oto vestibular evaluation

Question 1

Define first-degree, second-degree, and third-degree

nystagmus.

Answer 1

● FIrst degree: Occurring when gazing in the direction of the
fast component
● Second degree: Occurring when gazing in the direction of
the fast component or at midline
● Third degree: Occurring when gazing in all directions

Question 2

Describe Alexander’s law?

Answer 2

The amplitude of the nystagmus will intensify when the
patient looks in the direction of the fast phase. Alexander’s
law describes the pattern of nystagmus in a patient with a
unilateral peripheral vestibular deficit.

Question 3

Describe Ewald’s three laws?

Answer 3

1. The axis of nystagmus parallels the anatomic axis of the semicircular canal that generated it.
2. In the lateral semicircular canals, ampullopetal endo-
   lymph movement causes greater stimulation than ampullofugal movement.
3. In the superior and posterior semicircular canals, the
   reverse is true.

Question 4

Describe examination findings that help distinguish between central and peripheral vestibular deficits.

Answer 4

● Central deficits may occur in any direction (vertical,
horizontal, or torsional), may alternate direction, do not
suppress with visual fixation, do not fatigue, rarely are
associated with hearing loss, often have other abnormal
neurologic examination findings, have minimal latency
with positional change, and often less severe.
● Peripheral deficits are unidirectional; horizontal only (no
vertical component), suppresses with visual fixation,
often with concurrent hearing loss, otherwise normal
neurological examination, positional nystagmus that
often has a 2 + second latency, generally more severe.

Question 5

Describe the direction of nystagmus with irritative

and destructive vestibulopathy?

Answer 5

Irritative vestibulopathy is associated with a fast phase
beating toward the affected ear, whereas destructive
vestibulopathy is associated with a fast-phase beating away
from the affected ear.

Question 6

What is the purpose of Frenzel goggles?

Answer 6

● Frenzel goggles assist in evaluating for nystagmus.
● Frenzel goggles magnify and illuminate the patient’s eyes
and prevent gaze fixation.

Question 7

What inner ear structure and nerve do thermal

calorics testing interrogate?

Answer 7

Thermal calorics measure the responsiveness of the
horizontal semicircular canal (and superior vestibular nerve)
to thermal stimuli and is one of the few quantitative
evaluations that can test the two ears independently.

Question 8

Describe the effects of cold and warm irrigation

during caloric testing.

Answer 8

Cold causes the fast phase of nystagmus to beat toward the
opposite ear, whereas warm causes the fast phase to beat
toward the ipsilateral ear.

Question 9

How is electronystagmography (ENG) or video-

nystagmography (VNG) useful in the evaluation of the dizzy patient?

Answer 9

Nystagmography comes in several forms (ENG or VNG) and
serves to quantitatively measure eye movements while
performing positional testing or calorics.

Question 10

What is computerized dynamic posturography?

Answer 10

This technique, used to quantify postural control in an
upright (standing) position in either static or dynamic
conditions, requires coordination of sensory input, motor
output, and central integration.

Question 11

What inner ear structure and cranial nerve does

VEMP testing interrogate?

Answer 11

Saccule and inferior vestibular nerve

Question 12

How is computerized dynamic posturography

performed?

Answer 12

The patient is placed on a platform that is capable of
performing various movements and sensing patient sway
(oscillations). Additionally, a visual backdrop is placed in
front of the patient and can be held stationary or can move.
The patient is then subjected to six increasingly difficult
tests.

Question 13

What pattern of results may be seen in a
malingering patient during computerized dynamic
posturography?

Answer 13

The patient has poor scores with easier tasks, but as the task difficulty increases, the patient may do disproportionately better.

Question 14

What does the dynamic visual acuity test eval-

uater?

Answer 14

It tests for impaired ability to preceive objects accurately
during head movement. Normally, the vestibular ocular
reflex maintains the direction of gaze on a fixed target by

moving the eyes in the opposite direction of head move-
ment.

Question 15

Dysdiadochokinesia is a sign of dysfunction in-

volving what structure?

Answer 15

Dysdiadochokinesia, the difficulty with performing rapid
alternating movements, is considered a sign of cerebellar
pathology.

Question 16

How is the Fukuda test performed, and what does

it evaluate?

Answer 16

The patient is asked to march in place with eyes closed for

50 steps. Rotation (> 30 degrees) may indicate asym-
metrical labyrinthine function. Rotation generally occurs toward the side of the lesion.

Question 17

What is purpose of the vestibulo-ocular reflex?

Answer 17

This reflex generates eye movements in response to head
motions perceived by the peripheral vestibular system,
permitting visual fixation on an object while the head is
moving.

Question 18

How do you perform a head-thrust test?

Answer 18

The patient is asked to fixate on the examiner’s nose while
the head is passively and rapidly rotated in the excitatory
direction of a semicircular canal. Normally, the patient will
be able to maintain fixation on the examiner.

Question 19

What constitutes a positive head-thrust test?

Answer 19

In the case of a left hypoactive labyrinth, the vestibulo-
ocular-reflex will be impaired, and the head-thrust test toward the patient’s left side will be positive; the examiner
will note the patient’s eyes to rotate with the head, and
after a brief delay, a “catch-up saccade” toward the right will bring the gaze back toward the examiner.

Question 20

Describe the Hennebert sign?

Answer 20

Induction of nystagmus or vertigo with changes in external auditory canal pressure (tragal pressure, pneumatic otos-
copy)

Question 21

What conditions are associated with a positive

Hennebert sign?

Answer 21

Superior semicircular canal dehiscence, perilymphatic fistula, lateral semicircular canal fistula from chronic ear disease, or otosyphilis

Question 22

Describe a positive Tullio phenomenon.

Answer 22

Tullio phenomenon is noise-induced activation of the
vestibular system resulting in dizziness and/or nystagmus.
Historically, it is associated with syphilis but may occur with
inner ear fistula and/or dehiscence syndromes.

Question 23

How is a Romberg test performed?

Answer 23

The patient stands with feet close together and arms at the
sides. The clinician evaluates the relative amount of body
sway with the patient’s eyes closed compared with when
they are open.

Question 24

What is a Romberg test evaluating?

Answer 24

Somatosensation and proprioception carried out by the

cerebellum and dorsal column-medial lemniscus

Question 25

In what clinical situations would rotary chair

testing be useful?

Answer 25

Because rotatory chair testing evaluates bilateral semicircular
canal function simultaneously (unlike caloric testing), it may
be used for evaluating suspected bilateral vestibular loss
(after meningitis, vestibulotoxic medications, etc.).

Question 26

What symptom is classically associated with severe

bilateral peripheral vestibular hypofunction?

Answer 26

Oscillopsia