Visual, Auditory, and Vestibular Systems

Question 1

visual acuity

Answer 1

• smallest row of numbers a pt can accurately read which is a function of central vision involving the macula
• can read at 20 what pop can read at 100=20/100
• corrective lenses

Question 2

what suggests an ocular problem

Answer 2

-abnml visual acuity
-improved acuity when looking through a pinhole in a plastic card
VS: impaired visual acuity from a lesion of the ON or macula which is not improved when looking through a pinhole/corrective lenses

Question 3

blind spot

Answer 3

everyone has a physiological one in the temporal visual field of each eye, since optic disc in the nasal retina is devoid of rods and cones

Question 4

papilledema

Answer 4

• inc ICP causes the ON to appear swollen on exam
• both discs affected
• flame hemorrhages may be seen around the optic discs

Question 5

scotomas

Answer 5

pathological abnml blind spots elsewhere in the visual field of one eye where vision is lost or decreased

Question 6

right homonymous hemianopsia (with macular sparing)

Answer 6

lesion in the left occipital lobe

Question 7

right superior homonymous quadrantanopsia (pie in the sky)

Answer 7

left inferior optic radiation (TEMPORAL lobe, Meyer’s loop)

Question 8

right inferior homonymous quadrantanopsia

Answer 8

left superior optic radiation (PARIETAL lobe)

Question 9

cortical blindness

Answer 9

• severe visual loss from b/l occipital lobe lesions
• usually a stroke syndrome from thrombosis of the distal basilar artery or emboli down its posterior cerebral artery branches
• pt cant see but pupillary light reflex is intact and optic discs appear nml (b/c retinal ganglion cells are not involved)

Question 10

conductive deafness

Answer 10

• caused by impaired air conduction of sound stimuli such as: wax plugging up external ear canal, fused bony ossicles
• problem before the hair cell receptors
• low-tone hearing loss

Question 11

nerve sensorineural deafness

Answer 11

• caused by damage of hair cell receptors or auditory nerve from: drug toxicity or persistent exposure to loud noise
• high tone hearing loss

Question 12

what causes severe or complete unilat nerve deafness

Answer 12

CN8 lesion

Question 13

why is air conduction normally more efficient than bone conduction

Answer 13

because of the amplification system wherein air conduction allows detection of airborne sounds by the TM and ossicles which amplify the stimuli before sounds are transmitted to the cochlea

Question 14

Weber test

Answer 14

if louder on one side-ipsi conductive deafness or contra nerve deficit

Question 15

conductive deafness and tuning fork

Answer 15

if conductive deafness has occurred in one ear the vibrating tuning fork is heard better in that deaf ear since bone conduction is enhanced when room or environmental sounds are suppressed or reduced

Question 16

Rinne test

Answer 16

compare air conduction to bone conduction; if louder on the mastoid=conductive deafness

Question 17

Dix-Hallpike maneuver

Answer 17

simple bedside test of vestibular system; tests benign positional vertigo

Question 18

acute labyrinthitis

Answer 18

• labyrinth of inner ear affected by inflamm or viral infxn
• causes severe vertigo with n/v, hearing impairment and gait unsteadiness
• also: nystagmus, u/l dec hearing, and gait ataxia
• tx w benzos, antihistamine, or antiemetic meds

Question 19

Meniere’s disease

Answer 19

• recurrent tinnitus, vertigo, and deafness
• membranous labyrinth ruptures, K-rich endolymph leaks into surrounding perilymph and disrupts ionic gradient required for nml hair cell fxn
• tx w benzos, antihistamine, or antiemetic meds
• repeated episodes=complete permanent deafness

Question 20

benign positional vertigo

Answer 20

• common in elderly pts
• degeneration of otoliths and displaced calcium crystals and other debris lodge around cilia of semicircular canal hair cells