Improvements in trunk sway observed for stance and gait tasks during recovery from an acute unilateral peripheral vestibular deficit

OBJECTIVES: Our aim was to track improvements in postural control during recovery from an acute unilateral peripheral vestibular deficit (UVL), presumably due to vestibular neuritis, and to determine if recovery rates were different for stance and gait tasks. Postural control was quantified using simple measurements of trunk sway: amplitudes of trunk sway angle and angular velocity, in the roll and pitch directions as well as task duration, were examined for a battery of stance and gait tasks. These measures were collected at the onset of the deficit and then 3 weeks and 3 months later. STUDY DESIGN: A repeated-measures design was used for UVL subjects and age-matched healthy controls. Stance tasks involved standing on 1 or 2 legs with eyes open or closed. Gait tasks consisted of tandem gait, walking normally with eyes closed, or with the head rotating or head pitching, walking up and down stairs and walking over a series of low barriers. Stance and tandem gait tasks were repeated using a foam support surface instead of a normal floor. PATIENTS: Twenty-eight patients with acute UVL were examined. MAIN OUTCOME MEASURES: The range of trunk sway angular displacement and angular velocity in the pitch and roll directions was measured for each task in addition to task duration. The measures were compared with those of normal subjects. RESULTS: The amplitudes of pitch trunk sway for 2-legged stance tasks with eyes closed underwent the greatest reduction 3 weeks after UVL onset. At 3 months, trunk sway was almost normal for all 2-legged stance tasks. One-legged stance tasks with eyes open showed a similar but slower improvement. Stance time without a fall showed a very rapid improvement for 1-legged tasks but was still shorter than that of normal subjects at 3 months. Trunk sway for the simple gait tasks was within normal range at 3 months; however, task duration was still longer than normal. More complex gait tasks, such as walking 8 tandem steps on foam or walking up and down stairs, showed no improvement in trunk roll sway at 3 months. A mix of variables from mainly gait tasks best identified a balance deficit due to UVL, with complex gait tasks becoming more important for identification purposes as compensation progressed. The accuracy of UVL identification with durations alone was 75% of the accuracy with combined trunk sway and duration measures. CONCLUSIONS: These data suggest that recovery of normal trunk control during the compensation process for unilateral vestibular hypofunction is more rapid for stance tasks than gait tasks. Even at 3 months, trunk sway for complex gait tasks was not normal. Thus, trunk sway for gait tasks provides a better insight into remaining deficits in balance control of vestibular-loss patients than the sway of stance tasks.     

Otolith function in patients with head trauma

This study evaluates the otolith function of patients with head trauma, postulating that otolith dysfunction is a cause of nonspecific dizziness after head trauma. We prospectively enrolled 28 patients referred within 3 months after head trauma between March 2007 and December 2009. Pure tone audiometry, caloric testing and otolith function tests, including cervical vestibular evoked myogenic potential (cVEMP) and subjective visual vertical (SVV) tests, were performed on all patients. The relationship between otolith function and otologic symptoms was analyzed. Of the 28 patients with head trauma, 18 complained of dizziness and 12 experienced hearing loss, including 6 patients who complained of both. On defining otolith dysfunction as an abnormal cVEMP or abnormal SVV, a significant difference in otolith dysfunction existed between the groups with and without dizziness [72 (13/18) vs. 20% (2/10)]. In contrast, no significant difference in otolith dysfunction was detected between the abnormal and normal hearing groups. A significant number of the patients who complained of nonspecific dizziness after trauma had abnormal otolith function. After trauma, when patients complain of dizziness, vestibular function tests, including otolith function tests, should be considered.     

Effect of age and height on trunk sway during stance and gait

The aim of the studies reported here was to quantify changes in balance control for stance and gait tasks with age and to pinpoint possible advantages and difficulties in using these tasks and measures derived from them to identify pathological balance control in patients. Some 470 normal subjects in the age range 6 to 82 were examined for a battery of 14 stance and gait tasks. During the tasks, angular velocity transducers mounted at lumbar 1-3 measured pitch and roll angular velocities of the body. A combination of outcome measures from several tasks was used to create an overall balance control index. Three types of sensory analyses on pitch angle and velocity amplitudes for stance trials were used to quantify possible changes in the contributions of visual, somatosensory and vestibular inputs to balance control with age for 2-legged stance tasks. Correlation analysis on task variables was used to determine the relationship of subjects' age and height on outcome measures. Outcome measures showed a characteristic "L" or "U" shaped profile with a rapid decrease in values between 7 and 25 years of age, a plateau until 55 then a gradual increase with age after 55 years of age for most stance and gait tasks. The sensory analysis technique using differences between stance tests indicated that visual contributions to balance control continuously increased with age between the ages of 15 and 80, and vestibular and lower leg somatosensory contributions remain relatively constant with age. Sensory analysis calculated as commonly-used quotients of outcome measures revealed large variance across all ages, asymmetric distributions, and no clear trends in sensory contributions to stance with age. A third technique based on a discriminant function analysis using measures from model patient populations indicated that proprioceptive but not vestibular contributions first increased with age and then decreased after 55 years of age. Correlations of outcome measures with age and height indicated that both contributed equally to changes in outcome measures between the ages of 7 and 25, otherwise height had no effect. We conclude that both stance and gait tasks should be selected for identifying changes in balance control from that of healthy persons with a preference for gait tasks as these show less variation with age. Because of the large increases in variance in the elderly and those younger than 20 years, appropriate age-matched reference values should be employed to ascertain if trunk sway is out of normal ranges.     

Preoperative postural control of patients with vestibular schwannoma assessed by visual feedback posturography

BACKGROUND: The need for an objective method to describe the functional postural control of patients with vestibular schwannoma in agreement with their subjective sensation of balance. Objectives: The objective was to compare the postural control of 49 patients with unilateral vestibular schwannoma (VS) with that of healthy subjects by using visual feedback posturography (VFP). We aimed to find out if preoperative postural control of the patients correlates with their subjective sensation of balance. METHODS: In the VFP, while standing on the platform, patients were instructed to move their center of gravity (COG) marker to the targets as fast and accurately as possible. Hit delay (HD) to the targets, hold percentage (HP) within the targets, COG marker velocity (CMV) to the targets, and balance index (BI) were calculated. We rated intensity of balance disturbance using a 5-point qualitative scale. RESULTS: Twenty-two (45%) patients had at least one abnormal VFP parameter, and 49% of patients were simultaneously symptomatic. Mean hit delay (HD), hold percentage (HP), and balance index (BI) were significantly worsened in patients with VS (p < 0.05). Increased HD and BI correlated significantly with subjective sensation of imbalance (p = 0.02). CONCLUSIONS: The overall deficit in preoperative postural control of the VS patients was not severe, and this finding agreed well with their subjective sensations.     

Abnormal deviation of subjective visual horizontal in patients with vestibular schwannoma

OBJECTIVES: This study was aimed to examine the correlation between the results of subjective visual horizontal (SVH) and other vestibular function tests in patients with untreated unilateral vestibular schwannoma (VS). METHODS: The subjects comprised 40 consecutive patients (17 men, 23 women) with VS who underwent vestibular function tests before surgery and had surgically and histopathologically confirmed unilateral VS. The vestibular function tests included SVH, caloric, and vestibular evoked myogenic potential (VEMP) tests. RESULTS: Of the 40 patients, 31 (77.5%) showed deviation of the SVH toward the affected side down. Especially in 8 patients (20.0%), abnormal deviation (more than 2.2 degrees) toward the affected side down was seen. None of the patients showed abnormal deviation toward the unaffected side down. On the caloric test, the proportion of absent caloric responses and the percent canal paresis in patients with an abnormal SVH was significantly higher than those in patients with a normal SVH. The proportion of abnormal VEMP responses was higher and the percent VEMP asymmetry was smaller in patients with an abnormal SVH than in patients with a normal SVH; however, the differences were not significant. CONCLUSIONS: Abnormal results on the caloric test and/or VEMP test were more frequently seen in VS patients with abnormal deviation of the SVH.     

Subjective visual vertical and subjective visual horizontal measures in patients with chronic dizziness

OBJECTIVES: We aimed to find the frequency of otolith organ pathologies in the clinical picture of common dizziness etiologies in the chronic stage. METHOD: Subjective visual vertical and subjective visual horizontal measures were assessed in patients who had persistent or recurrent dizziness at least 2 months after the acute period. Every patient was tested in three head positions: neutral, right, or left deviation in the roll plane. Test results were compared with those of the control group. RESULTS: Seventy-three patients and 18 controls were examined. Fifty-eight of the patients had peripheral vestibular disease; 15 of them had central vestibular disease. Left subjective visual horizontal (SVH) and right SVH measures of the peripheral group were significantly different from those of the control group (p < .01). There was no difference in any test between the peripheral and central groups. When we put a cut off point for abnormality (0, 1) according to mean +/- 2 SD of the control group, the peripheral and central groups had very high significant differences from the control group. Approximately 25 to 50% of our patients had pathologic subjective visual vertical or SVH measures according to test type. CONCLUSION: These results showed that the otolith system must be evaluated in the chronic period of dizziness, especially in patients who frequently visit their physician, and modifications in treatment programs must be conducted.     

主观视觉垂直线和水平线检查软件的研发与应用

目的 自主研发主观视觉垂直线(SVV)、主观视觉水平线(SVH)检查软件。主要用于判断双侧耳石器功能的对称性和优势偏向侧,评估耳石器功能的静态代偿状态,指导前庭康复。 方法 研发SVV/SVH检查软件,结合消除视觉参考的桶状设备及暗环境检查室,收集80例健康志愿者检查数据,确定正常参考值范围。研究方法为横断面研究。 结果 80例健康志愿者,SVV检查平均值偏离度范围为:-3.00°~3.00°,其平均值的均值(±标准差)为:-0.29(±1.42)°;SVH检查平均值偏离度范围为:-4.00°~3.50°,其平均值的均值(±标准差)为:-0.38(±1.84)°。 结论 自主研发的SVV/SVH软件95%正常值参考范围分别为:-3.13°~2.55°,-4.06°~3.30°;此检查软件和设备可以用于前庭耳石器机能状态的评估,与其他前庭检查设备如前庭诱发肌源性检查、双温试验、甩头试验等相结合,全面评估患者的前庭功能和前庭代偿状态,指导前庭康复。     

Autonomic correlates of stuttering and speech assessed in a range of experimental tasks

Electrodermal activity, peripheral blood flow, and heart rate were recorded from 19 stutterers and 19 normal speakers during performance of jaw movements, a strenuous breath-holding task, reading, and spontaneous speech. The tasks were selected to produce a range of autonomic activation and thus help scale autonomic activation for speech relative to other motor behaviors. Speaking was associated with relatively large increases in autonomic activity in both stutterers and normal speakers. There were no differences between the two groups of speakers, suggesting that the stutterers did not have abnormally high levels of autonomic activation in speech. Within the group of stutterers, the more extreme increases in arousal (specifically increases in measures reflecting sympathetic arousal) were correlated with the occurrence and increased severity of disfluent speech. Significant correlations were found for the intervals prior to, during, and after speech. Although significantly correlated with disfluency, measures of autonomic arousal accounted for small percentages of the variances of fluency and severity. The results are consistent with the hypothesis that sympathetic arousal accompanies the breakdowns in speech motor processes characteristic of stuttering. Mechanisms linking autonomic nervous system functions and somatic sensorimotor processes involved in speech production are discussed.     

Chemosensory function assessed with psychophysical testing and event-related potentials in patients with atrophic rhinitis

Atrophic rhinitis (AR) is a chronic inflammation of the nose characterized by an atrophy of the nasal mucosa. This is typically associated with an impaired sense of smell and a subjective sensation of poor nasal breathing. The aim of this study is to assess chemosensory function in patients suffering from AR using psychophysical testings and event-related potentials (ERP) responses. A cohort of nine patients was extensively studied. Eight out of nine had secondary AR sequela of a bilateral total inferior turbinectomy whereas one patient had a primary AR. All the patients had a clinical evaluation using Sniffin’ Sticks test and a retro-olfaction test and an electrophysiological evaluation based upon ERPs obtained after both olfactory and trigeminal stimuli. All the patients complained of a poor nasal breathing and presented a distortion of the chemosensory function. Actually, the orthonasal psychophysical testing showed that four patients out of nine had anosmia, three out of nine had hyposmia and two out of nine were normosmic. All the patients demonstrated retro-olfaction scores inferior to the normal values. The chemosensory ERP showed that seven patients had no olfactory response whereas six had no trigeminal response. Four patients had neither olfactory nor trigeminal ERP response. In conclusion, this study demonstrates that most patients with AR secondary to a total bilateral inferior turbinectomy have a reduction of the chemosensory function measured objectively by psychophysical testings and ERP. Moreover, the trigeminal responses were absent in all the cases.     

Idiosyncratic compensation of the subjective visual horizontal and vertical in 60 patients after unilateral vestibular deafferentation

Objective To investigate long-term compensation mechanisms of utricular function after translabyrinthine surgery for vestibular schwannoma. Correlations between the subjective visual horizontal (SVH) and subjective visual vertical (SVV) and other parameters of vestibular compensation were studied. The correlation between the SVH and SVV was also investigated to see whether these measurements are compatible for patients.

Material and Methods Sixty consecutive patients were investigated 3 months before and 6 months after surgery by means of electronystagmography and SVH and SVV tests. Tumor size was measured using MRI.

Results The SVH and SVV increased significantly towards the ipsilesional side postoperatively. Preoperative tilt correlated with age. Postoperative tilt correlated weakly with preoperative caloric sensitivity and inversely with tumor size. The correlation between the SVH and SVV was high both before and after surgery (r_s>0.74; p<0.001).

Conclusions The long-term compensation of static tilt perception was dependent on age and not on dynamic canal functions. We propose an idiosyncrasy in the SVH and SVV compensation after unilateral vestibular deafferentation, incongruous with the general course of vestibular compensation. The results suggest a probable dependence on non-vestibular information, i.e. proprioception, in facilitating compensation of static vestibular deficits. The similarity between the SVH and SVV measurements confirms that either test can be used clinically for patients with vestibular lesions.     

Idiosyncratic compensation of the subjective visual horizontal and vertical in 60 patients after unilateral vestibular deafferentation

OBJECTIVE: To investigate long-term compensation mechanisms of utricular function after translabyrinthine surgery for vestibular schwannoma. Correlations between the subjective visual horizontal (SVH) and subjective visual vertical (SVV) and other parameters of vestibular compensation were studied. The correlation between the SVH and SVV was also investigated to see whether these measurements are compatible for patients. MATERIAL AND METHODS: Sixty consecutive patients were investigated 3 months before and 6 months after surgery by means of electronystagmography and SVH and SVV tests. Tumor size was measured using MRI. RESULTS: The SVH and SVV increased significantly towards the ipsilesional side postoperatively. Preoperative tilt correlated with age. Postoperative tilt correlated weakly with preoperative caloric sensitivity and inversely with tumor size. The correlation between the SVH and SVV was high both before and after surgery (r(s) > 0.74; p < 0.001). CONCLUSIONS: The long-term compensation of static tilt perception was dependent on age and not on dynamic canal functions. We propose an idiosyncrasy in the SVH and SVV compensation after unilateral vestibular deafferentation, incongruous with the general course of vestibular compensation. The results suggest a probable dependence on non-vestibular information, i.e. proprioception, in facilitating compensation of static vestibular deficits. The similarity between the SVH and SVV measurements confirms that either test can be used clinically for patients with vestibular lesions.     

Vibration-induced shift of the subjective visual horizontal: a sign of unilateral vestibular deficit.

BACKGROUND: Vibration to the head or neck excites vestibular and neck muscle spindle afferents. Can such vibrations improve the sensitivity of the subjective visual horizontal (SVH) test to chronic unilateral deficit of the vestibular system? DESIGN: Controlled experimental study. SETTING: Tertiary referral center. PATIENTS AND CONTROLS: Thirteen healthy subjects and 23 patients with chronic unilateral vestibular deficits after vestibular neurectomy or neurolabyrinthitis. Results of head-impulse test showed unilateral loss of function of all 3 semicircular canals in 14 patients and loss of anterior and lateral semicircular canals in 9 patients. INTERVENTION: Unilateral vibration (92 Hz; 0.6-mm amplitude) applied to sternocleidomastoid muscle (SCM) or mastoid bone. MAIN OUTCOME MEASURE: Results of SVH test (in degrees). RESULTS: Without vibration, 13 of 23 patients and all healthy subjects had SVH of less than 3 degrees (sensitivity, 43%; specificity, 100%). During vibration to the ipsilesional SCM, SVH increased to greater than 3 degrees in 21 of 23 patients but in only 1 of 13 healthy subjects (sensitivity, 91%; specificity, 92%). The patient group had significantly greater SVH shifts to the ipsilesional side than did healthy subjects in response to SCM and mastoid bone vibration on either side. The SVH shift during vibration to the ipsilesional SCM was significantly greater than that during vibration to the contralesional muscle (P<.001) or to the mastoid bone on either side (P<.05). The vibration-induced SVH shift was significantly greater in those patients with loss of 3 semicircular canals than in those with loss of 2 (P<.01). CONCLUSIONS: The sensitivity of the SVH test to chronic unilateral vestibular deficits can be improved by applying vibration to the SCM. The magnitude of vibratory SVH shift is related to the extent of unilateral deficit of the otolithic organs, vertical canals, or both.     

Clinical use of subjective visual horizontal and vertical in patients of unilateral vestibular neuritis.

OBJECTIVES: Subjective visual horizontal (SVH) and subjective visual vertical (SVV) used to assess otolith dysfunction and ipsilesional deviation of SVV and SVH in unilateral vestibular dysfunction is well known. The goal of this study was to investigate the clinical use of SVH/SVV and a dizziness scale in the clinical setting of acute unilateral vestibular neuritis. METHODS: Thirty-five patients with unilateral vestibular neuritis were investigated. Every patient was diagnosed by physical examination and electronystagmography. Subjective visual horizontal and SVV were assessed during the acute or subacute period; the Dizziness Handicap Inventory (DHI) and Vestibular Disorder Activities of Daily Living Scale (VADL) were used for a self-dizziness scale at the same time. All patients underwent rehabilitation therapy. Subjective visual horizontal/SVV and DHI/VADL were assessed again approximately 4 weeks later. Postrehabilitation SVH/SVV and DHI/VADL data were compared with initial data. RESULTS: Dizziness Handicap Inventory and VADL were improved after 4 weeks of rehabilitation, and the deviation toward ipsilesional side SVH and SVV was also improved. CONCLUSION: These results demonstrate that SVH and SVV correlated with clinical dizziness symptoms in patients with acute unilateral vestibular neuritis. Therefore, SVH and SVV would be useful tools for the evaluation of clinical manifestations of unilateral vestibular neuritis.     

Changes in the perceived head transversal plane and the subjective visual horizontal induced by Coriolis stimulation during gondola centrifugation

For studying the influence of the vertical semicircular canals on spatial orientation in roll, the subjective visual horizontal (SVH) and the subjective transversal plane of the head (STP) were measured in a situation where the vertical canals sense a roll-velocity stimulus while the otolith organs persistently signal that the head is upright in roll. During gondola centrifugation (resultant gravitoinertial force vector 2.5 G, gondola inclination 66 degrees) subjects were exposed to controlled rotational head movements (angular speed 27 degrees/s, magnitude 40 degrees) about the yaw (body z-) axis, produced by means of a motor-driven helmet. This causes a roll-plane Coriolis stimulus to the canals, while the otoliths persistently sense upright head position in roll. The subjects reported intense sensations of rotation and tilt in the roll plane. This was reflected in tilts of both the SVH and STP. The initial tilt of the SVH was 13.0 +/- 9.7 degrees (mean +/- S.D., n=10). The STP was changed in the opposite direction. The initial tilt was 23.8 +/- 12.2 degrees (mean +/- S.D., n=5). The changes in the SVH and STP were not of equal magnitude. A few subjects who had almost no deviations in the SVH showed pronounced tilts of the STP. The time constant for exponential decay of the tilts of the SVH and STP was on average approximately 1 minute. These findings indicate that a difference in activity of the vertical canals in the right versus left ear may cause substantial tilts of the SVH even if there is no asymmetry in the activity of the otolith system. Further, the canal stimulus may induce a tilt of the fundamental egocentric frame of reference.     

Effects of unilateral loss of vestibular function on the vestibulo-ocular reflex and postural control

Long-term recovery from surgically induced unilateral loss of vestibular function was studied in 14 patients. Seven patients underwent surgical extirpation or section of the vestibular nerve, and seven patients underwent labyrinthectomy without vestibular nerve section. The vestibulo-ocular reflex (VOR) and postural control were evaluated preoperatively and monitored for up to 4 years postoperatively with use of pseudorandom rotation (combined sinusoidal frequencies from 0.009 to 1.5 Hz) and moving platform posturography. Immediately following surgery all patients showed minimal reductions in the VOR gain constant, but marked reduction in the time constant, and marked increase in slow eye velocity bias. Bias returned to normal values within about 10 days, but time constants never returned to normal values. Results of standard Romberg tests in these patients were normal throughout the preoperative and postoperative periods. However, all patients showed marked postural control abnormalities in tests of the ability to maintain balance in unusual sensory environments in the immediate postoperative period. Seventy-five percent of the patients eventually recovered normal postural control. Postural control returned to near baseline performance with a time course similar to that of the VOR bias. However, postural control also continued to improve after the recovery of VOR bias was complete.     

Otolith mass asymmetries in the utricle and saccule of flatfish

The otolith mass of the saccules and utricles of plaice, Pleuronectes platessa (n = 39) and turbot, Psetta maxima (n = 21) was measured using an electronic microbalance. In the right-eyed plaice, the left utricular otoliths were found to be significantly heavier than the right (p < 0.0001), whereas no significant difference was found between left and right saccular otoliths (p < 0.751). In the left-eyed turbot, both the right utricular and saccular otoliths were found to be significantly heavier (in both cases, p < 0.0001). While the gene and regulative protein responsible for the peripheral biomineralisation process have been identified, it remains unclear how the symmetry between the right and left otoliths in fish species is regulated. Here it is likely that an additional central mechanism is involved. It must be assumed that similar processes govern the systematic asymmetry observed in flatfish such as the plaice and turbot. Taken together these findings are strongly suggestive of concomitant CNS modification and metamorphic plasticity, presumably represented in genetic code.