Sinusoidal Harmonic Acceleration Test Research Articles

The Need for Vestibular Implants in a Tertiary Referral Ear, Nose, and Throat Center and Its Relation to Hearing Status.

Patients with bilateral vestibulopathy (BVP) are at increased risk of falling and have poor quality of life. Several research groups are currently developing and investigating vestibular implants to treat BVP. The goal was to identify how many patients can be considered eligible for vestibular implantation. The objective vestibular implantation criteria for research were applied to the results of the caloric irrigation test, the sinusoidal harmonic acceleration test, the video head impulse test, and the cervical and ocular vestibular evoked myogenic potential tests. Vestibular implant eligibility was situated between 3.6% and 15.7% (semicircular canal implant: 3.6%; otolith implant: 15.7%; combined implant: 4.8%). Only 16 out of the 29 patients (55%) eligible for a vestibular implant had bilateral severe-to-profound hearing loss. The remaining 45% (13/29) thus have better hearing in at least 1 ear. Vestibular implant eligibility in an ear, nose, and throat department was situated between 3.6% and 15.7%, depending on the type of implant that was considered. In addition, the data showed that 45% of the eligible patients had normal-to-moderate hearing in at least 1 ear. In other words, only recruiting patients with (bilateral) severe-to-profound hearing loss for vestibular implantation leads to the systematic exclusion of about half of the candidates. Structure-preserving surgical techniques are thus a major future challenge in the field of vestibular implantation.

Aging effect and test-retest reliability of the sinusoidal harmonic acceleration test and velocity step test using nanotorque rotatory chair

IntroductionRotatory chair testing has been used to evaluate horizontal canal function. Frequently used tests include sinusoidal harmonic acceleration test (SHAT) and velocity step test (VST). ObjectivesAssessment of age effect on the SHAT and VST and assessment of test-retest reliability of the parameters of those two tests. MethodsA prospective study was performed on 100 subjects with no ear or vestibular complaints and normal vestibular evaluation. They were divided into two groups; Group A: below 50 years of age and Group B: 50 years of age or above. SHAT was presented at frequencies 0.02, 0.04, 0.08, 0.16, 0.32, 0.64 Hz with a peak velocity of 60°/s. VST was performed using a maximum velocity of 100°/s with acceleration and deceleration of 200°/s2. Thirty subjects were tested twice to assess reliability. ResultsStudy participants ranged in age from 20 to 67 years. Regarding group A, the mean age was 30.92 ± 7.31 and 55.36 ± 4.61 for group B. No significant differences were found in SHAT parameters between the two groups. As well, there was no significant difference in VST per-rotatory time constant, however, post-rotatory time constant was significantly longer for Group B (P value < 0.05). Intraclass correlation coefficient (ICC) values showed moderate to good reliability (ICC 0.580–0.818) for SHAT parameters for the lower frequencies and indicated moderate reliability for VST time constant (ICC 0.509–0.652). ConclusionsAge has no significant effect on the parameters of SHAT and VST. Test-retest reliability is generally good for both tests.

Normative data for rotational chair considering motion susceptibility.

ObjectiveRotational Chair Test (RCT) is considered one of the most critical measures for vestibular functionality, which generally includes the sinusoidal harmonic acceleration test (SHAT), velocity step test (VST), and visual suppression (VS). The purpose of this study was to establish normal values for different age groups on the RCT and investigate whether motion susceptibility, such as with a history of motion sickness or migraine, has any effects on test metrics.MethodsOne hundred and nine subjects aged from 20 to 59 years who were free from neurotological and vestibular disorders were enrolled. According to the history of motion sickness or migraine, participants were divided into four groups: the motion sickness (MS) group (n = 13), the migraine group (n = 8), comorbidity group (n = 11), and the control group (n = 77). The 77 subjects without any history of MS and migraine were then further separated into four age groups: youth group (20–29 years), young and middle-aged group (30–39 years), middle-age group (40–49 years), and middle-age and elderly group (50–59 years). All participants underwent SHAT, VST, and VS, and a comprehensive set of metrics including gain, phase, asymmetry, time constant (TC), and Fixation Index were recorded.ResultsRegarding the VST and VS, no significant differences were observed either across the four groups (MS, migraine, comorbidity, and control group) or four age categories within the control group. For SHAT, VOR gain at the frequency of 0.01 Hz, VOR phase from 0.08 to 0.64 Hz, and asymmetry at 0.01, 0.16, and 0.64 Hz indicated significant differences among various age groups (P < 0.05 for all comparisons). The VOR phase lead was lower in the migraine and comorbidity group than that in the control group at 0.64 Hz (P = 0.027, P = 0.003, respectively).ConclusionsAge slightly affects the result of SHAT, but not for VST and VS. VOR gain is more susceptible to aging at low frequency, while the phase is opposite. Subjects with both migraine and motion sickness show abnormal velocity storage mechanisms. Phase bias should be considered when assessing motion susceptibility with the RCT. SHAT is more sensitive than VST in terms of reflecting motion susceptibility.

Influence of Tasking During Vestibular Testing.

Purpose The purpose of this study was to investigate the effectiveness of different types of tasking on the measurement of peak slow phase velocity (SPV) for caloric testing and rotary chair testing. Method This study evaluated the peak SPV response for caloric testing and rotary chair across five conditions. Three verbal, one tactile, and one condition without tasking were used for both caloric testing and rotary chair. The subjects consisted of 20 young adults (age range: 22-33 years, M = 26.65, SD = 3.72; seven male, 13 female) with normal vestibular function and no history of ear surgery or vestibular disorder. Study participation consisted of two visits with 24 hr minimum between each, one for caloric testing and one for rotary chair testing. The test completed at each visit was counterbalanced. Caloric Testing: The caloric irrigations were performed 5 times, with the ears randomized and tasking conditions randomized. Rotary Chair Testing: Rotary chair sinusoidal harmonic acceleration testing was performed 5 times at 0.08 Hz with the tasking conditions randomized. Results Tasking of any kind resulted in significantly larger peak SPV responses when compared to the no tasking condition for rotary chair testing. When comparing each type of tasking, no significant differences were noted. No significant difference was noted when comparing the conditions with tasking to the no tasking condition for caloric testing. Conclusions Clinically, either mental or tactile tasking can be utilized as a method to reduce VOR suppression during rotary chair testing. As no difference was found when comparing different verbal tasks to each other, the type of tasking can be catered to the patient. If verbal tasking cannot be completed, the braiding tactile task is a valid substitution. Caloric results varied widely across subjects and did not reach statistical significance, so conclusions on the need for tasking cannot be drawn.

Frequency characteristics of horizontal semicircular canals damage and the ultrastructure analysis of crista ampullaris in patients with Meniere's disease

Objective: To investigate the frequency characteristics and the pathological characteristics of the horizontal crista ampullaris in patients with Meniere's disease,and to analyse its structural basis. Methods: Between March, 2019 and November, 2019, seventy-two patients diagnosed as Meniere's disease (27 males and 45 females, aged from 13 to 74 years, with a course of disease ranging from 4 months to 32 years)in Shandong Provincial ENT Hospital were included.Caloric test, sinusoidal harmonic acceleration test (SHA), video-head impulse test (v-HIT), Gadolinium-enhanced inner-ear 3D-FLAIR MRI and pure tone audiometry were conducted in the patients. The function of the horizontal semicircular canal in these patients were analysed as well as its relationship with the degree of endolymphatic hydrops,clinical stage and duration. Light microscopy and transmission electron microscopy were used to observe the ultrastructure of horizontal semicircular canal crista ampullaris from six patients with refractory Meniere's disease who underwent labyrinthectomy. The number of type Ⅰ and type Ⅱ vestibular hair cells, the common pathophysiological changes of horizontal semicircular canal crista ampullaris were investigated in these patients. Statistical analysis was performed using SPSS 19.0. Results: With the increase of detection frequency, the abnormal rate decreased gradually. The abnormal rate of caloric test was 69.4% (50/72), SHA 51.4% (37/72), V-HIT 36.1% (26/72), comparation of the positive rate among the three tests showed statistically significant differences(P<0.05).Neither caloric test nor SHA had correlation with the degree of hydrops(P>0.05), but v-HIT(r=0.434,P<0.01).There was correlation with clinical stage to SHA and v-HIT(r=0.338,0.462,P<0.01), except caloric test(P>0.05).No significant relation was found with caloric test, SHA, v-HIT and course of disease(P>0.05).Morphological observation found abnormal monolayer epithelialization of the horizontal semicircular canal crista ampullaris significantly decreased number of type Ⅱ hair cells compared with type Ⅰhair cells. Hair cells showed perinuclear vacuolization, cytoplasmic vacuoles, mitochondrial electron density increasement and loss of stereocilia. Conclusions: The horizontal semicircular canal damage in the patients with Meniere's disease has a frequency-dependent characteristic, mainly occurres in low frequency area. With progress of the disease, the high frequency area of ampulla will be impaired gradually, and it is related to the degree of endolymphatic hydrops and hearing level. Hair cell injury would be observed,the frequency characteristics may be more associated with the disorder of type Ⅱ hair cells.

Vestibular recruitment: new application for an old concept

IntroductionVestibular recruitment is a sign of hyperexcitability of central vestibular neurons and may be characteristic of peripheral vestibular damage. ObjectiveTo define the post-caloric recruitment index and its ability to predict the stage of vestibular compensation and peripheral lesion. MethodsFirst of all, we demonstrated that larger values in the cold post-caloric stimulation compared to warm stimulation were equivalent to vestibular recruitment observed during the sinusoidal harmonic acceleration test. In the next step, patients with vestibular complaints and asymptomatic controls were submitted to the caloric test. We calculated post-caloric recruitment index for the control group. Among the study group, we analyzed the relation between post-caloric recruitment and unilateral weakness as well as the types of vestibular diagnoses. ResultsMean post-caloric recruitment was 17.06% and 33.37% among the control and study group, respectively. The ratio between post-caloric recruitment and unilateral weakness was 1.3 in the study group. Among recruiting subjects, no significant difference of unilateral weakness from the lesioned or healthy side was observed. We found no differences in vestibular diagnoses between recruiting and non-recruiting subjects. ConclusionPost-caloric recruitment index identified asymmetric vestibular tonus and central compensation. The normal value was established at 17.06%.

The Antwerp Vestibular Compensation Index (AVeCI): an index for vestibular compensation estimation, based on functional balance performance

PurposeTo create an index that is a measure of the amount of vestibular compensation and for which only functional balance performance is needed.MethodsThe medical charts of 62 eligible peripheral vestibular dysfunction (PVD) patients were analyzed retrospectively. To be included, the following vestibulo-ocular reflex (VOR) and balance performance data had to be available: (1) caloric and sinusoidal harmonic acceleration test (SHA) and (2) standing balance sum-eyes closed (SBS-EC), Timed Up and Go Test and Dynamic Gait Index. Patients were divided into three groups: normal caloric- and SHA test (group 1), abnormal caloric- and normal SHA test (group 2, PVD compensated) and abnormal caloric- and SHA test (group 3, PVD uncompensated). Next to the use of non-parametric tests to study the VOR and balance variables, logistic regression was used to identify the balance measures that predict whether PVD patients were compensated or uncompensated. This resulted also in the construction of a continuous measure representing the degree of compensation.ResultsLogistic regression identified SBS-EC and age to classify uncompensated from compensated patients with sensitivity of 83.9% and specificity of 72.4%. Then an index was created, called the Antwerp Vestibular Compensation Index, AVeCI = − 50 + age × 0.486 + SBS-EC × 0.421. A patient belongs to the uncompensated group when AVeCI < 0 and to the compensated group when AVeCI > 0, with respective group means of − 5 and 5.ConclusionAVeCI stages the degree of compensation of PVD patients and can serve to evaluate rehabilitation effects.

Vestibular function after cochlear implantation: A test battery and case-by-case approach.

ObjectivesThe purpose of this study was to assess the effects of cochlear implantation on the functional integrity of the horizontal semicircular canal using multiple methodologies, and to discuss and highlight the limitations of using isolated vestibular tests to assess vestibular function in surgical ears.MethodsTen cochlear implant patients were consented to undergo a preoperative and 3‐month postoperative vestibular assessment. The horizontal semicircular canal (SCC) was assessed using three different vestibular test measures that assess function using different stimuli and at different frequencies ranges: caloric testing, sinusoidal harmonic acceleration testing in the rotary chair, and video head impulse testing in the plane of the horizontal SCC. Data was analyzed using different methods: descriptive, statistical, and by an examination of individual case studies.ResultsEach analysis method yielded a different interpretation. Statistical analysis showed no significant group mean differences between baseline pre‐op vestibular test results and 3‐month post‐op vestibular test results. Descriptive analysis showed 30% of individuals presented with postoperative abnormal vestibular testing findings. A case study examination showed that only one patient presented with a post‐op decrease in vestibular function in the implanted ear.ConclusionsThere are several limitations of conventional vestibular testing in postsurgical cochlear implant patients. A test‐battery approach, including case history, and test interpretation made on a case‐by‐case basis is needed to determine whether the patient has undergone vestibular damage, is at risk for falling, or in need of further management.Level of Evidence2b individual cohort study.

Analysis of broadband sinusoidal harmonic acceleration test results for normal young people

Objective: We tested more frequency (0.01-3.0 Hz) of the sinusoidal harmonic acceleration test(SHAT) by the NKI rotation chair, aimed to analyze the results of the normal youth. Methods: Fifty normal young people were tested with sinusoidal harmonic acceleration by NKI rotation chair. Including 24 men and 26 women, aged from 20 to 40 years old, with median age of 27 years, with no vestibular dysfunction participated in the present study. All the volunteers accepted the sinusoidal harmonic acceleration test by the NKI rotation chair, the frequency included 0.01 Hz, 0.02 Hz, 0.03 Hz, 0.05 Hz, 0.1 Hz, 0.2 Hz, 0.3 Hz, 0.6 Hz, 1.0 Hz, 1.5 Hz, 2.0 Hz, 3.0 Hz. Taken the gain, phase, and asymmetry as the parameters, the trait of each frequency was analysed. Results: From 0.01 Hz to 1.5 Hz, the gain increased close to 1 gradually, and with fluctuates slightly at the 2.0 Hz and 3.0 Hz frequencies. The phase decreased as frequencies increased close to 0 at 0.3 Hz. The frequency above 0.6 Hz presented negative. Asymmetric values were distributed on both positive and negative sides at each frequency and were different from each other, both values were less than 20%. Conclusion: Broadband SHAT can accurately assess the horizontal semicircular canal function at different frequencies in a wider frequency range, and objectively, reflect the physiological function of the horizontal semicircular canal, and expand the clinical value of traditional SHAT.

Perioperative vestibular assessment and testing

Vestibular disorders can be difficult to accurately diagnose and manage. A careful history and focused physical examination are typically adequate to establish a diagnosis and initiate medical treatment. Vestibular testing is an important component of the work-up, but it is particularly essential for patients being considered for surgical intervention for a vestibular disorder, where the testing can be used to more definitively confirm a suspected diagnosis and to determine baseline vestibular organ function. In this article, we will first briefly review key components of the history and physical examination of patients with vestibular complaints. We will then discuss the most commonly used vestibular tests and their role in the preoperative assessment of patients undergoing vestibular surgery, including nystagmography, caloric testing, rotary chair testing, video head impulse testing, and vestibular evoked myogenic potential testing.

Vestibular testing in children with severe-to-profound hearing loss

Many studies showed that children with sensorineural hearing loss (SNHL) have possible vestibular affection which is related to the severity of cochlear pathology. Objectivesthis work is designed to evaluate vestibular function in children with congenital severe to profound SNHL and correlate the degree of hearing loss with the results of vestibular tests. Methods: this work included 52 children divided into two groups; control group consisted of 20 normal hearing children with no vestibular complaints, and study group consisted of 32 children with congenital severe to profound SNHL. All children were submitted to basic audiologic evaluation, combined vestibular evoked myogenic potentials, sinusoidal harmonic acceleration test (SHA) of rotatory chair test. Resultsall children in the control group had normal oVEMP and cVEMPs results while abnormal cVEMPs and oVEMPs results were found in 89% and 96.9% of the tested ears of the study group respectively. Sinusoidal harmonic acceleration test results were normal in control group with significant reduction in gain, phase lead and higher level of asymmetry in 50% of the children in study group. There was a significant relation between the degree of hearing loss and the cVEMPs, oVEMPs abnormalities, while SHA test results showed no such relationship. ConclusionThere is an evident vestibular abnormalities in children with severe to profound sensorineural hearing loss as revealed by the rotatory chair testing and VEMPs recordings. Vestibular assessment is very important in such group as it has an impact on their rehabilitation plan.

Vestibular and oculomotor function in children with CP: Descriptive study

ObjectiveWe aimed to describe vestibular/oculomotor function of 7–12-year-old children with CP, Gross Motor Function Classification System (GMFCS) levels (I-III), in comparison to an age-matched control group to understand the effect of the vestibular system on activities and participation of children with CP. MethodsVestibular, oculomotor and balance function were tested in children with CP. Central and peripheral vestibular function was examined using an enclosed rotary chair and infrared video goggles (100 Hz) that measured eye movements. Oculomotor tests included smooth pursuit and optokinetic nystagmus (OKN). Vestibulo-Ocular Reflex (VOR) tests, done in complete darkness, included step rotation (STEP), sinusoidal harmonic acceleration (SHA) test, VOR cancellation and enhancement, and subjective visual vertical and horizontal (SVV/SVH). The integrity of the saccule was tested with the Cervical Vestibular Evoked Myogenic Potential. If able, the participants' balance abilities were examined using the Sensory Organization Test (SOT) to determine ability to maintain standing balance during six conditions that challenged the visual, somatosensory and vestibular systems. Independent t-tests and Mann-Whitney U tests were used to compare results between groups. ResultsForty-one children with CP (mean age = 9.44 years, SD = 1.66; 23F/18M; Gross Motor Function Classification System levels: I (n = 19), II (n = 7), III (n = 15) and thirty-three typically developing (TD) children (mean age = 10.16 years, SD = 1.6; 13F/20M) were recruited from the Birmingham, AL community. There was no significant difference between children with CP and TD children in saccular function (i.e. C-VEMP test), and peripheral vestibular end organ (i.e. SHA test and STEP test), VOR enhancement, or OKN gain. Velocity gain for horizontal smooth pursuit was significantly worse in children with CP (p = 0.009), compared to TD children. Poor mediation of central vestibular function were that evident with significantly higher VOR cancellation gain in children with CP (p < 0.0001), compared to TD children and significantly higher SVV variance (p = 0.002), SVH mean (p = 0.001), and SVH variance (p < 0.0001) in children with CP compared to TD children. Compromised balance abilities in children with CP was evident with significantly lower composite scores (p < 0.0001), vestibular ratio (p < 0.0001), and visual ratio (p = 0.021). The somatosensory ratio (p = 0.798) of children with CP was similar to children with TD. ConclusionsAlthough peripheral vestibular function was intact, children with CP had difficulty coupling eye and head movement (VOR cancellation), using the vestibular system for postural control (SOT), demonstrated poor perception of upright (SVV/SVH), and had difficulty following a slow moving target (smooth pursuit eye movement). These results implicate a central vestibular and oculomotor function impairment the severity of which corresponded with severity of the level of CP.

Audiovestibular findings in autoimmune diseases

BackgroundAudiovestibular manifestations are reported in autoimmune diseases including hearing loss and vestibular symptoms.ObjectivesThis study is designed to evaluate the audiovestibular manifestations in patients with different autoimmune diseases especially asymptomatic cases.Subjects and MethodsThis work included two groups: study group (29 cases with different autoimmune diseases) and control group (20 healthy subjects). All participantswere subjected to basic audiologic evaluation, Sinusoidal harmonic acceleration (SHA) test of the rotatory chair at different frequencies (.01-.64Hz).Resultspatients with ADs showed elevated hearing thresholds (>25dBHL) at all tested frequencies. As regard SHA test, only 5 cases from the study grop showed normal results, while the rest of cases showed vestibular hypofunction (bilateral in 22 cases and unilateral in 3 cases).ConclusionAudiovestibular symptoms are common in different autoimmune diseases even asymptomatic cases. SHA test showed that vestibular affection is much more frequent than expected. So, regular screening of hearing and vestibular functions in patients with autoimmune should be done, for better and early management.

The Influence of Caffeine on Rotary Chair and Oculomotor Testing.

When patients are given instructions before vestibular function testing, they are often asked to refrain from ingesting caffeine 24 h before testing. However, research regarding the effects of caffeine on the outcome of vestibular function testing is limited. To evaluate whether the results from rotational chair tests are influenced by caffeine. Participants were tested after consuming a caffeinated beverage (i.e., coffee containing ∼300 mg of caffeine), as well as after abstaining from caffeinated beverages. The participants underwent oculomotor testing, sinusoidal harmonic acceleration testing, optokinetic testing, visual enhancement/suppression testing, subjective visual vertical/horizontal testing, trapezoidal step testing, and unilateral utricular centrifugation testing. Thirty healthy young controls aged 18-40 yr (mean = 23.28 yr; 9 males, 21 females) participated in the study. Rotational chair tests were completed with the Neuro Kinetics rotary chair (Pittsburgh, PA). VEST 7.0 software was used to collect and analyze the participants' eye movements (I-Portal VOG; Neuro Kinetics). IBM SPSS was used to statistically analyze the results. Statistically significant differences were found for the results from several oculomotor tests (i.e., vertical saccades [SCs], horizontal SCs, and optokinetics), whereas the remaining rotational chair tests did not reveal any statistically significant differences between sessions. If a statistically significant difference was found, the participants were then stratified based on the amount of caffeine they consumed on a daily basis. This stratification was accomplished based on the guidelines from the International Coffee Organization. When the data were analyzed based on the stratified groups, statistically significant results remained in the no/low caffeine intake group, whereas no statistically significant results remained in the moderate/high caffeine intake group. Clinically speaking, the largest effect was seen in those individuals who did not typically ingest large amounts of caffeine, whereas the results were not found to be significantly different in those individuals who were typical caffeine consumers. This strengthens the argument that it is not necessary to require that individuals refrain from consuming caffeinated beverages before oculomotor/rotary chair testing as the results from typical caffeine consumers are not significantly affected. Although statistically significant results were found for a number of the oculomotor function tests, the ingestion of caffeine had little influence on the clinical interpretation of the responses. Therefore, the results from the present study indicate that it is not necessary to require that healthy young individuals abstain from caffeine before undergoing rotary chair/oculomotor testing. Further research is necessary to determine whether there is also a limited effect of caffeine on rotary chair/oculomotor test results from older individuals, as well as individuals diagnosed with a vestibular impairment.

The Clinical Efficacy of Vestibular Function Tests in Patients with Acute Unilateral Vestibulopathy

Objectives Aim of this study is to investigate the clinical efficacy of the vestibular function tests (VFTs) and the predictability of lesion side of vestibular asymmetry parameters in acute unilateral peripheral vestibulopathy. Methods Medical records and results of VFTs (caloric, rotatory chair, and head impulse tests) of 57 patients with acute unilateral vestibulopathy were reviewed retrospectively. The VFTs were examined within 7 days after the clinical onset. Results For the caloric test, 74% showed significant canal paresis and the predictability of lesion side was 88%. For the sinusoidal harmonic acceleration test, 91% had low gain in at least 1 Hz, phase lead showed 70%, 89% showed phase asymmetry and the predictability of lesion side was 90%. For velocity step test, 67% had abnormal Tc asymmetry and the predictability of lesion side was 95%. In bedside head impulse test (HIT), abnormal catch up saccades were observed in 89% and the predictability of lesion side was 100%. For the video HIT, cover or overt catch-up saccades were observed in 95% and the predictability of lesion side was 100%. One hundred percent (100%) had low gain on the video HIT, but the lesion sides were uncertain because of bilateral involvements or artifacts. Conclusions The most important things in the diagnosis of acute unilateral vestibulopathy are typical clinical symptoms and spontaneous nystagmus. A combination of rotatory, caloric, and HITs will result in a more complete examination of the vestibular system. Among them, HIT is recommended as the best tool in acute unilateral vestibulopathy. Keywords: Acute unilateral vestibulopathy; Vestibular function tests; Caloric test; Rotatory chair test; Head impulse test 중심 단어: ì¼ì¸¡ì„±ì „ì •ìž¥ì• , ì „ì •ê¸°ëŠ¥ê²€ì‚¬

Vestibular Function Change in a Vasopressin-Induced Hydrops Model.

A vasopressin-induced endoymphatic hydrops model can represent an acute vertiginous attack in Menière's disease (MD). Previous animal models are not appropriate to evaluate the efficacy of new treatments for hydrops because they cannot represent an acute attack of MD. Recently, a new dynamic model was introduced for acute hydrops exacerbation using the vasopressin type 2 receptor agonist, desmopressin (1-deamino-8-D-Arginine vasopressin, VP); however, resulting changes in vestibular function have not been investigated. A total of 37 guinea pigs were used. Two to 4 weeks after surgical ablation of endolymphatic sacs in 33 guinea pigs, acute exacerbation of hydrops was induced by a single VP injection in 18 animals (group A). Next, two VP injections at 1 hour interval were administered to investigate the effect of multiple VP doses on vestibular function in the other 15 animals (group B). In the remaining four animals, VP was injected without surgery for the control group (control). Bidirectional sinusoidal harmonic acceleration (SHA) tests of vestibular function were performed. "Type I response" was defined as when the maximum slow-phase velocity (SPV) during left rotation (toward the operated ear) was lower than that during right rotation (toward the normal ear). In contrast, "Type II response" was defined as when maximum SPV at the left rotation was higher than that at the right rotation. Vestibular symmetry scores were analyzed at baseline and after each of two VP injections given 1 hour apart. Vestibular symmetry scores increased at 1 hour after VP injection in all 18 animals in group A (p < 0.001). Two hours after VP injection, symmetry score decreased to the initial score. Two different types of vestibular response were observed after VP. However, the symmetry scores between type I and II responses were not significantly different (p = 0.173). In all 15 animals of Group B, vestibular asymmetry was sustained over 3 hours when two VP injections were given 1 hour apart. In three of Group B, the type of vestibular response changed from type II response to type I response after the 2nd VP injection; however, no animal demonstrated a shift from type I to type II response. VP can transiently induce an acute exacerbation of hydrops and asymmetric vestibular dysfunction in guinea pigs. This model could help in studying new treatments for acute hydrops and in explaining the mechanism of bidirectional nystagmus in MD.

Rotational and Collic Vestibular-Evoked Myogenic Potential Testing in Normal Developing Children and Children With Combined Attention Deficit/Hyperactivity Disorder.

Vestibular dysfunction in childhood can have a major effect on a child's developmental process. Balance function has been reported to be poorer in children with attention deficit and hyperactivity disorder (ADHD) than in their typically developing peers. Due to contradictory available evidence and the paucity of research on vestibular function specifically in children with combined ADHD (cADHD), we designed this aged-matched study to assess vestibular function in children with cADHD. We enrolled 30 typically developing children (15 boys and 15 girls; mean age, 9 years 6 months; range, 7 to 12 years) and 33 children (19 boys and 14 girls; mean age, 9 years 0 months; range, 7 to 12 years) with cADHD diagnosed by our research psychiatrist. Typically developing controls were used to obtain normative data on vestibular testing and to examine the impact of age on the vestibular response parameters, and these results were compared with those of the cADHD group. All children underwent the sinusoidal harmonic acceleration subtype of the rotary chair test (0.01, 0.02, 0.08, 0.16, and 0.32 Hz) and the cervical vestibular-evoked myogenic potential (cVEMP) test. At all five frequencies in the sinusoidal harmonic acceleration test, there was no significant correlation between age and any of the following rotary chair response parameters in typically developing children: vestibulo-ocular reflex (VOR) gain, phase, asymmetry, and fixation index. Furthermore, there was no significant correlation between age and any of the following cVEMP parameters for the right and left ears of control group: p1 and n1 latency, amplitude, threshold, and amplitude ratio. Significantly higher VOR gains were observed for children with cADHD at frequencies of 0.01 (p = 0.001), 0.08 (p < 0.001), 0.16 (p = 0.001), and 0.32 (p = 0.003) Hz, when compared with the control group. Furthermore, fixation abilities were significantly lower in the cADHD group than in the control group at 0.16 (p < 0.001) and 0.32 (p < 0.001) Hz. cVEMP parameters showed no significant differences between the two groups. Our results showed higher VOR gains and poorer fixation abilities in children with cADHD compared with typically developing children. Cerebellar dysfunction in patients with ADHD has been well documented in the literature, and our findings of cVEMP and rotary chair tests for these children showed impaired vestibular function in these children, based on increased VOR gain values and decreased fixation capabilities. Because VOR gain is mediated through the inferior olive and controlled by the cerebellum, our results suggest that central inhibition of vestibular function may be deficient in children with cADHD, resulting in higher VOR gains. Also, there is general agreement that failure of fixation suppression indicates a central lesion. The lesion can originate from the parietal-occipital cortex, the pons, or the cerebellum. However, failure of fixation suppression is most prominent in lesions involving the midline cerebellum that could be counted for children with cADHD. We believe that this contribution is theoretically and practically relevant as high VOR gains and decreased suppression capabilities may result in symptoms of reading and writing difficulties, learning disabilities, vertigo, and motion sickness in these children. Therefore, assessment of vestibular function in children with cADHD at a young age must be considered when developing rehabilitation protocols for these children.

Comparisons in Outcome and Subject Comfort between Rotation Chair Systems

Background and ObjectivesA rotation chair test has been used to evaluate the function of the horizontal semicircular canals. Currently, two chair systems according to the presence of cylindrical darkroom are used in a clinic setting. However, it has not been thoroughly investigated whether one system is superior to the other system or not. In this study, we aimed to compare test outcomes and subject convenience between two systems.Subjects and MethodsTwenty subjects with no history of otologic disease were enrolled. Subjects were tested with two systems: system [A] with a cylindrical chamber and system [B] with no chamber. The results of sinusoidal harmonic acceleration (SHA), step velocity (SV), and visual fixation (VFX) tests were compared between the systems. Subject convenience was assessed with a questionnaire survey and results were compared between the systems.ResultsThere were no significant differences in gain or asymmetry in SHA test between the systems. However, the phase of system [A] was significantly lower than that of system [B] at 0.16 Hz. There was no significant difference between the systems in directional preponderance (DP) gain or DP time constant. Regarding the VFX test, gain was higher in system [A] than system [B]. Subjects reported less stuffiness and less anxiety with system [B] than system [A], while preferring the system [A] goggles.ConclusionsA rotation chair system without a darkroom can provide a more comfortable experience for subjects in terms of stuffiness and anxiety, while showing comparable results in SHA and SV tests with a darkroom system.

Rotational chair testing in patients with unilateral peripheral vestibular disorders

Abstract The aim of the study was to evaluate the rotational chair (RC) sinusoidal harmonic acceleration (SHA) test and the rotational velocity step (RVS) test in patients with unilateral peripheral vestibular disorders. This study was retrospective in nature. It was conducted in a clinical tertiary care vestibular function test center. A total of 119 patients (63 men and 56 women) with documented unilateral peripheral vestibular lesions were evaluated with bithermal binaural caloric and sinusoidal and step velocity RC tests. Clinical, caloric, and RC tests were carried out. The study group was selected by including patients with a clinical diagnosis suggestive of peripheral vestibular lesions and with documented unilateral caloric weakness matching the clinical diagnosis, and by excluding patients with a clinical diagnosis suggestive of a peripheral vestibular lesion but not documented by unilateral caloric weakness, as well as patients with incomplete tests or uninterpretable data (due to poor recordings or eye movement artifacts). Caloric testing was performed using an infrared video-oculographic system and a Brookler-Grams closed-loop irrigation unit with standard bithermal irrigations of 30 and 44°C for 45 s each in the following order: L30°C, R30°C, R44°C, and L44°C. The RC testing paradigms used in this study were the rotational SHA test and the RVS test. When patients were classified on the basis of etiology, the most common cause of dizziness in the study group was found to be Mιniθre’s disease (34.9%), followed by vestibular neuritis (31.1%). Seventy-two patients in the study group demonstrated right caloric weakness and 47 patients demonstrated left caloric weakness, whereas only 18 of 119 patients demonstrated directional preponderance. When the RC SHA test parameters (gain, phase, and symmetry) in the study group were compared with the manufacturer’s normal values, statistically significant difference was seen in vestibulo-ocular reflex (VOR) gain at low frequencies (0.01-0.08 Hz), in VOR phase at all frequencies, and in VOR symmetry at low frequencies (0.01-0.04 Hz). In summary, despite the encouraging results of the discriminating power of caloric testing, it should be emphasized that RC testing has its own unique capabilities, such as the following: (i) it is a physiologic stimulus whose frequency and amplitude can be varied precisely; (ii) the stimulus is unrelated to physical features of the external ear or temporal bone; (iii) it is useful in children who may not tolerate caloric testing; and (iv) it is very useful in assessing patients receiving vestibulotoxic drugs. Multiple stimuli of varying intensities can be applied to the vestibular system within a relatively short period of time.

Vestibular Testing Data in Migraine‐Associated Vertigo

Objectives: (1) Describe data on comprehensive vestibular testing in migraine-associated vertigo patients. (2) Delineate specific findings in vestibular testing that can assist in the diagnosis and treatment of migraine-associated vertigo. Methods: A retrospective case review of individuals diagnosed with migraine-associated vertigo after evaluation by an otologist, a neurologist, and who had vestibular testing between January 1, 2010, and June 31, 2012, at a tertiary referral center. Videonystagmography (VNG), sinusoidal harmonic acceleration (SHA) testing, and cervical vestibular evoked myogenic potential (cVEMP) testing were analyzed. Results: Eighty-three patients met inclusion criteria; 63 had a diagnosis of primary migraine-associated vertigo. An additional 20 patients had a secondary diagnosis including Ménières disease, intracranial hypertension, and a history of cranial surgery (secondary migraine-associated vertigo). The average patient was 49 years old, with 82% being female. There was no statistically significant difference between the 2 groups. Overall, 30% of migraine-associated vertigo patients had abnormal caloric testing with a 60% average unilateral weakness. The unilateral weakness was to the right 77% of the time. When VNG, SHA, and cVEMP testing were combined, 24 patients (29%) had an identifiable vestibular weakness; 75% had a peripheral source and 25% had central vestibular findings. A total of 50% of patients with a peripheral weakness were fully compensated, 33% were partially compensated, and 17% were poorly compensated. Conclusions: In patients with primary and secondary migraine-associated vertigo, approximately two-thirds of patients were found to have normal vestibular testing. When there was an identifiable vestibular weakness, 75% were peripheral with only 50% fully compensated.