Selective impairment of horizontal vestibulo-ocular reflexes in acute Wernicke's encephalopathy

Akdal, Gülden; MacDougall, Hamish G.; Chen, L.; Tanrıverdizade, Tural; Yiğitaslan, Onur; Hálmagyi, G. Michael

doi:10.1016/j.jns.2016.04.013

Cited by 23 publications

(15 citation statements)

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“…The classic triad of altered mental status, ocular motor abnormality, and ataxia may not be present, and form fruste cases without overt encephalopathy present with acute bilateral vestibular loss (BVL) selectively affecting horizontal but not vertical VOR (92). Such dissociation might be characteristic of aWE, as has been demonstrated by search-coil and VOG recordings of individual SCC plane HIT (93, 140) (Figure 13). Presumably, thiamine deficiency has selective and profound detrimental effect on the medial vestibular nucleus.…”

Section: Quantitative Hit In Central Vestibular Disordersmentioning

confidence: 56%

“…It is the most important test in differentiating central from peripheral vestibular disorders, especially when traditional neurological deficits may be subtle or absent, such as in acute vestibular syndrome (AVS) (88, 89), subclinical internuclear ophthalmoplegia (90, 91), and early Wernicke’s encephalopathy (92, 93). HIT gain and compensatory saccades can be quantified using search coils (8, 94), or high-speed video-oculography (VOG) (4, 5).…”

Section: Quantitative Hit In Central Vestibular Disordersmentioning

confidence: 99%

“…(B) Monocular, right eye (blue) video HIT recording of another patient, again demonstrating severe loss of HC function with preservation of vertical canal function. Reproduced from the study by Akdal et al (93), used with permission from Elsevier.…”

Section: Quantitative Hit In Central Vestibular Disordersmentioning

confidence: 99%

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The Video Head Impulse Test

et al. 2017

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In 1988, we introduced impulsive testing of semicircular canal (SCC) function measured with scleral search coils and showed that it could accurately and reliably detect impaired function even of a single lateral canal. Later we showed that it was also possible to test individual vertical canal function in peripheral and also in central vestibular disorders and proposed a physiological mechanism for why this might be so. For the next 20 years, between 1988 and 2008, impulsive testing of individual SCC function could only be accurately done by a few aficionados with the time and money to support scleral search-coil systems—an expensive, complicated and cumbersome, semi-invasive technique that never made the transition from the research lab to the dizzy clinic. Then, in 2009 and 2013, we introduced a video method of testing function of each of the six canals individually. Since 2009, the method has been taken up by most dizzy clinics around the world, with now close to 100 refereed articles in PubMed. In many dizzy clinics around the world, video Head Impulse Testing has supplanted caloric testing as the initial and in some cases the final test of choice in patients with suspected vestibular disorders. Here, we consider seven current, interesting, and controversial aspects of video Head Impulse Testing: (1) introduction to the test; (2) the progress from the head impulse protocol (HIMPs) to the new variant—suppression head impulse protocol (SHIMPs); (3) the physiological basis for head impulse testing; (4) practical aspects and potential pitfalls of video head impulse testing; (5) problems of vestibulo-ocular reflex gain calculations; (6) head impulse testing in central vestibular disorders; and (7) to stay right up-to-date—new clinical disease patterns emerging from video head impulse testing. With thanks and appreciation we dedicate this article to our friend, colleague, and mentor, Dr Bernard Cohen of Mount Sinai Medical School, New York, who since his first article 55 years ago on compensatory eye movements induced by vertical SCC stimulation has become one of the giants of the vestibular world.

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Section: Quantitative Hit In Central Vestibular Disordersmentioning

confidence: 56%

Section: Quantitative Hit In Central Vestibular Disordersmentioning

confidence: 99%

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The Video Head Impulse Test

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“…It holds great promise in the acute differentiation of acute posterior circulation stroke from unilateral peripheral vestibulopathy [19][20][21] based on search coil recording, which has unequivocally demonstrated the diagnostic value of gain and catch-up saccade analysis. 22 Many vestibular disorders, both peripheral [23][24][25] and central, [26][27][28] rapidly evolve over time and have known specific treatments and can now be reassessed without subjecting patients to repeated lengthy testing. As both lateral and vertical SCCs can be evaluated, different patterns of SCC involvement have emerged that carry diagnostic significance: selective sparing of AC function has been demonstrated to be specific for certain causes of bilateral vestibulopathy (BV), 29 whereas selective impairment of PC function is uncommon and usually associated with additional audiovestibular loss.…”

Section: Practical Aspectsmentioning

confidence: 99%

Video Head Impulse Testing: From Bench to Bedside

Chen

Hálmagyi

2020

Semin Neurol

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Over 30 years ago, the head impulse test (HIT) was measured with search coil recordings and it provided robust evidence for a new test of vestibular function that could detect impairment of a single semicircular canal, that is, the lateral canal. Over the next two decades, the diagnostic spectrum of HIT was expanded to the testing of vertical canals, differentiation of central from peripheral vestibulopathy, and incorporation of visual interaction—the suppressed head impulse. However, HIT measurement was limited to very few specialized laboratories that were able to maintain the time-consuming and expensive operation of the scleral search coil system, which is the gold standard in eye movement recording. The video HIT (vHIT) was validated for the first time over 10 years ago, against the search coils, and its introduction into dizzy clinics worldwide has revolutionized the practice of neuro-otology. Here we review the basic physiology, practical aspects, and clinical application of the vHIT.

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“…But testing with HIMPs has shown that there can be decline in absolute VOR gain, equal in both canals of a pair. For example, complete bilateral canal loss or bilateral anterior or posterior or horizontal canal loss [21,22]. These new discoveries [23] have dramatically increased our understanding of semicircular canal function, and they help to explain some of the otherwise very puzzling patient complaints of vestibular symptoms despite caloric testing showing normal symmetrical horizontal canal function.…”

Section: Advantagesmentioning

confidence: 99%

Clinical application of the head impulse test of semicircular canal function

Curthoys

Manzari²

2017

Hearing Balance and Communication

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Objective: To review the theory, the validity and the clinical application and the new developments of the video head impulse test (vHIT) of semicircular canal function. vHIT has now superseded the caloric test as the first-line clinical test for vestibular patients. Outcomes: This review examines the origin and rationale for vHIT: how it is carried out; pitfalls in testing; the validation of the test; the interpretation of overt and covert compensatory saccades in patients with vestibular loss; how the area VOR gain is calculated. Results: The advantages of the test are considered: it is so innocuous that it can be given to patients even during acute vertigo attacks, and given repeatedly at short intervals; it is very successful for testing young children; it tests all six semicircular canals, and, unlike the caloric test, provides measures of the absolute level of canal function and so is valuable for monitoring the effect of ototoxic antibiotics as well as identifying bilateral vestibular loss. Patients with Meni ere's disease have normal canal function, although their caloric results generally indicate otherwise, with hydrops being the possible cause for that divergence. vHIT has shown the new vestibular syndrome of bilateral loss of vertical canal function and it is now being used for identifying the likely cause of vertigo of patients arriving at a hospital Emergency Roomnormal semicircular canal function in such patients indicating increased probability of a stroke. The theory and application of the new, but already widely used, variant called the suppression head impulse test (SHIMPs) is explained. SHIMPs is even simpler and more intuitive than the standard vHIT test and probably even better for testing children. Conclusion: This review provides the theoretical foundations for the practical application of the clinical vHIT test which has revolutionized the clinical testing of semicircular canal function. Abbreviations: VOR: vestibulo-ocular reflex; HIT: head impulse test; vHIT: video head impulse testthe technology; HIMP: the head impulse testthe procedure; SHIMP: the suppression head impulse testthe procedure;

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Selective impairment of horizontal vestibulo-ocular reflexes in acute Wernicke's encephalopathy

Cited by 23 publications

References 7 publications

The Video Head Impulse Test

The Video Head Impulse Test

Video Head Impulse Testing: From Bench to Bedside

Clinical application of the head impulse test of semicircular canal function

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