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Kojima Y, Ling L, Phillips JO. Compensatory saccade in the vestibular impaired monkey. Front Neurol 2023; 14:1198274. [PMID: 37780695 PMCID: PMC10538121 DOI: 10.3389/fneur.2023.1198274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 08/11/2023] [Indexed: 10/03/2023] Open
Abstract
Introduction Loss of the vestibulo-ocular reflex (VOR) affects visual acuity during head movements. Patients with unilateral and bilateral vestibular deficits often use saccadic eye movements to compensate for an inadequate VOR. Two types of compensatory saccades have been distinguished, covert saccades and overt saccades. Covert saccades occur during head rotation, whereas overt saccades occur after the head has stopped moving. The generation of covert saccades is part of a central vestibular compensation process that improves visual acuity and suppresses oscillopsia. Understanding the covert saccade mechanism may facilitate vestibular rehabilitation strategies that can improve the patient's quality of life. To understand the brain mechanisms underlying covert saccades at the neural level, studies in an animal model are necessary. In this study, we employed non-human primates whose vestibular end organs are injured. Methods We examined eye movement during the head-impulse test, which is a clinical test to evaluate the vestibulo-ocular reflex. During this test, the monkeys are required to fixate on a target and the head is rapidly and unexpectedly rotated to stimulate the horizontal semi-circular canals. Results Similar to human subjects, monkeys made compensatory saccades. We compared these saccades with catch-up saccades following a moving target that simulates the visual conditions during the head impulse test. The shortest latency of the catch-up saccades was 250 ms, which indicates that it requires at least 250 ms to induce saccades by a visual signal. The latency of some compensatory saccades is shorter than 250 ms during the head impulse test, suggesting that such short latency compensatory saccades were not induced visually. The peak velocity of the short latency saccades was significantly lower than that of longer latency saccades. The peak velocity of these longer latency saccades was closer to that of visually guided saccades induced by a stepping target. Conclusion These results are consistent with studies in human patients. Thus, this study demonstrates, for the first time, compensatory covert saccades in vestibular impaired monkeys.
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Affiliation(s)
- Yoshiko Kojima
- Department of Otolaryngology-HNS, University of Washington, Seattle, WA, United States
- National Primate Research Center, Virginia Merrill Bloedel Hearing Research Center, University of Washington, Seattle, WA, United States
| | - Leo Ling
- National Primate Research Center, Virginia Merrill Bloedel Hearing Research Center, University of Washington, Seattle, WA, United States
| | - James O. Phillips
- Department of Otolaryngology-HNS, University of Washington, Seattle, WA, United States
- National Primate Research Center, Virginia Merrill Bloedel Hearing Research Center, University of Washington, Seattle, WA, United States
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Grove CR, Wagner A, Yang VB, Loyd BJ, Dibble LE, Schubert MC. Greater Disability Is Associated with Worse Vestibular and Compensatory Oculomotor Functions in People Living with Multiple Sclerosis. Brain Sci 2022; 12:1519. [PMID: 36358444 PMCID: PMC9688247 DOI: 10.3390/brainsci12111519] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 11/01/2022] [Accepted: 11/06/2022] [Indexed: 08/15/2023] Open
Abstract
Globally, there are nearly three million people living with multiple sclerosis (PLW-MS). Many PLW-MS experience vertigo and have signs of vestibular dysfunction, e.g., low vestibulo-ocular reflex (VOR) gains or the presence of compensatory saccades (CSs), on video head impulse testing (vHIT). We examined whether the vestibular function and compensatory oculomotor behaviors in PLW-MS differed based on the level of MS-related disability. The VOR gain, CS frequency and latency, and gaze position error (GPE) were calculated from the individual traces obtained during six-canal vHIT for 37 PLW-MS (mean age 53.4 ± 12.4 years-old, 28 females) with vertigo and/or an imbalance. The subjects were grouped by their Expanded Disability Status Scale (EDSS) scores: PLW-min-MS (EDSS = 1.0-2.5, n = 8), PLW-mild-MS (EDSS = 3.0-4.5, n = 23), and PLW-moderate-MS (EDSS = 5.0-6.0, n = 6). The between-group differences were assessed with Kruskal-Wallis tests. The VOR gains for most of the canals were higher for PLW-min-MS compared to PLW-mild- and mod-MS, respectively. CS occurred less often in PLW-min-MS versus PLW-mild- and mod-MS, respectively. No clear trend in CS latency was found. The GPE was often lower for PLW-min-MS compared to PLW-mild- and mod-MS, respectively. Thus, our data demonstrate that worse VOR and compensatory oculomotor functions are associated with a greater MS-related disability. PLW-MS may benefit from personalized vestibular physical therapy.
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Affiliation(s)
- Colin R. Grove
- Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Andrew Wagner
- Department of Otolaryngology-Head and Neck Surgery, The Ohio State University, Columbus, OH 43212, USA
- School of Health and Rehabilitation Sciences, The Ohio State University, Columbus, OH 43212, USA
| | - Victor B. Yang
- School of Medicine, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Brian J. Loyd
- School of Physical Therapy and Rehabilitation Sciences, University of Montana, Missoula, MT 59812, USA
| | - Leland E. Dibble
- Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, UT 84108, USA
| | - Michael C. Schubert
- Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, MD 21287, USA
- Department of Physical Medicine and Rehabilitation, Johns Hopkins University, Baltimore, MD 21287, USA
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Wagner AR, Grove CR, Loyd BJ, Dibble LE, Schubert MC. Compensatory saccades differ between those with vestibular hypofunction and multiple sclerosis pointing to unique roles for peripheral and central vestibular inputs. J Neurophysiol 2022; 128:934-945. [PMID: 36069428 PMCID: PMC9550564 DOI: 10.1152/jn.00220.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 08/22/2022] [Accepted: 09/03/2022] [Indexed: 11/22/2022] Open
Abstract
Individuals with peripheral or central vestibular dysfunction recruit compensatory saccades (CSs) in response to high acceleration, yaw head impulses. Although CSs have been shown to be an effective strategy for reducing gaze position error (GPE) in individuals with peripheral hypofunction, for individuals with central vestibular dysfunction, the effectiveness of CS is unknown. The purpose of our study was to compare the effectiveness of CS, defined as the ability to compensate for head velocity and eye position errors, between persons with central and peripheral vestibular dysfunction. We compared oculomotor responses during video head impulse testing between individuals with unilateral peripheral vestibular deafferentation, a disorder of the peripheral vestibular afferents, and individuals with multiple sclerosis, a condition affecting the central vestibular pathways. We hypothesized that relative to individuals with peripheral lesions, individuals with central dysfunction would recruit CSs that were delayed and inappropriately scaled to head velocity and GPE. We show that CSs recruited by persons with central vestibular pathology were not uniformly deficient but instead were of a sufficient velocity to compensate for reductions in VOR gain. Compared to those with peripheral vestibular lesions, individuals with central pathology also recruited earlier covert CS with amplitudes that were better corrected for GPE. Conversely, those with central lesions showed greater variability in the amplitude of overt CS relative to GPE. These data point to a unique role for peripheral and central vestibular inputs in the recruitment of CS and suggest that covert CSs are an effective oculomotor strategy for individuals with multiple sclerosis.NEW & NOTEWORTHY Compensatory saccades (CSs) are recruited by individuals with unilateral vestibular deafferentation (UVD) to compensate for an impaired vestibulo-ocular reflex (VOR). The effectiveness of CS in multiple sclerosis (MS), a central vestibular impairment, is unknown. We show that in UVD and in MS, covert CSs compensate for reduced VOR gain and minimize gaze position error (GPE), yet in >50% of individuals with MS, overt CS worsened GPE, suggesting unique roles for peripheral and central vestibular inputs.
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Affiliation(s)
- Andrew R Wagner
- Otolaryngology - Head and Neck Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio
- School of Health and Rehabilitation Sciences, The Ohio State University, Columbus, Ohio
| | - Colin R Grove
- Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland
| | - Brian J Loyd
- School of Physical Therapy and Rehabilitation Sciences, University of Montana, Missoula, Montana
| | - Leland E Dibble
- Department of Physical Therapy and Athletic Training, University of Utah, Salt Lake City, Utah
| | - Michael C Schubert
- Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland
- Department of Physical Medicine and Rehabilitation, Johns Hopkins University, Baltimore, Maryland
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Le TTC, Brewer K, Serrador J, Schubert MC. Veterans with dizziness recruit compensatory saccades in each semicircular canal plane although VOR gain is normal. J Vestib Res 2020; 30:47-53. [PMID: 32083608 DOI: 10.3233/ves-200692] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Exposure to brain injury via blast or blunt mechanisms disrupts multiple sensorimotor systems simultaneously. Large numbers of US Gulf War era and Operation Iraqi/Enduring Freedom veterans with traumatic brain injury (TBI) are suffering the symptom of dizziness - presumed due to "Multi-Sensory Impairment", a clinical pattern of damage to the auditory, visual and vestibular sensorimotor systems. OBJECTIVE To describe the oculomotor response to rapid head rotation in a population of veterans with dizziness. We also describe the reliability of using the video head impulse test (vHIT) in a veteran population. METHODS We used the vHIT to evaluate the vestibular-ocular reflex (VOR) gain and presence of compensatory saccades (CS) in each semicircular canal of 81 veterans (31% TBI) with dizziness. Data was collected using the ICS Otometric™ vHIT. Data was processed using both the Otometric™ software and custom software written in MATLAB™. This data was evaluated through Kruskal-Wallis rank-sum test and analysis of regression. RESULTS Veterans with dizziness recruit CS in all semicircular canal planes even though their VOR gain is normal. The vHIT is a reliable clinical test to quantify the metrics of the VOR and CS in veterans. CONCLUSION Veterans with dizziness symptoms use compensatory saccades in all planes of semicircular canal rotation, despite having normal peripheral VOR gain during rapid head rotation. The video head impulse test is a stable measure of vestibular slow phase and metrics of compensatory saccades in veterans with dizziness.
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Affiliation(s)
- Thuy Tien C Le
- Department of Biomedical Engineering, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Kelly Brewer
- Department of Veteran Affairs, Veterans Biomedical Institute, War Related Illness and Injury Study Center, East Orange, NJ, USA
| | - Jorge Serrador
- Department of Biomedical Engineering, Rutgers New Jersey Medical School, Newark, NJ, USA.,Department of Veteran Affairs, Veterans Biomedical Institute, War Related Illness and Injury Study Center, East Orange, NJ, USA.,Department of Pharmacology, Physiology and Neuroscience, Rutgers Biomedical Health Sciences, Newark, NJ, USA.,Cardiovascular Electronics, National University of Ireland Galway, Galway, Ireland
| | - Michael C Schubert
- Laboratory of Vestibular NeuroAdaptation, Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Department of Physical Medicine and Rehabilitation, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Kunel'skaya NL, Baibakova EV, Guseva AL, Nikitkina YY, Chugunova MA, Manaenkova EA. [The compensation of the vestibulo-ocular reflex during rehabilitation of the patients presenting with vestibular neuritis]. Vestn Otorinolaringol 2018; 83:27-31. [PMID: 29488492 DOI: 10.17116/otorino201883127-31] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
AIM The objective of the present study was to elucidate the mechanisms behind the compensation of the vestibular ocular reflex and evaluate the effectiveness of vestibular rehabilitation in the patients presenting with vestibular neuritis (VN) with the application of the video head-impulse test (vHIT) and the dynamic visual acuity test (DVAT). METHODS The study included 26 patients with vestibular neuritis whose condition was assessed by scoring based on the dizziness handicap inventory, the dynamic visual acuity test, and the video head-impulse test with the evaluation of saccades and the degree of eye-head movement coordination (gain) before and after the course of vestibular rehabilitation. RESULTS The study has demonstrated that the course of vestibular rehabilitation of the patients presenting with vestibular neuritis resulted in a significant decrease in the scores of dizziness estimated based on the dizziness handicap inventory and an improvement of dynamic visual acuity in the case of the complete gain recovery as well as in the case of persisting impairment of the gain and the development of sufficient 'covert' saccade. Vestibular rehabilitation was unsuccessful in the patients with persistereduced gain and simultaneous development of 'covert' and 'overt' saccades.
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Affiliation(s)
- N L Kunel'skaya
- Department of Otorhinolaryngology, N.I. Pirogov Russian National Research Medical University, Moscow, Russia, 117997; L.I. Sverzhevskiy Research Institute of Clinical Otorhinolaryngology, Moscow Health Department, Moscow, Russia, 117152
| | - E V Baibakova
- L.I. Sverzhevskiy Research Institute of Clinical Otorhinolaryngology, Moscow Health Department, Moscow, Russia, 117152
| | - A L Guseva
- Department of Otorhinolaryngology, N.I. Pirogov Russian National Research Medical University, Moscow, Russia, 117997
| | - Ya Yu Nikitkina
- L.I. Sverzhevskiy Research Institute of Clinical Otorhinolaryngology, Moscow Health Department, Moscow, Russia, 117152
| | - M A Chugunova
- L.I. Sverzhevskiy Research Institute of Clinical Otorhinolaryngology, Moscow Health Department, Moscow, Russia, 117152
| | - E A Manaenkova
- L.I. Sverzhevskiy Research Institute of Clinical Otorhinolaryngology, Moscow Health Department, Moscow, Russia, 117152
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Lee SH, Kim SH, Kim SS, Kang KW, Tarnutzer AA. Preferential Impairment of the Contralesional Posterior Semicircular Canal in Internuclear Ophthalmoplegia. Front Neurol 2017; 8:502. [PMID: 29018402 PMCID: PMC5614936 DOI: 10.3389/fneur.2017.00502] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 09/08/2017] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The vertical vestibulo-ocular reflex (VOR) may be impaired in internuclear ophthalmoplegia (INO) as the medial longitudinal fasciculus (MLF) conveys VOR-signals from the vertical semicircular canals. It has been proposed that signals from the contralesional posterior semicircular canal (PSC) are exclusively transmitted through the MLF, while for the contralesional anterior canal other pathways exist. OBJECTIVE Here, we aimed to characterize dysfunction in individual canals in INO-patients using the video-head-impulse test (vHIT) and to test the hypothesis of dissociated vertical canal impairment in INO. METHODS Video-head-impulse testing and magnetic resonance imaging were obtained in 21 consecutive patients with unilateral (n = 16) or bilateral (n = 5) INO and 42 controls. VOR-gains and compensatory catch-up saccades were analyzed and the overall function (normal vs. impaired) of each semicircular canal was rated. RESULTS In unilateral INO, largest VOR-gain reductions were noted in the contralesional PSC (0.55 ± 0.11 vs. 0.89 ± 0.08, p < 0.001), while in bilateral INO both posterior (0.43 ± 0.11 vs. 0.89 ± 0.08, p < 0.001) and anterior (0.58 ± 0.19 vs. 0.88 ± 0.09, p < 0.001) canals showed marked drops. Small, but significant VOR-gain reductions were also found in the other canals in unilateral and bilateral INO-patients. Impairment of overall canal function was restricted to the contralesional posterior canal in 60% of unilateral INO-patients, while isolated involvement of the posterior canal was rare in bilateral INO-patients (20%). Reviewers correctly identified the INO-pattern in 15/21 (71%) patients and in all controls (sensitivity = 84.2% [95%-CI = 0.59.5-95.8]; specificity = 95.5% [95%-CI = 83.3-99.2]). CONCLUSION Using a vHIT based overall rating of canal function, the correct INO-pattern could be identified with high accuracy. The predominant and often selective impairment of the contralesional posterior canal in unilateral INO further supports the role of the MLF in transmitting posterior canal signals. In patients with acute dizziness and abnormal vHIT-results, central pathologies such as INO should be considered as well, especially when the posterior canal is involved.
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Affiliation(s)
- Seung-Han Lee
- Department of Neurology, Chonnam National University Hospital, Chonnam National University, Gwangju, South Korea.,Department of Neurology, Chonnam National University Medical School, Chonnam National University, Gwangju, South Korea
| | - Sang-Hoon Kim
- Department of Neurology, Chonnam National University Hospital, Chonnam National University, Gwangju, South Korea
| | - Sung-Sik Kim
- Department of Neurology, Chonnam National University Hospital, Chonnam National University, Gwangju, South Korea
| | - Kyung Wook Kang
- Department of Neurology, Chonnam National University Hospital, Chonnam National University, Gwangju, South Korea
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