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Flashcards in visual, auditory, and vestibular systems Deck (36):
1

Is impaired visual acuity from a lesion of the optic nerve or macula improved by looking through a pinhole or by corrective lenses?

no

2

Perimetry

computer flashes dots

3

blind spot, when does it enlarge

optic disc in the nasal retina is devoid of rods and cones

-papilledema: increased intracranial pressure causes the optic nerve to appear swollen on ophthalmoscopic exam

4

Scotomas

abnormal blind spots
due to:
1.lesions in the retina (infections or inflammation, macular degeneration, or retinal detachments)
2. lesions of the optic nerve (demyelination or ischemia)

5

constricted fields can be caused by glaucoma or retinal degenerative disease, but as the examiner moves back the visual field should enlarge, what is it called if it doesn't?

tunnel vision
-psych problem

6

Deficit: blindness in left eye
Lesion:

left optic nerve
11 00

7

Deficit: bitemporal heteronymous hemianopsia

inner optic chiasm
10 01

8

Deficit: binasal heteronymous hemianopsia

outer optic chiasm
01 10

9

Right homonymous hemianopsia

left optic tract

10

Right superior homonymous quadrantanopia

left inferior optic radiation (temporal lobe, meyer's loop)

11

Right inferior homonymous quadrantanopsia

left superior optic radiation (parietal lobe)

12

Right homonymous hemianopsia (with macular sparing)

left occipital lobe

13

Does congruence increase when the lesion is more anterior or posterior

posterior

14

Optic nerve lesions produce what 2 deficits?

scotomas or monocular blindness

15

Optic chiasm lesions produce what

heteronymous visual field defects

16

Lesions of the optic tract or optic radiation or occipital visual cortex

homonymous visual field defects

17

optic neuritis
What is it?
How does it look on ophthalmoscopic exam?
Who gets it?

sudden blindness of part or all of one eye, which may feel achy or tender with eye movements
-pupils constrict poorly when shined in the bad eye or not at all but constrict normal when light is shined in the good eye
-weeks to months later the vision returns completely or partially (RAPD)
Ophthalmoscopic exam: optic disc appears swollen with indistinct blurry margins
-get it in MS

18

Optic atrophy

optic disc appears more white or pale with sharply defined edges
-some loss of ganglion cell axons has occurred

19

Are most one eye visual deficits with abnormal pupillary light reflex and swelling of the optic disc due to lesions before or posterior to the lateral geniculate body?

before usually of lesions of the optic nerve or optic chiasm

20

What is a common lesion affecting the optic chiasm?

pituitary tumor
-arises from sella turcica
-pressure from below
-->superior temporal quadrants of the patient
-->endocrine symptoms as well

21

What most often causes lesions in the optic radiations?

tumors or ischemic infarctions

22

Cortical blindness

severe visual loss from bilateral occipital lobe lesions
-usually a stroke syndrome from thrombosis of the distal basilar artery or emboli down its posterior cerebral branches

-pupillary light reflex is intact and the optic disc appears normal since the retinal ganglion cells are not involved

23

Conductive deafness

impaired air conduction of sound stimuli-water or wax plugging up the external ear canal or fusion or disruption of the bony ossicles

24

Nerve(sensorineural) deafness

damage or impairment of the hair cell receptors or auditory nerve
as from drug toxicity or persistent exposure to loud nois

25

low tone loss

conduction

26

high tone loss

sensorineural

27

complete unilateral nerve deafness

8th cranial nerve lesion
-since the more proximal auditory pathways are bilaterally represented

28

Which is normally more efficient air or bone conduction

air

29

Weber test

top of skull
-nerve deafness-both air and conduction impaired in bad ear so better heard in normal ear

-conduction deafness-better in bad ear because in that ear the environment noise is suppressed so bone conduction is enhanced

30

Rinne test

mastoid process-->outside the ipsilateral ear
-should be heard by air conduction when it stops being heard through bone conduction
-if partial nerve deafness than air conduction is better than bone but if conduction deafness the air no longer more efficient so it is not heard

31

ENG
electronystagmogram

used to record eye movements and nystagmus induced by currents of warm or cool air entering the external ear
-determines whether right or left vestibular system is impaired

32

Dix-Hallpike maneuver

head is tilted and lowered
-if this position creates rotatory nystagmus, that posterior semicircular canal is over sensitive and is likely to cause positional vertigo

33

What can cause sudden severe unilateral deafness?

trauma
-petrous bone fracture
-ischemia in the territory of the AICA

34

acute labyrinthitis

viral infection or inflammation cuasing severe vertigo with nausea and vomiting and hearing impairment and unsteadiness of gait
1. nystagmus
2. unilateral decreased hearing
3. gait ataxia

-resolves within days to weeks

35

Meniere's disease

recurrent episodes of vertigo, deafness and tinnitius
-membranous labyrinth swells and reptures allowing potassium rich endolymph to leak into surrounding perilymph, disrupting the ionic gradient required for normal hair cell function

same symptoms as acute labyrinthitis
1. nystagmus
2. unilateral decreased hearing
3. gait ataxia
but can progress to
permanent deafness

-dietary restriction of salt and diuretics can reduce production of endolymph and lessen risk of chronic deafness

36

benign positional vertigo

degeneration of otoliths and displaced calcium crystals and other debris can lodge around the cilia of the semicircular canal hair cells making them over sensitive to minute movements of the head