Quantifying the Vestibulo-Ocular Reflex with Video-Oculography: Nature and Frequency of Artifacts

Mantokoudis, Georgios; Tehrani, Ali S. Saber; Kattah, Jorge C.; Eibenberger, Karin; Guede, Cynthia I.; Zee, David S.; Newman‐Toker, David E.

doi:10.1159/000362780

Cited by 152 publications

(146 citation statements)

References 36 publications

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“…Proper vHIT examination technique is crucial to avoid measurement artifacts. 17 For accurate VOR gain measurements, ballistic head impulses of sufficient speed (ideally approximately 200 8 /s) are important, while tight goggle fit must be ensured to avoid slippage. For the subsequent saccade pattern, the ending of the impulse is of paramount importance.…”

Section: Resultsmentioning

confidence: 99%

A new saccadic indicator of peripheral vestibular function based on the video head impulse test

et al. 2016

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Objective: While compensatory saccades indicate vestibular loss in the conventional head impulse test paradigm (HIMP), in which the participant fixates an earth-fixed target, we investigated a complementary suppression head impulse paradigm (SHIMP), in which the participant is fixating a head-fixed target to elicit anticompensatory saccades as a sign of vestibular function.Methods: HIMP and SHIMP eye movement responses were measured with the horizontal video head impulse test in patients with unilateral vestibular loss, patients with bilateral vestibular loss, and in healthy controls.Results: Vestibulo-ocular reflex gains showed close correlation (R 2 5 0.97) with slightly lower SHIMP than HIMP gains (mean gain difference 0.06 6 0.05 SD, p , 0.001). However, the 2 paradigms produced complementary catch-up saccade patterns: HIMP elicited compensatory saccades in patients but rarely in controls, whereas SHIMP elicited large anticompensatory saccades in controls, but smaller or no saccades in bilateral vestibular loss. Unilateral vestibular loss produced covert saccades in HIMP, but later and smaller saccades in SHIMP toward the affected side. Cumulative HIMP and SHIMP saccade amplitude differentiated patients from controls with high sensitivity and specificity.Conclusions: While compensatory saccades indicate vestibular loss in conventional HIMP, anticompensatory saccades in SHIMP using a head-fixed target indicate vestibular function. SHIMP saccades usually appear later than HIMP saccades, therefore being more salient to the naked eye and facilitating vestibulo-ocular reflex gain measurements. The new paradigm is intuitive and easy to explain to patients, and the SHIMP results complement those from the standard video head impulse test. Classification of evidence:This case-control study provides Class III evidence that SHIMP accurately identifies patients with unilateral or bilateral vestibulopathies. Neurology ® 2016;87:410-418 GLOSSARY AUC 5 area under the curve; BVL 5 bilateral vestibular loss; HIMP 5 conventional head impulse paradigm; SHIMP 5 suppression head impulse paradigm; UVL 5 unilateral vestibular loss; vHIT 5 video head impulse test; VOR 5 vestibuloocular reflex.

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Section: Resultsmentioning

confidence: 99%

A new saccadic indicator of peripheral vestibular function based on the video head impulse test

et al. 2016

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“…Although the device software's algorithms reject grossly invalid HITs, some VOG artifacts remain (24). All HITs accepted by the device software were reassessed by two masked, independent, trained human raters offline to ensure that only valid data were included.…”

Section: Discussionmentioning

confidence: 99%

“…Each HIT was classified as interpretable (no disruptive artifacts or fast eye movements during the VOR) or uninterpretable. Detailed methods and quality standards for assessing artifacts and interpretability are reported elsewhere (24). Uninterpretable impulse data were excluded from all analyses in this article, and we refer to the remaining valid data presented here as filtered VOG HIT results.…”

Section: Discussionmentioning

confidence: 99%

VOR Gain by Head Impulse Video-Oculography Differentiates Acute Vestibular Neuritis from Stroke

Mantokoudis¹,

Tehrani²,

Wozniak³

et al. 2015

Otology &Amp; Neurotology

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Objective: Vestibular neuritis is often mimicked by stroke (pseudoneuritis). Vestibular eye movements help discriminate the two conditions. We report vestibulo-ocular reflex (VOR) gain measures in neuritis and stroke presenting acute vestibular syndrome (AVS). Methods: Prospective cross-sectional study of AVS (acute continuous vertigo/dizziness lasting 924 h) at two academic centers. We measured horizontal head impulse test (HIT) VOR gains in 26 AVS patients using a video HIT device (ICS Impulse). All patients were assessed within 1 week of symptom onset. Diagnoses were confirmed by clinical examinations, brain magnetic resonance imaging with diffusion-weighted images, and follow-up. Brainstem and cerebellar strokes were classified by vascular territoryVposterior inferior cerebellar artery (PICA) or anterior inferior cerebellar artery (AICA). Results: Diagnoses were vestibular neuritis (n = 16) and posterior fossa stroke (PICA, n = 7; AICA, n = 3). . VOR gains were asymmetric in neuritis (unilateral vestibulopathy) and symmetric in PICA stroke (bilaterally normal VOR), whereas gains in AICA stroke were heterogeneous (asymmetric, bilaterally low, or normal). In vestibular neuritis, borderline gains ranged from 0.62 to 0.73. Twenty patients (12 neuritis, six PICA strokes, two AICA strokes) had at least five interpretable HIT trials (for both ears), allowing an appropriate classification based on mean VOR gains per ear. Classifying AVS patients with bilateral VOR mean gains of 0.70 or more as suspected strokes yielded a total diagnostic accuracy of 90%, with stroke sensitivity of 88% and specificity of 92%. Conclusion: Video HIT VOR gains differ between peripheral and central causes of AVS. PICA strokes were readily separated from neuritis using gain measures, but AICA strokes were at risk of being misclassified based on VOR gain alone.

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“…VOG saccade analyses will likely be influenced by the effectiveness of algorithms that filter eye blinks and other pseudo-saccade artifacts. 37 VOG gain measures depend on the computational algorithm used 38 to factor for goggle slippage from inertia. 39 Our study has several limitations.…”

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confidence: 99%

Head impulse gain and saccade analysis in pontine-cerebellar stroke and vestibular neuritis

et al. 2014

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Objective: We sought to quantify and compare angular vestibulo-ocular reflex (aVOR) gain and compensatory saccade properties elicited by the head impulse test (HIT) in pontine-cerebellar stroke (PCS) and vestibular neuritis (VN).Methods: Horizontal HIT was recorded #7 days from vertigo onset with dual-search coils in 33 PCS involving the anterior inferior, posterior inferior, and superior cerebellar arteries (13 AICA, 17 PICA, 3 SCA) confirmed by MRI and 20 VN. We determined the aVOR gain and asymmetry, and compensatory overt saccade properties including amplitude asymmetry and cumulative amplitude (ipsilesional trials [I]; contralesional trials [C]). Results:The aVOR gain (normal: 0.96; asymmetry 5 2%) was bilaterally reduced, greater in AICA (I 5 0.39, C 5 0.57; asymmetry 5 20%) than in PICA/SCA strokes (I 5 0.75, C 5 0.74; asymmetry 5 7%), in contrast to the unilateral deficit in VN (I 5 0.22, C 5 0.76; asymmetry 5 54%). Cumulative amplitude (normal: 1.1°) was smaller in AICA (I 5 4.2°, C 5 3.0°) and PICA/SCA strokes (I 5 2.1°, C 5 3.0°) compared with VN (I 5 8.5°, C 5 1.3°). Amplitude asymmetry in AICA and PICA/SCA strokes was comparable, but favored the contralesional side in PICA/SCA strokes and the ipsilesional side in VN. Saccade asymmetry ,61% was found in 97% of PCS and none of VN. Gain asymmetry ,40% was found in 94% of PCS and 10% of VN.Conclusion: HIT gains and compensatory saccades differ between PCS and VN. VN was characterized by unilateral gain deficits with asymmetric large saccades, AICA stroke by more symmetric bilateral gain reduction with smaller saccades, and PICA stroke by contralesional gain bias with the smallest saccades. Saccade and gain asymmetry should be investigated further in future diagnostic accuracy studies. Classification of evidence:This study provides Class II evidence that aVOR testing accurately distinguishes patients with PCS from VN (sensitivity 94%-97%, specificity 90%-100%). Acute vestibular syndrome (AVS), characterized by prolonged spontaneous vertigo, 1 is frequently due to vestibular neuritis (VN) but may be caused by pontine-cerebellar stroke (PCS).2-4 A negative clinical head impulse test (HIT), or absence of compensatory saccade, plus assessment for skew deviation and direction-changing nystagmus predict PCS in the context of AVS 5-8 better than the reference standard, diffusion-weighted imaging (DWI), which may be falsely negative. 8,9 Because clinical HIT is subjective, 10 quantitative assessment is desirable. A small videooculographic (VOG) study has compared the angular vestibulo-ocular reflex (aVOR) gain, the ratio of eye velocity to head velocity, in a contemporaneous group of patients with AVS consisting of PCS and VN.11 However, the quantitative aspect of the pivotal sign of clinical

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Quantifying the Vestibulo-Ocular Reflex with Video-Oculography: Nature and Frequency of Artifacts

Cited by 152 publications

References 36 publications

A new saccadic indicator of peripheral vestibular function based on the video head impulse test

A new saccadic indicator of peripheral vestibular function based on the video head impulse test

VOR Gain by Head Impulse Video-Oculography Differentiates Acute Vestibular Neuritis from Stroke

Head impulse gain and saccade analysis in pontine-cerebellar stroke and vestibular neuritis

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