Symptomatic high frequency/acceleration vestibular loss: consideration of a new clinical syndrome of vestibular dysfunction

Conclusion Symptomatic high frequency/acceleration vestibular loss is a distinct clinical entity that can be missed on conventional ENG with caloric testing. Under certain circumstances, symptomatic patients with a high frequency/acceleration vestibular loss should undergo an MSSC study for confirmation, if required.

Objective To document that normal electronystagmography (ENG) with conventional bithermal caloric testing is inadequate for diagnosing clinically significant high frequency/acceleration vestibular loss.

Material and methods Patients with clinical symptoms and signs of persistent peripheral vestibular dysfunction despite normal conventional bithermal caloric testing on ENG underwent high frequency/acceleration horizontal magnetic scleral search coil (MSSC) eye movement studies. The clinical findings and results from audiometric tests, conventional ENG with bithermal caloric tests and MSSC tests were reviewed.

Results Eleven patients were identified as having an abnormal MSSC study, indicating a high frequency/acceleration vestibular loss consistent with their clinical history despite normal or equivocal bithermal caloric responses on conventional ENG. Although valuable, ENG caloric testing evaluates lateral semicircular canal function and should be considered a non-physiological test primarily of low frequency vestibular function. High frequency/acceleration head thrust testing clinically detected a “high frequency/acceleration vestibular loss” in 8/11(72.7%) cases.     

Symptomatic high frequency/acceleration vestibular loss: consideration of a new clinical syndrome of vestibular dysfunction

CONCLUSION: Symptomatic high frequency/acceleration vestibular loss is a distinct clinical entity that can be missed on conventional ENG with caloric testing. Under certain circumstances, symptomatic patients with a high frequency/acceleration vestibular loss should undergo an MSSC study for confirmation, if required. OBJECTIVE: To document that normal electronystagmography (ENG) with conventional bithermal caloric testing is inadequate for diagnosing clinically significant high frequency/acceleration vestibular loss. MATERIAL AND METHODS: Patients with clinical symptoms and signs of persistent peripheral vestibular dysfunction despite normal conventional bithermal caloric testing on ENG underwent high frequency/acceleration horizontal magnetic scleral search coil (MSSC) eye movement studies. The clinical findings and results from audiometric tests, conventional ENG with bithermal caloric tests and MSSC tests were reviewed. RESULTS: Eleven patients were identified as having an abnormal MSSC study, indicating a high frequency/acceleration vestibular loss consistent with their clinical history despite normal or equivocal bithermal caloric responses on conventional ENG. Although valuable, ENG caloric testing evaluates lateral semicircular canal function and should be considered a non-physiological test primarily of low frequency vestibular function. High frequency/acceleration head thrust testing clinically detected a "high frequency/acceleration vestibular loss" in 8/11(72.7%) cases.     

Garnett Passe and Rodney Williams Memorial Lecture: New clinical tests of unilateral vestibular dysfunction

Vertigo is caused by unilateral vestibular dysfunction. Unilateral vestibular dysfunction represents either vestibular overactivity as benign positional vertigo or underactivity as in labyrinthitis or both, at different times, as in a Ménière's attack. Unilateral dysfunction could also be central rather than peripheral, such as in a lateral medullary syndrome. Unilateral vestibular dysfunction could affect any of the five different sensory areas in the labyrinth, the three semicircular canals and the two otoliths, or their brainstem connections. For rigorous diagnosis of the cause of vertigo, ideally one would have robust, reproducible, quantitative vestibular function tests sensitive to dysfunction of each of the five sensory regions in each ear. In working towards this ideal we have, over the last 15 years, developed three new vestibular function tests: (1) impulsive tests of individual semicircular canal function, (2) evoked potential tests of saccular function and (3) subjective visual horizontal tests of utricular function. The physiological rationale of these three tests is reviewed as well as the interpretation of their results in various diseases.     

主观视觉水平线在单侧前庭周围性病变中的应用研究

目的 探讨外周单侧前庭功能减退患者的主观视觉水平线特点及其对前庭功能评定的临床价值.方法 分别对85例外周单侧前庭功能减退患者及39名健康对照组人群行主观视觉水平线、主观视觉垂直线及冷热试验等前庭功能检测,以主观视觉水平线及主观视觉垂直线偏斜角度、冷热试验优势偏向(directional preponderance,DP)值、单侧半规管轻瘫(unilateral weakness,UW)值为参数,分析总结外周单侧前庭功能减退患者的主观视觉水平线特点,主观视觉水平线、主观视觉垂直线之间及其分别与DP、UW值、病程的相关性.以SPSS 16.0软件对数据进行统计学分析.结果 健康对照组主观视觉水平线、主观视觉垂直线的偏斜角度为-2,～2.以此为判定阳性与阴性的标准.外周单侧前庭功能减退患者的主观视觉水平线、主观视觉垂直线阳性者分别为46例(54.1%)、43例(50.6%),二者比较差异无统计学意义(χ2=12.5,P=0.481);DP阳性者55例(64.7%),与主观视觉水平线、主观视觉垂直线比较,差异均无统计学意义(χ2值分别为0.19、2.86,JP值分别为0.164、0.067).外周单侧前庭功能减退患者的主观视觉水平线与主观视觉垂直线偏斜角度呈正相关(r=0.939,P<0.01),且二者与DP值均呈正相关(r值分别为0.648、0.658,P值均<0.05),与UW值无相关性(r值分别为0.048、0.085,P值均>0.05).根据主观视觉水平线或主观视觉垂直线、DP、UW3个参数的阳性或阴性组合,可分别构成3种主要结果形式,即:主观视觉水平线(+)DP(+)UW(+),主观视觉水平线(-)DP(+)UW(+),主观视觉水平线(-)DP(-)UW(+);主观视觉垂直线(+)DP(+)UW(+),主观视觉垂直线(-)DP(+)UW(+),主观视觉垂直线(-)DP(-)UW(+).以上6种形式的病程中位数分别为5.0、10.0、15.0 d,5.0、9.5、14.5 d,分别行多样本秩和检验,差异均有统计学意义(χ2水平线:8.80,P=0.012;χ2垂直线=6.26,P=0.040).结论 主观视觉水平线可以评估耳石器(椭圆囊)功能.外周单侧前庭功能减退患者的主观视觉水平线、主观视觉垂直线偏斜角度随病程和前庭代偿进程呈动态变化,可用于前庭静态代偿评定.

Abstract：

Objective To analyze the characteristics of subjective visual horizontal ( SVH) and evaluate its clinical value for vestibular function in peripheral unilateral vestibular hypofunction ( UVH). Methods Eighty-five patients with UVH (study group) and 39 normal persons (control group) accepted vestibular function tests, including SVH, subjective visual vertical ( SVV ) and caloric test by video-nystagmography. The parameters of the angle of SVH and SVV, directional preponderance ( DP) and unilateral weakness(UW) of caloric test were observed. The correlation between SVH/SVV, DP, UW and the course of disease were investigated respectively. SPSS 16. 0 software was used to analyze the data. Results Reference range of SVH and SVV was from - 2° to 2° in the control group. Among the 85 patients, 46 cases(54. 1% ) and 43 cases(50. 6% ) had the abnormal values of SVH and SVV respectively, with no statistical significance( χ2 = 12. 5, P = 0. 481 ) by chi square test Fifty-five cases (64. 7% ) withabnormal DP had no statistical significance when compared with SVH and SVV respectively (χ2 values were 0. 19 and 2.86, respectively, P value were 0. 164, 0.067, respectively). In UVH, there were positive correlation between SVH, SVV and DP( r value was 0. 939, 0. 648, 0. 658, all P <0. 05) respectively, but no correlation between UW and SV H or SVV (r value was 0. 048, 0. 085, all P > 0. 05). According to the permutation and combination of the four parameters, positive or negative, three main groups could be defined [SVH(+)DP(+)UW( +), SVH( -)DP( +)UW( +), SVH( -)DP( -)UW( +); SVV( + ) DP ( +)UW( +), SVV( -)DP( +)UW( +), SVV( -)DP( -)UW( +)]. The course of disease in the three main groups was positively skewed distribution,with median of 5. 0, 10. 0, 15. 0 d and 5. 0, 9. 5, 14. 5 d respectively. By Kruskal-Wallis Test, χ2 value were 8. 80 and 6. 26, respectively( P value were 0.012, 0. 040, respectively), with statistical significance between the above three main groups. Conclusions The SVH value can evaluate the function of the otolithic. The angle of SVH and SVV are changing in the course of disease, SVH and SVV can be used as a guidance of the vestibular compensation evaluation.     

Unterberger stepping test: a useful indicator of peripheral vestibular dysfunction?

Deviation of gait in a stepping test has been proposed as a useful indicator of peripheral labyrinthine dysfunction. A prospective study of 26 patients suspected of having uncompensated peripheral labyrinthine dysfunction and 49 normal patients with normal labyrinthine dysfunction showed no significant difference in performance of the Unterberger stepping test between patients with electronystagmographically significant canal paresis and those with normal vestibular function.     

Optimal parameters for the clinical test of dynamic visual acuity in patients with a unilateral vestibular deficit

OBJECTIVE: To determine the influence of frequency and direction of head movement and type of vision chart on the score of a clinical test of dynamic visual acuity (DVA). METHODS: The subjects were 31 healthy individuals (22 to 79 years old) and 10 patients (19 to 70 years old) with a unilateral vestibular deficit owing to surgical resection of an acoustic neuroma. They read a Snellen or an E-chart while their head was passively moved +/- 20 degrees back and forth in the horizontal or vertical direction at one of four frequencies (0.5, 1.0, 1.5, and 2.0 Hz). The DVA score was the difference in the number of lines on the vision chart that could be read with the head passively moved versus with the head immobile. RESULTS: Four healthy subjects had a low DVA score during horizontal head movements at the fastest frequency (2.0 Hz) with the Snellen chart. In patients, DVA scores significantly decreased as head movement frequency increased from 0.5 to 1.0 Hz and from 1.0 to 1.5 Hz, during horizontal and vertical movements, and with both vision charts (p < .001). The DVA scores of healthy subjects were more consistent across three trials with the E-chart than with the Snellen chart at 1.0 and 0.5 Hz (horizontal movements, p < .01) and at 1.5 and 1.0 Hz (vertical movements, p < .01). CONCLUSIONS: This study provides new indications on the optimal parameters for the clinical test of DVA. From the results, it is recommended that DVA be tested during horizontal and vertical head movements at a frequency of 1.5 Hz with the E-chart.     

Diagnostic precision in a new rotatory vestibular test

Quantification of the vestibulo-ocular reflex for the purpose of clinical diagnostics is dependent upon measurements within that portion of the dynamic range which has a constant gain, independent of visual contamination. Head oscillation at about 3 Hz is characterized by unity gain irrespective of visual influence. At lower frequencies visual tracking dominates compensatory eye movements and fixation suppression of the VOR can be quantified precisely. The new test is based upon power spectral analysis of compensatory eye movements during rotatory stimulation on a powerful hydraulic rotation chair. There is evidence suggesting that this test can precisely quantify vestibular lesions and provide side detection of peripheral damage.     

Effects of visual input on galvanic body sway test of unilateral vestibular deficiency in patients with unilateral vestibular schwannoma

OBJECTIVE: Galvanic body sway tests (GBSTs) are performed with eyes fixed and closed. However, quantitative effect of fixation on GBST has been unknown. The purpose of this study is to address this question. METHODS: We evaluated GBSTs of patients with unilateral vestibular schwannomas and normal controls, while their eyes were open and closed. We evaluated three GBST parameters: maximum amplitude of the response, velocity and latency of the onset of response. RESULTS: Closing the eyes diminished stability, resulting in increased amplitude and velocity of the responses. However, apparent contribution to the latency of response could not be found. Contribution of visual fixation seems to be greater in apparatus with vestibular hypo-function than without it. Unilateral weakness (UW) was calculated for each parameter, and significant correlation, between with eyes fixed and closed, was found only for velocity parameter. CONCLUSION: Fixation would stabilize the body of subjects, and diminish GBST responses. GBST with and without fixation can be evaluated together, using certain coefficient. On the other hand, fixation would not have any contribution to the latency of the GBST response. When we evaluate vestibular dysfunction of patients with unilateral vestibular schwannomas, velocity parameter should be employed.     

Value of the rotation test in acute unilateral vestibular disorders

The electronystagmographically recorded response of the spontaneous nystagmus and of the per- and postrotatory nystagmus were examined in 70 patients suffering from acute unilateral vestibular disorders. Within a short time the SPN declined logarithmically compared to the reduction of the perrotatory directional preponderance. But the postrotatory nystagmus levels changed only a little in the course of time. The patient's symptoms did not correlate with results of the rotatory test or the intensity of the SPN. The graphs of both parameters (maximal velocity of the slow nystagmus phase and nystagmus frequency in culmination range) which had been analysed showed an almost identical course. Obviously two independent functions are recorded by the caloric and rotatory vestibular test: the rotatory test is said to describe the extent of the central compensation. The lack of conformity in the results of various vestibular tests, including the rotating chair, limit the reliability of the individual tests and indicate that different methods of investigation should always be carried out especially in medico-legal cases.     

闭目踏步试验对单侧外周前庭损伤的定侧价值

目的 探讨闭目踏步试验对单侧前庭病变的定侧价值.方法 可定病变侧别的单侧前庭外周功能损伤患者126例,其中颞骨外伤11例,突发性聋伴眩晕94例,前庭神经炎21例;健康对照组50例.原地闭目踏步50步,发生倾倒,侧移1 m或偏转＞45°为存在偏向.实验数据采用SPSS13.0软件进行x2检验.结果 126例患者中50.0%(63/126)偏向患侧,24.6%(31/126)偏向健侧,25.4%(32/126)无偏向.发病3 d内的23例患者中偏向健侧39.1%(9/23),偏向患侧39.1%(9/23),21.8%(5/23)无偏向;随着时间的延长,偏向患侧和无偏向的比例增大,病程超过1个月的22例患者中1例偏向健侧,病程超过2个月的患者不再偏向健侧.发病1周内偏向健侧的17例患者,在随访的2周内,35.3%变为偏向患侧.观察到自发性眼震的35例患者中22.9%(8/35)闭目踏步偏向和自发性眼震同侧.结论 急性外周前庭受损不能根据闭目踏步试验偏向进行患侧的确定,要根据症状和其他检查一起综合考虑.     

Locomotor dysfunction after surgical lesions in the unilateral vestibular nuclei region in squirrel monkeys.

The present experimental results in squirrel monkeys indicated that the performance of psycho-physically advanced locomotor task (squirrel monkey rail test) was severely impaired after the placement of the medium to relatively large surgical lesions in the unilateral vestibular nuclei area, and therefore, confirmed that this brain-stem structure is essential for the signal relay and/or input coordination. The severest locomotor disability was found 10-14 days after the surgery; thereafter, squirrel monkeys showed very gradual and only limited degree of performance recovery. The post-ablative performance levels were no better than 1/5 of their pre-ablative performance levels.     

单侧前庭周围性眩晕的平稳跟踪实验结果分析

目的:对单侧前庭周围性眩晕的眼震图平稳跟踪实验(SPT)结果进行定性、定量分析并探讨其影响因素。方法:应用法国Synapsys视频眼震图仪对185例单侧前庭周围性眩晕患者(实验组)和51例正常人(对照组)行SPT和自发性眼震(SN)检测,以SPT水平眼跟踪波的增益值及SN为评定参数,对SPT眼动波形及增益进行定性、定量分析,并分析SPT眼动增益与SN强度之间的相关性。结果:实验组SPT呈现为Ⅰ、Ⅱ、Ⅲ型波,分别为105例(56.8%)、72例(38.9%)、8例(4.3%),存在SN者58例(31.4%),无Ⅳ型波。对照组仅呈现Ⅰ、Ⅱ型波,分别为38例(74.5%)、13例(25.5%),无Ⅲ、Ⅳ型波及SN。量化分析:对照组、实验组总体及定性划分后各型波的强、弱侧增益之间进行t检验,均差异有统计学意义(P<0.05);2组Ⅰ、Ⅱ型波的弱侧增益值之间均差异有统计学意义,强侧增益值之间均差异无统计学意义。对照组总体及定性划分后Ⅰ、Ⅱ波的左右侧增益值均差异无统计学意义(均P>0.05),强弱侧增益值比较均差异有统计学意义(均P<0.05)。实验组总体和定性划分后的Ⅰ、Ⅱ、Ⅲ型波的强、弱侧增益值比较,均差异有统计学意...     

Relation of video-head-impulse test and caloric irrigation: a study on the recovery in unilateral vestibular neuritis

The head-impulse test (HIT) is an important test for examining unilateral vestibular hypofunction. The new video-head-impulse test (vHIT) is more sensitive and specific than the clinical bedside-head-impulse test. Alternatively, one can test for vestibular hypofunction with the caloric irrigation test. Various studies have shown that both tests may not always identify vestibular hypofunction; instead, the results of the tests might be contradictory. To further explore the question, of whether vHIT and caloric irrigation test the same part of the angular horizontal vestibulo-ocular reflex (VOR), we examined patients with unilateral vestibular neuritis at different points in time. The tonic vestibular imbalance (e.g., subjective-visual-vertical, ocular torsion and spontaneous nystagmus) and dynamic dysfunction of VOR (vHIT and bithermal caloric irrigation) were measured and quantified. While parameters of the tonic vestibular imbalance were well described by single exponential decay functions, dynamic parameters were less well defined. Therefore, to better compare the time course of pairs of two different parameters, we used a linear regression analysis. No linear correlation was found in the group and individually for the gain asymmetry and the ipsilesional gain of the vHIT with the unilateral weakness of the bithermal caloric irrigation tests. Linear correlation was found for most parameters of tonic vestibular imbalance. These findings are further evidence that vHIT and caloric irrigation test different parts of the angular VOR.     

Vestibular rehabilitation outcomes in chronic vertiginous patients through computerized dynamic visual acuity and Gaze stabilization test.

OBJECTIVE: To evaluate the efficiency of the rehabilitative protocols in patients with labyrinthine hypofunction, focusing on computerized dynamic visual acuity test (DVAt) and Gaze stabilization test (GST) specifically evaluating the vestibulo-oculomotor reflex (VOR) changes due to vestibular rehabilitation. DESIGN: Consecutive sample study. SETTING: Day hospital in Ears, Nose, and Throat Rehabilitation Unit. SUBJECTS: Thirty-two patients with chronic dizziness with a mean age of 60.74 years. INTERVENTION: Patients performed one cycle of 12 daily rehabilitation sessions (2 h each) consisting of exercises aimed at improving VOR gain. The rehabilitation program included substitutional and/or habitudinal exercises, exercises on a stability platform, and exercises on a moving footpath with rehabilitative software. MAIN MEASURES: Dizziness Handicap Inventory and Activities-specific Balance Confidence Scale. Computerized dynamic posturography, computerized DVAt, and GST. RESULTS: The patients significantly improved in all the tests. CONCLUSION: Vestibular rehabilitation improved the quality of life by reducing the handicap index and improving the ability in everyday tasks. The recovery of the vestibular-ocular reflex and vestibular-spinal reflex efficiency was objectively proven by instrumental testing. The DVAt and the GST allow to objectively quantify the fixation ability at higher frequencies and speeds (main VOR function). Moreover, these new parameters permit to completely evaluate vestibular rehabilitation outcomes, adding new information to the generally used tests that only assess vestibulospinal reflex.     

Vestibulo-ocular compensation following unilateral vestibular deafferentation.

Vestibulo-ocular compensation following vestibular deafferentation was investigated in 26 acoustic neuroma patients following tumor removal and in 5 Menière's disease patients following vestibular nerve section by using sinusoidal harmonic acceleration testing. All three test parameters (phase lead, gain, and asymmetry), when averaged, shifted significantly on the first postoperative test (average 0.4 months after operation). A marked progression in central compensation with gain returning to the range of normal control values was seen in the tests performed 1 to 6 months (average 2.6 months) postoperatively. However, phase lead and asymmetry (especially at 0.01, 0.02, 0.04, and 0.08 Hz) remained outside the range of normal control values, and all three parameters failed to return to their preoperative level even when tested at more than 12 months (average 20.2 months) after operation. This finding indicates that the deficits of the vestibulo-ocular reflex to head acceleration are of long duration if not permanent.     

The clinical utility of vestibular autorotation test in patients with vestibular migraine

Objective: To investigate the characteristics and clinical utility of vestibular autorotation test (VAT) in patients with vestibular migraine.

Methods: This study included two groups, an experimental group (441 patients) and a control group (65 healthy subjects). Both groups undertook VAT; the parameters evaluated were horizontal gain/phase, vertical gain/phase and asymmetry. The differences in VAT results between the two groups were investigated.

Results: There were no statistical differences between the VAT data of the control group when compared to the reference value from the manufacturer (p?>?.05). There were statistically significant differences in VAT results between the experimental and control group, namely elevated horizontal gain at frequency 2, 3, 4 and 5?Hz, horizontal phase delay at frequency 2, 4, 5 and 6?Hz, elevated vertical gain at frequency 2?6Hz and vertical phase delay at frequency 4?6Hz.

Conclusion: The results of this study using VAT in VM patients demonstrate elevated horizontal gain, vertical gain and delay in horizontal phase, vertical phase. We suggest the application of VAT as a diagnostic tool which may provide objective evidence that can contribute to the diagnosis of VM and also in differential diagnosis.     

Head-shaking nystagmus: a sensitive indicator of vestibular dysfunction

This study investigated 258 consecutive patients with the complaint of vertigo undergoing vestibular function tests between August 1992 and July 1994. The head-shaking nystagmus test was performed in a passive fashion with the patient placed in a sitting position with the head anteflexed at 30° and oscillated ±45° horizontally for 30 cycles in 15 s; the post head-shaking nystagmus was recorded by electronystagmography. Conventional bithermal caloric tests were conducted with the normal limit of canal paresis set at 20%. The results show significant correlation between head-shaking nystagmus and canal paresis. Head-shaking nystagmus is more sensitive than canal paresis in predicting vestibular dysfunction. The sensitivity of head-shaking nystagmus in detecting a canal paresis was 90%. Although the direction of head-shaking nystagmus does not always accord with the side of peripheral vestibular dysfunction, it is an indicator of vestibular dysfunction and this test could be performed easily as a screening test in every otoneurological investigation.