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Money-Nolan LE, Flagge AG. Factors affecting variability in vestibulo-ocular reflex gain in the Video Head Impulse Test in individuals without vestibulopathy: A systematic review of literature. Front Neurol 2023; 14:1125951. [PMID: 36970532 PMCID: PMC10034038 DOI: 10.3389/fneur.2023.1125951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 02/20/2023] [Indexed: 03/11/2023] Open
Abstract
IntroductionThe purpose of this systematic review was to summarize and synthesize published evidence examining variations in vestibulo-ocular reflex (VOR) gain outcomes for the Video Head Impulse Test (vHIT) in healthy individuals without vestibulopathy in order to describe factors that may influence test outcomes.MethodsComputerized literature searches were performed from four search engines. The studies were selected based on relevant inclusion and exclusion criteria, and were required to examine VOR gain in healthy adults without vestibulopathy. The studies were screened using Covidence (Cochrane tool) and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement standards (PRISMA-2020).ResultsA total of 404 studies were initially retrieved, of which a total of 32 studies met inclusion criteria. Four major categories were identified which lead to significant variation in VOR gain outcomes: participant-based factors, tester/examiner-based factors, protocol-based factors, and equipment-based factors.DiscussionVarious subcategories are identified within each of these classifications and are discussed, including recommendations for decreasing VOR gain variability in clinical practice.
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Chen F, Chen Z, Zhang Y, Wei X, Zhao H, Hu J, Cheng Y, Ren X, Zhang Q. Association Analysis of HIMP and SHIMP Quantitative Parameters in Patients With Vestibular Neuritis and Healthy Participants. Front Neurol 2021; 12:748990. [PMID: 34777221 PMCID: PMC8579954 DOI: 10.3389/fneur.2021.748990] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 09/06/2021] [Indexed: 11/13/2022] Open
Abstract
Background: The Head Impulse Paradigm (HIMP) and Suppression Head Impulse Paradigm (SHIMP) are objective, quantitative methods that directly test the vestibulo-ocular reflex (VOR) and are increasingly becoming a standard in evaluating patients with vestibular disorders. Objective: The main objective was to assess the correlations between HIMP and SHIMP parameters in patients with superior vestibular neuritis (VN) and healthy participants. Additionally, the correlations between the parameters of each method were analyzed. Methods: A retrospective cohort, non-randomized study was designed. HIMP and SHIMP were performed on 40 patients with VN and 20 healthy participants (40 ears). HIMP and SHIMP parameters were measured and calculated. Pearson's or Spearson's correlations were used to establish the associations among them. Results: A strong positive correlation was found between HIMP and SHIMP gain (Pearson's r = 0.957, p = 0.000), while strong negative correlations were detected between HIMP and SHIMP saccade amplitudes (r = -0.637, p = 0.000) and percentages of overt saccades (r = -0.631, p = 0.000). In HIMP, strong and moderate positive correlations were identified between gain and saccade amplitude (R 2 = 0.726, p = 0.000) and gain and saccade percentage (R 2 = 0.558, p = 0.000), respectively. By contrast, an extremely weak positive correlation was observed between gain and latency (R 2 = 0.053, p = 0.040). In SHIMP, strong and moderate positive correlations were found between gain and saccade percentage (R 2 = 0.723, p = 0.000) and gain and saccade amplitude (R 2 = 0.525, p = 0.000), respectively, but no correlation was detected between gain and latency (R 2 = 0.006, p = 0.490). Conclusions: HIMP and SHIMP-related parameters were highly correlated (inter-method). Within each method (intra-method), moderate to strong correlations in VOR assessment were observed. These results further contribute to our understanding of the relationship between HIMP and SHIMP as well as to the diagnosis.
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Affiliation(s)
- Feiyun Chen
- Department of Otorhinolaryngology Head and Neck Surgery, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Zichen Chen
- Department of Otorhinolaryngology Head and Neck Surgery, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Yuzhong Zhang
- Department of Otorhinolaryngology Head and Neck Surgery, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Xinyu Wei
- Department of Otorhinolaryngology Head and Neck Surgery, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Huandi Zhao
- Department of Otorhinolaryngology Head and Neck Surgery, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Juan Hu
- Department of Otorhinolaryngology Head and Neck Surgery, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Ying Cheng
- Department of Otorhinolaryngology Head and Neck Surgery, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Xiaoyong Ren
- Department of Otorhinolaryngology Head and Neck Surgery, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Qing Zhang
- Department of Otorhinolaryngology Head and Neck Surgery, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.,Department of Otorhinolaryngology Head and Neck Surgery, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.,Shanghai Jiaotong University School of Medicine Ear Institute, Shanghai, China.,Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
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Starkov D, Vermorken B, Van Dooren TS, Van Stiphout L, Janssen M, Pleshkov M, Guinand N, Pérez Fornos A, Van Rompaey V, Kingma H, Van de Berg R. The Effect of Different Head Movement Paradigms on Vestibulo-Ocular Reflex Gain and Saccadic Eye Responses in the Suppression Head Impulse Test in Healthy Adult Volunteers. Front Neurol 2021; 12:729081. [PMID: 34630303 PMCID: PMC8492894 DOI: 10.3389/fneur.2021.729081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 08/18/2021] [Indexed: 02/03/2023] Open
Abstract
Objective: This study aimed to identify differences in vestibulo-ocular reflex gain (VOR gain) and saccadic response in the suppression head impulse paradigm (SHIMP) between predictable and less predictable head movements, in a group of healthy subjects. It was hypothesized that higher prediction could lead to a lower VOR gain, a shorter saccadic latency, and higher grouping of saccades. Methods: Sixty-two healthy subjects were tested using the video head impulse test and SHIMPs in four conditions: active and passive head movements for both inward and outward directions. VOR gain, latency of the first saccade, and the level of saccade grouping (PR-score) were compared among conditions. Inward and active head movements were considered to be more predictable than outward and passive head movements. Results: After validation, results of 57 tested subjects were analyzed. Mean VOR gain was significantly lower for inward passive compared with outward passive head impulses (p < 0.001), and it was higher for active compared with passive head impulses (both inward and outward) (p ≤ 0.024). Mean latency of the first saccade was significantly shorter for inward active compared with inward passive (p ≤ 0.001) and for inward passive compared with outward passive head impulses (p = 0.012). Mean PR-score was only significantly higher in active outward than in active inward head impulses (p = 0.004). Conclusion: For SHIMP, a higher predictability in head movements lowered gain only in passive impulses and shortened latencies of compensatory saccades overall. For active impulses, gain calculation was affected by short-latency compensatory saccades, hindering reliable comparison with gains of passive impulses. Predictability did not substantially influence grouping of compensatory saccades.
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Affiliation(s)
- Dmitrii Starkov
- Division of Balance Disorders, Department of Otorhinolaryngology and Head and Neck Surgery, Maastricht University Medical Center, Maastricht, Netherlands.,Faculty of Physics, Tomsk State Research University, Tomsk, Russia
| | - Bernd Vermorken
- Division of Balance Disorders, Department of Otorhinolaryngology and Head and Neck Surgery, Maastricht University Medical Center, Maastricht, Netherlands
| | - T S Van Dooren
- Division of Balance Disorders, Department of Otorhinolaryngology and Head and Neck Surgery, Maastricht University Medical Center, Maastricht, Netherlands
| | - Lisa Van Stiphout
- Division of Balance Disorders, Department of Otorhinolaryngology and Head and Neck Surgery, Maastricht University Medical Center, Maastricht, Netherlands
| | - Miranda Janssen
- Division of Balance Disorders, Department of Otorhinolaryngology and Head and Neck Surgery, Maastricht University Medical Center, Maastricht, Netherlands.,Department of Methodology and Statistics, Care and Public Health Research Institute (CAPHRI), Maastricht University, Maastricht, Netherlands
| | - Maksim Pleshkov
- Division of Balance Disorders, Department of Otorhinolaryngology and Head and Neck Surgery, Maastricht University Medical Center, Maastricht, Netherlands.,Faculty of Physics, Tomsk State Research University, Tomsk, Russia
| | - Nils Guinand
- Division of Balance Disorders, Department of Otorhinolaryngology and Head and Neck Surgery, Maastricht University Medical Center, Maastricht, Netherlands.,Service of Otorhinolaryngology Head and Neck Surgery, Department of Clinical Neurosciences, Geneva University Hospitals, Geneva, Switzerland
| | - Angelica Pérez Fornos
- Service of Otorhinolaryngology Head and Neck Surgery, Department of Clinical Neurosciences, Geneva University Hospitals, Geneva, Switzerland
| | - Vincent Van Rompaey
- Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium.,Department of Otorhinolaryngology and Head and Neck Surgery, Antwerp University Hospital, Edegem, Belgium
| | - Herman Kingma
- Division of Balance Disorders, Department of Otorhinolaryngology and Head and Neck Surgery, Maastricht University Medical Center, Maastricht, 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 Center, Maastricht, Netherlands.,Faculty of Physics, Tomsk State Research University, Tomsk, Russia
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ElSherif M. Effect of different head impulse procedures on vestibulo-ocular reflex gain. ACTA OTORRINOLARINGOLOGICA ESPANOLA 2021; 72:218-221. [PMID: 34294220 DOI: 10.1016/j.otoeng.2020.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 04/30/2020] [Indexed: 10/20/2022]
Abstract
OBJECTIVE to study the effects on vestibulo-ocular reflex (VOR) gain using both video head impulse test (vHIT) and Suppression Head impulse test (SHIMP) either using the outward or the inwards head impulse. METHODS Twenty healthy subjects were enrolled in the study. They were examined using otometric vHIT and SHIMP test lateral plane using the lateral outwards head impulse ten impulses for each side and the inwards head impulse ten impulses for each side. The VOR gain resulting from the outwards versus inwards head impulse during the vHIT and SHIMP were statistically compared. RESULTS Twenty healthy subjects, 10 Males and 10 females with a mean age 35±11.7. Paired t- test showed no statistical significance difference in the mean VOR gain of right lateral semicircular canal (1.1±.12) using outwards versus (1.03 ± .22) inwards head impulses, nor for the left lateral semicircular canal mean VOR gain (1.1 ± .22) using outwards head impulse (1.1 ± .3) for inwards head impulse in vHIT. Paired t- test showed no statistical significance difference in the mean VOR gain of right lateral semicircular canal (0.96 ± 0.2)using outwards versus (1.04 ± 0.2) inwards head impulses, nor for the left lateral semicircular canal mean VOR gain (0.98 ± 0.25) using outwards head impulse (1.1 ± 0.28) for inwards head impulse in SHIMP test. No statistical significant difference was found between the VOR gain resulting from the right versus the left semicircular canal. CONCLUSION The starting head position does not affect the VOR gain using both vHIT and SHIMP tests.
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Affiliation(s)
- Mayada ElSherif
- Audiovestibular medicine, OtoRhinolaryngology department Alexandria University, Egypt.
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ElSherif M. Effect of different head impulse procedures on vestibulo-ocular reflex gain. ACTA OTORRINOLARINGOLOGICA ESPANOLA 2021. [DOI: 10.1016/j.otorri.2020.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Takahashi K, Johkura K. Adduction-abduction asymmetry in video head impulse test gain. Auris Nasus Larynx 2021; 48:1229-1230. [PMID: 34092435 DOI: 10.1016/j.anl.2021.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/26/2021] [Accepted: 05/18/2021] [Indexed: 11/17/2022]
Affiliation(s)
- Koji Takahashi
- Department of Clinical Laboratory, Yokohama Brain and Spine Center, Yokohama, Japan
| | - Ken Johkura
- Department of Clinical Laboratory, Yokohama Brain and Spine Center, Yokohama, Japan; Department of Neurology, Yokohama Brain and Spine Center, Yokohama, Japan.
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Jacobsen CL, Abrahamsen ER, Skals RK, Hougaard DD. Is regression gain or instantaneous gain the most reliable and reproducible gain value when performing video head impulse testing of the lateral semicircular canals? J Vestib Res 2021; 31:151-162. [PMID: 34057110 DOI: 10.3233/ves-180669] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Several different video Head Impulse Test (vHIT) systems exist. The function of each individual semicircular canal (SCC) may be determined by performing this test. All vHIT systems provide information about the function of the vestibular ocular reflex by means of two modalities: SACCADES and GAIN. However, different gain calculation methods exist. OBJECTIVE Primary endpoint:•Is instantaneous gain or regression gain the most reproducible and reliable gain value when performing vHIT with testing of the lateral SCCs?Secondary endpoints:•Comparison of each of the instantaneous gain values at 40, 60, and 80ms with the regression gain.•Examination of any intra- and inter examiner variability.•Mean instantaneous gain values, and at different velocities, compared with regression gain values of the lateral SCCs. METHODS 60 subjects between 18-65 years were included. All patients filled out the Dizziness Handicap Inventory (DHI) questionnaire and underwent four separate vHIT tests, two by an experienced neurotologist and two by an inexperienced examiner. RESULTS/CONCLUSIONS 240 datasets were obtained, displaying both regression and instantaneous gain values. Regression gain was more reproducible than instantaneous gain. The experienced examiner provided the most reproducible results.When comparing instantaneous gain, we found the gain at 40 ms to be the least reproducible. There was no significant difference between 60 ms and 80 ms.For both examiners no significant intra examiner variability was found.
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Affiliation(s)
- Chris L Jacobsen
- Department of Otolaryngology, Head & Neck Surgery and Audiology, Aalborg University Hospital, Aalborg, Denmark
| | - Emil R Abrahamsen
- Department of Otolaryngology, Head & Neck Surgery and Audiology, Aalborg University Hospital, Aalborg, Denmark.,Department of Clinical Medicine, Aalborg University Hospital, Aalborg, Denmark
| | - Regitze K Skals
- Unit of Epidemiology and Biostatistics, Aalborg University Hospital, Aalborg, Denmark
| | - Dan D Hougaard
- Department of Otolaryngology, Head & Neck Surgery and Audiology, Aalborg University Hospital, Aalborg, Denmark.,Department of Clinical Medicine, Aalborg University Hospital, Aalborg, Denmark
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Associations of Vestibular Tests With Penn Acoustic Neuroma Quality of Life Scores After Resection of Vestibular Schwannoma. Otol Neurotol 2020; 41:e241-e249. [DOI: 10.1097/mao.0000000000002462] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Park JW, Kim TS, Cha EH, Kang BC, Park HJ. Differences in video head impulse test gains from right versus left or outward versus inward head impulses. Laryngoscope 2018; 129:1675-1679. [DOI: 10.1002/lary.27607] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/17/2018] [Indexed: 01/04/2023]
Affiliation(s)
- Jun Woo Park
- Department of Otorhinolaryngology-Head and Neck Surgery, Asan Medical Center; University of Ulsan College of Medicine; Seoul Republic of Korea
| | - Tae Su Kim
- the Department of Otorhinolaryngology-Head and Neck Surgery; Kangwon National University School of Medicine; Chuncheon Republic of Korea
| | - Eun Hye Cha
- Department of Otorhinolaryngology-Head and Neck Surgery, Asan Medical Center; University of Ulsan College of Medicine; Seoul Republic of Korea
| | - Byung Chul Kang
- Department of Otorhinolaryngology-Head and Neck Surgery, Ulsan University Hospital; University of Ulsan College of Medicine; Ulsan Republic of Korea
| | - Hong Ju Park
- Department of Otorhinolaryngology-Head and Neck Surgery, Asan Medical Center; University of Ulsan College of Medicine; Seoul Republic of Korea
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Abstract
PURPOSE OF REVIEW In the last decades, researchers suggested that clinical assessment of labyrinthine function in detail became easy thanks to video head impulse tests (VHITs), vestibular evoked myogenic potential test (VEMP) and video-oculography (VOG). It has been argued that they can replace electronystagmography, the caloric and rotatory chair tests. This review addresses the latest evaluations of these tests and the opportunities they offer, but also the limitations in clinical practice. RECENT FINDINGS The VHIT and suppression head impulse test (SHIMP) are under ideal circumstances able to accurately identify deficits of the VOR in 3D. However, in a relevant part of the patient population, pupil tracking is inaccurate, video-goggles slip and VOR quantification is problematic. The dissociation between the VHIT and caloric test suggests that these tests are complementary. A new 3D-VOG technique claims to quantify eye torsion better than before, opening multiple diagnostic possibilities. VEMPs remain difficult to standardize. Variability in normal cervical vestibular-evoked myogenic potential amplitude is large. VEMPs become smaller or absent with age, raising questions of whether there is a lower normal limit at all. Recent research shows that the labyrinth is directly stimulated in the MRI offering new opportunities for diagnostics and research. SUMMARY In clinical practice, the VHIT, SHIMP, VEMP and new 3D-VOG techniques improve diagnostic power. Unfortunately, technical issues or variability prevent reliable quantitative evaluation in a part of the regular patient population. The traditional caloric and rotatory chair test can still be considered as valuable complementary tests.
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Walther LE. Current diagnostic procedures for diagnosing vertigo and dizziness. GMS CURRENT TOPICS IN OTORHINOLARYNGOLOGY, HEAD AND NECK SURGERY 2017; 16:Doc02. [PMID: 29279722 PMCID: PMC5738933 DOI: 10.3205/cto000141] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Vertigo is a multisensory syndrome that otolaryngologists are confronted with every day. With regard to the complex functions of the sense of orientation, vertigo is considered today as a disorder of the sense of direction, a disturbed spatial perception of the body. Beside the frequent classical syndromes for which vertigo is the leading symptom (e.g. positional vertigo, vestibular neuritis, Menière’s disease), vertigo may occur as main or accompanying symptom of a multitude of ENT-related diseases involving the inner ear. It also concerns for example acute and chronic viral or bacterial infections of the ear with serous or bacterial labyrinthitis, disorders due to injury (e.g. barotrauma, fracture of the oto-base, contusion of the labyrinth), chronic-inflammatory bone processes as well as inner ear affections in the perioperative course. In the last years, diagnostics of vertigo have experienced a paradigm shift due to new diagnostic possibilities. In the diagnostics of emergency cases, peripheral and central disorders of vertigo (acute vestibular syndrome) may be differentiated with simple algorithms. The introduction of modern vestibular test procedures (video head impulse test, vestibular evoked myogenic potentials) in the clinical practice led to new diagnostic options that for the first time allow a complex objective assessment of all components of the vestibular organ with relatively low effort. Combined with established methods, a frequency-specific assessment of the function of vestibular reflexes is possible. New classifications allow a clinically better differentiation of vertigo syndromes. Modern radiological procedures such as for example intratympanic gadolinium application for Menière’s disease with visualization of an endolymphatic hydrops also influence current medical standards. Recent methodical developments significantly contributed to the possibilities that nowadays vertigo can be better and more quickly clarified in particular in otolaryngology.
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Yang CJ, Lee JY, Kang BC, Lee HS, Yoo MH, Park HJ. Quantitative analysis of gains and catch-up saccades of video-head-impulse testing by age in normal subjects. Clin Otolaryngol 2016; 41:532-8. [PMID: 26453356 DOI: 10.1111/coa.12558] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/04/2015] [Indexed: 12/01/2022]
Abstract
OBJECTIVES To evaluate video-head-impulse test (vHIT) results in normal subjects, to determine the normative values of vHIT for the vestibulo-ocular reflex (VOR) and to characterise the catch-up saccades (CSs). DESIGN Prospective cohort study. SETTING Tertiary care academic referral centre. PARTICIPANTS Fifty healthy subjects with no history of vestibular impairment, ten each in their 20's, 30's, 40's, 50's and 60's, underwent vHITs in the lateral semicircular canal plane. MAIN OUTCOME MEASURES vHIT gains and the incidence and amplitudes of covert and overt CSs. RESULTS The mean vHIT gain was 1.02 ± 0.07, and the mean gain asymmetry was 2.39 ± 1.96%, with no significant differences among age groups. CSs were observed during 22.6% of the trials and in 49% of the ears. The incidence of CSs was not associated with age. The mean velocity of CSs was 55.5 ± 16.9°/s, and its mean interaural difference was 11.8 ± 10.7°/s. CONCLUSIONS vHIT gains were consistently equal to 1.0 in all age groups (20's to 60's), suggesting that abnormal criteria for vHIT gain (e.g. 0.8) and gain asymmetry (e.g. 8%) can be used, regardless of age. CSs were observed in about half of normal ears, suggesting that VOR is a hypometric system. The amplitudes and interaural difference of CSs were also similar in all age groups, suggesting that abnormal criteria for CS amplitude (e.g. 100°/s) and interaural difference (e.g. 40°/s) can be used, regardless of age.
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Affiliation(s)
- C J Yang
- Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - J Y Lee
- Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - B C Kang
- Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - H S Lee
- Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - M H Yoo
- Department of Otorhinolaryngology-Head & Neck Surgery, Korea University Ansan Hospital, Ansan, Korea
| | - H J Park
- Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
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