Visual, Auditory and Vestibular System

Question 1

What causes enlargement of the blind spot?

Answer 1

Papilledema (increased intracranial pressure)

Question 2

What is a scotoma?

Answer 2

Pathological blinds in one eye, from ocular, retinal, or optic nerve disorder

Question 3

What is the etiology of a visual field deficit that enlarges with distance between patient and the examiner?

Answer 3

glaucoma, or retinal degeneration

Question 4

What is the etiology of a visual field deficit that does not enlarge with distance?

Answer 4

Psychogenic “tunnel vision” - this is not a physiologic process

Question 5

Heteronymous loss of vision refers to LOV in what fields?

Answer 5

temporal/temporal or nasal/nasal

Question 6

A bitemporal heteronymous hemianopsia occurs due to a lesion where (LOV on temporal/temporal sides)

Answer 6

Lesion in the medial optic chiasm

Question 7

What lesion would cause a right nasal visual deficit?

Answer 7

A lesion compressing the right outer optic chiasm

Question 8

Lesions in the right optic tract ( or lateral geniculate), right optic radiation or right visual cortex in the occipital lobe would lead to what types of visual defects?

Answer 8

Left homonymous hemianopsia.

Visual field deficits on the left side of both eyes

Question 9

Where would a lesion be located that causes a left superior homonymous quandratanopsia?

Answer 9

Lesion in the right temporal optic radiations

Question 10

Heteronymous hemianopsias can only occur where?

Answer 10

At the optic chiasm

Question 11

How does optic neuritis present?

Answer 11

Sudden visual loss on one eye - either a scotoma or total blindess

Eye movements may be painful

Question 12

Optic neuritis is commonly associated with which neurologic disease?

Answer 12

Multiple Sclerosis

Question 13

How does the eye appear on fundoscopic exam in someone with optic neuritis?

Answer 13

The optic disc appears swollen and inflamed

Question 14

If someone presents with unilateral swollen optic discs, what is the most likely etiology?

Answer 14

Optic neuritis

Question 15

if someone presents with bilateral swollen optic discs, what is the most likely etiology?

Answer 15

Papilledema (due to increased intracranial pressure)

Normal vision will be lost or impaired if left untreated

Question 16

On what structure does a pituitary tumor arise?

Answer 16

Sella turcica

Question 17

What does the pituitary tumor compress?

Answer 17

The optic chiasm- from below

Question 18

What is the progression of visual loss due to a pituitary tumor?

Answer 18

Initially superior temporal quadrantic effect, followed by heteronymous bitemporal hemianopsia

Question 19

In addition to visual deficits caused by compression of the optic chiasm, pituitary tumors secrete three hormones that cause a variety of other symptoms. What are they?

Answer 19

Prolactin
ACTH
Growth hormone

Question 20

Other than congenital defects, what else can cause cortical blindness?

Answer 20

Thrombosis or occlusion of the posterior cerebral arteries.

Occipital infarct –> cortical blindness

Question 21

A clot at the top of the basilar artery where it branches into the right and left posterior cerebellar arteries can lead to bilateral occipital blindness. How will this effect the pupillary light reflex?

Answer 21

Despite total blindness, the pupillary light reflex is normal and no optic atrophy develops

Question 22

How does visual information from the eye get to the brain (and where in the brain does it synapse)?

Answer 22

Visual information from the eye goes through the lateral geniculate nucleus in the thalamus and then reaches the visual cortex. It synapses at V1 (visual cortex one) in the calcarine fissure of the occipital lobe.

Question 23

What is a conductive deafness? What tones are lost?

Answer 23

Conductive deafness arises from impaired air conduction of air stimuli. It results in loss of low tones.

Can be due to impacted wax, or an ossicle lesion

Question 24

What is nerve (sensorineural) deafness? What tones are lost?

Answer 24

Sensorineural deafness arises from degeneration of hair cells or the auditory nerve. It results in loss of high tones

Can be due to noise damage, drug toxicity, ischemia or trauma

Question 25

Where is the tuning fork placed during the Weber test?

Answer 25

The top of the head

Question 26

What does the Weber test tell us?

Answer 26

If the sound is louder on one side, it indicates one of the two:

1) Ipsilateral conductive deafness (ipsilateral sensorineural hearing is perceived as louder)
2) Contralateral nerve deficit

Question 27

Where is the tuning fork placed during the Rinne test?

Answer 27

On the bone just behind the ear (on the mastoid)

Question 28

What does the Rinne test tell us?

Answer 28

The rinne test compares air conduction to bone conduction.

If the Weber-lateralized ear has a positive Rinne test (AC>BC), that generally means the absence of conduction loss in that ear, and the reason sound had been perceived as louder on that side is because a sensorineural loss is present contralaterally; an ipsilateral negative Rinne test (BC>AC), on the other hand, would confirm ipsilateral conductive hearing loss (although contralateral sensorineural hearing loss may still be present.

Question 29

What does the Nylen-Barany or Dix-Hallpike maneuver

test for?

Answer 29

Positional vertigo

Question 30

What causes benign positional vertigo?

Answer 30

degenerated otoliths, calcium crystals lodge around cilia of semicircular canal hair cells, making them “over-sensitive”;

• minor movements cause impulses in the vestibular system

Question 31

What are treatments for positional vertigo?

Answer 31

Head-positioning exercises with intermittant antihistamines or benzodiazepenes

Question 32

What causes acute labyrinths?

Answer 32

viral infection or inflammation of the inner ear labyrinth

Question 33

What are the symptoms of an acute labyrinth?

Answer 33

Asymmetrical nystagmus, unilateral hearing loss and gait ataxia on examination

Question 34

What is the treatment for acute labyrinths?

Answer 34

Acute labyrinths resolve in days to weeks- you can treat the vertigo with antihistamines, benzodiazepenes or antiemetic medications

Question 35

What is Meniere’s disease?

Answer 35

The membranous labyrinth swells and ruptures –> intermixed endolymph and perilymph.

This impairs receptors and can lead to permanent deafness upon repeated bouts.