# Video head impulse test

The video head impulse test (vHIT) is a clinical vestibular test in which lightweight video goggles record eye movements during brief, rapid, passive head turns, quantifying the vestibulo-ocular reflex (VOR) gain and catch-up saccades for each semicircular canal in a dizzy patient.<sup>[1](https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2017.00258/full)</sup> It answers a practical question: is the vestibulo-ocular reflex of a given canal impaired, and is the lesion likely peripheral rather than central? Because it is easier to use in clinics than search coils, even in patients with acute [vestibular neuritis](https://www.edgepedia.org/vestibular-neuritis), it has supplanted caloric testing as the initial test of choice in many dizzy clinics.<sup>[1](https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2017.00258/full)</sup><sup> • </sup><sup>[2](https://pubmed.ncbi.nlm.nih.gov/19805730/)</sup>

| Key fact | Value |
|---|---|
| What is measured | VOR gain (eye velocity ÷ head velocity) and catch-up saccades, per canal<sup>[1](https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2017.00258/full)</sup> |
| Normal horizontal gain | Approximately 0.8–1.2; below 0.8 (horizontal) or 0.7 (vertical) generally abnormal<sup>[3](https://www.e-rvs.org/journal/view.php?number=1013)</sup> |
| Impulse parameters | Peak velocity 150–300°/s, duration 100–200 ms, amplitude ~15–20°, 10–20 trials per side<sup>[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC11204878/)</sup> |
| Frequency range tested | 1–5 Hz, versus about 0.003 Hz for caloric irrigation<sup>[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC11204878/)</sup> |
| Acute vestibular neuritis | Low gains in 78–95% of patients in the acute phase<sup>[5](https://www.mdpi.com/2039-4349/12/4/43)</sup> |
| Stroke screening | Gain differentiates vestibular neuritis from posterior circulation stroke with 88% sensitivity, 92% specificity<sup>[1](https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2017.00258/full)</sup> |
| Introduced | 2009, by the Sydney group and, in parallel, a Munich group<sup>[6](https://nyaspubs.onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.2008.03730.x)</sup> |

## How it works

The VOR stabilizes gaze by driving eye velocity equal and opposite to head velocity. It is one of the fastest reflexes in the body, with a latency under 8 ms, so during a rapid head turn the eyes are driven by the canals before slower, visually guided eye movements (latency 70–100 ms) can contribute; vHIT therefore evaluates the VOR at high frequencies of 1–5 Hz.<sup>[3](https://www.e-rvs.org/journal/view.php?number=1013)</sup>

Head impulses reach angular accelerations of 2,000–4,000°/s², about 100 times greater than motorized chair rotations (rarely above 100°/s/s). At these accelerations the contralateral canal of the working pair is silenced, so the response predominantly reflects the target canal, allowing each of the six canals to be assessed separately.<sup>[7](https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2023.1147253/full)</sup>

Gain is the central number: the ratio of the area under the eye velocity curve to the area under the head velocity curve during the impulse, written \( G_{\mathrm{VOR}} = A_{\mathrm{eye}} / A_{\mathrm{head}} \). Normal gain is close to 1.0; in unilateral vestibular loss, gain during head turns toward the affected ear is usually below 0.7.<sup>[1](https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2017.00258/full)</sup> When gain is low, the eyes fall behind the head and corrective catch-up saccades bring gaze back to target; their presence, timing, and amplitude carry diagnostic information in their own right.<sup>[6](https://nyaspubs.onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.2008.03730.x)</sup>

## How it is done

The patient wears tight-fitting goggles carrying a high-speed eye camera (about 250 Hz sampling) and head-velocity sensors, and fixates a target on the wall. After calibration, the examiner stands behind the patient and delivers abrupt, unpredictable, passive head turns in the plane of the canal pair being tested: horizontal (lateral canal) impulses first, then, for vertical canal pairs, impulses after rotating the head 30–40° to the right or left (LARP and RALP planes).<sup>[3](https://www.e-rvs.org/journal/view.php?number=1013)</sup>

Recommended impulse characteristics are a peak velocity of 150–300°/s, duration of 100–200 ms, and amplitude of roughly 15–20°, with 10–20 acceptable trials per side.<sup>[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC11204878/)</sup> Ideal impulses are ballistic at approximately 200°/s with no end-of-impulse overshoot.<sup>[8](https://www.neurology.org/doi/10.1212/WNL.0000000000002827)</sup>

Gain is computed with a wide window, from the start of the impulse until head velocity returns to or crosses 0°/s, using the desaccaded eye velocity trace; this position (area) gain best minimizes artifacts from small goggle slips, whose biphasic movements tend to cancel over the full window.<sup>[1](https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2017.00258/full)</sup> Interpretation combines the gain trace with the saccade record: matching head and eye velocity curves with gain in the normal range indicate normal function, while low mean gain with pathological saccades indicates vestibular dysfunction.<sup>[9](https://www.jove.com/v/59012/testing-all-six-semicircular-canals-with-video-head-impulse-test)</sup>

## Origin

The underlying clinical sign, the bedside head impulse test, was described by G. M. Halmagyi and I. S. Curthoys in "A Clinical Sign of Canal Paresis" (Archives of [Neurology](https://www.edgepedia.org/neurology), 1988): the clinician turns the patient's head abruptly while the patient fixates the clinician's nose and watches for a corrective saccade.<sup>[10](https://doi.org/10.1001/archneur.1988.00520310043015)</sup> Objective measurement had relied on the scleral search coil method introduced by David A. Robinson in 1963, which was accurate but impractical for routine diagnostic use.<sup>[11](https://doi.org/10.1109/tbmel.1963.4322822)</sup>

The video version was reported in 2009 by two groups in the same volume of the [Annals of the New York Academy of Sciences](https://www.edgepedia.org/annals-of-the-new-york-academy-of-sciences). Konrad P. Weber, Hamish G. MacDougall, G. Michael Halmagyi, and Ian S. Curthoys described a lightweight, nonslip, high-speed video-[oculography](https://www.edgepedia.org/oculography) system detecting both overt and covert catch-up saccades,<sup>[6](https://nyaspubs.onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.2008.03730.x)</sup> and Klaus Bartl, Nadine Lehnen, Stefan Kohlbecher, and Erich Schneider independently showed that head-mounted high-frame-rate video-oculography could assess VOR gain for individual canals at the bedside against search coils.<sup>[12](https://nyaspubs.onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.2009.03850.x)</sup> MacDougall and colleagues validated the 250 Hz video system against simultaneous search coils in 2009 (concordance correlation coefficient 0.930; sensitivity and specificity 1.0 in the studied groups).<sup>[2](https://pubmed.ncbi.nlm.nih.gov/19805730/)</sup> Vertical canal testing was added in 2013 by Hamish Gavin MacDougall and colleagues in PLoS ONE.<sup>[13](https://doi.org/10.1371/journal.pone.0061488)</sup> Based on these papers, Otometrics (Taastrup, Denmark) developed the ICS Impulse goggles.<sup>[7](https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2023.1147253/full)</sup>

## Variants

The standard paradigm, now called HIMP (head impulse paradigm), uses an earth-fixed target: compensatory catch-up saccades indicate vestibular loss. The suppression head impulse paradigm (SHIMP), introduced by Hamish G. MacDougall and colleagues in Neurology in 2016, reverses this: the patient fixates a head-mounted laser target, so healthy subjects make large anticompensatory saccades while patients with vestibular loss make small ones or none.<sup>[8](https://www.neurology.org/doi/10.1212/WNL.0000000000002827)</sup> SHIMP removes covert saccades from the gain measurement,<sup>[7](https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2023.1147253/full)</sup> and its gain is unaffected by spontaneous nystagmus.<sup>[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC11204878/)</sup> HIMP and SHIMP gains correlate closely (\( R^{2} = 0.97 \)), with SHIMP gains about 0.06 lower.<sup>[8](https://www.neurology.org/doi/10.1212/WNL.0000000000002827)</sup>

The two widely used commercial systems, EyeSeeCam (Interacoustics) and ICS Impulse (Otometrics), agree well for horizontal canals: in patients with acute unilateral vestibular disorders, affected-side horizontal gains correlated significantly (r = 0.80, P < 0.01) with no significant difference between models. For vertical canals, however, gains were significantly higher with EyeSeeCam than with ICS Impulse, so each model needs its own vertical-canal reference values.<sup>[14](https://journals.lww.com/onojournal/fulltext/2024/06000/comparing_video_head_impulse_testing_in_patients.2.aspx)</sup> In the ICS Impulse approach, vertical testing uses LARP and RALP impulses with gaze directed along the plane of the stimulated canal pair, minimizing torsion.<sup>[7](https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2023.1147253/full)</sup>

## Applications

In acute vestibular neuritis, 78–95% of patients show low vHIT gains and caloric unilateral hypofunction, with only 5–10% dissociated results.<sup>[5](https://www.mdpi.com/2039-4349/12/4/43)</sup> Because vHIT gain can differentiate vestibular neuritis from posterior circulation stroke with 88% sensitivity and 92% specificity, it is used to screen potential stroke patients in the emergency room.<sup>[1](https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2017.00258/full)</sup>

For bilateral vestibulopathy, saccade-based criteria perform strongly: cumulative HIMP saccade amplitude above 0.78°/trial discriminated bilateral vestibular loss from controls with 100% sensitivity and 100% specificity in the SHIMP study cohort.<sup>[8](https://www.neurology.org/doi/10.1212/WNL.0000000000002827)</sup> vHIT's vertical canal testing also distinguishes superior vestibular neuritis (85% of cases) from inferior neuritis (15%), which calorics cannot.<sup>[3](https://www.e-rvs.org/journal/view.php?number=1013)</sup>

Against caloric testing, the two methods are complementary rather than interchangeable. In chronic dizziness, a meta-analysis of eleven studies (2,670 patients) found caloric testing abnormal in 55% versus 21% for vHIT, with vHIT sensitivity of 0.341 and specificity of 0.939 against calorics, so vHIT cannot replace caloric testing as a screening test in chronic disease.<sup>[15](https://www.sciencedirect.com/science/article/pii/S1808869421000082)</sup> In one consecutive series of 893 dizzy patients, dissociation occurred in 18.1%, most often abnormal calorics with normal vHIT, mainly [Ménière's disease](https://www.edgepedia.org/menieres-disease) and vestibular neuritis.<sup>[16](https://pubmed.ncbi.nlm.nih.gov/32319245/)</sup> vHIT is also used to monitor intratympanic gentamicin treatment of Ménière's disease.<sup>[1](https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2017.00258/full)</sup>

## Limitations and alternatives

False normals are the main pitfall. In partial lesions and Ménière's disease the high-frequency VOR measured by vHIT can be preserved while low-frequency function is lost: in 172 patients with caloric unilateral weakness ≥25%, pathological vHIT was found in only 41% overall, in 63% of acute versus 33% of non-acute patients.<sup>[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC11204878/)</sup> Low-velocity impulses also miss deficits; testing at 240°/s is 17–20% more sensitive than at 80°/s in vestibular neuritis.<sup>[4](https://pmc.ncbi.nlm.nih.gov/articles/PMC11204878/)</sup>

Technical artifacts matter. Goggle slippage and poor calibration distort the gain calculation, which is why the wide-window position gain is preferred.<sup>[1](https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2017.00258/full)</sup> Head tilt reduces the measured head velocity by the cosine of the tilt angle; at 25° tilt the horizontal head velocity reads 0.906 of the true value, spuriously raising gain.<sup>[7](https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2023.1147253/full)</sup> Monocular right-eye recording systems carry a rightward gain bias, a mean 9.1% difference favoring the right side across 212 healthy subjects.<sup>[17](https://pmc.ncbi.nlm.nih.gov/articles/PMC10273913/)</sup> Abnormal vHIT with normal calorics can also reflect central lesions, including AICA stroke and flocculus lesions.<sup>[18](https://journals.sagepub.com/doi/full/10.1177/01455613221113790)</sup>

Compared with the alternatives: the bedside head impulse test is faster but less accurate; in a 2025 cross-sectional study using vHIT as the reference, bedside HIT had 74% diagnostic accuracy (sensitivity 57%, specificity 89%, Cohen's Kappa 0.468).<sup>[19](https://journals.lww.com/ijoo/fulltext/2025/04000/comparison_of_video_head_impulse_test_and_bedside.8.aspx)</sup> Search coils remain more accurate for stroke differentiation (94–97% sensitivity, 90–100% specificity) but are impractical for routine use.<sup>[1](https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2017.00258/full)</sup> Normative gain cutoffs also vary between laboratories: 0.8 (or 0.79) is commonly used, while one device-specific study found normal ranges of 0.72–1.04 (left) and 0.72–1.28 (right) with gain <0.72 alone giving 80% sensitivity.<sup>[17](https://pmc.ncbi.nlm.nih.gov/articles/PMC10273913/)</sup>

## References

1. [The Video Head Impulse Test (Halmagyi, Curthoys et al., Frontiers in Neurology 2017)](https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2017.00258/full)
2. [The video head impulse test: diagnostic accuracy in peripheral vestibulopathy (MacDougall et al., Neurology 2009)](https://pubmed.ncbi.nlm.nih.gov/19805730/)
3. [Clinical usefulness of the video head impulse test: a narrative review (Research in Vestibular Science)](https://www.e-rvs.org/journal/view.php?number=1013)
4. [Application of a Video Head Impulse Test in the Diagnosis of Vestibular Neuritis (2024 review)](https://pmc.ncbi.nlm.nih.gov/articles/PMC11204878/)
5. [Dissociation between Caloric and Video Head Impulse Tests in Dizziness Clinics (review)](https://www.mdpi.com/2039-4349/12/4/43)
6. [Impulsive Testing of Semicircular-Canal Function Using Video-oculography (Weber, MacDougall, Halmagyi, Curthoys, Annals of the New York Academy of Sciences, 2009)](https://nyaspubs.onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.2008.03730.x)
7. [A review of the geometrical basis and the principles underlying the use and interpretation of the video head impulse test (vHIT) in clinical vestibular testing (Frontiers in Neurology 2023)](https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2023.1147253/full)
8. [A new saccadic indicator of peripheral vestibular function based on the video head impulse test (MacDougall et al., Neurology 2016;87(4):410-418, SHIMP paper; publisher page, excerpts merged from PMC4977115 copy)](https://www.neurology.org/doi/10.1212/WNL.0000000000002827)
9. [Testing of all Six Semicircular Canals with Video Head Impulse Test Systems (JoVE, 2019, DOI 10.3791/59012-v)](https://www.jove.com/v/59012/testing-all-six-semicircular-canals-with-video-head-impulse-test)
10. [G. M. Halmagyi, I. S. Curthoys (1988). A Clinical Sign of Canal Paresis. Archives of Neurology.](https://doi.org/10.1001/archneur.1988.00520310043015)
11. [David A. Robinson (1963). A Method of Measuring Eye Movemnent Using a Scieral Search Coil in a Magnetic Field. IEEE Transactions on Bio-medical Electronics.](https://doi.org/10.1109/tbmel.1963.4322822)
12. [Head Impulse Testing Using Video-oculography (Bartl, Lehnen, Kohlbecher, Schneider, Annals of the New York Academy of Sciences, 2009)](https://nyaspubs.onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.2009.03850.x)
13. [Hamish Gavin MacDougall and colleagues (2013). The Video Head Impulse Test (vHIT) Detects Vertical Semicircular Canal Dysfunction. PLoS ONE.](https://doi.org/10.1371/journal.pone.0061488)
14. [Comparing Video Head Impulse Testing in Patients With Acute Vestibular Dysfunction (Otology & Neurotology, 2024)](https://journals.lww.com/onojournal/fulltext/2024/06000/comparing_video_head_impulse_testing_in_patients.2.aspx)
15. [Does the video head impulse test replace caloric testing in the assessment of patients with chronic dizziness? A systematic review and meta-analysis](https://www.sciencedirect.com/science/article/pii/S1808869421000082)
16. [Dissociated Results between Caloric and Video Head Impulse Tests in Dizziness: Prevalence, Pattern, Lesion Location, and Etiology (Lee et al., PubMed record)](https://pubmed.ncbi.nlm.nih.gov/32319245/)
17. [Refining the Video Head Impulse Test Diagnostic Accuracy: A Case-Control Study (2023)](https://pmc.ncbi.nlm.nih.gov/articles/PMC10273913/)
18. [Clinical characteristics of patients with dizziness/vertigo showing a dissociation between caloric and video head impulse test results](https://journals.sagepub.com/doi/full/10.1177/01455613221113790)
19. [Comparison of Video Head Impulse Test and Bedside Head Impulse Test in Patients of Dizziness: A Cross-sectional Study (2025)](https://journals.lww.com/ijoo/fulltext/2025/04000/comparison_of_video_head_impulse_test_and_bedside.8.aspx)

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*Topic: Encyclopedia › Life and health › Human health and medicine › Clinical assessment and procedures › Diagnosis and clinical assessment › Physical examination and clinical signs › Neurological examination*

*Initially written Sep 29, 2026 · Edited: Oct 15, 2026*

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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license