Visual, Auditory and Vestibular Systems

Question 1

Visual acuity:

How is it tested?

What does it test?

Interpret 20/100:

Answer 1

Visual acuity pertains to the smallest row of numbers or letters a patient can accurately read

Each eye is tested separately, reading the smallest size of numbers/letters on a Snellen wall chart

it is a function of central vision involving the macula

It is recorded as a fractional number, which compares the patients vision with the normal populations.

20/100 = what the pt can read at a distance of 20 feet, the NL population read at 100 feet

Question 2

What can impaired visual acuity imply?

How would you distinguish between a correctable problem vs an more serious issue?

Answer 2

Abnormal acuity could be due to an ocular problem (when a patient needs glasses) or a lesion of the optic nerve or macula.

If acuity improves when looking through a pinhole, it is suggestive of an ocular problem; when it does not improve when looking through a pin hole or corrective lenses, it is suggestive of an optic nerve or macular issue

Question 3

Visual Field Exam:

What is being tested?

How is it tested?

Answer 3

Mainly examines peripheral vision

Perimetry - quantitative method of testinv visual field, with dots on a computer screen

Beside, w/physician flickers fingers on the peripheral fields of the physician and patient

Question 4

Where is the normal blind spot of a person located?

Answer 4

Everyone normally has a physiological “blind spot” in the temporal visual field of each eye, since the optic disc (optic nerve head) in the nasal retina is devoid of rods and cones.

Question 5

What is papilledema?

Answer 5

Increased intracranial pressure causes the optic nerve to appear swollen on opthalamoscopic examination.

The blind spot of an eye abnormally enlarged in size in the presence of papilledema

Question 6

What are scotomas?

What causes scomatas (2):

what are 3 underlying disease states associated with sarcomatas?

Answer 6

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

Due to lesions in the retina (infections, inflammation, macular degen or rentinal detachments) or optic nerve (demyelination or ischemia)

associated with glaucoma or retinal degenerative disease

or psychiatric if the visual field is “tunneled” versus “constricted”

Question 7

What is hemianopsia?

Answer 7

visual loss/impairment in half (either nasal half or temporal half) of the visual field of each eye

Question 8

Describe what type of deficit is a homonymous hemianopsia?

It is caused by _____ (3).

How is the visual field impaired?

Answer 8

deficit of the nasal half of one eye and the temporal half of the other

Caused by: lesion in the contralateral optic tract OR the contralateral inferior (temporal lobe) and superior (parietal lobe) optic radiations or the contralateral occipital lobe.

Left Side: affect the nasal half of the right eye and temporal half of the left

Right Side: affect the nasal half of the left and temporal half of the right eye

Question 9

When would you see macular sparing?

Answer 9

Macular sparing = preservation of central vision

Because of extensive macular represenation in the occipital visual cortex, smaller occipiatal lesions may spare macular function

Question 10

Describe what a quadrantic homonymous deficit (homonymous quadrantanopsia),

visual deficit:

cause:

Answer 10

A smaller lesion affecting only the ….

inferior optic radiations @ temporal lobe / Meyer’s loop– > superior visual field deficit on the contralateral side

OR

superior optic radiations @parietal lobe –> inferior visual field deficity on the contralateral side

Question 11

Heteronymous hemianopsia

Answer 11

Visual deficity involving the nasal halves of both eyes OR the temporal halves of both eyes

lesions affecting the optic chiasm at the midline would interrupt the decussating fibers from both nasal retinae –> bilateral temporal visual field losses

Question 12

Optic nerve lesions produce ______

Optic chiasm lesions produce _______

Optic tract or optic radiations or occipital visual cortex lesions produce ___________

Answer 12

Optic nerve –> scotomas or monocular blindness

Optic Chiasm –> heteronymous visual field defects

Optic tract/optic radiation/occipital visual cortex –> homonymous visual field defects

Question 13

What are acute unilateral optic nerve lesions usually due to in… young adults

older adults

Answer 13

In young adults usually due to demyelination (MS)

in older adults usually due to ischemia

Question 14

Optic Neuritis:

What type of vision changes occur?

How do the pupils react?

How will the optic disc appear on opthalmoscope exam?

Will someone recover from this?

Answer 14

= inflammation of the optic nerve, usually due to lesions in the optic nerve or optic chiasm (not w/visual pathway lesions posterior to lateral geniculate body)

Vision: sudden blindness of part (scotoma) OR all of one eye; can feel achy or tender w/eye movement

Pupils: in affected eye, pupils constrict poorly or not at all; unaffected eye constrict normal to light

Optic Disc: affected disc appears swollen with indistinct, blurry margins (optic disc can appear normal if inflammation is deepr/more posterior)

Recovery? weeks –> months complete or partial recovery (partial recovery, possibly with relative afferent pupillary defect) - could lead to optic atropy (white/pale disc, with sharp edges)

Question 15

Likely dx if BOTH eyes appear swollen and indistic?

Answer 15

Papilledema

(rare for acute optic neuritis to occur in both eyes simultaenousy)

Question 16

Papilledema:

Cause:

Etiologies (4):

Opthalmascope findnigs (2):

Sx:

Answer 16

= optic disc swelling

due to increased intracranial pressure, usually affecting both optic discs after a period of several hours

Etiologies: extensive brain tumor or intracranial mass, meningoencephalitis or pseudotumor cerebri

Findings: flame hemorrhages, disappearance of blood vessels

Sx: H/A, N/V, impaired consciousness from the elevated ICP

Question 17

What is a common lesion affecting the optic chiasm?

Which fibers are the first to be affected?

SX:

Answer 17

a pituitary tumor arising from the stella turcica, could exert pressure on the center of the chiasm from below

The decussating, infrerior, nasal rentinal fibers would be the first to be affected –> deficit in the superior temporal quadrants

Total lesion of the center of the optic chiasm –> bitemporal heteronymous hemianopia

SX: pituitary tumor itself would likely also cause endocrines signs and symptoms

Question 18

Optic readiation lesions:

common causes (2)

a hit to the inferior optic radations –>

Answer 18

Tumors or ischemia can lead to lesions in the optic radiations

A lesion to Meyer’s loop (inferior optic radiations bent anterior in the temporal lobe) –> contralateral superior homonymous quadrantanopsia (“pie in the sky”)

Question 19

Cortical blindness is…

common causes (2)

Pulpillary light reflex is _____

The optic disc appears ____ since the retinal ganglion cells are (yes/no) invovled

Answer 19

= severe visual loss from bilateral occipital lobe lesions

due to: stroke syndrome from thrombosis* of the distal basilar artery or *emboli down its posterior cerebral artery branches

although the patient is unable to see, the pupillary light reflex is INTACT and the optic discs appear NORMAL since the retinal ganglion cells are NOT invovled

Question 20

Conductive deafness is caused by ________ of sound stimuli, such as water or wax plugging up the external ear canal, fusion or disruption of the bony ossicles

In an audiogram, ____ (low/high) is typical of conductive deafness

Answer 20

caused by IMPAIRED AIR CONDUCTION

It is a problem BEFORE the hair cell recetors

LOW-TONE hearing loss is typical of conductive deafness

Question 21

Nerve (sensorineural) deafness is caused by damage or impairment of the ______ or _______

In an audiogram, ____ (low/high) tone hearing loss is indicative of nerve/sensorineural deafness

Answer 21

damage or impairment of the hair cell receptors or auditory nerve

caused from drug toxicity or persistent exposure to loud noise

High-tone hearling loss occurs with nerve/sensorineural deafness

Question 22

Severe or complete unilateral nerve deafness is usually due to cranial nerve ____ lesions;

ischemia of _______ artery or trauma to _____ bone could be causitive factors

VS bilateral lesions are…

Answer 22

CN VIII lesions –> unilateral nerve deafness

causes: trauma* (esp petrous bone fractures), ischemia in the territory of the *anterior inferior cerebellar artery

more proximal, ascending auditory pathways are bilaterally represented

Question 23

What type of test can help determine the type of deafness present (3)?

Answer 23

1. Audiogram:

Low-tone hearing loss –> conductive deafness

High-tone hearing loss –> nerve/sensorineural deafness

2. Tuning fork (128 Hertz frequency C)
   * *Weber Test* hold vibrating tuning fork at the top of the skull or middle of the forehead*
   * [if lounder on one side = ipsilateral conductive deafness OR contralateral nerve defect]*

vibration heard BETTER in NL ear –> ​Nerve deafness

vibration heard BETTER in DEAF ear –>conductive deafness

*RINNE Test* hold vibrating tuning fork at the mastoid bone, when no longer heard, move outside the ipsilateral ear where it should still be heard normally (air conduction > bone conduction)

• if partial nerve deafness – air > bone, so still should be heard*
• if conductive deafness – air isNOT more efficient, thus not heard*

Question 24

Dysfunction of the vestibular system produces what types of symptoms:

Answer 24

Dizziness or vertigo

Question 25

What test could be used to test the vestibular system?

Answer 25

1. Dix-Hallpike Maneuver: positional maneuver to test for benign positional vertigo. The patient is moved rapidly from a sitting position to a recumbet, lateral, head-hanging @ 45degrees on the right or left. Vertigo and rotary nystagmus is induced towards the affected ear when down = posterior semicircular canal is “overly sensitive” to head movement - likely causing positional vertigo

Question 26

In acute labyrinthitis, the labyrinth of the inner ear may be affected by a viral or inflammation –> sx such as (3)…

Do symptoms resolve?

What Rx can be given to help the symptoms (3):

Answer 26

acute labyrinthitis –> N/V, hearing impairment, unsteadiness of gait; nystagmus, unilateral decreased hearing and gait ataxia are found in examination

symptoms resolve within days to weeks

temporarily helped with benzodiazepine, antihistamine or antiemetic medciation

Question 27

Meniere’s Disease presents as recurrent episodes of ____, _____ and ______.

The ________ labyrinthin swells and ruptures, allowing ______ rich endolympth to leak into the surrounding ______ –> disruption of the _______ required for normal hair cell function

RX (5)

Answer 27

reucrrent episodes of VERTIGO, DEAFNESS and TINNITUS

The MEBRANOUS labyrinth swells up and ruptures –> POTASSIUM - rich endolymph to leak into the surrouding PERILYMPH –> disruption of the IONIC GRADIENT required for normal hair cell function

sx are similar to acute labyrinthitis; recurrent meiniere’s episodes could lead to complete and permanet deafness

RX: antiemerics, antihistamines, benzodiazepine (same as acute labyrinthitis) + DIETARY salt restriction and diuretic medication may help reduce production of endolymph and lessen the risk of chronic deafness

Question 28

Benign Positional Vertigo, seen commonly in ______ (young/old) patients

Due to: degenration of _____ and displaced _______ and other derbis that can lodge around the cilia of ______________, making them oversensitive to minor movements of the head.

SX:

Dx testing:

RX:

Answer 28

BPV is common in the ELDERLY

Due to: degenration of otoliths and displaced calcium crystals and other derbis that can lodge around the cilia of semicircular canal hair cells, making them oversensitive to minor movements of the head

SX: transiet/annoying vertigo when standing up or turning their heads

DX: Dix-hallpike maneuver

RX: dix-hallpike maneuver (try to disperse some of the debris in the semincircular canals or help patients readapt to head movements