No abstract available.
Head Impulse Test* ; Head*

Vestibular function can be evaluated using various clinical and laboratory findings. Among these, head heave and vestibular evoked myogenic potential (VEMP) represent the otolith-ocular response, which is dynamic rather than static. There have been no reports of tap-evoked VEMP and head-heave in dizzy patients. Here, we report dissociation between ocular VEMP to head tap and the head heave test in acute vestibulopathy.
Head Impulse Test ; Head ; Humans

BACKGROUND AND OBJECTIVES: The bedside head impulse test (bHIT) in bare eyes often overlooks possible vestibular losses by missing the corrective saccade. This is why it is necessary to compare bHIT against video head impulse test (vHIT), which is more accurate in identifying vestibular losses than the bedside test. SUBJECTS AND METHOD: A total of 51 vHIT positive ears underwent the study, and out of those, 47 were diagnosed with dizziness. bHIT and vHIT were performed for patients, and the occurrence rate of overt saccade (OS) was calculated. RESULTS: Among the 51 vHIT positive ears, 33 (64.7%) were bHIT positive ears and 18 ears (35.3%) were bHIT negative. Patterns of positive vHIT were classified as A: no corrective saccade, B: covert saccade (CS) only, C: OS only, and D: CS with OS (CS+OS), which were 45 out of 51 ears (88%). The occurrence rate of OS was higher in the bHIT positive group than in the bHIT negative group (p=0.05), and higher in the CS negative group (CS-) than in the CS positive group (CS+) (p<0.001). CONCLUSION: Possible causes of false negative results of bHIT are seen as following: the absence of corrective (covert and overt) saccade, the occurrence of CS only, and missing the OS during the bHIT (probably due to low occurrence rate of OS). The occurrence of CS should be considered as an important factor in false negative bHIT when lowering the occurrence rate of OS.
Dizziness ; Ear ; Head Impulse Test* ; Head* ; Humans ; Methods ; Saccades

BACKGROUND AND OBJECTIVES: The conventional instrument for video head impulse test (vHIT) records the movement of the right eye only. The aim of this study was to evaluate the changes in the gain of vHIT results qdue to different directions of head rotation directons at different target distances and rotation speeds. SUBJECTS AND METHOD: Horizontal head impulse was recorded by vHIT in 20 normal subjects. vestibulo-ocular reflex (VOR) gains to the right and left directions were compared at different test conditions. Two different impulses with low (50-150 deg/sec) and high (200-300 deg/sec) peak-head-velocities were tested and the subjects were also instructed to fixate a laser dot on a screen at different distances of 60, 100, and 200 cm. Eye movements were recorded on the right eye. RESULTS: Regardless of the target distances and peak-head-velocities, the VOR gains to the rightward head rotation were significantly greater than those to the leftward head rotation. In more than 85% of normal subjects, vHIT gain to the rightward head rotation was greater than that to the leftward head rotation. Mean gain asymmetries were 2.16-3.33% and the mean interaural vHIT gain differences were 0.04-0.07. CONCLUSION: Regardless of the target distances and peak-head-velocities, the VOR gains to the rightward head rotation were significantly greater than those to the leftward head rotation. Directional asymmetry of VOR gain should be considered when interpreting vHIT results in patients with vestibular disorders.
Eye Movements ; Head Impulse Test* ; Head* ; Humans ; Reflex, Vestibulo-Ocular

Recently with the introduction of video head impulse test (vHIT), it can be easily performed quantitative and objective measurement of vestibulo-ocular reflex (VOR). vHIT has been used as a clinical vestibular function test that can individually evaluate the function of each semicircular canal. Loss of VOR gain and corrective catch-up saccades that occur during the vHIT usually indicate peripheral vestibular hypofunction, whereas in acute vestibular syndrome, normal vHIT should prompt a search for a central lesion. In this study, we will examine the principle of vHIT and its interpretation, and explain its clinical application in peripheral and central vestibulopathy. In addition, we will compare the caloric test and the differences, and review the most recently introduced suppression head impulse paradigm test.
Caloric Tests ; Head Impulse Test ; Head ; Reflex, Vestibulo-Ocular ; Saccades ; Semicircular Canals ; Vestibular Function Tests

OBJECTIVES: Suppression head impulse paradigm (SHIMP) in video head impulse test is now newly used to test vestibular function. The aim of this study was to analyze normative values of SHIMP for healthy Korean subjects in each decade of life. METHODS: SHIMP and HIMP responses were measured with the video head impulse test in 70 healthy subjects. Vestibulo-ocular reflex gain and anticompensatory saccade were analyzed and compared at each decade of life. RESULTS: All subjects produced anticompensatory saccades in SHIMP. Gain values did not vary significantly with age. Gain values in SHIMP were lower than gain values in HIMP. The gain values of rightward impulse were higher than the gain values of leftward impulse. CONCLUSIONS: Gain values and anticompensatory saccades in SHIMP were consistently equal in each decade of life. Normative values of SHIMP seems largely unaffected by aging.
Aging ; Head ; Head Impulse Test ; Healthy Volunteers ; Reflex, Vestibulo-Ocular ; Saccades

BACKGROUND AND OBJECTIVES: We evaluated the correlation between video head impulse test (vHIT) and dizziness handicap inventory (DHI), which is commonly used to quantify severity of dizziness in vestibular neuritis (VN). SUBJECTS AND METHOD: Twenty VN patients undergoing vHIT either at the acute or follow-up stages of treatment were assessed by DHI questionnaire. Gain and gain asymmetry (GA) were correlated with DHI scores and abnormal vHIT rates were compared according to the severity of dizziness (mild ≤30; moderate-to-severe ≥32). RESULTS: vHIT gains significantly increased from the acute to follow-up stages (from 0.45±0.18 to 0.70±0.25), whereas GA and DHI scores decreased (GA, from 0.36±0.15 to 0.22±0.18; DHI scores, from 35±26 to 23±23). Although vHIT gains or GA showed no correlation with DHI scores at the acute stage, vHIT gains showed significant correlation with DHI scores at the follow-up (R-sq=0.32, p=0.01) stage. vHIT gains and GA did not differ according to the severity of dizziness during the acute stage; however, vHIT gains (0.78±0.25) of patients with mild dizziness were significantly higher than those (0.51±0.14) with moderate-to-severe dizziness at the follow-up stage. During the follow-up, all patients with moderate-to-severe dizziness showed abnormal vHIT gain, but 43% of patients with mild dizziness showed abnormal vHIT gain, showing a significant difference (p<0.05). CONCLUSION: Reduced vHIT gain was significantly correlated with high degrees of dizziness at the follow-up, but not at the acute stage, suggesting that high-frequency canal dysfunction is contributed in part by the subjective dizziness at the follow-up. Our findings suggest that vHIT might give an indirect evidence for implementing vestibular rehabilitation for enhancing impaired vestibular function and relieving subjective dizziness.
Dizziness ; Follow-Up Studies ; Head Impulse Test ; Head ; Humans ; Methods ; Rehabilitation ; Vestibular Neuronitis

BACKGROUND AND OBJECTIVES: Video head impulse test system (vHIT) is an easy-to-use test and there are numerous studies showing its efficacy. The aim of the study was to evaluate the clinical usefulness of vHIT as an initial test in determining vestibular hypofunction in patients with dizziness. SUBJECTS AND METHOD: The study recruited 103 outpatients who visited our ear clinic with dizziness. We performed both bedside head impulse test (bHIT), vHIT and bithermal caloric tests for 103 patients. Both bHIT and vHIT were consecutively performed in each subject on the same day by the same examiner. RESULTS: The sensitivity of bHIT and vHIT was determined based on the bithermal caloric test results, which showed that vHIT was more sensitive than bHIT. There was a significant negative correlation between vHIT gain and canal paresis (p < 0.05). Results of some patients indicated dissociation between vHIT and caloric test. CONCLUSION: T here is a significant correlation between the results of vHIT and caloric test. Although vHIT does not replace the caloric test, it would be useful to evaluate the initial vestibular loss in patients with dizziness.
Caloric Tests* ; Dizziness ; Ear ; Head Impulse Test* ; Head* ; Humans ; Methods ; Outpatients ; Paresis

Cerebral venous infarction is associated with a wide variety of clinical symptoms and signs, which may often delay appropriate diagnosis. Unilateral vestibular deficit as a presenting sign of cerebral venous infarction has rarely been reported. We report a patient with cerebral venous infarction who had severe prolonged vertigo, vomiting, occipital headache, positive head thrust testing, and unilateral caloric weakness as main clinical features. Although the patient had occipital headache, overall symptoms and signs closely mimicked those of acute peripheral vestibulopathy.
Diagnosis ; Head Impulse Test ; Headache ; Humans ; Infarction* ; Vertigo ; Vestibular Neuronitis ; Vomiting

To analyze the functional change of horizontal semicircular canals after cochlear implantation.Eighteen patients were enrolled in this study.Their vestibular function was evaluated by using the caloric test and video head impulse test before and one week,one month after CI surgery,respectively.The unilateral weakness(UW),slow phase velocity(SPV)in caloric test and gain in video head impulse test(vHIT-G)were observed.Caloric test was abnormal when UW>25% or SPV mean<6°/s,while vHIT was abnormal when vHIT-G<0.8.The SPV of the implanted ear were[(10.36±8.01)°/s;(14.77±14.24)°/s]pre-operatively,[(6.45±7.52)°/s;(5.14±4.67)°/s]1 week post-operatively and[(6.05±3.86)°/s;(6.27±4.17)°/s]1 month post-operatively.Statistically significant difference(<0.05)was found between pre-and post-operative period.The vHIT-G of the implanted ear were(0.73±0.33)pre-operatively,(0.65±0.32)1 week post-operatively and(0.71±0.36)1 month post-operatively.There was no statistically significant difference of vHIT-G between preand post-operative period((pre-operative/1 week post-operative)=0.084,(pre-operative/1 month post-operative)=0.679).Four patients presented with vertigo and one of them manifested slight unsteadiness post-operatively.All symptoms resolved within 7 days.These symptoms had no correlate with age,gender,implantedear and results of vestibular test.Cochlear implantation can affect the horizontal semicircular canal function,and the video head impulse test and caloric test should be used in a complementary fashion.
Caloric Tests ; Cochlear Implantation ; adverse effects ; methods ; Head Impulse Test ; Humans ; Semicircular Canals ; physiopathology ; Vertigo