An Interactive Teaching Atlas

Core modules

• 01 · Introduction — What VEMPs measure, why they matter, and a brief history.
• 02 · Anatomy & Physiology — Saccule, utricle, the two divisions of the vestibular nerve, and the reflex arcs.
• 03 · Recording Technique — Stimuli, electrode placement, parameters, EMG correction, common pitfalls.
• 04 · Normal Waveforms — Interactive wave simulator, normative ranges, the IAR explained.

Disease conditions

• 05.1 · Superior Canal Dehiscence — Third-window VEMP signature — lowered threshold, augmented amplitude.
• 05.2 · Ménière's Disease — Endolymphatic hydrops — reduced amplitudes and frequency-tuning shift.
• 05.3 · Vestibular Neuritis — Topographic diagnosis: superior vs inferior vs total neuritis.
• 05.4 · Vestibular Migraine — VEMP in vestibular migraine — common but heterogeneous abnormalities.
• 05.5 · BPPV — Benign paroxysmal positional vertigo — utricular VEMP findings.
• 05.6 · Vestibular Schwannoma — Sensitivity ~81%, specificity ~53% — adjunct to MRI work-up.
• 05.7 · Multiple Sclerosis — Central demyelination — latency prolongation, even with normal MRI.

For the full discussion of each condition, see the corresponding chapter in the interactive atlas. The print-all view summarises module structure; the substantive text lives on each module page.

Self-assessment (24 questions)

1. FOUNDATION
   What does a VEMP test primarily assess?
   • A. The hearing portion of the inner ear (cochlea)
   • B. The otolith organs (saccule and utricle) of the inner ear
   • C. The semicircular canals only
   • D. The facial nerve
   Answer: B. VEMPs assess the otolith organs — the saccule (via cVEMP) and the utricle (via oVEMP). They are the only routine clinical test of otolith function.
2. FOUNDATION
   From which muscle is the cervical VEMP (cVEMP) recorded?
   • A. Inferior oblique (eye muscle)
   • B. Sternocleidomastoid (neck muscle)
   • C. Frontalis (forehead)
   • D. Orbicularis oculi (eyelid)
   Answer: B. The cVEMP is recorded from the tonically contracted sternocleidomastoid (SCM) on the same side as the stimulated ear. The oVEMP, by contrast, is recorded from the inferior oblique under the eye.
3. FOUNDATION
   The oVEMP appears on the side ___ to the stimulated ear, while the cVEMP appears on the side ___ to the stimulated ear.
   • A. ipsilateral; contralateral
   • B. contralateral; ipsilateral
   • C. ipsilateral; ipsilateral
   • D. contralateral; contralateral
   Answer: B. The oVEMP is a contralateral response (recorded under the eye on the opposite side from the stimulated ear). The cVEMP is an ipsilateral response (recorded from the SCM on the same side as the stimulated ear).
4. FOUNDATION
   The most established clinical use of VEMP testing is in which condition?
   • A. Benign paroxysmal positional vertigo (BPPV)
   • B. Vestibular migraine
   • C. Superior semicircular canal dehiscence (SCD)
   • D. Acoustic neuroma screening
   Answer: C. The 2017 AAN practice guideline rated VEMP evidence as Level B for SCD — its strongest endorsement. VEMP shows characteristic lowered thresholds and increased amplitudes in SCD due to the 'third-window' effect.
5. FOUNDATION
   Which type of stimulus is most commonly used in routine clinical VEMP testing?
   • A. Pure tone at 250 Hz
   • B. Tone burst at 500 Hz
   • C. White noise at conversational level
   • D. Speech
   Answer: B. The 500 Hz tone burst is the standard stimulus for clinical VEMP testing. It produces the largest amplitudes in healthy ears because the otolith organs are best tuned to this frequency.
6. TRAINEE
   The two diagnostic peaks of a typical cVEMP are:
   • A. N1 (~10 ms) and P1 (~16 ms)
   • B. P1 (~13 ms) and N1 (~23 ms)
   • C. P1 (~5 ms) and N1 (~10 ms)
   • D. N1 (~30 ms) and P1 (~50 ms)
   Answer: B. The cVEMP shows an initial positive peak (P1, also called p13) around 13 ms followed by a negative peak (N1, n23) around 23 ms. The oVEMP is the mirror — N1 (n10) around 10 ms followed by P1 (p16) around 16 ms.
7. TRAINEE
   The cVEMP is generated via which reflex pathway?
   • A. Vestibulo-ocular reflex
   • B. Vestibulo-collic reflex
   • C. Cochleo-vestibular reflex
   • D. Stapedial reflex
   Answer: B. The cVEMP is generated via the vestibulo-collic reflex: saccular afferents → inferior vestibular nucleus → medial vestibulospinal tract → ipsilateral SCM motor neurons. It is an INHIBITORY modulation of the tonically contracted SCM.
8. TRAINEE
   Which nerve division carries the afferent volley for the cVEMP?
   • A. Superior vestibular nerve
   • B. Inferior vestibular nerve
   • C. Cochlear nerve
   • D. Facial nerve
   Answer: B. The saccule is innervated by the inferior vestibular nerve, which carries the cVEMP afferent volley. The superior vestibular nerve innervates the utricle and drives the oVEMP. This anatomical split is what allows topographic diagnosis of vestibular neuritis.
9. TRAINEE
   An IAR (interaural asymmetry ratio) of approximately what value is generally considered the upper limit of normal?
   • A. 10–15 %
   • B. 33–40 %
   • C. 60–70 %
   • D. Over 80 %
   Answer: B. Most laboratories use an IAR cut-off of 33–40 %. Values above this suggest an asymmetric otolith response. Each lab should establish its own norms because the cut-off depends on stimulus, electrode montage and EMG correction.
10. TRAINEE
    In SCD, what is the most characteristic cVEMP finding?
    • A. Absent response on the affected side
    • B. Lowered threshold and increased amplitude on the affected side
    • C. Markedly prolonged P1 latency
    • D. Reversed polarity
    Answer: B. SCD produces a third-window effect: sound and pressure are more efficiently transmitted to the vestibular system, lowering the threshold (often <70 dBnHL) and increasing amplitude on the affected side. High-frequency oVEMP (2–4 kHz) is now considered the most sensitive single measure.
11. TRAINEE
    A patient presents with right-sided vertigo, an absent right cVEMP, but a normal right oVEMP and normal caloric responses bilaterally. The most likely diagnosis is:
    • A. Superior vestibular neuritis
    • B. Inferior vestibular neuritis
    • C. Ménière's disease
    • D. Superior canal dehiscence
    Answer: B. Inferior vestibular neuritis affects only the inferior division: saccule (cVEMP) and posterior canal. The superior division — utricle (oVEMP) and horizontal canal (caloric) — is preserved. This pattern is often missed without cVEMP testing.
12. TRAINEE
    The 2017 AAN practice guideline rated the evidence for VEMP in SCD diagnosis as:
    • A. Level A (established)
    • B. Level B (probable)
    • C. Level U (insufficient evidence)
    • D. Level C-negative (not recommended)
    Answer: B. The AAN gave VEMP a Level B recommendation for SCD — its strongest endorsement, meaning it 'substantively aids diagnosis'. For Ménière's, migraine, and BPPV the rating was Level C-negative.
13. TRAINEE
    Why must the SCM muscle be tonically contracted during cVEMP recording?
    • A. To prevent neck pain
    • B. Because cVEMP is an inhibitory modulation of ongoing muscle activity
    • C. To improve electrode adhesion
    • D. To activate the cochlear pathway
    Answer: B. The cVEMP represents brief INHIBITION of an actively contracting SCM. Without ongoing contraction there is no muscle activity to inhibit, and no recordable response.
14. TRAINEE
    Which of these is a common cause of an apparently absent cVEMP that resolves with corrective action?
    • A. Underlying schwannoma
    • B. Inadequate SCM contraction
    • C. Brainstem stroke
    • D. Acute Ménière's attack
    Answer: B. The most common cause of an absent cVEMP is inadequate SCM contraction — not pathology. EMG biofeedback often rescues an 'absent' response.
15. CLINICIAN
    Which VEMP finding is now considered the MOST sensitive single measure for SCD?
    • A. cVEMP threshold at 500 Hz
    • B. oVEMP N1 amplitude (especially at high frequencies, 2–4 kHz)
    • C. cVEMP P1 latency
    • D. oVEMP P1 latency
    Answer: B. Increased oVEMP N1 amplitude — particularly preservation of oVEMP responses at high frequencies (2–4 kHz) where normal ears no longer respond — is now considered the most sensitive single VEMP measure for SCD.
16. CLINICIAN
    In Ménière's disease, a 'frequency-tuning shift' refers to:
    • A. Best response frequency moving from 500 Hz toward 1 kHz
    • B. Best response frequency dropping below 100 Hz
    • C. Loss of all frequency-specific responses
    • D. Reversed polarity at low frequencies
    Answer: A. Normal saccules respond best at 500 Hz. In hydropic saccules (e.g. Ménière's), the peak shifts upward toward 1 kHz, reflecting altered mechanical properties of the distended macula.
17. CLINICIAN
    Reported sensitivity of cVEMP for vestibular schwannoma is approximately:
    • A. 20–30 %
    • B. 50–60 %
    • C. 80–85 %
    • D. Close to 100 %
    Answer: C. A study of 78 patients with untreated unilateral schwannoma reported cVEMP sensitivity of ~80.8% with specificity ~52.7% — comparable to caloric testing. Sensitivity is higher for extracanalicular tumours than purely intracanalicular ones.
18. CLINICIAN
    Which finding most strongly suggests a CENTRAL (rather than peripheral) cause of VEMP abnormality?
    • A. Reduced amplitude on the affected side
    • B. Markedly prolonged P1 latency with relatively preserved amplitude
    • C. Lowered threshold
    • D. Absence of response
    Answer: B. Peripheral lesions typically affect AMPLITUDE; central lesions more often affect LATENCY. Markedly prolonged P1 with preserved amplitude is a red flag for central demyelination or brainstem pathology.
19. CLINICIAN
    In multiple sclerosis, VEMPs can be abnormal even when MRI is normal. The reported diagnostic yield of combining p13-n23 and n34-p44 abnormalities is approximately:
    • A. About 20 %
    • B. About 50 %
    • C. About 70 %
    • D. Close to 95 %
    Answer: C. Eleftheriadou et al. found p13-n23 abnormal in 50% and n34-p44 abnormal in 43%; combined yield was approximately 71%.
20. CLINICIAN
    A 2025 systematic review of VEMP in vestibular migraine concluded that:
    • A. VEMP is highly specific and should be a routine diagnostic test
    • B. Abnormalities are common (most often reduced amplitudes and increased asymmetry) but findings are heterogeneous and not yet diagnostic
    • C. VEMP is uniformly normal in vestibular migraine
    • D. Only cVEMP — never oVEMP — is affected
    Answer: B. The 2025 systematic review of 28 studies found 23 reported abnormalities — most often reduced amplitudes, increased asymmetry, oVEMP more affected than cVEMP. But heterogeneity precludes diagnostic use.
21. CLINICIAN
    A meta-analysis comparing cVEMP and oVEMP in BPPV found:
    • A. cVEMP abnormalities are more frequent than oVEMP
    • B. oVEMP abnormalities are more frequent than cVEMP
    • C. Both are equally affected
    • D. Neither is affected in BPPV
    Answer: B. oVEMP abnormalities (utricular dysfunction) are more common than cVEMP abnormalities in BPPV, consistent with the theory that dislodged otoconia originate principally from the utricular macula.
22. CLINICIAN
    In a patient with a known unilateral conductive hearing loss in the test ear, the most appropriate alternative for VEMP testing is:
    • A. Increase the air-conducted stimulus intensity to 110 dBnHL
    • B. Use bone-conducted vibration (BCV) at Fz with a mini-shaker
    • C. Abandon VEMP testing
    • D. Use a 4 kHz pure tone instead
    Answer: B. AC stimuli are attenuated by middle ear pathology. BCV at Fz (midline forehead) bypasses the middle ear entirely. BCV-specific norms must be used because latencies differ slightly from AC-evoked responses.
23. CLINICIAN
    Welgampola et al. demonstrated which key finding regarding surgical management of SCD?
    • A. VEMP responses worsen permanently after canal plugging
    • B. VEMP thresholds normalise after surgical plugging of the dehiscence
    • C. VEMPs are unaffected by surgery
    • D. Plugging causes inversion of VEMP polarity
    Answer: B. Welgampola and colleagues showed that VEMP thresholds normalise after successful surgical plugging of the dehiscence — establishing causality between the third-window effect and the VEMP abnormality.
24. CLINICIAN
    Curthoys and colleagues (2025) argued that recent rodent studies questioning the saccular origin of cVEMP:
    • A. Definitively show that cVEMP is generated by semicircular canals
    • B. Are most likely due to species differences and do not invalidate the saccular origin in humans at clinical parameters
    • C. Prove that VEMPs cannot be used clinically
    • D. Support replacing the cVEMP with the oVEMP entirely
    Answer: B. Curthoys et al. (2025) concluded the rat is a poor model for human VEMPs. Single-unit studies in primates and guinea pigs continue to support the saccular origin of the cVEMP and utricular origin of the oVEMP at clinical parameters.

Glossary (68 terms)

AAN guideline (American Academy of Neurology guideline)

The 2017 American Academy of Neurology practice guideline on cervical and ocular VEMP testing. Rates evidence as Level B for SCD diagnosis and Level C-negative for routine use in Ménière's, vestibular migraine, and BPPV.

Absent response

No reproducible VEMP at the highest tolerated stimulus intensity. Implies severe receptor or nerve dysfunction — but inadequate muscle contraction must be excluded first.

Active electrode

The recording electrode placed over the muscle of interest (SCM belly for cVEMP, infraorbital ridge for oVEMP). Picks up the differential signal that becomes the displayed waveform.

Air-conducted stimulus (AC)

Sound delivered through the ear canal (insert earphone or headphone). The default route for clinical VEMP testing; subject to attenuation by conductive hearing loss.

Alternating polarity

Stimulus delivery alternating compression and rarefaction of the diaphragm to cancel stimulus artefact. Recommended for clinical VEMP recording.

Amplitude

The peak-to-peak voltage of the VEMP, measured in microvolts (µV). Reduced or absent amplitudes suggest receptor or peripheral nerve dysfunction.

Analysis window

The portion of each averaged sweep displayed for measurement, typically 0–50 or 0–100 ms post-stimulus, with a 10-ms pre-stimulus baseline.

Augmented amplitude

Peak-to-peak amplitude larger than the lab-specific upper limit. Most characteristically seen on the affected side in SCD (third-window effect).

Autophony

Hearing one's own voice as too loud or reverberant. A classic symptom of SCD, resulting from altered transmission of body-generated sounds through the third window.

Bandpass filter

Electronic filter that passes frequencies between a high-pass and low-pass cut-off. Typical VEMP settings are 5–30 Hz high-pass and 1000–3000 Hz low-pass; the oVEMP often uses a lower high-pass.

Bone-conducted vibration (BCV)

Mechanical stimulus delivered via a vibrator placed at Fz (midline forehead) or the mastoid. Bypasses the middle ear, so unaffected by conductive hearing loss. Particularly effective for evoking the oVEMP.

BPPV (Benign paroxysmal positional vertigo)

Brief vertigo triggered by head position change due to otoconia displaced from the utricle into a semicircular canal (most commonly the posterior canal). VEMP has no role in diagnosis but oVEMP abnormalities are common in recurrent cases.

Caloric test

Stimulation of the horizontal semicircular canal by warm and cool irrigation of the ear canal. Tests the superior vestibular nerve — complementary to VEMP, which tests the otolith branches.

Click

A 100-microsecond rectangular pulse delivered through earphones. An older alternative to the tone burst; has a broader frequency spectrum but is less frequency-selective.

Conductive hyperacusis

Abnormal sensitivity to one's own internal sounds (footsteps, heartbeat, eye movements). Pathognomonic of third-window disorders.

Corrected amplitude

Raw cVEMP P1–N1 amplitude divided by mean rectified pre-stimulus EMG. Reduces variability due to differences in muscle contraction strength.

cVEMP (Cervical VEMP)

Cervical vestibular evoked myogenic potential — a brief inhibitory modulation of tonic sternocleidomastoid EMG, recorded ipsilateral to the stimulated ear. Tests the saccule and the inferior vestibular nerve.

dBnHL

Decibels normal hearing level — a clinical reference scale calibrated against the threshold of normal-hearing young adults. Most VEMP protocols use 95–100 dBnHL stimuli (≈ 120 dB SPL).

EMG biofeedback

A visual bar on the recording system that shows the patient how strongly their SCM is contracting. Helps maintain consistent muscle activation during cVEMP recording.

EMG correction (EMG normalisation)

Procedure to compensate for variable underlying SCM contraction in cVEMP recording. The raw P1–N1 amplitude is divided by the mean rectified pre-stimulus EMG, producing the 'corrected amplitude' used for between-subject comparison.

Endolymphatic hydrops

Distension of the endolymphatic compartment of the inner ear. Considered the histopathological substrate of Ménière's disease; produces reduced VEMP amplitudes and a frequency-tuning shift.

Forehead tap

Bedside VEMP stimulus delivered with a tendon hammer or reflex hammer at the midline forehead. A simple, rapid way to elicit oVEMPs without specialised equipment.

Frequency tuning

The dependence of VEMP amplitude on stimulus frequency. Normal otolith organs are tuned to 500 Hz; tuning shifts can be diagnostically informative.

Frequency-tuning shift

Upward shift of peak VEMP frequency response — from 500 Hz toward 1 kHz — observed in endolymphatic hydrops. More specific to Ménière's than amplitude reduction alone.

Galvanic vestibular stimulation (GVS)

Direct electrical stimulation of vestibular afferents via electrodes over the mastoid processes. Mostly research; bypasses receptor mechanisms and tests downstream pathways directly.

Ground electrode

The system common-reference electrode, typically placed on the upper forehead. Reduces electrical interference between the patient and the amplifier.

Hair cell

The sensory receptor of the inner ear. Type I hair cells are flask-shaped and surrounded by a calyceal nerve ending; Type II hair cells are cylindrical with bouton endings. VEMP responses depend on Type I striolar hair cells.

Hennebert's sign

Pressure-induced nystagmus or vertigo elicited by tragal pressure or pneumatic otoscopy. Suggests a third-window disorder.

Impedance

Electrical resistance between an electrode and the skin, measured in ohms. Clean VEMP recording requires < 5 kΩ at every electrode; achieved with skin abrasion and conductive gel.

Inferior oblique

Small extraocular muscle that elevates and laterally rotates the eye. The oVEMP is recorded over the inferior oblique on the side contralateral to the stimulated ear.

Inferior vestibular nerve (Inferior division)

The second division of the vestibular nerve. Carries afferents from the saccule and posterior semicircular canal. Generates the cVEMP via the vestibulo-collic reflex.

Interaural asymmetry ratio (IAR)

A measure of side-to-side VEMP amplitude asymmetry: IAR = |L − R| / (L + R) × 100. Values above 33–40% are generally considered abnormal.

Internal auditory canal (IAC)

Bony canal in the petrous temporal bone through which the cochlear and vestibular nerves and the facial nerve pass from the brainstem to the inner ear. The most common site of vestibular schwannoma.

Irregular afferent

A vestibular nerve fibre that fires with irregular interspike intervals at rest. Irregular afferents innervate striolar hair cells and respond preferentially to high-frequency stimuli, including sound and vibration — the population responsible for VEMP generation.

Jongkees formula

Originally devised for caloric responses, the formula (|L − R| / (L + R)) × 100 is also applied to VEMP amplitudes to compute the interaural asymmetry ratio.

Latency

The time from stimulus onset to a peak of the response, measured in milliseconds. Prolonged latency suggests slowed conduction (e.g. central demyelination, retrolabyrinthine lesion).

Macula

The sensory epithelium of an otolith organ, containing hair cells covered by a gelatinous layer in which the otoconia are embedded. Each otolith organ has one macula.

Membranous labyrinth

The fluid-filled epithelial structures inside the bony labyrinth, including the cochlear duct, three semicircular ducts, and the saccule and utricle.

Ménière's disease (Meniere disease)

Episodic vertigo with fluctuating low-frequency sensorineural hearing loss and tinnitus. Histopathological substrate is endolymphatic hydrops; VEMPs commonly show reduced amplitudes and a frequency-tuning shift on the affected side.

Multiple sclerosis (MS)

Chronic immune-mediated demyelinating disease of the CNS. Brainstem plaques can produce prolonged VEMP latencies, sometimes when MRI is normal — supporting VEMP's role as a complementary functional test.

N1 (n23 (cVEMP), n10 (oVEMP))

The first negative peak of the VEMP. In the cVEMP, N1 occurs at approximately 23 ms after the stimulus (following P1). In the oVEMP, N1 is the EARLIER peak, at approximately 10 ms, preceding P1.

Otoconia (Otoliths (crystals))

Tiny calcium carbonate crystals embedded in the otolith membrane above each macula. Their inertia is what allows the otolith organs to detect linear acceleration. Displaced otoconia in a semicircular canal cause BPPV.

Otolith organs (Otoliths)

Collective name for the saccule and utricle — the two gravity-sensing organs of the inner ear. Distinguished from the three semicircular canals, which sense rotation.

oVEMP (Ocular VEMP)

Ocular vestibular evoked myogenic potential — a brief excitatory response recorded over the inferior oblique muscle contralateral to the stimulated ear. Tests the utricle and the superior vestibular nerve.

P1 (p13)

The first positive peak of the cVEMP, occurring at approximately 13 ms after the stimulus. Together with N1, it defines the diagnostic cVEMP complex.

Presbyvestibulopathy

Age-related decline in vestibular function. Manifests as bilaterally reduced VEMP amplitudes and increased proportion of absent responses, particularly after the seventh decade.

Reduced amplitude

Peak-to-peak amplitude smaller than the lab-specific lower limit. Suggests partial receptor or nerve dysfunction (e.g. Ménière's disease, presbyvestibulopathy).

Reference electrode

An electrode placed on a relatively quiet site (e.g. medial clavicle for cVEMP, cheek for oVEMP) that provides the differential pair for the active electrode.

Regular afferent

A vestibular nerve fibre with low resting variability that responds best to sustained head position and slow accelerations. Regular afferents innervate extrastriolar hair cells and contribute little to the VEMP.

Saccule

One of the two otolith organs of the inner ear. Its macula lies in the vertical plane and detects vertical linear acceleration and gravity. The saccule is innervated by the inferior vestibular nerve and is the receptor that generates the cVEMP.

SCD (Superior semicircular canal dehiscence, Superior canal dehiscence)

Absence of bone over the superior semicircular canal, creating a 'third window' in the inner ear. Causes sound- and pressure-induced vertigo, autophony, conductive hyperacusis, and characteristically augmented low-threshold VEMP responses.

Sensitivity

The probability that a diagnostic test will be positive in a patient who has the disease. Reported VEMP sensitivities range from ~80% for SCD and schwannoma to ~50–70% for MS.

Specificity

The probability that a diagnostic test will be negative in a patient who does not have the disease. VEMP specificity varies widely by condition and protocol — high-frequency oVEMP gives the best specificity for SCD.

Sternocleidomastoid (SCM)

Large strap-like neck muscle that flexes and rotates the head. The cVEMP is recorded as a brief inhibitory modulation of its tonic contraction.

Striola

A curved zone running across each otolith macula at which the kinocilium orientation of the hair cells reverses. Striolar hair cells are predominantly Type I and are innervated by irregularly-firing afferents that generate the VEMP response.

Superior vestibular nerve (Superior division)

One of the two divisions of the vestibular nerve (CN VIII). Carries afferents from the utricle, superior semicircular canal, and horizontal semicircular canal. Generates the oVEMP via the vestibulo-ocular reflex.

Sweep averaging

Synchronous averaging of many time-locked stimulus presentations to extract the VEMP from ongoing background EMG. 100–250 sweeps are typically averaged per run.

Third-window effect

Mechanism by which abnormal communication between the inner ear and surrounding structures (e.g. superior canal dehiscence) increases the inner ear's responsiveness to sound and pressure. Produces lowered VEMP thresholds and augmented amplitudes.

Threshold

The lowest stimulus intensity that still produces a reproducible VEMP. A lowered threshold (e.g. < 70 dBnHL on cVEMP) is the most specific finding for SCD.

Tone burst

A short pulse of a pure tone — typically 500 Hz, 2-ms rise/fall, 2-ms plateau — used as the standard auditory stimulus for clinical VEMP testing.

Topographic diagnosis

Localising a vestibular lesion to a specific structure (saccule vs utricle, superior nerve vs inferior nerve) by combining VEMP with caloric and other tests. The combination resolves what 'a vestibular problem' actually means.

Tullio phenomenon

Sound-induced vertigo, oscillopsia, or eye movements — classically associated with third-window disorders such as SCD. Named after Pietro Tullio's 1929 experiments on pigeons.

Utricle

One of the two otolith organs. Its macula lies in the horizontal plane and detects horizontal linear acceleration and head tilt. The utricle is innervated by the superior vestibular nerve and is the receptor that generates the oVEMP.

Vestibular migraine

A common cause of episodic vertigo associated with a migraine diathesis. VEMP findings are heterogeneous — reduced amplitudes and increased asymmetry ratios are common but not diagnostic.

Vestibular neuritis

Acute unilateral vestibulopathy, usually presumed post-viral. May affect the superior division alone (most common), the inferior division alone, or both. VEMP/caloric pattern allows topographic localisation.

Vestibular schwannoma (Acoustic neuroma)

Benign tumour arising from the vestibular nerve sheath, usually within the internal auditory canal. VEMP sensitivity ~81%, specificity ~53%; useful adjunct but MRI remains the diagnostic standard.

Vestibulo-collic reflex (VCR)

Disynaptic reflex from saccular afferents through the inferior vestibular nucleus and medial vestibulospinal tract to the ipsilateral sternocleidomastoid. The cVEMP is its surface EMG representation.

Vestibulo-ocular reflex (VOR)

Reflex that stabilises gaze during head movement. The oVEMP exploits a sound- and vibration-evoked component of the VOR mediated by utricular afferents to the contralateral inferior oblique.

References

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