vHIT Gain Research Articles

Vestibular Function Tests for Vestibular Migraine: Clinical Implication of Video Head Impulse and Caloric Tests.

Vestibular migraine (VM) is one of the most common causes of episodic vertigo. We reviewed the results of multiple vestibular function tests in a cohort of VM patients who were diagnosed with VM according to the diagnostic criteria of the Barany Society and the International Headache Society and assessed the efficacy of each for predicting the prognosis in VM patients. A retrospective chart analysis was performed on 81 VM patients at a tertiary care center from June 2014 to July 2015. Patients were assessed by the video head impulse test (vHIT), caloric test, vestibular-evoked myogenic potentials (VEMPs), and sensory organization test (SOT) at the initial visit and then evaluated for symptomatic improvement after 6 months. Complete response (CR) was defined as no need for continued medication, partial response (PR) as improved symptoms but need for continued medication, and no response (NR) as no symptomatic improvement and requiring increased dosage or change in medications. At the initial evaluation, 9 of 81 patients (11%) exhibited abnormal vHIT results, 14 of 73 (19%) exhibited abnormal caloric test results, 25 of 65 (38%) exhibited abnormal SOT results, 8 of 75 (11%) exhibited abnormal cervical VEMP results, and 20 of 75 (27%) exhibited abnormal ocular VEMP results. Six months later, 63 of 81 patients (78%) no longer required medication (CR), while 18 (22%) still required medication, including 7 PR and 11 NR patients. Abnormal vHIT gain and abnormal caloric results were significantly related to the necessity for continued medication at 6-month follow-up (OR = 5.67 and 4.36, respectively). Abnormal vHIT and caloric test results revealed semicircular canal dysfunction in VM patients and predicted prolonged preventive medication requirement. These results suggest that peripheral vestibular abnormalities are closely related to the development of vertigo in VM patients.

Video head impulse in comparison to caloric testing in unilateral vestibular schwannoma

Conclusions: Although there was a statistically significant relationship between the results of the vHIT and the caloric test, the limited strength of this relationship suggests that, for unilateral vestibular schwannoma (UVS), caloric testing and vHIT may provide complementary information on vestibular function.Objective: There is limited information that can be used to determine which of the video head impulse test (vHIT) and caloric test might be better used in the diagnosis and management of UVS. In this study, a group of participants with un-operated UVS was studied using both methods.Methods: The subjects’ vestibular function was assessed using the vHIT and caloric testing. Tumour size was quantified using MRI and their balance disturbance assessed using the Jacobsen Dizziness Handicap Inventory (DHI).Results: Twenty of 30 subjects had an abnormal canal paresis according to the Jongkees’ criterion (> 0.25); however, only 10/30 had an ipsilesional vHIT gain of <0.79. Canal paresis could be predicted from the ipsilesional and contralesional vHIT gains. Tumour size could also be predicted from the ipsilesional vHIT gain and canal paresis. However, DHI scores could not be predicted from the degree of canal paresis, vHIT gain, or the MRI measures.

Determining vestibular hypofunction: start with the video-head impulse test

Caloric testing is considered the 'reference standard' in determining vestibular hypofunction. Recently, the video-head impulse test (vHIT) was introduced. In the current study we aimed to assess the diagnostic value of the vHIT as compared to caloric testing in determining vestibular function. In a cross-sectional study between May 2012 and May 2013, we prospectively analysed patients with dizziness who had completed caloric testing and the vHIT. For the left and right vestibular system we calculated the mean vHIT gain. We used a gain cut-off value of 0.8 for the vHIT and presence of correction saccades to define an abnormal vestibular-ocular reflex. An asymmetrical ocular response of 22% or more (Jongkees formula) or an irrigation response with a velocity below 15°/s was considered abnormal. We calculated sensitivity, specificity, positive and negative predictive values with 95% confidence intervals for the dichotomous vHIT. Among 324 patients [195 females (60%), aged 53±17years], 39 (12%) had an abnormal vHIT gain and 113 (35%) had an abnormal caloric test. Sensitivity was 31% (23-40%), specificity 98% (95-99%), positive predictive value was 88% (74-95%), and negative predictive value 73% (67-77%). In case of vHIT normality, additional caloric testing remains indicated and the vHIT does not replace the caloric test. However, the high positive predictive value of the vHIT indicates that an abnormal vHIT is strongly related to an abnormal caloric test result; therefore, additional caloric testing is not necessary. We conclude that the vHIT is clinically useful as the first test in determining vestibular hypofunction in dizzy patients.

Quantitative analysis of gains and catch‐up saccades of video‐head‐impulse testing by age in normal subjects

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). Prospective cohort study. Tertiary care academic referral centre. 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. vHIT gains and the incidence and amplitudes of covert and overt CSs. 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. 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.

Chronic Symptoms After Vestibular Neuritis and the High-Velocity Vestibulo-Ocular Reflex.

As the anterior and posterior semicircular canals are vital to the regulation of gaze stability, particularly during locomotion or vehicular travel, we tested whether the high-velocity vestibulo-ocular reflex (VOR) of the three ipsilesional semicircular canals elicited by the modified Head Impulse Test would correlate with subjective dizziness or vertigo scores after vestibular neuritis (VN). Recovery after acute VN varies with around half reporting persistent symptoms long after the acute episode. However, an unanswered question is whether chronic symptoms are associated with impairment of the high-velocity VOR of the anterior or posterior canals. Twenty patients who had experienced an acute episode of VN at least 3 months earlier were included in this study. Participants were assessed with the video head impulse test (vHIT) of all six canals, bithermal caloric irrigation, the Dizziness Handicap Inventory (DHI), and the Vertigo Symptoms Scale short-form (VSS). Of these 20 patients, 12 thought that they had recovered from the initial episode whereas 8 did not and reported elevated DHI and VSS scores. However, we found no correlation between DHI or VSS scores and the ipsilesional single or combined vHIT gain, vHIT gain asymmetry orcaloric paresis. The high-velocity VOR was not different between patients who thought they had recovered and patients who thought they had not. Our findings suggest that chronic symptoms of dizziness after VN are not associated with the high-velocity VOR of the single or combined ipsilesional horizontal, anterior, or posterior semicircular canals.

Effects of Hand Placement Technique on the Video Head Impulse Test (vHIT) in Younger and Older Adults.

To investigate the effects of hand placement techniques on the video head impulse test (vHIT) responses (i.e., gain, velocity) in older and younger adults and to determine intra-rater and inter-rater reliability of the horizontal vHIT. Descriptive, reliability study. University research laboratory. Forty healthy adults grouped by age with negative history of current or previous vestibular diseases between the ages of 20 and 88 years (mean = 46.60, standard deviation 23.20). Three examiners each used two hand placement techniques (chin and head) to elicit the horizontal vHIT responses. Both the examiner and hand placement orders were counterbalanced to account for order and fatigue effects. The outcome measures of interest were vHIT gain and velocity. A two-way between-subject factorial analysis of variance revealed a significant main effect for hand placement technique and gain response. Mean values for vHIT gain were higher for head technique. Significant main effects were observed for the velocity response for hand placement technique and age group. Mean velocity values were higher for chin technique and lower velocities were observed in the older age group. Intra- and inter-rater reliability scores were consistent for gain values; however, poor to fair inter-rater reliability scores were observed for velocity values. It is suggested that clinical sites select one hand placement technique for the measure to provide consistency of protocol. Establishing clinical norms using the one selected method to verify reliability within and across clinicians is suggested before examination with a disordered population.

Vestibular function in cochlear implantation: Correlating objectiveness and subjectiveness.

To evaluate vestibular function before and after cochlear implantation (CI) STUDY DESIGN: A prospective descriptive study. Thirty consecutive patients with profound sensorineural hearing loss undergoing CI. Objective assessment of vestibular function was performed with the caloric test and video head impulse test (vHIT) in patients before and after CI. Dizziness Handicap Inventory (DHI) was used for subjective assessment before and after CI. Thirty patients received CI with 21 by round window approach and nine by anteroinferior cochleostomy. Vestibular results were categorized into four groups: no changes (20 patients), changes in the caloric test and vHIT (3 patients, all with DHI changes; P = 0.0001), changes in vHIT gain but not in caloric test (3 patients, all with DHI changes; P = 0.005), no changes in the caloric test and vHIT gain but only saccades appear (4 patients, all with DHI changes; P = 0.011). Although CI is a safe surgery with few major complications, it is a procedure that can produce dizziness. The vHIT reveals that 30% of patients demonstrate postoperative change in vestibular function. Therefore, when examining a CI patient with postoperative symptoms of dizziness, results of the vHIT test and gain as well as the presence of saccades, along with an increase DHI score, are parameters to consider in their evaluation. 4.

A study of the relationship between the video head impulse test and air calorics.

The video head impulse test (vHIT) has been proposed as an objective approach to detect peripheral vestibular disorder in a clinical setting. Data from several studies indicate that the vHIT is a useful addition to the vestibular test battery and can give complementary information to caloric testing. This study explores the relationship between lateral canal vestibular occular reflex gain measured using the vHIT system and canal paresis indicated using air calorics in a sample of patients attending a clinic for balance disorder. Sensitivity and specificity of the vHIT test relative to calorics was studied for a clinical sample of 51 patients (20 male, 31 female) who attended a private clinic for balance disorders. vHIT gains were compared to the manufacturer's normative range and to data from a normative study using 30 young volunteers. Of 14 patients in the clinical sample that had significant canal paresis indicated by air calorics, only 4 showed a significant abnormality in either canal using a measurement of vHIT gain. vHIT gain does not correlate with canal paresis as indicated by air caloric testing. vHIT gain appears relatively insensitive to peripheral vestibular disorder as indicated by air caloric testing, although patients that had no caloric response on one side showed abnormal vHIT gain. vHIT testing may be a useful addition to the existing vestibular test battery, but it does not appear to be an alternative to it.