NOD 1 Afferent System and Neuroimaging Review

anterior to the chiasm

Where is the lesion/problem if there is unilateral vision loss?

amblyopia

What is the one exception to the localization of a lesion/problem causing unilateral vision loss?

between chiasm and occipital cortex

Where does the lesion localize if there is a homonymous hemianopia?

4

How many HPIs must be recorded?

foveolar vision, estimates central scotoma size, screens for hemianopic defects and metamorphopsia, functional visual loss and suggests anatomical localization

What does Snellen acuity measure and screen for?

foveal disease

What does the presence of metamorphopsia indicate?

any patient that isn't 20/20

When should pinhole be done?

central media opacity or scotoma, amblyopia, non-organic vision loss, pathology

What is indicated by no improvement even with pinhole?

40'

What should stereopsis be in a patient with 20/20?

20/400

What acuity is the number on a dollar bill?

20/70

What acuity are the serial numbers on a dollar bill?

20/40 - 20/50

What acuity of the numbers on a wristwatch?

5 degrees

What would the estimated size of a central scotoma be on a patient with 20/50 acuity?

20

What would the estimated size of a central scotoma be on a patient with 20/200 acuity?

20/70

What would the estimated acuity be on a patient with a 7 degree central scotoma?

red

What color is optic nerve function most sensitive to?

red desaturation (stationary red target) and confrontation fields with red target moved throughout field

What tests can be used to compare optic nerve function between both eyes?

brachium of the superior colliculus to get the pretectal nucleus

What does the light reflex pathway use?

no

Is the presence of an RAPD related to anisocoria?

optic neuropathy

What does the presence of an RAPD indicate?

anterior the LGN

Where would a lesion causing an RAPD localize to?

compression, glaucoma, inflammation, infarction, demyelination, trauma, papilledema

What are optic neuropathies that can cause an RAPD?

CRAO, CRVO, RD w/ macular involvement, macular disease

What are retinal causes of an RAPD?

early release

What does a 1+ RAPD grade indicate?

no initial movement followed by early release

What does a 2+ RAPD grade indicate?

immediate release

What does a 3+ RAPD grade indicate?

amaurotic pupil associated w/ no light perception

What does a 4+ RAPD grade indicate?

the good eye

Which eye is the neutral density filter placed over?

0.3 log filter over an eye

How is a neutral density filter used to tease out a subtle RAPD?

reverse RAPD testing, compare direct and consensual response to light

What is the next step if 1 pupil doesn't respond to light during RAPD testing?

outer retina or choroid

Where does a lesion resulting in a defect that fails to respect both horizontal and vertical meridians localize to?

arcutes

Where does a lesion resulting in a defect that respects the horizontal meridian localize to?

chiasm or retrochiasm

Where does a lesion resulting in a defect that respects the vertical meridian localize to?

occipital cortex

Where does a lesion resulting in a defect that respects both the horizontal and vertical meridians localize to?

No

Does the papillomacular bundle respect the horizontal raphe?

arcuate bundles

What retinal nerve fiber bundles respects the horizontal raphe?

temporal defect or enlarged blind spot

Which defects are not consistent with glaucoma?

nasal step, bjerrum scotoma, arcuate defect

What are typical glaucomatous defects?

No

Is optic disc pallor associated with glaucoma?

the ON appearance must match the VF and glaucoma is usually bilateral

If the visual field defect is consistent with glaucoma, what else must be present to be able to officially diagnose it as glaucoma?

enlarged blind spot, arcuate

What visual field defect is seen in a patient with papilledema?

central/cecocentral

What visual field defect is seen in a patient with optic neuritis?

altitudinal

What visual field defect is seen in a patient with NAAION?

devastating field loss

What visual field defect is seen in a patient with AAION?

central/cecocentral

What visual field defect is seen in a patient with toxic/nutritional optic neuropathy?

incongruous

The more anterior the lesion, the more _____________ the defect.

congruous

The more posterior the lesion, the more _____________ the defect.

total or complete hemianopia

When is it not possible to assess congruity of a defect?

RNFL thickness

What part of the OCT report must be reviewed when assessing for papilledema?

No

Is elevation of the NRR without RNFL thickness elevation indicative of papilledema?

optic nerve disease/damage

What is ganglion cell loss concerning for?

loss, pallor, edema

What must you look for when assessing the health of the neuro retinal rim/optic disc?

thickest regions swell first

Which regions is elevation first seen in edema?

ischemic optic neuropathy, compression, inflammation, trauma, hereditary/mitochondrial

What are non-glaucomatous causes of cupping?

1 month

How long after damage to the ganglion cells or their axons does pallor develop?

LGN and forward

Where would a lesion have to be to cause pallor?

compression, infection, inflammation

What does diffuse neuro retinal rim pallor indicate?

toxic/nutritional, demyelinating, compression, infection, inflammation

What does temporal neuro retinal rim pallor indicate?

optic tract compression

What does bow tie or band atrophy neuro retinal rim pallor indicate?

ischemic/NAION, infection, inflammation

What does altitudinal neuro retinal rim pallor indicate?

glaucoma

What does neuro retinal rim obliteration indicate?

glaucoma, compression

What does neuro retinal rim thinning without pallor indicate?

compression

What does neuro retinal rim thinning with pallor of the remaining neuro retinal rim indicate?

papilledema, optic neuritis, NAAION, AAION, Neuro-retinitis, disc drusen, anomalous disc

What are causes of indistinct optic disc margins?

1 mm

What is the length of the papilla optic nerve segment?

30 mm

What is the length of the intra-orbital optic nerve segment?

6 mm

What is the length of the intra-osseous optic nerve segment?

10 mm

What is the length of the intracranial optic nerve segment?

falx cerebri

What divides the cerebral hemispheres?

tentorium cerebelli

What divides the occipital lobe from the cerebellum?

septum pellucidum

What divides the lateral ventricles?

CT or X-ray

What imaging is used for bone?

2 layers of grey and white matter

What does the septum pellucidum consist of?

meninges

What is the falx cerebri derived from?

tells you the location/plane of the section you are viewing

What is a SCOUT scan?

bright

How do EOMs appear in an MRI with contrast?

grey

How do EOMs appear in an MRI without contrast?

temporalis muscle

What is being marked by the yellow star?

masseter

What is being marked by the pink star?

lateral pterygoid muscle

What is being marked by the blue star?

medial pterygoid muscle

What is being marked by the orange star?

paranasal sinuses

What drains mucus into the nasal cavity?

eustachian tube in the nasopharynx

What connects the paranasal sinuses to the middle ear?

close proximity (referred pain / trauma)

What is the relationship between the orbital cavity and the paranasal sinuses?

10 mm

How much space should be between the chiasm and pituitary in suprasellar cistern?

tissue density

What does a CT focus on?

tissue signal intensity

What does a MRI focus on?

CSF, fat, air

What is considered hypodense on a CT scan?

calcium, hemorrhage, metal, bone, iodine

What is considered hyperdense on a CT scan?

brain

What is considered isodense on a CT scan?

bone and blood

What is a CT scan useful in looking for?

CT

What scan would be helpful to detect a nerve sheath meningioma?

axial and coronal only

What sections are possible using a CT scan?

ionizing radiation, limited by head movement, more allergic rxns to its contrast

What are disadvantages of a CT scan?

sella turcica and suprasellar cistern

What cannot be viewed using a CT scan?

shellfish allergies, asthma, DM, kidney dysfunction

Who is CT contrast contraindicated in?

BUN/creatinine levels

What must be check prior to administering CT contrast to a patient?

CTA

What is the study of choice to look for aneurysms?

cervico-medullary junction, pituitary gland, pineal region, corpus callosum

What is the sagittal section of an MRI useful for viewing?

No

Is there radiation exposure in an MRI?