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and Colebatch (2013) and Smith, McCaslin, Jacobson, and Burkard (2019). In the study by Lim et al.
(2013), stimuli were delivered by both air and bone
conduction. For the study by Smith et al. (2019), stimuli were delivered by air conduction only. The stimulus in both studies was a 500 Hz tone burst. Lim et al.
examined the effects of increasing stimulus duration
from 2 to 10 ms. Smith et al. (2019) presented subjects
with stimulus durations of 2 to 25 ms. In both investigations, increasing the stimulus duration beyond 2
ms produced a reduction of oVEMP amplitude. Thus,
figure 16–23. The effect of stimulus intensity on the oVEMP amplitude.
Murnane, O. D., Akin, F. W., Kelly, K. J., and Byrd, S. (2011). Effects
From
of stimulus and recording parameters on the air conduction ocular
vestibular-evoked myogenic potential. Journal of the American Acad-
emy of Audiology, 22, 469–480. Used with permission.
there was no benefit to increasing stimulus duration
beyond 2 ms.
Stimulus Monaural/Binaural
Wang, Jaw, and Young (2009) reported their experience
recording oVEMPs in response to monaural and binaural 500 Hz tone burst stimulation (i.e., 95 dB nHL). The
authors reported no significant differences in response
threshold, latencies, or amplitudes when data obtained
from the two modes of stimulation were compared.
16. VESTIBULAR-EVOKED MYOGENIC POTENTIALS (VEMPS) 425
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figure 16–24. The effect of stimulus rate on oVEMP amplitude from the right and
left eye. negative is up in this figure. From Chang, C.
Young, Y. H. (2010). Effects of repetition rate of bone-conducted vibration on ocular
and cervical vestibular-evoked myogenic potentials. Clinical Neurophysiology, 121,
2121–2127.
Used with permission.
M., Cheng, P. W., Wang, S. J., and
The investigators suggested that binaural stimulation produced significant time savings over monaural
stimulation.
Despite the oVEMP being represented intermittently ipsilateral to the stimulus ear, Kim and Ban
(2012) examined what effect, if any, binaural stimulation would have on the oVEMP. The investigators
presented 500 Hz tone burst stimuli monaurally and
binaurally on three occasions. The investigators measured peak latency of N1, amplitude of N1–P1, and
the interaural differences for these data points. The
authors reported no significant differences in the peakto-peak amplitude and amplitude asymmetry ratios
when monaural and binaural data were compared. The
interclass correlation coefficients ranged from 0.68 to
0.98. The latency of N1 was significantly later for the
binaural presentation compared with monaural stimulation. This latency delay occurred possibly because the
response to binaural stimulation represented the admixture of ipsilateral and contralateral waveforms. Also, the
ipsilaterally recorded oVEMP occurred later than the
contralaterally recorded oVEMP. Accordingly, the product of bilateral stimulation would be expected to be a
distortion of the waveform recorded in response to monaural stimulation. The greatest effect was the reduction
in test time that occurred for binaural stimulation. The
oVEMP air-conducted and bone-conducted stimulus
protocols are presented in Tables 16–7 and 16–8.
tab le 16 –7. oVEMP Air-Conducted Stimulus Protocol
Frequency 500 Hz
Level 95 dB nHL
Gating Blackman
Rate 5.1/s
table 16–8. oVEMP Bone-Conducted Stimulus Protocol
Frequency 500 Hz
Level 150 dB peak FL (31.6 N peak)
(Papathanasiou et al., 2014)
Gating 6 ms duration (2 ms rise/fall)
Rate 5 Hz
Location of
stimulator
Mastoid or Glabella
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Recording Variables
Electrode Placement
Electrodes are silver/silver chloride disposable electrodes. The locations of the recording electrodes are
shown in Figures 16–25 and 16–26.
The skin should be degreased with rubbing alcohol at the left and right infraorbital midlines (i.e., the
electrodes should be placed as close to the middle bottom of the lower eyelid as possible). These electrodes
serve as active (or non-inverting) inputs to channels 1
(left eye) and 2 (right eye) of the differential amplifier.
The reference (or inverting) input for channels 1 and 2
Figure 16–25. A model prepared for a two-channel oVEMP recording
using the active electrode (infraorbital 1 cm) referenced to the infraorbital 3 cm electrode.
Figure 16–26. A model prepared for a two-channel oVEMP using the
electrode montage described by Sandhu et al (2013). Active electrodes are placed on the belly of inferior oblique muscle and referenced to the electrode at the inner canthus position.
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is a single electrode placed on the chin (i.e., common
reference in our protocol) that is “jumpered” into the
reference electrode inputs for channels 1 and 2 (see
Figure 16–25). Alternately, the reference can be two
electrodes placed 2 to 3 cm inferior to each of the near
infraorbital electrodes. This is the protocol followed by
most clinicians. The ground electrode is placed at FPz
or Fz for the sake of convenience but could be placed
anywhere on the body (Colebatch, 2013). Closely
spaced bipolar electrodes are very sensitive to signals
occurring between the two electrodes and relatively
insensitive to other signals generated on the face/
body. However, we found (Piker et al., 2011) that the
near infraorbital reference electrodes were recording,
on average, 30% of the oVEMP amplitude recorded by
the active electrode, creating a problem called reference
contamination.
When reference contamination occurs, the oVEMP
recorded by the reference electrode is subtracted in the
differential amplifier from the oVEMP recorded by the
active electrode. The net effect is an “artificial” reduction or phase cancellation of part or all of the oVEMP
recorded by the active electrode. In our experience very
little of the oVEMP is volume conducted to the chin. The
advantage of the referential technique (i.e., as opposed
to the bipolar recording method) is the enhancement of
the N1–P1 amplitude. The single disadvantage of this
technique is the potential for EMG generated at the
chin to be “injected” into the signal-averaged responses
recorded from the infraorbital electrodes.
An interesting recent report by Sandhu, George,
and Rea (2013) was a reexamination of the effects of
the location of the active electrode. The investigators
placed the reference electrode at its normal location
(i.e., below the contralateral eye at midline) but placed
a series of five active electrodes infraorbitally and equidistant from the inner canthus to the outer canthus. The
ground electrode was placed on the sternum (see Figure 16–26). The investigators reported that the largest
oVEMP was recorded from the electrode just lateral
to the infraorbital midline electrode when it was referenced to the electrode placed at the inner canthus.
The investigators reasoned that that electrode montage
optimized the recording of the oVEMP, since the active
electrode was placed over the belly of the inferior
oblique muscle (i.e., where the maximum response is
recorded) and the reference was placed over its tendon
at the inner canthus, which is electrically neutral (i.e.,
theoretically none of the evoked potential is recorded
from that location). It has been our experience that the
inner canthus reference site provides superior oVEMP
amplitudes regardless of age. Over the past five years
our recommendation for a reference electrode location
has evolved from the chin (as a common reference to
the two channels) to the inner canthi.
Lastly it should be mentioned that it is possible to
record the oVEMP without a reference electrode (i.e., a
monopolar or “reference free” recording). A monopolar
reference is useful when placement of a reference electrode would be expected to inject reference contamination into the recording.
Amplification
The oVEMP is one to two orders of magnitude smaller
than the cVEMP and therefore requires 10 to 100
times more amplification to bring the signal within
range of the signal averager. This means that amplification values of 50,000× to 100,000× are necessary to
increase the magnitude of the raw EMG signal to be
within the range of the signal averaging computer so
that the oVEMP can be extracted. Since this is a much
smaller response than the cVEMP and because this
is not entirely a stimulus-synchronized attenuation of
evoked EMG from the inferior oblique (IO) muscle, it
is necessary to reject EMG artifacts. This means artifact
rejection must be enabled to record the oVEMP.
Filtering
The subject of optimal bandpass filtering has been
addressed in the recent literature. Wang, Jaw, and
Young (2013) recorded the oVEMP to acoustical stimuli
using high-pass filter settings of 1, 10, and 100 Hz and
low-pass filter settings of 500, 1000, and 2000 Hz. The
investigators reported that the bandpass yielding the
best amplitude oVEMP without affecting its latency
was 1 to 1000 Hz.
Burkard and colleagues (2013, personal communication) also have examined systematically the effect of
filter bandpass on oVEMP amplitude. They observed
that the critical frequencies that must be available
for signal averaging are ~20 Hz for the high-pass filter and 200 Hz for the low-pass filter. The spectra of
the oVEMP show little energy in the response beyond
Hz (Burkard 2013, personal communication).
140
Subject Factors
Gaze Effects
Although it has been reported that the oVEMP can be
recorded with the patient’s eyes at center gaze (Huang,
Yang, & Young, 2012) and in patients with closed eyes
(i.e., although the waveforms looked quite different
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from the conventional oVEMP; Huang et al., 2012),
the oVEMP is best recorded with the patient gazing
upward ~20 degrees or more (Govender, Rosengren, &
Colebatch, 2009; Hsu, Wang, & Young, 2009). Moving
the eye from center gaze to upward gaze is believed
to position the contralateral inferior oblique muscle
closer to the active (non-inverting) infraorbital electrode. This observation about gaze position effects on
the oVEMP was also supported by the results of Murnane et al. (2011), who reported that maximal amplitude of the oVEMP was recorded with subjects gazing
at 30 degrees vertically (i.e., the study examined the
effects of gaze angles from 5–30 degrees; Figure 16–27).
It is significant that Rosengren, Colebatch, Straumann, and Weber (2013), who systematically examined gaze effects, reported that the increase in oVEMP
amplitude with upward gaze could not be explained
entirely by the reduction in the distance of the contralateral infraorbital recording electrode to the IO muscle. Instead, it was the investigator’s contention that
upward gaze increased the tonic activity in the IO muscle, and much as occurs with the SCM, the onset of the
tone burst results in a stimulus-initiated reduction in
that tonic activity. If this is in fact true, what is not clear
is why the oVEMP is a negative-positive waveform
instead of a positive-negative waveform. The oVEMP
recording protocol is shown in Table 16–9.
Age Effects
A number of processes occur as we age that have an
effect on the normal function of the peripheral and
figure 16–27. The effect of gaze angle on oVEMP amplitude. From
Murnane, O.D., Akin, F. W., Kelly, K. J., and Byrd, S. (2011). Effects of stimulus and recording parameters on the air conduction ocular vestibular-evoked myogenic potential. Journal of the American Academy of
Audiology, 22, 469–480. Used with permission.
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table 16–9. oVEMP Recording Protocol
Inverting electrode (reference) 3 cm infraorbital or chin (conventional
reference electrode placement is
immediately below the infraorbital
midline electrode)
Noninverting electrode (active) Infraorbital midline
Ground (Earth) Forehead (i.e., Fz)
Electrode impedances ≤10,000 ohms, with interelectrode
impedance differences ≤
Channels Two (ipsilateral and contralateral
infraorbital midline responses)
Amplification (gain)
Artifact rejection Enabled
Filter bandpass 1–10 Hz to 500–1000 Hz
Epoch 100 ms (with a 20-ms prestimulus period)
Number of accepted samples 150
Number of completed averages 2
× 30,000 to 50,000
2000 ohms
central vestibular systems. These age-related changes
are addressed in detail elsewhere in this text (Chapter 25); however, we address a few of the age-related
changes here.
There have been documented age-related effects at
the hair cell level as well as at the level of the afferent
neurons (Ishiyama, 2009). The loss of both hair cells and
first-order afferents has been documented in the cristae, the utricle, and the saccule. A decrease in hair cell
density occurs after age 50 years. The greatest effects
may be observed in the saccules and the cristae, with
less age-related damage occurring for the utricle. That
is, when young and older individuals were compared,
hair cell density was reduced by 40% at the cristae, 24%
at the saccule, and 21% at the utricle (Rosenhall, 1973).
More specifically the fetal cristae contain ~7,800 hair
cells and this is reduced to 4,700 for adults between
the ages of 71 and 95 years (i.e., a reduction of 38% on
average). A reduction of 30% in hair cell density in the
senescent mouse produces a reduction of VOR gain at
0.8 Hz. That gain reduction produces “retinal smear”
during movements of the head or head and body. In the
human, VOR gain shows significant reductions beyond
age 70 years.
There are age effects specific to the utricle and
saccule. Many of the changes affect the otolith crystals.
The density of the calcium carbonate crystals is reduced
and the normal regeneration of the crystals is impaired
with age. This results in reduced otoconial volume,
fractured otoconia (i.e., producing debris in the canal
and an increasing the likelihood of benign paroxysmal
positional vertigo), and even the generation of “giant”
otoconia. In parallel with structural changes affecting
the end organ, there can be impaired perfusion of the
end organ. Over and above these changes there has
been reported a 25% reduction in neurons at Scarpa’s
ganglion, and a 37% loss of afferents when comparing
younger adults with older adults.
Hsu et al. (2009) evaluated age-related differences
in oVEMP latency and amplitude. Subjects were adults
(24–33 years of age, N = 15) and children (3–13 years of
age, N = 15). The stimulus was a tone burst presented at
105 dB nHL. The authors did not report age-related differences in N1 latency, P1 latency, or the N1–P1 interval
or the peak-to-peak amplitude of the oVEMP.
Chang et al. (2012) evaluated the effect of age on
oVEMPs recorded in response to bone-conducted vibration and galvanic stimulation. Since the galvanic stimulus bypasses the end organ and stimulates the afferent
nerve fibers directly, an abnormal or absent boneconducted oVEMP with a normal galvanic oVEMP
would suggest an end organ impairment, whereas a
unilaterally delayed galvanic oVEMP would suggest
an impairment in neural conduction. The investigators reported significant N1 latency delays for a group
of subjects older than 60 years compared with groups
younger than 60 years. There were nonsignificant differences in the prevalence of the galvanic oVEMP suggesting that age differences observed in the prevalence
of bone-conducted oVEMPs reflected age changes
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in the peripheral vestibular system. The effect of age
and stimulus type on the prevalence of the oVEMP is
shown in Table 16–10.
The study of age effects on the oVEMP is complicated by the differing stimuli used by investigators
to evoke the response (e.g., electrical/galvanic, bone
conduction, skull tap, acoustical click, acoustical tone
burst) and the methods used to obtain the data (e.g.,
threshold versus suprathreshold stimulation for evaluation of effects of stimulus frequency).
Tseng, Chou, and Young (2010) examined 70 subjects with an age range of 24 to 76 years. They placed the
subjects into six groups representing six age decades.
The stimuli were delivered by bone conduction stimulation. All subjects from ages 20 to 59 years generated
oVEMPs. Conversely 55% of those subjects aged 60 to
69 years and 40% 70 years and older failed to generate
an oVEMP. With age treated as a continuous variable,
both N1 latency (r = 0.54) and N1–P1 amplitude (r =
−0.37) showed age effects. The investigators reported
a positive correlation between N1 latency and age and
a significant negative correlation between age and N1–
P1 amplitude.
Nguyen, Welgampola, and Carey (2010) evaluated
53 subjects between the ages of 20 and 70 years. Stimuli
were acoustical clicks and 500 Hz bursts, skull taps (i.e.,
delivered with a specially modified tendon hammer),
and skull vibration (i.e., delivered with a Bruel & Kjaer
Mini-shaker). The interclass correlation coefficients
between subject age and oVEMP for tone burst stimuli
ranged from 0.81 (N10 amplitude) to 0.79 (N10–P15
peak-to-peak amplitude) to 0.50 (for the amplitude
asymmetry of the N10–P15 peak-to-peak amplitude).
Unlike the report by Tseng, when age and oVEMP
amplitudes were plotted as continuous variables there
was no significant relationship. This finding was also
at odds with the findings of Iwasaki et al. (2007), who
reported a linear decrease in oVEMP amplitude with
table 16–10. Prevalence of the oVEMP in Response to
Galvanic and Bone-Conducted Stimuli
Galvanic oVEMP
Age Group
20 to 29 years 100 100
30 to 39 years 100 100
40 to 49 years 100 100
50 to 59 years 100 86
60 to 69 years 84 63
% Prevalence
BC oVEMP
% Prevalence
age when the stimuli were skull taps and skull vibration (i.e., mini-shaker).
Rosengren et al. (2011) examined age effects on
the oVEMP in response to forehead taps, lateral (mastoid) vibration, and both air- and bone-conducted tone
bursts. Subjects were 61 normal individuals aged 18 to
80 years. The oVEMPs evoked with taps and vibration
did not demonstrate age effects. The authors reported
a moderate correlation between oVEMP amplitude
and age for acoustical clicks and bone-conducted tone
bursts. The authors reported elevated oVEMP thresholds by 6 dB on average when oVEMP threshold intensities were compared with cVEMP threshold intensities
for 500 Hz tone burst stimuli. Response prevalence was
93% for stimuli of an intensity of 110 dB L
. Ocular
Aeq
VEMPs demonstrated latencies that were significantly
longer with age for air-conducted clicks and 500 Hz
tone bursts.
Piker et al. (2011) examined the effects of age on
N1 and P1 latency, N1–P1 peak-to-peak amplitude, N1
interaural latency difference, and interaural N1– P1
amplitude asymmetry. Subjects were young individuals (mean age 12.5 years), middle-aged adults (mean
age 34 years), and old adults (mean age 63 years). The
authors reported significant decreases in N1–P1 peakto-peak amplitude when young subjects and middleage subjects were compared with older subjects. With
age treated as a continuous variable, the correlation
coefficient for oVEMP peak-to-peak amplitude was
negative and statistically significant (r2 = .14, p < .001).
Further, there were significant age differences in N1
threshold intensity (see below).
Age Effects of oVEMP Threshold. Increased age
results in elevated oVEMP thresholds. When treated
as a continuous variable, oVEMP threshold correlated
positively with subject age (r2 = .11, p = .002). In fact,
there was a 3.4 dB difference in N1 thresholds when
data from young adults and old adults were compared
(i.e., threshold occurred at higher intensities for old
adult subjects) (Piker et al., 2011).
Age Effects of oVEMP Tuning. The effects of age on
the “tuning” of the oVEMP was addressed by Piker
and colleagues (2013). Stimuli consisted of acoustical
tone bursts of frequencies 125, 250, 500, 1000, 1500,
and 2000 Hz that were presented at 127 dB pSPL. All
stimuli were presented in a pseudo-randomized manner for each run so that the effects of fatigue might be
distributed evenly across all stimuli. Subjects ranged
in age from 22 to 78 years (N = 39, mean age 46 years,
±15.7 years). Subjects were placed into three age groups
consisting of young, middle, and older adults. The
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investigators reported that best frequency occurred
for 500 and 750 Hz tone bursts (i.e., stimulus yielding
the greatest amplitude oVEMP), although there were
no significant differences in oVEMP amplitudes across
age groups for each frequency. Whereas the best frequency to evoke the oVEMP for young adult subjects
was 750 Hz, the best frequency increased to 1000 Hz
stimulus for older adult subjects. Armed with this
information, the authors cautioned that clinicians
might choose different evoking stimuli depending on
the age of their patients (e.g., 500 Hz tone bursts for
younger adults and 1000 Hz for older adults if they
failed to generate an oVEMP in response to the 500 Hz
stimulus).
It is our practice to first record the oVEMP in
response to 95 dB nHL, 500 Hz tone bursts delivered
monaurally. Responses are replicated at least one time
so that reproducibility of the data can be assessed.
Where the response exists we then use a bracketing
technique to estimate oVEMP threshold separately for
the left and right ears.
When a negative waveform is plotted as a downward deflection, the normal oVEMP appears as a “W.”
with the first negative peak occurring at ~11 ms. The
variables we quantify include: N1 latency, P1 latency,
N1–P1 peak-to-peak amplitude, interaural N1 latency
differences, and interaural differences in N1–P1 amplitude (in percent). The most common abnormality
encountered is either a unilaterally or bilaterally absent
oVEMP, or a unilaterally abnormal reduction in oVEMP
amplitude. Rarely does a latency prolongation occur.
When a latency prolongation occurs, it usually occurs
bilaterally and signifies an impairment in central trans-
mission occurring either in the afferent or efferent limbs
of the reflex arc. Table 16–11 shows normative data for
the oVEMP gathered in our laboratory.
cVEMP AND oVEMP TEST RESULTS
IN
SELECT DISEASES
Superior Semicircular Canal
Dehiscence Syndrome (SSCDS)
The approach to the identification of SSCDS with the
oVEMP has gone in two directions. The underlying
assumption for each approach is that the dehiscence
results in an abnormal “augmentation” of the normal
response to either air-conducted or bone-conducted
stimuli. For example, normals do not generate oVEMPs
in response to 4000 Hz tone bursts. However, Manzari,
Burgess, McGarview, and Curthoys (2013) observed
that patients with SSCDS clearly generated oVEMPs
in response to either an air- or bone-conducted 4000
Hz tone burst. None of their normal controls generated
oVEMPs to the same stimulus. In this way the investigators suggested that they had created a one-trial protocol for the identification of SSCDS.
In a slightly different implementation, Zuniga,
Janky, Nguyen, Welgampola, and Carey (2013)
recorded both oVEMPs and cVEMPs in response to
air-conducted and bone-conducted clicks and 500 Hz
tone bursts. They recorded responses from patients
placed in different age groups. The authors reported
that the absolute peak-to-peak amplitude of N1–P1
Ta ble 16–11. Comparison of Characteristic Parameters of oVEMP Among the Three Age Groups
Age
Group
(yr)
1 (<18) 20 12.1 (1.1) 17.1 (1.3) 5.2 (1.1) 1.2 (.9) 5.3 (2.8) 14 (10) 90.7 (3.7)
2 (18–49) 58 12.5 (.88) 17.6 (1.1) 5.0 (.84) .61 (.59) 5.1 (3.1) 13 (10) 92.8 (2.9)
3 (≥ 50) 22 12.7 (1.3) 17.2 (2.3) 4.0 (2.3) 1.4 (1.1) 1.5* (1.4) 16 (12) 94.1* (1.9)
Total 100 12.4 (1.0) 17.4 (1.3) 5.0 (1.3) .85 (.81) 4.4 (3.1) 14 (10) 92.5 (3.2)
p value 0.116 0.346 0.077 0.019 <0.001 0.755 0.007
Note. p value = one-way analysis of variance test. Data are expressed as mean (sd).
*p < .05, Bonferroni-adjusted t-test.
Source: Data from Piker, E. G., Jacobson, G. P., McCaslin, D. L., and Hood, L. J. (2011). Normal characteristics of the ocular vestibular
evoked myogenic potential. Journal of the American Academy of Audiology, 22, 222–230.
N
(ears)
N1
Latency,
ms
P1
Latency,
ms
N1–P1
Latency,
ms
Interaural
N1
Latency
Difference,
ms
N1–P1
Amplitude,
µV
Interaural
Amplitude
Asymmetry
Ratio, %
Threshold,
dB nHL
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discriminated well between patients with (sensitivity) and without (specificity) SSCDS. In fact, using
their absolute amplitude criterion, both sensitivity
and specificity values exceeded 90%. For example, the
investigators reported that using an upper limit of 17.1
µV yielded sensitivity and specificity of 100% and 98%,
respectively This absolute N1 amplitude upper limit
varied by age (Tables 16–12 and 16–13 from Zuniga
et al., 2013).
It would appear that there now exist two methods
that have been offered by investigators for the identification of SSCDS that do not rely on the tedious activity of oVEMP threshold estimation. The authors of this
table 16–12. oVEMP Sensitivity and Specificity for the Diagnosis of Superior Canal Dehiscence
Syndrome
Cutoff Value Sensitivity (%) Specificity (%)
Tone-burst oVEMP Peak-to-peak
amplitudes
Tone-burst oVEMP N1 amplitudes >7.5
Click oVEMP Peak-to-peak
amplitudes
Click o
VEMP N1 amplitudes >2.5
>11.7
>17.1
>20.3
chapter suggest that the examiner might create twostage criteria for the identification of SSCDS patients:
(1) “Does there exist an oVEMP in response to a 4000
Hz, air-conducted tone burst stimulus?” and (2) “Does
the amplitude of the oVEMP in response to a 500 Hz,
95 dB nHL, air-conducted tone burst stimulus equal or
exceed 17.1 µV?” If the answer to either or both of these
questions is “yes,” the likelihood is high that the patient
has a dehiscent or even a “near dehiscent” (Ward et al.,
2013) superior semicircular canal. It is important to
note that the 17.1 µV criterion applies only to data collected with the same reference electrode site that was
reported by Zuniga et al. (2013).
100
100
97
100
>9.3
>9.9
>9.9 100 100
>6.6
100
93
100
94
88
98
100
94
100
100
68
100
Source: Data from Zuniga, M. G., Janky, K. L., Nguyen, K. D., Welgampola, M. S., and Carey, J. P. (2013). Ocular
versus cervical VEMPs in the diagnosis of superior semicircular canal dehiscence syndrome. Otology and
Neurotology, 34, 121–126.
table 16–13. Ocular Vestibular Evoked Myogenic Potential Sensitivity and
Specificity for Patients with Superior Canal Dehiscence
Cutoff Value (µv)
(Peak-to-Peak-
Age Decade
30s 17.5 100 100
40s 22
50s 16.6
60s 14.8 100 100
Source: Data from Zuniga, M. G., Janky, K. L., Nguyen, K. D., Welgampola, M. S., and
Carey, J. P. (2013). Ocular versus cervical VEMPs in the diagnosis of superior semicircular canal dehiscence syndrome. Otology and Neurotology, 34, 121–126.
Amplitude) Sensitivity (%) Specificity (%)
.0 100 100
21.3
100
90
94
100
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Vestibular Neuritis
Shin et al. (2012) examined 30 patients with superior
vestibular neuritis (SVN), 3 patients with inferior vestibular neuritis (IVN), and 8 patients with both branches
impaired, then compared them with data obtained from
60 normal controls. The investigators reported absent
oVEMPs and caloric responses and normal cVEMPs
for patients with SVN. They reported normal caloric
responses and oVEMPs and absent cVEMPs in patients
with IVN, and absent cVEMPS and oVEMPs and caloric
responses for patients with both vestibular nerve
branches affected.
SUMMARY: CAVEATS
REGARDING VEMP TESTING
It would be misleading to end this chapter without stating briefly a few caveats about pathologies affecting the
oVEMPs and cVEMPs (adapted from Curthoys, Manzari, Smulders, & Burgess, 2009). Abnormal oVEMP
and cVEMP certainly can occur in the presence of significant impairments affecting either or both the saccules, utricles, and superior and/or inferior vestibular
nerves. However, absent VEMPs can occur when there
is a conductive hearing impairment that reduces the
sound intensity reaching the vestibular end organs. So
it is essential to obtain a recent audiogram and immittance test before acoustical stimuli are used to evoke
a VEMP. When a conductive impairment significantly
reduces the intensity of the acoustical stimulus, the
examiner must use an alternative method to translate
the otoliths (e.g., mechanical stimulation, vibratory
stimulation). Additionally, significant neuromuscular disease (e.g., myasthenia gravis) can produce an
abnormal VEMP even when the vestibular end organs
are intact. Diseases of the central nervous system (e.g.,
multiple sclerosis) can also produce abnormal VEMP
tests where the end organs are normally functioning.
Last, and certainly not least, there are a myriad of
technical mistakes that young and seasoned clinicians
can make that can reduce or eliminate the likelihood
of recording a VEMP. These errors include: incorrect
placement of electrodes, over- or under-amplification
of the bioelectrical activity, incorrect routing of the
stimulus (i.e., sending the stimulus to the right ear for
a left ear VEMP test), and testing an ear that is occluded
with cerumen. This is only the beginning of a long list
of possible technical errors. Given these assumptions
it is best to approach each patient as “normal until
proven otherwise.”
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