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When we evaluate you, we test you by putting your head in a position that recreates your symptoms while examining your eyes for the tell-tale rapid, involuntary movement of the eyes called nystagmus.
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In general, one needs to consider the input, central processing, and output for physiological responses.
According to Naranjo, VEMP amplitudes are increased by threat and fear (Naranjo et al, 2016) showing that there are also other inputs to consider.
According to Oh et al (2016), the cVEMPs are mediated by the vestibular nuclei and uncrossed medial vestibulospinal tract descending in the lower brainstem and spinal cord. The output for cVEMP responses is the sternocleidomastoid (SCM) muscle, which is innervated by the accessory (11th) cranial nerve.
VEMPs are recorded using an evoked response computer, a sound generator, and surface electrodes to pick up neck muscle activation or other muscles if this is of interest.
Higher than normal thresholds or low amplitudes may be found in persons with saccule disorders as well as conductive hearing loss. The general rule of thumb with hearing and cVEMP's is that conductive hearing loss obliterates air conducted VEMP's, and that sensorineural hearing loss does little or nothing to VEMP's. Figure: VEMP obtained in an individual with a modest left sided conductive hearing loss, using a Bio-Logic Navigator Pro. Figure: cVEMP obtained in an individual with a profound right sensorineural hearing loss, using a Bio-Logic Navigator Pro. A potential pitfall in a person with a complete sensorineural hearing loss, is that one has no way of determining whether they also have also have a conductive component to their hearing loss. The reflex scales to tonic EMG -- once again -- if you don't activate the neck muscle, you don't get a response. Another (but bad) method of obtaining activation is to have patients sit upright with their chin turned over the contralateral shoulder to tense the SCM muscle.
Because the response is generally ipsilateral (carefully note the qualification), one theoretically can use bilateral stimuli and bilateral recording to reduce the number of trials (Huang et al, 2006; Young, 2006). Practically, one cannot do both -- 3 repetitions as well as thresholds, because of fatigue.
To rule out PAM potentials, you can run your cVEMP initially or perhaps in between other runs, without contracting the SCM. One can also broadly criticize all studies of VEMPs in that the core dogma driving the enthusiasm in doing VEMP tests is implausible. Variability due to these technical problems might be reduced by adjusting for these factors.
We have experimented with this technique ourselves and decided that it was worse than using a very careful electrode placement and having patient's lift their head up straight (ensuring equal activation of both SCM). The number of studies using this test has grown remarkably, and we have devoted a separate page to oVEMPs. We have studied acoustically generated VEMP's in the gastrocnemius and triceps (Ruddissil et al, 2008; Cherchi et al, 2009). To summarize, although BC VEMP's are undoubtedly more reliable, their obvious problem lies in their inability to confine the stimulus to one ear.
Basta et al reported similar results for 500 hz tone bursts (2007) but with lower overall amplitudes using a Viking system. At the present writing (2011), it appears to us that in normal persons, and using the Bio-logic Nav-Pro, average VEMP amplitude decline from approximately 150 at the age of 20 to approximately 75 at the age of 70. The VEMP literature is rapidly increasing and it seems that there are considerable valuable diagnostic information to be obtained.
For some of the more popular disorders where VEMPs are used, we have separate pages, and have combined data from other VEMP protocols as well. VEMP obtained in an individual with left sided Ramsay-Hunt syndrome, using a Bio-Logic Navigator Pro.
As most types of vestibular neuritis spare the inferior vestibular nerve, cVEMPs would be expected to generally be normal in vestibular neuritis. Prolonged latency of cVEMPs has recently been suggested to be a sign of a retrocochlear (vestibular nerve) lesion, such as is found in vestibular neuritis. VEMP asymmetry in patient with small intracanalicular acoustic neuroma, without any hearing deficit.
In Vestibular neuritis, cVEMP's reportedly normalize more rapidly than canal related tests (Kim et al, 2008).
Vestibular nerve sections fail to control intractable vertigo due to Meniere's disease in about 5% of patients. A potential pitfall in doing cVEMP's in persons with VNS are contralateral responses and extraneous responses (mainly posterior auricular muscle responses). One might think that as VEMP's assess the saccule (an otolith organ), and because BPPV is thought to be due to another otolithic disease (loose otoconia from the utricle), that there might be abnormal VEMP's in persons with BPPV. We have not been impressed with sensitivity of cVEMPs to central disorders such as brainstem strokes. Several groups (Wang and Young, 2007; Akin et al, 2012) reported that cVEMP's are reduced in persons with noise induced hearing loss.
Instead our opinion is that there simply is reduction of air conducted VEMP's from hearing reduction.
We do not think that this test should be done by people who are not familiar with hearing -- i.e.
Regarding interpretation, it is simply not reasonable for general audiologists, who have no neurological background, to make inferences about brain function.
Akin FW, Murnane OD, Tampas JW, Clinard C, Byrd S, Kelly JK.The effect of noise exposure on the cervical vestibular evoked myogenic potential. Manzari L, Burgess AM, Curthoys IS.Ocular and cervical vestibular evoked myogenic potentials in response to bone-conducted vibration in patients with probable inferior vestibular neuritis. Manzari L, Burgess AM, McGarvie LA, Curthoys IS.Ocular and cervical vestibular evoked myogenic potentials to 500 Hz fz bone-conducted vibration in superior semicircular canal dehiscence.
An easy way to view some of the causes, statistics and dangers of hearing loss and noise exposure. Approximately 2 million people are profoundly deaf, and 30-40 percent of people over 65 have some type of hearing loss. 15 percent of children between the ages of 6-19 have measurable hearing loss in at least one ear. The Center for Hearing and Communication reports that exposure to a noisy subway, - for just 15 minutes a day - can cause permanent damage to hearing over time. The movement of a loose otolith is similar to when you shake one of those snow-scenes in a lucite globe. Barry Castaneda treats disoders or the Ear,Nose and Throat for adult and pediatric patients. Therefore, lesions involving the vestibular nuclei can present abnormalities of cVEMPs and medullary lesions involving the descending MLF or the spinal accessory nucleus impair cVEMPs. If either one of these structures were disturbed, one would expect alterations in the cVEMP as well. A corollary, is that if you get a response without neck muscle activation, it isn't a VEMP (maybe a PAM ? In this case, some experts recommend simply tilting the entire body up by about 30 degrees, so that there is less torque needed by the patient to hold their head up (Colebatch, personal communication).

We think this is a bad idea because you have no way of knowing how much tension the patient is producing, it is tiring, and patients can do something different on the right than on the left, without you knowing. We tried this method in our clinical practice, but discarded it for reasons explained below. Because there is a substantial response from the contralateral side on the left, one could assume wrongly that there was a present VEMP even in a person with a vestibular nerve section. There is some evidence that linked wrists might be a better choice for a reference though (Li et al, 1999).
It is faster but it reduces ones ability to localize the side of lesion because of crossover. Headphones are less reliable than inserts, because small errors in headphone placement can result in substantial changes in sound intensity, and loss of a cVEMP. This is important if you are using equipment that doesn't produce optimally loud stimuli (see below). After it went away when the sound generator was moved, we realized that the sound generator cannot be very close to the EMG leads. This technique would seem quite reasonable for adjusting for differences in electrode placement as well as neck anatomy. They did not use our favored technique -- instead of lifting the head up straight, they had subjects lift and turn their heads. This is unsurprising as bone conduction stimulates both ears and one would think that averaging across two ears would be more reliable than one. Technically, averaging of electrical consequences of galvanic input is difficult because there is a large electrical artifact associated with the stimulus itself. Galvanic stimulation excites distal vestibular nerve afferents, particularly those with irregular discharges, but any selectivity on this action on afferents arriving from the different vestibular end organs is uncertain. Galvanic VEMP's may be more reliable than acoustic VEMP's and thus be a better method of monitoring vestibulospinal connections through the spinal cord than acoustic VEMP's. These systems seem to produce lower amplitude results, perhaps due to differences in calibration. Ramsay-Hunt is a facial weakness, sometimes combined with 8th nerve neuritis, due to a recurrence of Herpes Zoster (the chicken-pox virus). In fact, in our clinical practice in Chicago, we sometimes use the pattern of very abnormal VENG, accompanied by very normal cVEMP to strongly suggest Vestibular neuritis -- i.e. We are somewhat dubious about this and think that in this case the first wave of the cVEMP may simply be missing, but later waves related to cochlear function are preserved, causing the appearance of a prolonged latency. However, this conclusion is suspect as the VEMP technique used in this study (head-turning) is intrinsically flawed (see discussion above). The potentials shown are replicable but they lack the characteristic below-baseline displacement for P1 (see below). The difficulty seems to be that the latencies in cVEMPs (at least with tone bursts), are so variable that there is inadequate sensitivity to disease. PSP is a rare degenerative disorder of the CNS that generally results in death within 5 years of diagnosis. The amplitude is low (30-50) but the latency is normal in this middle aged individual with genetically proven sca3 for 5 years, with gait ataxia, a small brainstem, and bilateral upgoing toes. A way around this may be to do bone-conduction cVEMPs when the air-conduction cVEMP is absent. Similarly, Zhou, Kenna, Stevens and Licameli (2008) reported cVEMP's are reduced in children with sensorineural hearing loss, and attributed this effect to saccule damage.
Similarly, in our opinion, most physical therapists do not have appropriate audiology training to interpret cVEMP's. Galvanic and acoustic vestibular stimulation activate different populationso of vestibular afferents. Short latency responses in the averaged electro-oculogram elicited  by vibrational impulse stimuli applied upon the skull: could they reflect the vestibulo-ocular reflex function ?
Head impulse test revealse residual semicircular canal function after vestibular neurectomy.
Click evoked EMG responses in sternocleidomastoid muscles: characteristics in normal subjects. An indicator of probable semicircular canal dehiscence: ocular vestibular evoked myogenic potentials to high frequencies. Vestibular evoked myogenic potentials versus vestibular test battery in patients with Meniere's disease. Clinical Significance of Vestibular Evoked Myogenc Potentials in Benign Paroxysmal Positional Vertigo.
Vestibular-evoked myogenic potential thresholds normalize on plugging superior canal dehiscence. Acoustic clicks activate both the canal and otolith vestibulo-ocular reflex pathways in behaving monkeys.
Augmentation of vestibular evoked myogenic potentials: An indication for distended saccular hydrops. According to the National Institutes of Health, National Council on Aging, approximately 12 percent of the U.S. Additionally, hearing loss occurs in 5 out of every 1,000 newborns, and over 90 percent of deaf children are born to hearing parents. The truth is that most people never do anything with the products they buy, so most of the time, they dona€™t get ANY results. Great Hills ENT serves the greater Austin area including Georgetown, Cedar Park, Lago Vista, Jonestown, Steiner Ranch, Lakeway, Spicewood and Point Venture. Sound stimulates the saccule, which activates the inferior vestibular nerve, lateral vestibular nucleus, 11th nerve nucleus, and then the sternocleidomastoid muscle (mostly ipsilaterally). In the author's laboratory, a Bio-Logic Navigator Pro does nearly all of the work, and sends the results to a desktop computer. It is a very big response, and as long as the person doing the test is attentive to details (getting the sound in both ears with proper placement of inserts or headphones, having the person lift their head through the entire trial, electrodes in the right place with proper impedance), it is very straightforward.
Although P1 is positive, it is shown negative on many cVEMPs, because of electrode placement (basically putting them on backwards). Lower than normal thresholds as well as asymmetrical amplitudes are found in persons with Tullio's phenomenon, which is dizziness induced by sound.
Each side is about 250 microvolt in size (which is far above the lower limit of normal, about 70). This recording was obtained using binaural stimulation (see comments regarding this method).
Thus, one could falsely conclude that there was no vestibular function on one side based on an absent VEMP. We think this is an excellent idea, but at present there are no amplitude norms for this procedure. Our recommendation, based on some unfortunate clinical experiences where binaural stimulation lead us astray, differs from others in the literature (e.g. We do not agree -- we feel that amplitudes are more useful than thresholds, given a well standardized protocol. See more discussion of the problems inherent in doing thresholds below under technical pitfalls.
Common things that go wrong here are asymmetrical placement of inserts, wax occluding one side, or a defective sound generator (the Bio-logic ones seem to go bad very often, when used for VEMPs -- it has happened to us 3 times in just 2 years !).

If you see stimulus artifact, or sinusoidal undulations to the trace, it is very likely that the electrodes are bad, someone put the sound generator box too close to the electrodes, the impedance was too high, or the evoked potential machine needs service. The sound generator produces a magnetic field which induces a strong artifact, if one places it close to one of the electrical leads.
Actually, there are three of these muscles -- posterior, superior and anterior auricular muscles - -all vestigial. For reasons developed above, we think that a run or two of monaural stimulation is a very good idea.
While not emphasized much in the literature, VEMP tests likely involve input from many senses, and are not confined to saccule or utricle inputs as has been suggested.
It would seem to us to be not quite as reasonable for adjusting for differences in muscle activation, because this might easily change during the 2 minute cVEMP itself.
Because this method introduces the variability due to head turning, in our opinion, their experimental design was simply designed to fail. It has been our general experience that the device that we use (Bio-Logic NavPro) produces larger potentials than most competing devices. VEMPs might, in theory, be useful for detecting residual function in the inferior vestibular nerve, as this branch of the vestibular nerve is sometimes intermingled with cochlear fibers (Lehnen et al, 2004). You should also check for the PAM (by doing a test with the head resting on the table) if there is something that appears to be a response on the sectioned side.
A possible confounding problem is that there may be middle ear disease after the injection due to the perforation required for transtympanic gentamicin. As we are dubious that latency is a useful measure at all, we are also dubious about the use of cVEMP's in BPPV. This may be an artifact of our methodology (tone burst), which is temporally a longer stimulus than a click. While this substitutes for the bone conduction audiogram, it requires more testing and potentially may fatigue the patient. While theoretically possible, we are dubious that a structure that requires 70db to elicit a minimal response would be very sensitive to noise. We shudder to think of what might go on in a practice where testing is being done universally without any knowledge of whether the patient has a conductive hearing deficit, or sound-checks being done on the equipment. Even more surprising' Listening to an MP3 player at high volumes over time can permanent damage to your hearing.
15 million people in the United States with hearing loss avoid seeking help, and people with hearing loss wait an average of 7 years before seeking help. The most reliable measure of the cVEMP response is the amplitude (Isaradisaikul et al, 2008). Prolonged latencies of P13 may be found in central disturbances (Murofushi et al, 2001), but practically these are very rarely encountered, and technical error is the source of most prolonged latencies.
Artifacts can also go across the midline, which reduces much of the value of using a binaural stimulus. In our opinion, a minimum of two repetitions should be obtained on each side, to be sure that the VEMP is reproducible or absent, as the case may be. At the present writing however, the clinical value of measuring latency (other than being sure you have a VEMP), remains somewhat elusive.
The literature suggests that amplitudes are more reliable than thresholds too (Isaradisaikul et al, 2008).
A common quality control problem in the cVEMP is an overly nice technician who allows the patient to put their head down during the test.
This is an intrinsic problem with doing cVEMP's in very young children, and perhaps it should just not be attempted at all.
Because cVEMP's are not far above the threshold provided by most evoked potential equipment, little things like not putting the insert in as far in one ear as the other can make a big difference.
In our experience with the latter, the thing that routinely goes bad with the evoked potential machine are the connectors and the insert driver. As nearly always one is trying to localize the side of lesion, we think that binaural cVEMP's are best avoided. Overall, it seems to us that their method may be better than the (poor) method of head-turning as it controls for intermittent effort which is a problem with the head-turning methodology. To us this suggests that a component of air-conducted VEMP response is either due to startle or multisensory convergence.
However, as cVEMPs require a very strong stimulus, it seems unlikely that they would be very sensitive. We don't have any examples to show here, so we will just mention what is in the literature.
This range overlapped substantially with age-matched controls, but may be another helpful method of identifying PSP. The saccule would more reasonably be damaged by excessive changes in linear acceleration as it is loaded by the otoconia. The testimonials you see on this web site are some of our better results and are not typical. The second is that if you do thresholds, you can't do a lot of repetition (because people get tired).
We presently continue to hold to the opinion that a careful, unrectified head-straight lifting VEMP is superior.
We are not at all sure how pFL levels of 120 db relates to the ordinary problem with clinical bone vibrators that only produce 60 db.
Head impulse tests for the posterior canal reveal residual function more more frequently than do cVEMPs (Lehnen et al, 2004). As VEMP circuitry is not thought to involve the cerebellum, it would be surprising to find abnormal VEMP's in any purely cerebellar condition. They stuck to the dose as directed and maintained a healthy lifestyle and balanced diet alongside it. At a minimum, cVEMP's done in persons who are (perhaps) not cooperative should be done with equipment that can monitor the EMG. The third is that they don't always work -- low thresholds are NOT always accompanied by radiographic evidence of superior canal dehiscence.
In our own practice (see above), but we have only studied two patients and found abnormally reduced amplitude for age in one and an absent VEMP in the other. A corollary is that if you really care that what you are measuring reflects the side you think you are measuring, don't use a bilateral cVEMP. The literature about PAM is confused -- some authors may have mistaken the much larger cVEMP's for PAM responses, and vice versa. These patients are unusual however and a longitudinal study would not be easy to carry out. As Machado-Joseph affects the brainstem, the mechanism for the reduced VEMP may lie in damage to other locations than the cerebellum. Our present position is that thresholds should not be done routinely, as they prevent one from doing a reliable amplitude.

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