Saccades of video head impulse test in Meniere's disease and Vestibular Migraine: What can we learn from?

Background:Saccades are often observed on video head impulse tests(vHIT)in patients with Meniere's Disease(MD)and Vestibular Migraine(VM).However,their saccadic features are not fully described.Objective:This study aims to identify the saccades characteristics of MD and VM.Methods:75 VM patients and 103 definite unilateral MD patients were enrolled in this study.First raw saccades were exported and analyzed.The VM patients were divided into left and right based on their ears,while the MD patients were separated into affected and unaffected subgroups based on their audiograms and symptoms.Results:The MD patients have more saccades on the affected side(85%vs.69%),and saccade velocity is more consistent than the contralateral side(shown by the coefficient of variation).The saccades occurrence rates on both sides are similar in VM(77%vs.76%),as are other saccadic parameters.The MD patients have more significant inter-aural differences than the VM patients,manifested in higher velocity(p-value 0.000),earlier arriving(p-value 0.010),and more time-domain gathered(p-value 0.003)on the affected side.Conclusions:Bilateral saccades are commonly observed in MD and VM.In contrast to MD,saccades on VM are subtle,scattered,and late-arrived.Furthermore,the MD patients showed inconsistent saccadic distribution with more velocity-uniform saccades on the affected side.

Analysis of video head impulse test saccades data in patients with vestibular migraine or probable vestibular migraine

Objective:Saccades accompanied by normal gain in video head impulse tests(vHIT)are often observed in patients with vestibular migraine(VM).However,they are not considered as an independent indicator,reducing their utility in diagnosing VM.To better understand clinical features of VM,it is necessary to understand raw saccades data.Methods:Fourteen patients with confirmed VM,45 patients with probable VM(p-VM)and 14 agematched healthy volunteers were included in this study.Clinical findings related to spontaneous nystagmus(SN),positional nystagmus(PN),head-shaking nystagmus(HSN),caloric test and vHIT were recorded.Raw saccades data were exported and numbered by their sequences,and their features analyzed.Results:VM patients showed no SN,PN or HSN,and less than half of them showed unilateral weakness(UW)on caloric test.The first saccades from lateral semicircular canal stimulation were the most predominant for both left and right sides.Neither velocity nor time parameters were significantly different when compared between the two sides.Most VM patients(86%)exhibited small saccades,around 35%of the head peak velocity,with a latency of 200e400 ms.Characteristics of saccades were similar in patients with p-VM.Only four normal subjects showed saccades,all unilateral and seemingly random.Conclusions:Small saccades involving bilateral semicircular canals with a scattered distribution pattern are common in patients with VM and p-VM.

Evaluation on Effectiveness of a New System as well as Analysis on Optimal Horizontal Eye Position for Vertical Video Head Impulse Test

Objective To compare the performances among three different systems for video head impulse test(vHIT),and to identify an optimal target angle for precisely evaluating the function of vertical semicircular canals in vHIT.Methods A two-center prospective study was done.Participants were sit 1.2 m away from the wall in a noise-proved room that dedicated for vHIT experiments.During the comparison experiments,similar settings were ensured in both hospitals,with the same distance to wall and angle of staring.For each equipment,the procedures followed the developers’recommendations.The same examiner performed the comparison between two systems in one location.For the eye-position projects,targets were placed on the wall sequentially at the pre-marked lines for different angles.For the comparison projects,9 and 13 participants were recruited,respectively.Any participant with otologic or vestibular disorders was excluded.A total of 26 healthy participants were recruited in the eye-position experiments,16 of which were further involved in inter-examiner tests.Results Our evaluations of three different systems showed that a new vHIT system,VertiGoggles®ZT-VNG-I(VG)performed as good as the long-tested Otometrics®ICS impulse(Oto)and EyeSeeCam®(ESC).During the comparison,we validated 25-degree,instead of right ahead at 0 degree,is a better place to set the targets when torsion was applied at vertical semicircular canal planes.Conclusion The new VG system is good for clinical practices.Furthermore,we proposed a new protocol to set the targets 25 degrees from right ahead after tilting head 45 degrees to evaluate vertical canals during vHIT.

The Changes of Baroreflex Sensitivity During Head-up Tilt Test and Its Clinical Significance in the Patients with Vasovagal Syncope

Objective To study thechanges of baroreflex sensitivity (BRS) during head - up tilt test (HUT) in patients with vasovagal syncope (VS), and to examine the relationship between baroreflex sensitivity and neurohormonal factors. Furthermore, to investigate the effects of the changes of BRS on VS. Methods Forty - two patients with unexplained syncope (Among the 42 patients, there were 22 patients with positive HUT and 20 patients with negative HUT respectively) and 20 healthy volunteers (with negative HUT) underwent passive head - up tilt testing, Ante-cubital vein blood samples were taken before and after HUT, or at syncope. The fasting plasma endothelin , serum nitric oxide (NO), serum NE were measured, the BRS was assessed on the basis of the linear regression slope the RR interval versus systolic arterial blood pressure during the increment in blood pressure after intravenous administration of phenylephrine. Results (1) During the syncope, the BRS significantly reduced in HUT(+) group than baseline. At the end of tilt, the level of plasma ET, serum NO in patients with positive HUT significantly increased compared with baseline or normal controls, and the plasma concentration of NE also had the trend of increase. (2) By multiple regression analysis, a significant negative correlation was found between baroreceptor sensitivity and the plasma ET, NO at the end of HUT in patients with positive HUT, but there was no relationship between BRS and NE. Conclusions During the syncope occure, the BRS in patients with VS decreased significantly compared with normal controls. The abnormal plasma ET, NO concen-tration might contribute to the mechanism of VS.

Minimal Vasovagal Dysautonomia in Patients with Rare or Unique Syncope

Introduction: It is common to find people sent to perform a Head Up Tilt Test (HUT) who suffered a single syncope, or syncopes that occur during certain periods and never appear again. We wonder how these people are different from those who have never had syncope. Methods: We found 300 patients who suffered only one (unique) or a maximum of 5 vasovagal syncopes during their life. And their HUT was positive for vasovagal dysautonomia. We compared them, with 120 healthy volunteers who have never had syncope. We try to explain how some constitutional predisposing factors act in these patients, and are associated with environmental triggers to precipitate the syncope. Results: We found differences between cases and controls in predisposing factors such as: heredity, joint hypermobility, baroreflex failure, venous compliance and some neurological diseases. Then an environmental factor acts as a trigger for syncope: prolonged standing, stress, pain and emotions, dehydration, use of certain drugs, abundant food. Conclusions: There are people with minimally expressed vasovagal dysautonomia who have an organic predisposition to present vasovagal syncopes (heredity, joint hypermobility, baroreflex failure, venous compliance, some neurological diseases, etc.). But this predisposition is not enough by itself to produce syncopes. One or more environmental factors must be added, acting as a trigger that would be the reason why these episodes are so infrequent.

Is the clinical head impulse test helpful in cochlear implantation candidacy evaluation?

Objective:Vestibular dysfunction is a known risk of cochlear implantation(CI).However,the utility of the physical exam to screen CI candidates for vestibular dysfunction is not well-studied.The objective of this study is to evaluate the preoperative role of the clinical head impulse test(cHIT)in subjects undergoing CI surgery evaluation.Study Design Setting,and Subjects:We conducted a retrospective review of 64 adult CI candidacy cases between 2017 and 2020 at a tertiary health care center.Methods:All patients underwent audiometric testing and evaluation by the senior author.Patients with an abnormal catch-up saccade contralateral to their worse hearing ear during cHIT were referred for formal vestibular testing.Outcomes included clinical and formal vestibular results,operated ear with regard to audiometric and vestibular results,and postoperative vertigo.Results:Among all CI candidates,44%(n=28)reported preoperative disequilibrium symptoms.Overall,62%(n=40)of the cHITs were normal,33%(n=21)were abnormal,and 5%(n=3)were inconclusive.There was one patient who presented with a false positive cHIT.Among the patients who endorsed disequilibrium,43%had a positive preoperative cHIT.Fourteen percent of the subjects(n=9)without disequilibrium had an abnormal cHIT.In this cohort,bilateral vestibular impairment(71%)was more common than unilateral vestibular impairment(29%).In 3%of the cases(n=2),surgical management was revisited or altered due to cHIT findings.Conclusion:There is a high prevalence of vestibular hypofunction in the CI candidate population.Self-reported assessments of vestibular function are often not congruent with cHIT results.Clinicians should consider incorporating cHITs as part of the preoperative physical exam to potentially avoid bilateral vestibular dysfunction in a minority of patients.