Chapter 41. Neuro-Otology Flashcards
Question 41-1:
The figure shows the audiogram of a patient who complains of hearing loss and tinnitus in the right ear.
Which is the most likely diagnosis?
A. Acoustic schwannoma
B. Hearing loss associated with noise exposure
C. Normal study
D. Meniere’s disease
Answer 41-1: A.
The patient shows normal hearing with the left
ear but the right ear shows decreased highfrequency
perception. This pattern of
asymetric hearing loss plus the lower
perfonnance on discrimination testing makes
the diagnosis of acoustic schwannoma most
likely. (p744)
Question 41-2:
The brainstem auditory evoked potential (BAEP) or auditory
brainstem response (ABR) is a sensitive test for evaluation of
the acoustic pathways including acoustic nerve. Which wave is
generated by the acoustic nerve?
A. I
B. III
C. V
D. None of these
Allswer 41-2: A.
The ABR is abnonnal in many patients with
acoustic schwannoma and in patients with
lesions at the cerebellopontine angle. Wave I
is generated by the acoustic nerve. Wave II
may also be in part from the acoustic nerve,
although responses of the cochlear nuclei have
also been implicated. Wave III is thought to
be generated in the region of the superior
olive, and wave V is generated at the level of
the inferior coUiculus. (p745)
Question 41-3:
What is the role of exercise therapy in treatment of patients with peripheral vestibulopathy?
A. There is no proved role for exercise therapy and rest for patients with vestibulopathy is most helpful
B. Exercise therapy can be curative and often is among the most effective treatments
C. Exercise therapy can help patient with benign positional vertigo but does not help patients with other causes of peripheral vestibulopathy
Answer 41-3: B.
Exercise therapy is often helpful and can be
curative. While there are extensive medical
options for treatment ofvestibulopathy, all of
these agents have the potential for real adverse
effects. (p747)
Question 41-4:
The figure shows the audiometric profile of a patient who
presents with the complaint of hearing loss.
Which is the most likely diagnosis?
A. Sensorineural hearing loss
B. Conductive hearing loss
C. Nonnal
D. Multiple sclerosis
Answer 414: C.
The figure shows nonnal audiometric
[mdings, and cannot explain the subjective
complaint of hearing loss. Multiple sclerosis
would not be expected to produce hearing loss
and does not usually produce abnormalities in
ABRs. In fact, the ABR is much less sensitive
than SEP and VEP for detection of clinicaUysilent
lesions in patients with suspected MS.
(p-743)
Question 41-5:
A patient with presumed conductive hearing loss on the basis of audiometry has acoustic reflex testing and is found to have an absent reflex. Which is the most appropriate interpretation of these findings?
A. The absent acoustic reflex supports the diagnosis of
conductive hearing loss
B. The absent acoustic reflexes is most likely due to technical difficulties
C. The absent acoustic reflex contradicts the diagnosis of
conductive hearing loss.
D. The acoustic reflex does not add information to the
diagnostic decision
Answer 41-5: A.
The acoustic reflex is a nonnal response
measuring contraction of the stapedius muscle
in response to a loud sound. The reflex serves
to tighten the tympanic membrane, thereby
increasing the impedance for conductive
transmission. Conductive hearing loss results
in failure of change ip membrane compliance
with stapedius muscle contraction, so the
reflex is lost. (p744)
Question 41-6:
A patient presents with complaints of tinnitus in the right ear but seems to have normal bearing on bedside testing. Acoustic reflex testing shows present reflex measured on both sides with stimulation of the left ear, but no reflex on either side with testing of the right ear. Which is the most likely site of the lesion?
A. Cochlea
B. Acoustic nerve
C. Facial nerve
D. Brainstem
Answer 41-6: B.
Loss of the acoustic reflex with stimulation of
the right side indicates that the lesion is of the
acoustic nerve on that side. Cochlear damage
can produce loss of the acoustic reflex, but the
hearing loss would be moderate to severe in
order for this loss to occur, apparently Dot
evident in this patient. Acoustic nerve lesions
typically produce loss of the acoustic reflex
when there is normal hearing. The tinnitus is
another item which suggests acoustic nerve
lesions, and would make acoustic
schwannoma especially likely. (p744)
Question 41-7:
You perform the interpretation of an ABR in an adult, but no historical information is provided. He response is normal except for an increased I-III interpeak latency. Which is the most likely diagnosis?
A. Multiple sclerosis
B. Acoustic schwannoma
C. Brainstem vascular disease
D. Cochlear hearing loss
Answer 41-7: B.
IncreasedJ-IIl interpeak latency of the ABR
suggests a lesion somewhere between the
acoustic nerve and the pons. The most likely
causes are acoustic schwannoma and
cerebellopontine tumors such as meningioma.
MS does not commonly produce an
abnOlmality in ABR., and when it does, it
affects brainstem pathways. The same can be
said for brainstem vascular disease. Cochlear
hearing loss produces loss of waves if severe,
rather than a specific I-m interval increase.
(p746)
Question 41-8:
Which of the following medications areused for management of patients with peripheral
vestibulopathy?
1. Promethazine
2. Meclizine
3. Diazepam
4. Ephedrine
Select: A = 1, 2, 3. B = 1, 3. C = 2, 4. D = 4 only. E = All
Answer 41-8: E.
Promethazine, meclizine, diazepam, and
ephedrine are aU among the many medications
used for peripheral vestibulopathy. Major
classes of drugs used include antihistamines,
antiemetics, anticholinergics,
sympailiomimetics, diuretics, and
tranquilizers. These agents can help the
symptoms of peripheral vestibulopathy.
Vestibular exercises also are beneficial and
can result in long-tenn improvement in the
condition.
Question 41-9:
Which of the following statements are true regarding the auditory brainstem response
(ABR)
1. ABR is used to differentiate sensorineural from conductive hearing loss
2. ABR is used to identify acoustic nerve lesions
3. Wave III is generated at inferior colliculus
4. Loss of all waves usually indicates severe hearing loss
Select: A = 1,2,3. B = 1, 3. C = 2, 4. D = 4 only. E = All
Answer 41-9: C
ARB is used to identify lesions of the acoustic
nerve including schwannoma. Also, the ABR
is sensitive to lesions at the cerebellopontine
angle including meningiomas. The ABR is not
particularly helpful for differentiation of
sensorineural from conductive hearing loss;
this would be the role of audiometric testing,
which is usually perfonned prior to the ABR.
(p745)
Question 41-10:
Which of the following statements are true regarding electronystagmograms?
1. The most important criterion for abnormality is a difference in response between the ears
2. Visual fixation can suppress much of the ENG response during caloric testing
3. Vertical eye movements are typically not tested
4. Primary position nystagmus can alter the nystagmus evoked by caloric testing
Select: A = 1,2,3. B = 1. 3. C = 2.4. D = 4 only. E = All
Answer 41-10: E.
All of these statements are true. ENG consists
of measuring eye movements during defined
tasks. Caloric tests are commonly performed,
where one ear at a time is irrigated with warm
or cold water and the eye movements
measured. Patients may also be asked to make
horizontal saccades. to ttack a horizontal
sinusoidal movement, and to watch an
optokinetic stimulus. Vertical eye movements
are typically not tested. Primary position
nystagmus can be seen during testing. and
stimuJus..evoked nystagmus may be altered by
spontaneous nystagmus in the primary
position. Most patients can suppress caloricinduced
nystagmus by at least 500.10, although
there is a population of normal patients who
cannot. (p739-742)
