sparing, where does the lesion HAVE TO BE?

Answer 17

Occipital lobe because that’s the only place with dual blood supply (with tip still there)

Question 18

Why is there macular sparing if you lesion one half of occipital lobe?

Answer 18

Because macula has dual blood supply, so if the tip is there, you have still have macula vision

Question 19

Can you get homonymous hemianopia without macular sparing?

Answer 19

Yes, if you have a gunshot wound that fucks up your occipital tip

Question 20

What would happen to a patient with bilateral occipital lobe strokes?

Answer 20

Complete cortical blindness

Question 21

What are the higher cortical visual disorders associated with the “What” Pathway?

Answer 21

1. Alexia without agraphia
2. Visual agnosias and prosopagnosia
3. Cerebral hemi-achromatopsia

Question 22

What are the higher cortical visual disorders associated with the “Where” Pathway?

Answer 22

1. Hemi-neglect
2. Balint’s syndrome (simultanagnosia)
3. Akinetopsia

Question 23

What is alexia without agraphia? Localization?

Answer 23

-unable to read (think of it as unable to recognize words)
-right homonymous hemianopia (because both inferior and superior fibers are fucked?)
-able to write
Localization:
LEFT occipital lobe and LEFT splenium of corpus callosum
Can be caused by temporal lobe TUMOR that fucks up the ability for left occipital lobe to get information

Question 24

What is visual agnosia/prosopagnosia? Localization?

Answer 24

Inability to recognize objects
-apperceptive
-associative (area 17 is intact, temporal lobe is intact, but the FIBERS connecting the two are disconnected)
Inability to recognize faces (prosopagnosia)
Localization:
Occipito-temporal (often bilateral), most specifically the FUSIFORM FACE AREA (FFA)

Question 25

What is the fusiform face area (FFA) in the inferior occipital-temporal lobe?

Answer 25

The main area in your brain that recognizes faces

Question 26

What are symptoms of cerebral hemi-achromatopsia? Localization?

Answer 26

Lack of color vision in homonymous hemifield
Presents with upper quadrantopsia (because you are fucking with the inferior fibers of optic radiation)
Localization:
Fusiform and lingual gyri in inferior occipital lobe…aka V4!!
Cause: PCA stroke

Question 27

Where are the lingual and fusiform gyri?

Answer 27

Inferior occipital lobe

Question 28

Where is the cuneus gyrus?

Answer 28

Gryus above the calcarine fissure

Question 29

What are symptoms of hemi-neglect? Localization?

Answer 29

Symptoms: ignorance or unawareness of objects in LEFT hemispace
Localization: RIGHT hemisphere, usually parietal lobe
They know where the left side is but they are choosing not to explore
Cause: stroke in parietal lobe (Posterior parietal area, PPA)
In the MRI, you can see that the eyeballs are turned to the right only…so already you can tell this guy can’t see anything in the left hemispace

Question 30

What are symptoms of Balint’s syndrome? Localization?

Answer 30

-simultanagnosia (inability to put together a scene from individual parts)
-ocular apraxia (cannot touch finger…but it is NOT a cerebellar dysfunction)
-optic ataxia (unable to reach under visual guidance)
Localization: BILATERAL parieto-occipital lobes
Common cause: CJD

Question 31

Balint’s syndrome

Answer 31

simultagnosia
caused by CJD
ocular apraxia and optic ataxia

Question 32

What type of symptoms does CJD give you?

Answer 32

Balint’s syndrome

Question 33

What is Akinetopsia? Localization?

Answer 33

Symptoms: inability to detect motion
Localization: lateral occipito-temporal (V5)

Question 34

What is V5?

Answer 34

Same shit as MT but this is what it is called in humans…fuck you palmer!