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Vermorken BL, Volpe B, van Boxel SCJ, Stultiens JJA, van Hoof M, Marcellis R, Loos E, van Soest A, McCrum C, Meijer K, Guinand N, Pérez Fornos A, van Rompaey V, Devocht E, van de Berg R. The VertiGO! Trial protocol: A prospective, single-center, patient-blinded study to evaluate efficacy and safety of prolonged daily stimulation with a multichannel vestibulocochlear implant prototype in bilateral vestibulopathy patients. PLoS One 2024; 19:e0301032. [PMID: 38547135 PMCID: PMC10977751 DOI: 10.1371/journal.pone.0301032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 02/02/2024] [Indexed: 04/02/2024] Open
Abstract
BACKGROUND A combined vestibular (VI) and cochlear implant (CI) device, also known as the vestibulocochlear implant (VCI), was previously developed to restore both vestibular and auditory function. A new refined prototype is currently being investigated. This prototype allows for concurrent multichannel vestibular and cochlear stimulation. Although recent studies showed that VCI stimulation enables compensatory eye, body and neck movements, the constraints in these acute study designs prevent them from creating more general statements over time. Moreover, the clinical relevance of potential VI and CI interactions is not yet studied. The VertiGO! Trial aims to investigate the safety and efficacy of prolonged daily motion modulated stimulation with a multichannel VCI prototype. METHODS A single-center clinical trial will be carried out to evaluate prolonged VCI stimulation, assess general safety and explore interactions between the CI and VI. A single-blind randomized controlled crossover design will be implemented to evaluate the efficacy of three types of stimulation. Furthermore, this study will provide a proof-of-concept for a VI rehabilitation program. A total of minimum eight, with a maximum of 13, participants suffering from bilateral vestibulopathy and severe sensorineural hearing loss in the ear to implant will be included and followed over a five-year period. Efficacy will be evaluated by collecting functional (i.e. image stabilization) and more fundamental (i.e. vestibulo-ocular reflexes, self-motion perception) outcomes. Hearing performance with a VCI and patient-reported outcomes will be included as well. DISCUSSION The proposed schedule of fitting, stimulation and outcome testing allows for a comprehensive evaluation of the feasibility and long-term safety of a multichannel VCI prototype. This design will give insights into vestibular and hearing performance during VCI stimulation. Results will also provide insights into the expected daily benefit of prolonged VCI stimulation, paving the way for cost-effectiveness analyses and a more comprehensive clinical implementation of vestibulocochlear stimulation in the future. TRIAL REGISTRATION ClinicalTrials.gov: NCT04918745. Registered 28 April 2021.
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Affiliation(s)
- Bernd L. Vermorken
- Department of Otorhinolaryngology and Head and Neck Surgery, Division of Balance Disorders, School for Mental Health and Neuroscience (MHENS), Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Benjamin Volpe
- Department of Otorhinolaryngology and Head and Neck Surgery, Division of Balance Disorders, School for Mental Health and Neuroscience (MHENS), Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Stan C. J. van Boxel
- Department of Otorhinolaryngology and Head and Neck Surgery, Division of Balance Disorders, School for Mental Health and Neuroscience (MHENS), Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Joost J. A. Stultiens
- Department of Otorhinolaryngology and Head and Neck Surgery, Division of Balance Disorders, School for Mental Health and Neuroscience (MHENS), Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Marc van Hoof
- Department of Otorhinolaryngology and Head and Neck Surgery, Division of Balance Disorders, School for Mental Health and Neuroscience (MHENS), Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Rik Marcellis
- Department of Nutrition and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, Netherlands
| | - Elke Loos
- Department of Otorhinolaryngology and Head and Neck Surgery, Division of Balance Disorders, School for Mental Health and Neuroscience (MHENS), Maastricht University Medical Centre, Maastricht, The Netherlands
- Department of Neurosciences, Research Group Experimental Oto-Rhino-Laryngology (ExpORL), KU Leuven, University of Leuven, Leuven, Belgium
- Department of Otorhinolaryngology-Head and Neck Surgery, University Hospitals Leuven, Leuven, Belgium
| | - Alexander van Soest
- Department of Otorhinolaryngology and Head and Neck Surgery, Division of Balance Disorders, School for Mental Health and Neuroscience (MHENS), Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Chris McCrum
- Department of Nutrition and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, Netherlands
| | - Kenneth Meijer
- Department of Nutrition and Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, Netherlands
| | - Nils Guinand
- Department of Otorhinolaryngology and Head and Neck Surgery, Division of Balance Disorders, School for Mental Health and Neuroscience (MHENS), Maastricht University Medical Centre, Maastricht, The Netherlands
- Division of Otorhinolaryngology Head and Neck Surgery, Department of Clinical Neurosciences, Geneva University Hospitals, Geneva, Switzerland
| | - Angélica Pérez Fornos
- Division of Otorhinolaryngology Head and Neck Surgery, Department of Clinical Neurosciences, Geneva University Hospitals, Geneva, Switzerland
| | - Vincent van Rompaey
- Department of Otorhinolaryngology and Head and Neck Surgery, Division of Balance Disorders, School for Mental Health and Neuroscience (MHENS), Maastricht University Medical Centre, Maastricht, The Netherlands
- Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
- Department of Otorhinolaryngology and Head and Neck Surgery, Antwerp University Hospital, Edegem, Belgium
| | - Elke Devocht
- Department of Otorhinolaryngology and Head and Neck Surgery, Division of Balance Disorders, School for Mental Health and Neuroscience (MHENS), Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Raymond van de Berg
- Department of Otorhinolaryngology and Head and Neck Surgery, Division of Balance Disorders, School for Mental Health and Neuroscience (MHENS), Maastricht University Medical Centre, Maastricht, The Netherlands
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Karababa E, Satar B, Genç H. Evaluation of effects of optokinetic and rotational stimuli with functional head impulse test (fHIT) in individuals with motion sickness. Eur Arch Otorhinolaryngol 2023; 280:3149-3156. [PMID: 36640202 DOI: 10.1007/s00405-023-07819-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Accepted: 01/02/2023] [Indexed: 01/15/2023]
Abstract
OBJECTIVES To evaluate effects of optokinetic and rotational stimulus in individuals with and without motion sickness (MS) using fHIT. METHODS The study included subjects aged 18-40; 35 subjects with MS for MS group and 35 subjects without vertigo for control group. Percentage of the correct answer (% CA) with and without optokinetic stimulus (o-fHIT) in the frontal plane in the fHIT test was compared in both groups. In addition, both group subjects were seated on an ordinary rotating office chair. % CA was compared between groups by applying rotational fHIT (r-fHIT) test after the subjects were rotated randomly to the right and left and also simultaneously moved their heads in the vertical plane. RESULTS There was no significant difference in % CA in fHIT o-fHIT and r-fHIT in the control group. Both groups showed a significant difference in % CA for fHIT, o-fHIT, and r-fHIT for all SCCs (p < 0.05). CONCLUSIONS Since individuals with MS are affected by optokinetic and rotational stimuli, fHIT performed after these stimuli can be used as an objective confirming test for diagnosing MS.
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Affiliation(s)
- E Karababa
- Department of Audiology, University of Health Sciences, Ankara, Turkey.
| | - B Satar
- Department of Ear Nose Throat, Faculty of Medicine, University of Health Sciences, Ankara, Turkey
| | - H Genç
- Department of Ear Nose Throat, Faculty of Medicine, University of Health Sciences, Ankara, Turkey
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The Role of the Functional Head Impulse Test with and without Optokinetic Stimuli in Vestibular Migraine and Acute Unilateral Vestibulopathy: Discovering a Dynamic Visual Dependence. J Clin Med 2021; 10:jcm10173787. [PMID: 34501235 PMCID: PMC8432176 DOI: 10.3390/jcm10173787] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 08/16/2021] [Accepted: 08/18/2021] [Indexed: 11/29/2022] Open
Abstract
(1) Background: Visually induced vertigo (i.e., vertigo provoked by moving visual scenes) can be considered a noticeable feature of vestibular migraines (VM) and can be present in patients suffering from acute unilateral vestibulopathy (AUV). Hypersensitivity to moving or conflicting visual stimulation is named visual dependence. (2) Methods: Visuo-vestibular interactions were analyzed via the functional Head Impulse Test (fHIT) with and without optokinetic stimulation (o-fHIT) in 25 patients with VM, in 20 subjects affected by AUV, and in 20 healthy subjects. We calculated the percentage of correct answers (%CA) without and with the addition of the optokinetic background (OB). (3) In VM groups, the %CA on the fHIT was 92.07% without OB and 73.66% with OB. A significant difference was found between %CA on the deficit side and that on the normal side in AUV, both without OB and with OB. (4) Conclusions: The fHIT results in terms of %CA with and without OB could be useful to identify the presence of a dynamic visual dependence, especially in patients suffering from VM. The difference in %CA with and without OB could provide instrumental support to help correctly identify subjects suffering from VM. We propose the use of the fHIT in clinical practice whenever there is a need to highlight a condition of dynamic visual dependence.
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Emekci T, Erbek HS. The relationship between functional head impulse test and age in healthy individuals. J Vestib Res 2021; 32:123-134. [PMID: 34120922 DOI: 10.3233/ves-210040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND fHIT is an easily applicable test battery that indirectly evaluates the vestibulo-ocular reflex (VOR) from a functional perspective. AIMS/OBJECTIVES The aim of this study was to Individuals determine the correlation between age and the percentage of correct answers (% CA) obtained in the functional head impulse test (fHIT) in healthy individuals. MATERIAL AND METHODS A total of 105 volunteers, 50 males and 55 females, between the ages of 18 and 70 years, participated in the study. A Beon Solution fHIT system (Zero Branco (TV), Italy) was used in the study. RESULTS In our study, a decrease in the mean % CA was observed in all semicircular canals (SCCs) with increasing age. Between age and mean % CA, a significant negative moderate (-0.311) correlation was observed in lateral SCCs, and a significant negative low (-0.257) correlation was observed in posterior SCCs (p < 0.05). In anterior SCCs, there was no statistically significant relationship between age and mean % CA (p > 0.05). CONCLUSIONS The present study performed in a healthy population will be helpful in terms of making comparisons in studies to be conducted in various vestibular diseases. It will also be a guide for identifying pathological consequences in vestibular diseases.
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Affiliation(s)
- Tuğba Emekci
- Necmettin Erbakan University, Faculty of Medicine ENT Clinic, Konya, Turkey
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Starkov D, Strupp M, Pleshkov M, Kingma H, van de Berg R. Diagnosing vestibular hypofunction: an update. J Neurol 2021; 268:377-385. [PMID: 32767115 PMCID: PMC7815536 DOI: 10.1007/s00415-020-10139-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/31/2020] [Accepted: 08/01/2020] [Indexed: 12/13/2022]
Abstract
Unilateral or bilateral vestibular hypofunction presents most commonly with symptoms of dizziness or postural imbalance and affects a large population. However, it is often missed because no quantitative testing of vestibular function is performed, or misdiagnosed due to a lack of standardization of vestibular testing. Therefore, this article reviews the current status of the most frequently used vestibular tests for canal and otolith function. This information can also be used to reach a consensus about the systematic diagnosis of vestibular hypofunction.
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Affiliation(s)
- Dmitrii Starkov
- Division of Balance Disorders, Department of Otorhinolaryngology and Head and Neck Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands.
- Faculty of Physics, Tomsk State Research University, Tomsk, Russia.
- Maastricht University ENT Department, P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands.
| | - Michael Strupp
- German Center for Vertigo and Balance Disorders, Ludwig Maximilians University, Munich, Germany
- Department of Neurology, Ludwig Maximilians University, Munich, Germany
| | - Maksim Pleshkov
- Division of Balance Disorders, Department of Otorhinolaryngology and Head and Neck Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands
- Faculty of Physics, Tomsk State Research University, Tomsk, Russia
| | - Herman Kingma
- Division of Balance Disorders, Department of Otorhinolaryngology and Head and Neck Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands
- Faculty of Physics, Tomsk State Research University, Tomsk, Russia
| | - Raymond van de Berg
- Division of Balance Disorders, Department of Otorhinolaryngology and Head and Neck Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands
- Faculty of Physics, Tomsk State Research University, Tomsk, Russia
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Versino M, Mandalà M, Colnaghi S, Ricci G, Faralli M, Ramat S. The integration of multisensory motion stimuli is impaired in vestibular migraine patients. J Neurol 2020; 267:2842-2850. [PMID: 32448951 DOI: 10.1007/s00415-020-09905-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 05/07/2020] [Accepted: 05/09/2020] [Indexed: 11/30/2022]
Abstract
BACKGROUND Vestibular migraine (VM) is a relatively recently acknowledged vestibular syndrome with a very relevant prevalence of about 10% among patients complaining of vertigo. The diagnostic criteria for VM have been recently published by the Bárány Society, and they are now included in the latest version of the International Classification of Headache Disorders, yet there is no instrumental test that supports the diagnosis of VM. OBJECTIVE In the hypothesis that the integration of different vestibular stimuli is functionally impaired in VM, we tested whether the combination of abrupt vestibular stimuli and full-field, moving visual stimuli would challenge vestibular migraine patients more than controls and other non-vestibular migraineurs. METHODS In three clinical centers, we compared the performance in the functional head impulse test (fHIT) without and with an optokinetic stimulus rotating in the frontal plane in a group of 44 controls (Ctrl), a group of 42 patients with migraine (not vestibular migraine, MnoV), a group of 39 patients with vestibular migraine (VM) and a group of 15 patients with vestibular neuritis (VN). RESULTS The optokinetic stimulation reduced the percentage of correct answers (%CA) in all groups, and in about 33% of the patients with migraine, in as many as 87% of VM patients and 60% of VN patients, this reduction was larger than expected from controls' data. CONCLUSIONS The comparison of the fHIT results without and with optokinetic stimulation unveils a functional vestibular impairment in VM that is not as large as the one detectable in VN, and that, in contrast with all the other patient groups, mainly impairs the capability to integrate different vestibular stimuli.
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Affiliation(s)
- Maurizio Versino
- Neurology Unit, ASST Settelaghi, Insubria University, DMC, Varese, Italy.,Neuro-Otology and Neuro-Ophthalmology Lab, IRCCS Mondino Foundation, Pavia, Italy
| | - Marco Mandalà
- Department of Otology and Skull Base Surgery, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Silvia Colnaghi
- Neuro-Otology and Neuro-Ophthalmology Lab, IRCCS Mondino Foundation, Pavia, Italy.,Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Pavia, Italy
| | - Giampietro Ricci
- Department of Surgery and Biomedical Sciences, University of Perugia, Perugia, Italy
| | - Mario Faralli
- Department of Surgery and Biomedical Sciences, University of Perugia, Perugia, Italy
| | - Stefano Ramat
- Department of Computer, Electric and Biomedical Engineering, University of Pavia, Via Ferrata, 5, 27100, Pavia, Italy.
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Functional Head Impulse Test With and Without Optokinetic Stimulation in Subjects With Persistent Postural Perceptual Dizziness (PPPD): Preliminary Report. Otol Neurotol 2019; 41:e70-e75. [PMID: 31789799 DOI: 10.1097/mao.0000000000002446] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
OBJECTIVE Persistent postural perceptual dizziness (PPPD) is a clinical condition characterized by unsteadiness present on most days for a period of at least 3 months. The aim of our work was to assess vestibular function, the role of anxiety, and possible interactions between visual and vestibular systems in patients with PPPD. STUDY DESIGN Cross-sectional prospective study. SETTING Tertiary referral center. PATIENTS Twenty-five PPPD patients. INTERVENTIONS Clinical history was collected before examination; vestibular function was assessed through bedside examination, video and functional head impulse test (video-HIT, f-HIT). The latter test was based on having the patient identify an optotype displayed on a computer screen during passive head rotations. The test was repeated while optokinetic stimulation (OKS) was given on the screen. Results were compared with those of 25 controls. State and trait anxiety levels were measured with the State-Trait Anxiety Inventory (STAI) questionnaire. Anxiety before and after vestibular examination was assessed using a VAS scale. MAIN OUTCOME MEASURE Results of video and functional HIT with and without OKS. RESULTS Video-HIT and f-HIT showed normal values in all subjects. f-HIT with OKS provoked more reading errors in patients than in controls. The interaction of group per time detected different decreasing trends between the two groups (p = 0.0002).Patients presented a reduction in anxiety levels after examination. Nine patients fulfilled diagnostic criteria for vestibular migraine, eight of whom presented nystagmus either to positional tests or vibration test. Only anxiety levels before testing were predictive of worsening of f-HIT with optokinetic stimulation (p = 0.0007). CONCLUSIONS Our data support the hypothesis that increased anxiety may play a role in visuo-vestibular interactions; moreover, they are not inconsistent with the hypothesis that OKS might provoke a "threatening effect," leading to gaze bias during examination.
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Versino M, Colnaghi S, Corallo G, Mandalà M, Ramat S. The functional head impulse test: Comparing gain and percentage of correct answers. PROGRESS IN BRAIN RESEARCH 2019; 248:241-248. [PMID: 31239135 DOI: 10.1016/bs.pbr.2019.04.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVES The video head impulse test (vHIT) provides as output a gain value that summarizes the behavior of the vestibulo-ocular reflex as the ratio of a measure of eye movement to the corresponding measure of head movement and is not directly informative of the functional effectiveness of the motor response. The functional HIT (fHIT) is based on the ability to recognize the orientation of a Landolt C optotype that briefly appears on a computer screen during passive head impulses imposed by the examiner over a range of head accelerations; accordingly fHIT is a functional measurement of the vestibular-ocular reflex since it measures the capability to keep clear vision and to read during head movement. METHODS We compared the results of the fHIT with those of the vHIT and the results of the Dizziness Handicap Inventory (DHI) questionnaire in a group of 27 vestibular neuritis patients recorded acutely and at 3-months follow-up. RESULTS Both the vHIT and fHIT exams correctly classified all patients as abnormal on the affected side when tested in the acute phase. After a 3-month follow-up, both were able to show that compensation phenomena had occurred. Otherwise the data from the two techniques were not correlated. More specifically, the fHIT detected more abnormalities than the vHIT, for head rotation toward the healthy side, both in the acute phase and after 3 months, and for head rotation toward the affected side after 3 months. The asymmetry indices, that compare the performance of the healthy to the affected side, also were larger for the fHIT than for the vHIT both at onset and after 3 months. There was no significant correlation between the different vHIT and fHIT parameters and indices, or with the DHI values after 3 months. CONCLUSIONS The fHIT data are able to detect a difference between the healthy and the affected side in the acute phase, and they show an improvement after 3 months. fHIT detects more abnormalities than vHIT, but both these techniques lack a correlation with the DHI score.
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Affiliation(s)
- Maurizio Versino
- Neurology Unit, ASST Settelaghi-Insubria University-DMC, Varese, Italy; Neuro-Otology and Neuro-Ophthalmology Laboratory, IRCCS Mondino Foundation, Pavia, Italy
| | - Silvia Colnaghi
- Neuro-Otology and Neuro-Ophthalmology Laboratory, IRCCS Mondino Foundation, Pavia, Italy; Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Pavia, Italy.
| | - Giulia Corallo
- Department of Otorhinolaryngology-Head and Neck Surgery, University of Siena, Siena, Italy
| | - Marco Mandalà
- Department of Otology and Skull Base Surgery, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Stefano Ramat
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Pavia, Italy
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Romano F, Bertolini G, Agostino D, Straumann D, Ramat S, Feddermann-Demont N. Functional Head Impulse Test in Professional Athletes: Sport-Specific Normative Values and Implication for Sport-Related Concussion. Front Neurol 2019; 10:387. [PMID: 31130909 PMCID: PMC6509415 DOI: 10.3389/fneur.2019.00387] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 03/29/2019] [Indexed: 02/05/2023] Open
Abstract
Dizziness, slow visual tracking, or blurred vision following active head (or body) movements are among the most common symptoms reported following sport-related concussion, often related to concurrent dysfunctions of the vestibular system. In some cases, symptoms persist even if bedside and auxiliary standard vestibular tests are unremarkable. New functional tests have been developed in recent years to objectify neurological alterations that are not captured by standard tests. The functional head impulse test (fHIT) requires the patient to recognize an optotype that is briefly flashed during head rotations with various angular accelerations (2,001–6,000 deg/s2) and assesses the proportion if correct answers (pca). 268 active professional athletes (23.70 ± 5.32y) from six different sports were tested using fHIT. Pca were analyzed both pooling head acceleration in the range of 2,001–6,000 deg/s2 and computing a single pca value for each 1,000 deg/s2 bin in the range 2,001–8,000 deg/s2. No significant difference (p = 0.159) was found between responses to head impulses in the plane of horizontal (pca: 0.977) and vertical semicircular canals (pca: 0.97). The sport practiced had a major effect on the outcome of the fHIT. Handball players achieved a better performance (p < 0.001) than the whole athlete group, irrespective of the direction of head impulses. The pca achieved by athletes practicing snowboard, bob and skeleton were instead significantly below those of the whole athlete group (p < 0.001) but only when vertical head impulses were tested. Overall, pca declined with increasing head acceleration. The decline was particularly evident in the range not included in the standard fHIT exam, i.e., 6,001–8,000 deg/s2 for horizontal and 5,001–8,000 deg/s2 for vertical head impulses. When vertical head impulses were tested, athletes practicing snowboard, bob and skeleton (non-ball sports) showed, beside the lower overall pca, also a steeper decline as a function of vertical head acceleration. The findings suggest that: (1) functional VOR testing can help understanding sport-specific VOR requirements; (2) the fHIT is able to detect and objectify subtle, sport-specific changes of functional VOR performance; (3) if sport-specific normative values are used, the fHIT test procedure needs to be optimized, starting from the highest acceleration to minimize the number of head impulses.
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Affiliation(s)
- Fausto Romano
- Department of Neurology, University of Zurich, Zurich, Switzerland.,Clinical Neuroscience Center, University Hospital of Zürich, Zurich, Switzerland.,Swiss Concussion Center, Zurich, Switzerland
| | - Giovanni Bertolini
- Department of Neurology, University of Zurich, Zurich, Switzerland.,Clinical Neuroscience Center, University Hospital of Zürich, Zurich, Switzerland.,Swiss Concussion Center, Zurich, Switzerland
| | | | - Dominik Straumann
- Department of Neurology, University of Zurich, Zurich, Switzerland.,Clinical Neuroscience Center, University Hospital of Zürich, Zurich, Switzerland.,Swiss Concussion Center, Zurich, Switzerland
| | - Stefano Ramat
- Department of Computer, Electric and Biomedical Engineering, University of Pavia, Pavia, Italy
| | - Nina Feddermann-Demont
- Department of Neurology, University of Zurich, Zurich, Switzerland.,Clinical Neuroscience Center, University Hospital of Zürich, Zurich, Switzerland.,Swiss Concussion Center, Zurich, Switzerland
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Ramaioli C, Cuturi LF, Ramat S, Lehnen N, MacNeilage PR. Vestibulo-Ocular Responses and Dynamic Visual Acuity During Horizontal Rotation and Translation. Front Neurol 2019; 10:321. [PMID: 31024422 PMCID: PMC6467074 DOI: 10.3389/fneur.2019.00321] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 03/14/2019] [Indexed: 11/13/2022] Open
Abstract
Dynamic visual acuity (DVA) provides an overall functional measure of visual stabilization performance that depends on the vestibulo-ocular reflex (VOR), but also on other processes, including catch-up saccades and likely visual motion processing. Capturing the efficiency of gaze stabilization against head movement as a whole, it is potentially valuable in the clinical context where assessment of overall patient performance provides an important indication of factors impacting patient participation and quality of life. DVA during head rotation (rDVA) has been assessed previously, but to our knowledge, DVA during horizontal translation (tDVA) has not been measured. tDVA can provide a valuable measure of how otolith, rather than canal, function impacts visual acuity. In addition, comparison of DVA during rotation and translation can shed light on whether common factors are limiting DVA performance in both cases. We therefore measured and compared DVA during both passive head rotations (head impulse test) and translations in the same set of healthy subjects (n = 7). In addition to DVA, we computed average VOR gain and retinal slip within and across subjects. We observed that during translation, VOR gain was reduced (VOR during rotation, mean ± SD: position gain = 1.05 ± 0.04, velocity gain = 0.97 ± 0.07; VOR during translation, mean ± SD: position gain = 0.21 ± 0.08, velocity gain = 0.51 ± 0.16), retinal slip was increased, and tDVA was worse than during rotation (average rDVA = 0.32 ± 0.15 logMAR; average tDVA = 0.56 ± 0.09 logMAR, p = 0.02). This suggests that reduced VOR gain leads to worse tDVA, as expected. We conclude with speculation about non-oculomotor factors that could vary across individuals and affect performance similarly during both rotation and translation.
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Affiliation(s)
- Cecilia Ramaioli
- German Center for Vertigo and Balance Disorders, University Hospital Munich, Munich, Germany.,Institute of Medical Technology, Brandenburg University of Technology Cottbus-Senftenberg, Senftenberg, Germany.,Department of Psychosomatic Medicine and Psychotherapy, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany
| | - Luigi F Cuturi
- Unit for Visually Impaired People, Italian Institute of Technology, Genoa, Italy
| | - Stefano Ramat
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Pavia, Italy
| | - Nadine Lehnen
- German Center for Vertigo and Balance Disorders, University Hospital Munich, Munich, Germany.,Institute of Medical Technology, Brandenburg University of Technology Cottbus-Senftenberg, Senftenberg, Germany.,Department of Psychosomatic Medicine and Psychotherapy, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany
| | - Paul R MacNeilage
- Department of Psychology, Cognitive and Brain Sciences, University of Nevada, Reno, NV, United States
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Lehnen N, Schröder L, Henningsen P, Glasauer S, Ramaioli C. Deficient head motor control in functional dizziness: Experimental evidence of central sensory-motor dysfunction in persistent physical symptoms. PROGRESS IN BRAIN RESEARCH 2019; 249:385-400. [PMID: 31325997 DOI: 10.1016/bs.pbr.2019.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Understanding the mechanisms of symptoms that are insufficiently explained by organic dysfunction remains challenging. Recently, it has been proposed that such "functional symptoms" are based on erroneous sensory processing in the central nervous system (CNS), with internal expectations dominating sensory inputs. In a pilot study, we used a head motor control set-up to assess the interplay between sensory input and expectation on the example of patients with functional dizziness. Eight patients and 11 age-matched healthy controls performed large active eye-head gaze shifts towards visual targets in the natural situation and with the head moment of inertia 3.3-fold increased. The latter induces head oscillations and the expected sensory outcome of the movement, estimated in the CNS, does not match the actual sensory input. Head oscillations were assessed in patients and in healthy subjects and compared to prior results from patients with organic disease (vestibular loss and cerebellar ataxia). Head oscillations in patients with functional dizziness were different from those of healthy subjects (F(1,17)=27.26, P<0.001, partial η2=0.62), and similar to those of patients with cerebellar ataxia, and with vestibular loss (F(2,19)=0.56, P=0.58). Even in the natural, unweighted, condition, head oscillations were higher in functional dizziness patients than in healthy subjects (P=0.001). Since an extensive work-up failed to demonstrate any explanatory peripheral vestibular, motor, or cerebellar organic dysfunction, these motor control deficits are a first indication of erroneous interplay between expectations and sensory input in the CNS that could account for persistent physical symptoms.
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Affiliation(s)
- Nadine Lehnen
- Department of Psychosomatic Medicine and Psychotherapy, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany; German Center for Vertigo and Balance Disorders, University Hospital Munich, Munich, Germany; Institute of Medical Technology, Brandenburg University of Technology Cottbus-Senftenberg, Senftenberg, Germany; Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University Munich, Planegg, Germany.
| | - Lena Schröder
- Department of Psychosomatic Medicine and Psychotherapy, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany; Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University Munich, Planegg, Germany
| | - Peter Henningsen
- Department of Psychosomatic Medicine and Psychotherapy, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Stefan Glasauer
- German Center for Vertigo and Balance Disorders, University Hospital Munich, Munich, Germany; Institute of Medical Technology, Brandenburg University of Technology Cottbus-Senftenberg, Senftenberg, Germany; Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University Munich, Planegg, Germany
| | - Cecilia Ramaioli
- Department of Psychosomatic Medicine and Psychotherapy, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany; German Center for Vertigo and Balance Disorders, University Hospital Munich, Munich, Germany; Institute of Medical Technology, Brandenburg University of Technology Cottbus-Senftenberg, Senftenberg, Germany
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Sjögren J, Fransson PA, Karlberg M, Magnusson M, Tjernström F. Functional Head Impulse Testing Might Be Useful for Assessing Vestibular Compensation After Unilateral Vestibular Loss. Front Neurol 2018; 9:979. [PMID: 30510538 PMCID: PMC6252383 DOI: 10.3389/fneur.2018.00979] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 10/30/2018] [Indexed: 11/13/2022] Open
Abstract
Background: Loss of the vestibulo-ocular reflex (VOR) affects visual acuity during head movements. Previous studies have shown that compensatory eye-saccades improve visual acuity and that the timing of the saccade is important. Most of the tests involved in testing VOR are made with passive head movement, that do not necessarily reflect the activities of daily living and thus not being proportionate to symptoms and distresses of the patients. Objective: To examine differences between active (self-generated) or passive (imposed by the examiner) head rotations while trying to maintain visual focus on a target. Method: Nine subjects with unilateral total vestibular loss were recruited (4 men and 5 women, mean age 47) and tested with video Head Impulse Test (vHIT) and Head Impulse Testing Device-Functional Test (HITD-FT) during passive and active movements while looking at a target. VOR gain, latencies of covert saccades, frequency of covert saccades and visual acuity were measured and analyzed. Results: Active head-impulses toward the lesioned side resulted in better visual acuity (p = 0.002) compared to conventional passive head-impulses and generated eye-saccades with significantly shorter latencies (p = 0.004). Active movements to the lesioned side generated dynamic visual acuities that were as good as when testing the intact side. Conclusion: Actively generated head impulses resulted in normal dynamic visual acuity, even when performed toward the side of total vestibular loss. This might be attributed to the appearance of short-latency covert saccades. The results show a strong relationship between self-generated movements, latencies of covert saccades and outcome in HITD-FT, i.e., a better dynamic visual function with less retinal slip which is the main function of the VOR. The method of active HITD-FT might be valuable in assessing vestibular compensation and monitoring ongoing vestibular rehabilitation.
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Affiliation(s)
- Julia Sjögren
- Department of Clinical Sciences Lund, Faculty of Medicine, Skåne University Hospital, Lund University, Lund, Sweden
| | - Per-Anders Fransson
- Department of Clinical Sciences Lund, Faculty of Medicine, Skåne University Hospital, Lund University, Lund, Sweden
| | - Mikael Karlberg
- Department of Clinical Sciences Lund, Faculty of Medicine, Skåne University Hospital, Lund University, Lund, Sweden
| | - Måns Magnusson
- Department of Clinical Sciences Lund, Faculty of Medicine, Skåne University Hospital, Lund University, Lund, Sweden
| | - Fredrik Tjernström
- Department of Clinical Sciences Lund, Faculty of Medicine, Skåne University Hospital, Lund University, Lund, Sweden
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Bernetti L, Pellegrino C, Corbelli I, Caproni S, Eusebi P, Faralli M, Ricci G, Calabresi P, Sarchielli P. Subclinical vestibular dysfunction in migraineurs without vertigo: A Clinical study. Acta Neurol Scand 2018; 138:270-277. [PMID: 29658983 DOI: 10.1111/ane.12941] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2018] [Indexed: 01/03/2023]
Abstract
OBJECTIVES This observational study aimed to investigate the presence of potential vestibular system subclinical dysfunction among migraineurs without a history of vertigo and dizziness compared with healthy controls. METHODS Patients diagnosed with episodic migraine with and without aura were enrolled. All patients and healthy controls underwent vestibular examination using the following conventional tests: sitting position, Pagnini-McClure's, Dix-Hallpike's, head hanging, video head impulse, subjective visual vertical, Romberg, Fukuda, and caloric vestibular stimulation by Fitzgerald-Hallpike's tests. Nystagmus and angular velocity of the slow phase during culmination phase was analyzed by video-nystagmography. RESULTS Overall, 33 patients (76% female, 7 with aura and 26 without aura; mean age (mean ± SD): 29.1 ± 4.3 years) and 22 controls (33% female, mean age: 30.8 ± 9.4 years) were enrolled. There were no statistically significant differences in demographic features between patients and controls. Caloric vestibular stimulation test results were found to differ among patients and controls. In particular, right and left angular velocity (AV) were highly correlated one another (r = 0.88, P < .001). Right AV (53.0 ± 6.7 vs 44.0 ± 9.6) and left AV (54.3 ± 5.3 vs 43.3 ± 9.0) were statistically higher in migraineurs as compared to controls (P < .001). Also right V-HIT (1.1 ± 0.1 vs 0.8 ± 0.4) and left V-HIT (1.1 ± 0.1 vs 0.7 ± 0.2) were statistically higher in migraineurs compared to controls (P < .001). CONCLUSION Our findings suggest a subclinical alteration of vestibular pathway in migraineurs who have never complained vertigo or postural imbalance. This finding supports the hypothesis of a vestibular-cerebellar dysfunction in migraineurs, particularly among those with aura.
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Affiliation(s)
- L. Bernetti
- Department of Medicine; Neurologic Clinic, Headache Centre; University of Perugia; Perugia Italy
| | - C. Pellegrino
- Department of Medicine; Otolaryngology and Head-Neck Surgery Clinic; University of Perugia; Perugia Italy
| | - I. Corbelli
- Department of Medicine; Neurologic Clinic, Headache Centre; University of Perugia; Perugia Italy
| | - S. Caproni
- Neuroscience Department; Neurologic Clinic; S. Maria Hospital of Terni; Terni Italy
| | - P. Eusebi
- Department of Medicine; Neurologic Clinic, Headache Centre; University of Perugia; Perugia Italy
| | - M. Faralli
- Department of Medicine; Otolaryngology and Head-Neck Surgery Clinic; University of Perugia; Perugia Italy
| | - G. Ricci
- Department of Medicine; Otolaryngology and Head-Neck Surgery Clinic; University of Perugia; Perugia Italy
| | - P. Calabresi
- Department of Medicine; Neurologic Clinic, Headache Centre; University of Perugia; Perugia Italy
- IRCCS, Santa Lucia Foundation; European Brain Research Institute; Rome Italy
| | - P. Sarchielli
- Department of Medicine; Neurologic Clinic, Headache Centre; University of Perugia; Perugia Italy
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The functional head impulse test: preliminary data. J Neurol 2018; 265:35-39. [PMID: 29868981 DOI: 10.1007/s00415-018-8910-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Revised: 05/17/2018] [Accepted: 05/17/2018] [Indexed: 10/14/2022]
Abstract
The functional head impulse test is a new test of vestibular function based on the ability to recognize the orientation of a Landolt C optotype that briefly appears on a computer screen during passive head impulses imposed by the examiner over a range of head accelerations. Here, we compare its results with those of the video head impulse test on a population of vestibular neuritis patients recorded acutely and after 3 months from symptoms onset. The preliminary results presented here show that while both tests are able to identify the affected labyrinth and to show a recovery of vestibular functionality at 3 months, the two tests are not redundant, but complementary.
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Bilateral vestibular impairment in Vogt Koyanagi Harada syndrome: a case report. Neurol Sci 2018; 39:1609-1611. [PMID: 29654419 DOI: 10.1007/s10072-018-3410-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 04/06/2018] [Indexed: 10/17/2022]
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Colnaghi S, Rezzani C, Gnesi M, Manfrin M, Quaglieri S, Nuti D, Mandalà M, Monti MC, Versino M. Validation of the Italian Version of the Dizziness Handicap Inventory, the Situational Vertigo Questionnaire, and the Activity-Specific Balance Confidence Scale for Peripheral and Central Vestibular Symptoms. Front Neurol 2017; 8:528. [PMID: 29066999 PMCID: PMC5641311 DOI: 10.3389/fneur.2017.00528] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 09/22/2017] [Indexed: 11/24/2022] Open
Abstract
Neurophysiological measurements of the vestibular function for diagnosis and follow-up evaluations provide an objective assessment, which, unfortunately, does not necessarily correlate with the patients' self-feeling. The literature provides many questionnaires to assess the outcome of rehabilitation programs for disequilibrium, but only for the Dizziness Handicap Inventory (DHI) is an Italian translation available, validated on a small group of patients suffering from a peripheral acute vertigo. We translated and validated the reliability and validity of the DHI, the Situational Vertigo Questionnaire (SVQ), and the Activities-Specific Balance Confidence Scale (ABC) in 316 Italian patients complaining of dizziness due either to a peripheral or to a central vestibular deficit, or in whom vestibular signs were undetectable by means of instrumental testing or clinical evaluation. Cronbach's coefficient alpha, the homogeneity index, and test-retest reproducibility, confirmed reliability of the Italian version of the three questionnaires. Validity was confirmed by correlation test between questionnaire scores. Correlations with clinical variables suggested that they can be used as a complementary tool for the assessment of vestibular symptoms. In conclusion, the Italian versions of DHI, SVQ, and ABC are reliable and valid questionnaires for assessing the impact of dizziness on the quality of life of Italian patients with peripheral or central vestibular deficit.
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Affiliation(s)
- Silvia Colnaghi
- Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Pavia, Italy
- Laboratory of Neuro-otology and Neuro-ophthalmology, C. Mondino National Neurological Institute, Pavia, Italy
| | - Cristiana Rezzani
- Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Pavia, Italy
| | - Marco Gnesi
- Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Pavia, Italy
| | - Marco Manfrin
- ENT Unit, Policlinico San Matteo Fondazione (IRCCS), Pavia, Italy
- Department of Clinical-Surgical, Diagnostic and Paediatric Sciences, University of Pavia, Pavia, Italy
| | - Silvia Quaglieri
- ENT Unit, Policlinico San Matteo Fondazione (IRCCS), Pavia, Italy
| | - Daniele Nuti
- Department of Otology and Skull Base, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Marco Mandalà
- Department of Otology and Skull Base, Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Maria Cristina Monti
- Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Pavia, Italy
| | - Maurizio Versino
- Laboratory of Neuro-otology and Neuro-ophthalmology, C. Mondino National Neurological Institute, Pavia, Italy
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
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de Waele C, Shen Q, Magnani C, Curthoys IS. A Novel Saccadic Strategy Revealed by Suppression Head Impulse Testing of Patients with Bilateral Vestibular Loss. Front Neurol 2017; 8:419. [PMID: 28868046 PMCID: PMC5563306 DOI: 10.3389/fneur.2017.00419] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 08/02/2017] [Indexed: 11/16/2022] Open
Abstract
Objective We examined the eye movement response patterns of a group of patients with bilateral vestibular loss (BVL) during suppression head impulse testing. Some showed a new saccadic strategy that may have potential for explaining how patients use saccades to recover from vestibular loss. Methods Eight patients with severe BVL [vestibulo-ocular reflex (VOR) gains less than 0.35 and absent otolithic function] were tested. All patients were given the Dizziness Handicap Inventory and questioned about oscillopsia during abrupt head movements. Two paradigms of video head impulse testing of the horizontal VOR were used: (1) the classical head impulse paradigm [called head impulse test (HIMPs)]—fixating an earth-fixed target during the head impulse and (2) the new complementary test paradigm—fixating a head-fixed target during the head impulse (called SHIMPs). The VOR gain of HIMPs was quantified by two algorithms. Results During SHIMPs testing, some BVL patients consistently generated an inappropriate covert compensatory saccade during the head impulse that required a corresponding large anti-compensatory saccade at the end of the head impulse in order to obey the instructions to maintain gaze on the head-fixed target. By contrast, other BVL patients did not generate this inappropriate covert saccade and did not exhibit a corresponding anti-compensatory saccade. The latencies of the covert saccade in SHIMPs and HIMPs were similar. Conclusion The pattern of covert saccades during SHIMPs appears to be related to the reduction of oscillopsia during abrupt head movements. BVL patients who did not report oscillopsia showed this unusual saccadic pattern, whereas BVL patients who reported oscillopsia did not show this pattern. This inappropriate covert SHIMPs saccade may be an objective indicator of how some patients with vestibular loss have learned to trigger covert saccades during head movements in everyday life.
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Affiliation(s)
- Catherine de Waele
- CNRS UMR 8257, Cognition and Action Group, Centre Universitaire des Saints-Peres, Universite Paris Descartes, Paris, France.,ENT Department, Salpetriere Hospital, Paris, France
| | - Qiwen Shen
- CNRS UMR 8257, Cognition and Action Group, Centre Universitaire des Saints-Peres, Universite Paris Descartes, Paris, France
| | - Christophe Magnani
- CNRS UMR 8257, Cognition and Action Group, Centre Universitaire des Saints-Peres, Universite Paris Descartes, Paris, France
| | - Ian S Curthoys
- Vestibular Research Laboratory, School of Psychology, The University of Sydney, Sydney, NSW, Australia
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Colagiorgio P, Versino M, Colnaghi S, Quaglieri S, Manfrin M, Zamaro E, Mantokoudis G, Zee DS, Ramat S. New insights into vestibular-saccade interaction based on covert corrective saccades in patients with unilateral vestibular deficits. J Neurophysiol 2017; 117:2324-2338. [PMID: 28404827 DOI: 10.1152/jn.00864.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 04/10/2017] [Accepted: 04/10/2017] [Indexed: 11/22/2022] Open
Abstract
In response to passive high-acceleration head impulses, patients with low vestibulo-ocular reflex (VOR) gains often produce covert (executed while the head is still moving) corrective saccades in the direction of deficient slow phases. Here we examined 23 patients using passive, and 9 also active, head impulses with acute (< 10 days from onset) unilateral vestibular neuritis and low VOR gains. We found that when corrective saccades are larger than 10°, the slow-phase component of the VOR is inhibited, even though inhibition increases further the time to reacquire the fixation target. We also found that 1) saccades are faster and more accurate if the residual VOR gain is higher, 2) saccades also compensate for the head displacement that occurs during the saccade, and 3) the amplitude-peak velocity relationship of the larger corrective saccades deviates from that of head-fixed saccades of the same size. We propose a mathematical model to account for these findings hypothesizing that covert saccades are driven by a desired gaze position signal based on a prediction of head displacement using vestibular and extravestibular signals, covert saccades are controlled by a gaze feedback loop, and the VOR command is modulated according to predicted saccade amplitude. A central and novel feature of the model is that the brain develops two separate estimates of head rotation, one for generating saccades while the head is moving and the other for generating slow phases. Furthermore, while the model was developed for gaze-stabilizing behavior during passively induced head impulses, it also simulates both active gaze-stabilizing and active gaze-shifting eye movements.NEW & NOTEWORTHY During active or passive head impulses while fixating stationary targets, low vestibulo-ocular gain subjects produce corrective saccades when the head is still moving. The mechanisms driving these covert saccades are poorly understood. We propose a mathematical model showing that the brain develops two separate estimates of head rotation: a lower level one, presumably in the vestibular nuclei, used to generate the slow-phase component of the response, and a higher level one, within a gaze feedback loop, used to drive corrective saccades.
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Affiliation(s)
- Paolo Colagiorgio
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Pavia, Italy
| | - Maurizio Versino
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy.,Laboratory of Neuro-otology and Neuro-ophthalmology, C. Mondino National Neurological Institute, Pavia, Italy
| | - Silvia Colnaghi
- Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Pavia, Italy.,Inter-Department Multiple Sclerosis Research Centre, C. Mondino National Neurological Institute, Pavia, Italy
| | - Silvia Quaglieri
- UOC Otorinolaringoiatria, Fondazione IRCCS San Matteo and University of Pavia, Pavia, Italy
| | - Marco Manfrin
- UOC Otorinolaringoiatria, Fondazione IRCCS San Matteo and University of Pavia, Pavia, Italy
| | - Ewa Zamaro
- Department of Otorhinolaryngology, Head and Neck Surgery, lnselspital, Bern University Hospital, University of Bern, Bern, Switzerland; and
| | - Georgios Mantokoudis
- Department of Otorhinolaryngology, Head and Neck Surgery, lnselspital, Bern University Hospital, University of Bern, Bern, Switzerland; and
| | - David S Zee
- Department of Neurology, Otolaryngology-Head and Neck Surgery, Neuroscience, Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Stefano Ramat
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Pavia, Italy;
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