Posturography does not test vestibulospinal function

Impact of Concussions on Postural Stability Performance Using the Head Shake-Sensory Organization Test

Background

A concussion is a traumatic brain injury that can result in vestibular and oculomotor dysfunctions. The Head Shake-Sensory Organization Test was developed from the original Sensory Organization Test to measure a subject's ability to maintain balance while moving their head.

Purpose

The purpose of this study was to compare the performance of adults with no history of concussion to those with a history of concussion on the Head Shake-Sensory Organization Test to determine if long-standing balance deficits are present after concussion.

Study Design

Cross-sectional study.

Methods

Subjects with a history of concussion and healthy normal controls completed the Dizziness Handicap Inventory, the Activities-Specific Balance Confidence Scale, the sensory organization test, the head shake SOT, and the Foam Head Shake-Sensory Organization test in a single testing session. Scores were analyzed for differences between the two groups.

Results

Twenty-five participants (nine patients with history of concussion and 16 healthy controls; mean age, 21.08±4.10 years) completed testing. The equilibrium scores in both groups significantly decreased with more complex tasks. Furthermore, the concussion group had significantly worse equilibrium scores than the control group during the Head Shake (p = 0.007) and Foam Head Shake-Sensory Organization Test (p = 0.002) tasks but not during the Sensory Organization Test task.

Conclusion

Adding head shake and foam cushion conditions to postural stability tests improves sensitivity in detecting balance deficits in individuals with a concussion.

Level of Evidence

3.

Increased roll tilt thresholds are associated with subclinical postural instability in asymptomatic adults aged 21 to 84 years

Background

Balance assessments that intentionally alter the reliability of visual and proprioceptive feedback (e.g., standing on foam with eyes closed) have become a standard approach for identifying vestibular mediated balance dysfunction in older adults. However, such assessments cannot discern which specific element of the vestibular system (e.g., semicircular canal, otolith, or combined canal-otolith) underlies the observed age-related changes in balance performance. The present study was designed to determine the associations between specific sources of vestibular noise and quantitative measures of quiet stance postural control measured during standard "vestibular" balance conditions.

Methods

A group of 52 asymptomatic adults (53.21 ± 19.7, 21 to 84 years) without a history of vestibular or neurologic disorders volunteered for this study. We measured a battery of five vestibular perceptual thresholds that assay vestibular noise with predominant contributions from the vertical canals, lateral canals, utricles, saccules, and the centrally integrated canal-otolith signal. In addition, participants completed two standard balance assessments that were each designed to prioritize the use of vestibular cues for quiet stance postural control-eyes closed on foam (Condition 4 of the Modified Romberg Balance Test) and eyes closed, on a sway referenced support surface (Condition 5 of the Sensory Organization Test).

Results

In age adjusted models, we found strong positive associations between roll tilt vestibular thresholds, a measure of noise in the centrally integrated canal-otolith signal, and the root mean square distance (RMSD) of the anteroposterior and mediolateral center of pressure (CoP) captured during eyes closed stance on a sway referenced support surface. The strength of the association between roll tilt thresholds and the RMSD of the CoP was between 3-times and 30-times larger than the association between postural sway and each of the other vestibular thresholds measured.

Conclusion

We posit that noise in the centrally estimated canal-otolith "tilt" signal may be the primary driver of the subclinical postural instability experienced by older adults during the "vestibular" conditions of balance assessments. Additional testing in adults with clinical balance impairment are needed to identify if roll tilt thresholds may also serve as a surrogate metric by which to detect vestibular mediated balance dysfunction and/or fall risk.

Effect of Repetitive Administration of a Next-generation Sensory Organization Test in Adults With and Without Vestibular Dysfunction

HYPOTHESIS

The overall aim was to assess the effects of repetitive testing on performance on a next-generation Sensory Organization Test (NG-SOT).

BACKGROUND

The psychometric properties of sensory organization assessment with a next-generation posturography device are not fully characterized. Thus, a better understanding of the reliability of the NG-SOT is required to support its use as an outcome measure.

METHODS

Forty adults (20 vestibular-impaired) participated. Test-retest reliability was determined using the interclass correlation coefficient [ICC (3,1)] for the composite, somatosensory, vision, vestibular, and visual preference scores. Learning effects were assessed by analyzing the change in the composite score over time.

RESULTS

Analyzing the NG-SOT scores across all participants produced the following interclass correlation coefficients [95% confidence interval (CI)]: composite = 0.95 (0.92, 0.97), somatosensory = 0.20 (-0.06, 0.44), vision = 0.93 (0.88, 0.96), vestibular = 0.91 (0.85, 0.94), and visual preference = 0.19 (-0.07, 0.43). The mean differences (95% CI; p value) for the composite score between administrations were: 2.7 (1.0, 4.4; 0.002) for visits 1 and 2; 1.4 (-0.3, 3.1; 0.099) for visits 2 and 3; 0.7 (-1.0, 2.4; 0.403) for visits 3 and 4; and 0.4 (-1.3, 2.1; 0.653) for visits 4 and 5.

CONCLUSIONS

Test-retest reliability was excellent for the composite, vision, and vestibular scores, but it was poor for the somatosensory and visual preference scores. A learning effect for the composite score was identified, but performance was stable after two administrations. Changes in the composite score that are greater than 6.5 points exceed the measurement error for the test.

Validation of a next-generation sensory organization test in adults with and without vestibular dysfunction

BACKGROUND

The traditional Sensory Organization Test (T-SOT) is a gold standard balance test; however, the psychometric properties of assessing sensory organization with a virtual-reality-based posturography device have not been established.

OBJECTIVE

Our overall aims were to assess the criterion, concurrent, and convergent validity of a next-generation Sensory Organization Test (NG-SOT).

METHODS

Thirty-four adults (17 vestibular-impaired) participated. We compared the area under the curve (AUC) for receiver operator characteristic (ROC) analysis for the T-SOT and NG-SOT composite scores. Between-group and between-test differences for the composite and sensory analysis scores from each SOT were assessed using Wilcoxon Rank Sum tests. Additionally, we ran Spearman correlations between the NG-SOT composite score and outcomes of interest.

RESULTS

The AUCs for the NG-SOT and T-SOT were 0.950 (0.883, 1) and 0.990 (0.969, 1) respectively (p = 0.168). The median composite, vision, and visual preference scores were lower on the NG-SOT compared to the T-SOT; whereas, the median somatosensory score was higher on the NG-SOT compared to the T-SOT. Associations between the composite score and patient-reported or performance-based outcomes ranged from poor to strong.

CONCLUSIONS

The NG-SOT is a valid measure of balance in adults. However, the results of the NG-SOT and T-SOT should not be used interchangeably.

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

PURPOSE

To create an index that is a measure of the amount of vestibular compensation and for which only functional balance performance is needed.

METHODS

The 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.

RESULTS

Logistic 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.

CONCLUSION

AVeCI stages the degree of compensation of PVD patients and can serve to evaluate rehabilitation effects.

Clinical significance of head shake movement in three planes in individuals with dizziness

PURPOSE

This study aims to evaluate the efficacy of head shake movement on three head movement planes (yaw, pitch and, roll) in patients with dizziness despite normal vestibular test results.

MATERIALS AND METHODS

Twenty individuals aged between 20 and 51 years with complaints of dizziness were included in the study, and their results were compared with the results from twenty age- and gender-matched controls. Participants were assessed using the Sensory Organization Test, Head Shake-Sensory Organization Test which is based on the modification of the Sensory Organization Test on the yaw, pitch, and roll planes, videonystagmography, caloric test, and Dizziness Handicap Inventory.

RESULTS

Significant differences were found in the yaw (p = 0.007), pitch (p < 0.001), and roll (p = 0.002) planes between the study and control groups of the Head Shake-Sensory Organization Test-5 scores. There were no statistically significant differences between the two groups of the Head Shake-Sensory Organization Test-2 scores in the yaw (p = 0.448), pitch (p = 0.213), and roll (p = 0.531) planes. When the sensitivity and specificity of Head Shake-Sensory Organization Test-5 conditions were examined, the highest specificity was observed in the pitch plane (100%), followed by the yaw (95%) and roll plane (95%).

CONCLUSION

Dynamic head movements are an important parameter for the evaluation of balance performance. The head shake modification could be used effectively in three-movement planes in individuals with dizziness.

Effects of Vestibular and Balance Rehabilitation on Sensory Organization and Dizziness Handicap

This retrospective study was undertaken to assess balance recovery and dizziness handicap in 32 patients after a vestibular and balance rehabilitation program. Outcomes were compared between 12 patients with peripheral vestibular disorders and 20 patients with central or mixed balance disorders. The patients were tested with posturography (sensory organization test [SOT]) and the Dizziness Handicap Inventory (DHI) before and after their therapy program. The vestibular SOT, composite SOT, and functional DHI scores obtained before and after exercise were significantly improved in both the peripheral and central groups. The visual SOT mean scores obtained before and after therapy were significantly different only for the group with central or mixed vestibular disorders. Changes in SOT scores were not directly correlated with changes in DHI scores. Outcome measures of vestibular rehabilitation protocols confirmed objective and subjective improvement of balance and dizziness handicap in patients with peripheral and central vestibular disorders.

Clinical efficacy of the Romberg test using a foam pad to identify balance problems: a comparative study with the sensory organization test

The modified Romberg test using a foam pad ("MRuFP") as a bedside examination has been used to assess the function of the complex sensory input needed for upright stance. The objective of this study was to assess its clinical value detecting vestibular falls in comparison with the sensory organization test (SOT), the gold standard. In total, 80 patients who had undergone the MRuFP, SOT, and bithermal caloric tests were included in this study. The MRuFPs were performed on two (height 12 cm, MRu2FP) or three (18 cm, MRu3FP) layers of foam pads. The odds ratios of falling on SOT were calculated. Iterative algorithms were used for linear curve fitting between the balance time on the MRuFP and SOT equilibrium score (ES). The diagnostic performance of MRuFP under different conditions was poor, with low sensitivity (0.07-0.63), when the results of SOT were used as the gold standard. However, the odds ratios of failing SOT condition 5 were 6.78 (95% CI = 1.26-36.50) for patients with abnormal findings on eyes closed (EC)-MRu2FP and 10.91 (95% CI = 2.58-46.11) for those on the EC-MRu3FP in patients without caloric weakness. In patients with caloric weakness, the odds ratio of failing SOT condition 5 for patients with abnormal findings on EC-MRu2FP was 7.0 (95% CI = 0.69-70.74, p > 0.05), and 32.0 for those on EC-MRu3FP (95% CI = 2.81-364.7). A linear equation was presented as the model fit (adjusted R(2) = 0.355) predicting the SOT condition 5 ES according to the balance time on EC-MRu3FP. In conclusion, the EC-MRu3FP, as a bedside examination, correlated well with SOT condition 5 as an objective measure.

Vestibular deficits leading to disequilibrium and falls in ambulatory amyotrophic lateral sclerosis

OBJECTIVE

To assess vestibular deficits in response to disequilibrium in ambulatory individuals with amyotrophic lateral sclerosis (ambALS).

DESIGN

All participants completed standard protocols for the Sensory Organization Test (SOT) by computerized dynamic posturography.

SETTING

Multidisciplinary amyotrophic lateral sclerosis clinic at an academic medical center.

PARTICIPANTS

Study participants (N=34) consisted of ambALS (n=19) and healthy controls (HC) (n=15).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Equilibrium scores (ESs) obtained from averaged sway amplitude in condition 5 (ES5) and condition 6 (ES6) of the SOT.

RESULTS

In conditions of altered somatosensory information with vision absent or vision sway-referenced, the mean ± SD scores for ambALS (ES5=51.4±22.5; ES6=50.8±22.1) were lower than those for HC (ES5=65.4±11.7, P≤.03; ES6=58.9±12.5, P>.05). Seven ambALS (37%) experienced a total of 19 falls during the sway-referenced support test conditions. There were no falls in the HC.

CONCLUSIONS

Nearly 37% of ambALS with normal clinical balance testing have decreased ability to use the vestibular input and required increased reliance on visual input for postural orientation to sustain equilibrium. The mechanism of this alteration in sensory preference is not completely clear. Extrapyramidal involvement early in ALS may be indicated.

Reliability and diagnostic accuracy of clinical tests of vestibular function for children

PURPOSE

To determine reliability, diagnostic values, and minimal detectable change scores, 90% confidence (MDC90) of pediatric clinical tests of vestibular function.

METHODS

Twenty children with severe to profound bilateral sensorineural hearing loss and 23 children with typical development, aged 6 to 12 years, participated. The Head Thrust Test, Emory Clinical Vestibular Chair Test, Bucket Test, Dynamic Visual Acuity, Modified Clinical Test of Sensory Interaction on Balance, and Sensory Organization Test were completed twice for reliability. Reference standard diagnostic tests were rotary chair and vestibular evoked myogenic potential. Reliability, sensitivity, specificity, predictive values, likelihood ratios, and MDC90 scores were calculated.

RESULTS

Reliability ranged from an intraclass correlation coefficient of 0.73 to 0.95. Sensitivity, specificity, and predictive values, using cutoff scores for each test representing the largest area under the curve, ranged from 63% to 100%. The MDC90 for Dynamic Visual Acuity and Modified Clinical Test of Sensory Interaction on Balance were 8 optotypes and 16.75 seconds, respectively.

CONCLUSIONS

Clinical tests can be used accurately to identify children with vestibular hypofunction.

Spatial rotational orientation ability in standing children with cerebral palsy

This study quantified perception and reorientation ability after passive horizontal rotations in thirteen children with cerebral palsy (CP). They stood barefoot on a platform in front of a fixed reference point (static posture task, SPT) and were then blindfolded and passively rotated with six velocity profiles (maximum angular velocity: 57°/s; rotation amplitudes: ±90°, ±180° and ±360°). After the perturbation, the blindfolded children were asked to point to the fixed reference point with their preferred hand (pointing task, PT) and to step back to the initial position on the stationary platform (reorientation task, RT). In order to gain further insight into rotational attitude, the results were comparatively examined with body segment rotations determined using standardized gait analysis (gait task, GT). The kinematic evaluations were conducted using an optoelectronic system: for SPT, PT and RT we confined the analysis, in the horizontal plane, to the head and upper pointing arm of the subject and to the platform; for GT a full body analysis was performed. When CP children were passively rotated towards their more affected side, they overestimated the imposed angle in PT but under-reproduced it in RT. A higher variability emerged in left-hemiplegic children, confirming that the spatial disorganization is predominantly related to right brain lesion. Patients tended to rotate in GT towards the more affected side while in RT they showed an opposite trend.

A NOVEL MEASUREMENT SYSTEM FOR QUANTITATIVE ASSESSMENT OF AGE-RELATED SENSORI-MOTOR DEGRADATION

Early identification of individuals with impaired balancing ability could lead to timely interventions and reduce the hazard of age-related falls. Numerous methods for researching the prevention of falls and age-related sensori-motor degradation have been proposed and tested. Most are either too expensive for practitioners or too physically demanding to use with seniors. A simple, reliable technique is desired. The aim of this research is to develop a practical and quantitative solution for assessment of age-related degradation of human sensori-motor function, which could in turn serve as a means of fall prevention among seniors. A novel testing apparatus, the dynamic balance testing platform, was developed. The design includes artificial neural network (ANN) technology to address the nonlinearity and redundancy in the neural network that controls sensori-motor functions. A total of 62 male subjects aged from 18 to 84 years were tested using the proposed method. Results showed that (1) the new device did reflect the sensori-motor degradation related to age, (2) reliable evaluation of sensori-motor function need not be complicated, time consuming, or costly, and (3) the developed equipment powered with ANN technology holds great potentials for predicting fall possibility. Overall, this study validated a strategy of fall prevention with a potential for prevalent use in the healthcare industry.

Posturography with virtual reality stimulations in normal young adults with no balance complaints

PURPOSE

To analyze the findings of posturography with virtual reality stimuli carried out in young healthy adults with no otoneurological complaints, based on the parameters center of pressure, limit of stability and sway speed for different visual stimuli, and regarding differences between female and male genders.

METHODS

Participants were 50 healthy individuals of both genders (50% female and 50% male) with ages ranging from 18 to 25 years (mean age 21.30 years), with no complaints regarding body balance, and with vestibular outcomes assessed through digital vectonistagmography within normal limits. Posturography was composed of 11 visual stimuli and determined the limit of stability area (LOS), the ellipse area, and the sway speed in ten sensorial conditions. Results were calculated for the studied age range and analyzed according to the values for each stimulus, with the aim to obtain normality parameters.

RESULTS

The average values obtained in posturography regarding limit of stability, ellipse area and sway speed for stimuli with viso-vestibular interaction presented significant differences between genders, and, in all cases, women obtained lower values than men.

CONCLUSION

The findings of posturography with virtual reality stimuli in healthy young adults evidence that the parameters center of pressure, limit of stability and sway speed present differences between genders and, therefore, must be considered separately.

Balance performance in head-shake computerized dynamic posturography: aging effects and test-retest reliability

BACKGROUND

The ability of the Sensory Organization Test (SOT) to detect subtle balance problems has been challenged. The Head-Shake Sensory Organization Test (HS-SOT) has been developed to improve the delineation of balance performance.

OBJECTIVE

The purposes of this study were: (1) to examine age-related differences in balance measured with the HS-SOT and (2) to establish the test-retest reliability of the HS-SOT in younger adults who were healthy and older adults who were healthy.

DESIGN

A test-retest design was used in this observational measurement study.

METHODS

Ninety-two younger adults who were healthy (mean age=28.3 years) and 73 older adults who were healthy (mean age=60.3 years) underwent the SOT and the HS-SOT. Seventy-seven of them (56 younger adults, 21 older adults) underwent the same assessments 1 to 2 weeks later.

RESULTS

The equilibrium scores in HS-SOT conditions 2 (head movements with eyes closed while standing on a firm surface) and 5 (head movements with eyes closed while standing on a sway-referenced surface) were significantly lower than those in tests without dynamic head movements added (SOT conditions 2 and 5). Older adults attained significantly lower scores in both HS-SOT conditions than their younger peers. The test-retest reliability values, reported as intraclass correlation coefficients (ICC [3,2]), of the HS-SOT scores in conditions 2 and 5 for the younger adults were .85 and .78, respectively; those for the older adults were .64 and .55, respectively. The corresponding minimal detectable change values for the former were 2.7 and 16.2, and those for the latter were 3.6 and 22.7.

LIMITATIONS

Only head rotation movements on the horizontal plane were tested.

CONCLUSIONS

Adding head movements to the SOT increased the separation of younger adults who were healthy and older adults who were healthy. The HS-SOT has good reliability, and the reported minimal detectable change values may facilitate the interpretation of clinical studies in which the HS-SOT is used to assess changes in balance performance in younger and older adults.

Construct validity of the assessment of balance in children who are developing typically and in children with hearing impairments

BACKGROUND

Children with hearing impairments have a higher risk for deficits in balance and gross motor skills compared with children who are developing typically. As balance is a fundamental ability for the motor development of children, a valid and reliable assessment to identify weaknesses in balance is crucial.

OBJECTIVE

The purpose of this study was to investigate the construct validity of posturography and clinical balance tests in children with hearing impairments and in children who are developing typically.

METHODS

The study involved 53 children with typical development and 23 children with hearing impairments who were between 6 and 12 years of age and without neuromotor or orthopedic disorders. All participants completed 3 posturography tests (modified Clinical Test of Sensory Interaction of Balance [mCTSIB], unilateral stance, and tandem stance) and 4 clinical balance tests (one-leg stance with eyes open and with eyes closed, balance beam walking, and one-leg hopping).

RESULTS

Three conditions of the mCTSIB, unilateral stance, and 2 clinical balance tests were able to distinguish significantly between the 2 groups. Children with hearing impairments showed more difficulties in balance tasks compared with children who were developing typically when 1 or 2 types of sensory information were eliminated or disturbed. The study showed only low to moderate correlations among the different methods of evaluating balance.

CONCLUSIONS

Clinical balance tests and posturography offer different but complementary information. An assessment protocol for balance consisting of posturography and clinical balance tasks is proposed. Static and dynamic balance abilities could not be differentiated and seem not to be a valid dichotomy.

Dizziness after traumatic brain injury: Overview and measurement in the clinical setting

Traumatic brain injury (TBI) may result in a variety of cognitive, behavioural and physical impairments. Dizziness has been reported in up to 80% of cases within the first few days after injury. The literature was reviewed to attempt to delineate prevalence of dizziness as a symptom, impairments causing dizziness, the functional limitations it causes and its measurement. The literature provides widely differing estimates of prevalence and vestibular system dysfunction appears to be the best reported of impairments contributing to this symptom. The variety of results is discussed and other possible causes for dizziness were reviewed. Functional difficulties caused by dizziness were not reported for this population in the literature and review of cognitive impairments suggests that existing measurement tools for dizziness may be problematic in this population. Research on the functional impact of dizziness in the TBI population and measurement of these symptoms appears to be warranted.

Assessment of diagnostic accuracy of foam posturography for peripheral vestibular disorders: analysis of parameters related to visual and somatosensory dependence

OBJECTIVES

Simple tests to detect peripheral vestibulopathy might be practically useful before conducting elaborate examinations. The purpose of this study was to assess the diagnostic accuracy of foam posturography for peripheral vestibulopathy, with emphasis on visual and somatosensory dependence.

METHODS

Two-legged stance tasks were conducted in patients with unilateral (n=68) and bilateral (n=16) vestibulopathy and healthy controls (n=66), under four conditions; eyes open with and without the foam rubber, and eyes closed with and without the foam rubber.

RESULTS

The values of six parameters; the velocity of movement of the center of pressure (COP) and envelopment area tracing by the movement of the COP in eyes closed/foam rubber, the Romberg's ratios of velocity and area with foam rubber, and the foam ratios (ratios of a measured parameter with to without the foam rubber), of velocity and area in eyes closed, were significantly higher in unilateral and bilateral vestibulopathy compared with the control (p<0.001). The area under the receiver operating characteristic curve for the Romberg's ratio of velocity with the foam rubber was the largest.

CONCLUSIONS

Foam posturography detected high levels of visual and somatosensory dependence in patients with vestibulopathy.

SIGNIFICANCE

Foam posturography is useful for preliminary assessment of possible peripheral vestibulopathy.

Test order effects of computerized dynamic posturography and calorics

PURPOSE

To determine whether there is a test order effect of the caloric subtest of videonystagmography on the Sensory Organization Test (SOT) of computerized dynamic posturography, and to assess the learning effect of multiple posturography test sessions on the SOT score.

METHOD

Scores on the 6 SOT conditions before and after caloric testing were compared for 10 participants age 18-36 years. Four SOT sessions were completed prior to caloric testing to assess the presence of a learning effect and establish precaloric baseline SOT scores. All participants had normal vestibular systems with no history of dizziness or imbalance.

RESULTS

Caloric testing had a significant effect on the equilibrium score for only 1 of 6 test conditions. While meeting statistical significance, the actual change in score for this condition was very small. Equilibrium scores improved for the more difficult test conditions between the 1st and 2nd SOT sessions.

CONCLUSION

Results indicate that there are minimal test order effects of calorics on the SOT. Results confirm that a significant improvement in score for more challenging test conditions occurs between SOT Sessions 1 and 2 as a result of learning. Therefore, clinicians must be cautious when using posturography to monitor patient improvement.

A Comparison of Psychometric Properties of the Smart Balance Master System and the Postural Assessment Scale for Stroke in People Who Have Had Mild Stroke

OBJECTIVE

To compare the psychometric properties (including the test-retest reliability, responsiveness, and predictive validity) of the Smart Balance Master (SBM) system and the Postural Assessment Scale for Stroke patients (PASS) in patients with mild stroke.

DESIGN

One repeated-measures design (at a 2-wk interval) was used to examine the test-retest reliability of the SBM and PASS, and another similar design was applied to investigate their responsiveness. Patients who participated in the responsiveness study were followed up approximately 1 year later, and the predictive validity of the SBM system and PASS were examined by assessing the patients' comprehensive activities of daily living (ADL) function.

SETTING

Three rehabilitation units in Taiwan.

PARTICIPANTS

Twenty patients with chronic stroke in the reliability study; 40 and 32 patients who had recently had a stroke in the responsiveness and predictive validity studies, respectively.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Three computerized tests of the SBM (the equilibrium score of the Sensory Organization Test, scores in rhythmic weight-shifting tests, and scores in the limits of stability test) and the PASS were used. The combination of the Barthel Index and Frenchay Activities Index was used to represent the comprehensive ADL function.

RESULTS

For the SBM, all but the weight-shifting tests of the SBM had moderate to high reliability (intraclass correlation coefficient [ICC] range, .78-.91). The responsiveness of the equilibrium score and the limits of stability test were moderate (effect size [d], .63) and small (d range, .27-.33), respectively, whereas the responsiveness of the weight-shifting tests was limited (d range, .04-.29). All but the weight-shifting tests of the SBM in the second evaluation had acceptable predictive validity for comprehensive ADL function (r2 range, .15-.17). The PASS showed high reliability (ICC=.84) and small responsiveness (d=.41), and the PASS in the second evaluation had acceptable predictive validity (r2=.24).

CONCLUSIONS

The PASS and the equilibrium score and limits of stability scores of the SBM had acceptable test-retest reliability, responsiveness, and predictive validity in patients with mild stroke, but the psychometric properties of the weight-shifting tests of the SBM should be further examined before consideration of their usage in patients with stroke.

Comparison of subjective and objective measurements of balance disorders following traumatic brain injury

Patients with mild traumatic brain injury (TBI) often complain of dizziness. However, these problems may be undetected by a clinical exam. Therefore, the purpose of this study was to evaluate the relationships between the subjective and objective measures of balance impairment. Ten patients with TBI (6 men and 4 women) and 10 matched controls participated in this study. Average duration since the TBI was 2.8 years (range 0.4-14.4). Six of the 10 subjects with TBI had abnormal imaging studies. All subjects and controls had a normal neuromuscular exam. Tinetti Balance Assessments were obtained and the TBI group was not significantly different from the control group. The Dizziness Handicap Inventory (DHI) score supported their complaints of "unsteadiness" and "imbalance" from the subjects with TBI. The DHI score was 32 +/- 23 (range 4-68) out of a maximum possible score of 100. Balance was tested using computerized dynamic posturography. The Sensory Organization Test score was significantly lower for subjects who had a TBI (70 +/- 12) compared to the control subjects (80 +/- 8), which indicated that the subjects with TBI had poorer balance than the control subjects. A 13-link biomechanical model of the human body was used to compute the kinematics of the whole body center of mass (COM) while walking on a level surface. The subjects with TBI had significantly less displacement in the anterior/posterior direction, walked significantly slower, had significantly greater medial/lateral sway and velocity than the normal controls, and had significantly greater medial/lateral imbalance. There was a significant relationship between the physical aspects of the DHI and posturography. There was also significant relationship between the physical, functional, and total DHI and the motion of the COM. Overall, the motion of the COM predicted between 42 and 69% of the DHI score. The present study has demonstrated that objective measurements can quantify the patient's functional deficits. Therefore, these objective measurement techniques should be used to assess the clinical complaints of imbalance from patients with TBI.

Interobserver reliability in evaluating postural stability between clinicians and posturography

OBJECTIVES

To assess the interobserver reliability in assessing postural stability and to compare with results obtained by computerized posturography.

DESIGN

Cross-sectional study.

SETTING

Balance clinic, teaching hospital.

PARTICIPANTS

81 patients attending with a primary complaint of imbalance.

MAIN OUTCOME MEASURES

Inter-rater reliability between two clinicians and the modified Clinical Test for the Sensory Interaction on Balance (mCTSIB) as assessed by the Neurocom VSR Balance Master platform.

RESULTS

Inter-rater reliability scores were high (0.53-0.81) for all conditions of the mCTSIB except for the easiest, i.e. firm surface eyes open, where concordance levels were poor to fair.

CONCLUSIONS

Overall there was good agreement between observers and the computerized mCTSIB.

Use of the Head Shake-Sensory Organization Test as an Outcome Measure in the Rehabilitation of an Individual with Head Movement Provoked Symptoms of Imbalance

BACKGROUND AND PURPOSE

The purpose of this case report is to highlight the Head Shake (HS) Sensory Organization Test (SOT) (HS-SOT) as an outcome measure in the rehabilitation of a patient with head movement provoked symptoms of dysequilibrium. Despite complaints of imbalance and head movement provoked symptoms, there are individuals who are able to score within normal limits on measures such as the SOT and Berg Functional Balance Test. The HS modification to the SOT can objectively identify abnormal vestibular inputs associated with head motion and maintaining balance.

METHODS

This case report describes the examination, intervention, and outcomes for a 71-year old female with a history of imbalance and decreased ambulatory endurance. During examination, the patient presented with SOT scores within functional limits. The HS-SOT was then implemented to assess vestibular function during head motion in standing, with eyes closed. The intervention included balance retraining, dynamic gait activities, lower extremity strengthening, and instruction in a home exercise program.

RESULTS

Improvements were noted for all measures. Initially, during the HS-SOT, the patient fell during all 6 trials of the HS modification to condition 5 and her equilibrium score was 12.Posttreatment, she was able to maintain her balance in 5 out of 6 trials and her score increased to 55. The patient reported increased ambulatory endurance and independence with functional activities (ie, walking and turning her head, and stair negotiation without use of a railing).

CONCLUSIONS

The HS-SOT quantified the complaint of head movement provoked symptoms for this individual with dysequilibrium and was useful in measuring success of an intervention.

Quantitative posturography in altered sensory conditions: a way to assess balance instability in patients with chronic whiplash injury

OBJECTIVES

To quantify neck mobility and posture with and without various postural perturbations.

DESIGN

A multivariable 2-group study with repeated measures and treatments.

SETTING

A human performance laboratory.

PARTICIPANTS

Eleven patients with chronic whiplash injury (mean age, 33.3+/-6.7 y; weight, 73.4+/-11.4 kg; height, 173.3+/-7.2 cm) with a sex- and age-matched control group (mean age, 33.1+/-6.8 y; weight, 68+/-12.5 kg; height, 171.5+/-6.3 cm).

INTERVENTIONS

Neck mobility and the effects of postural perturbations affecting the visual, vestibular, cutaneous, proprioceptive, and nociceptive systems were measured.

MAIN OUTCOME MEASURES

Active range of motion, neck position sense, and postural activity.

RESULTS

We found significantly reduced neck mobility and increased postural activity in the patient group compared with the control group. In patients, there was significantly greater postural activity with eyes closed, eyes open and speaking, and eyes closed with Achilles' tendons vibrations compared with eyes open with no vibrations. In the controls, there was no significant effect of experimental muscle pain on postural activity.

CONCLUSIONS

Patients with chronic whiplash injury had a protective response to neck movement and different tuning, sequencing, and execution of the postural synergies probably because of excessive reliance on visual input despite a possible deficit and altered vestibular and/or proprioceptive activity. In healthy volunteers, the pain induced by a single bolus injection of hypertonic saline was probably too limited in intensity and spreading to decrease postural stability.

Outcomes after rehabilitation for adults with balance dysfunction

OBJECTIVES

To assess balance, dynamic gait, and dynamic visual acuity outcomes after a vestibular and balance rehabilitation program and to determine which variables were significantly associated with improved balance and ambulation.

DESIGN

Retrospective case series.

SETTING

Outpatient setting at a tertiary care facility.

PARTICIPANTS

Twenty patients who were seen for vestibular and balance therapy between July 1999 and June 2000.

INTERVENTIONS

A customized exercise program was developed for each patient according to the results of the assessment and included the following interventions, as indicated: gaze stabilization, balance and gait training, and habituation exercises.

MAIN OUTCOME MEASURES

The Dynamic Gait Index (DGI), Berg Balance Scale (BBS), Dynamic Visual Acuity Test (DVAT), and computerized post urography (Sensory Organization Test [SOT]).

RESULTS

The mean change scores for the DGI showed significant improvement for both patients with peripheral vestibular dysfunction and patients with central balance disorders. For the central balance disorders group, the BBS score also showed significant improvement. No difference was noted for pretherapy and posttherapy SOT scores between groups. The total group appeared to show an average improvement of more than 2 lines on the visual acuity chart on the clinical DVAT. Patients who were 66 years or older were 1.5 times more likely to score less than 20 on the DGI, and those whose pretherapy vertical dynamic visual acuity was 20/80 or worse were 1.3 times more likely to score less than 20 on the DGI.

CONCLUSIONS

Patients showed functional improvements in balance, visual acuity, and gait stability after balance and vestibular physical therapy. Age and pretherapy vertical dynamic visual acuity score influenced dynamic gait outcome after a balance rehabilitation program.

Artificial Neural Networks and Center-of-Pressure Modeling: A Practical Method for Sensorimotor-Degradation Assessment

Numerous methods for studying the prevention of falls and age-related sensorimotor degradation have been proposed and tested. Some approaches are too impractical to use with seniors or too expensive for practitioners. Practitioners desire a simple, reliable technique. The goals of this research were to develop such an approach and to apply it in exploring the effect of Tai Chi on age-related sensorimotor degradation. The method employed artificial-neural-network (ANN) models trained by using individuals' center-of-pressure (COP) measurements and age. Ninety-six White and Chinese adults without Tai Chi training were tested. In contrast, a third group, Chinese seniors with Tai Chi training, was tested to ascertain any influence from Tai Chi on sensorimotor aging. This study supported ANN technology with COP data as a feasible tool in the exploration of sensorimotor degradation and demonstrated that Tai Chi slowed down the effects of sensorimotor aging.

Tai Chi improves standing balance control under reduced or conflicting sensory conditions11No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated

OBJECTIVE

To investigate the effects of long-term Tai Chi practice on balance control when healthy elderly Tai Chi practitioners stood under reduced or conflicting somatosensory, visual, and vestibular conditions, as compared with healthy elderly non-Tai Chi practitioners and young subjects.

DESIGN

Cross-sectional study.

SETTING

University-based rehabilitation center in Hong Kong.

PARTICIPANTS

Twenty elderly Tai Chi practitioners (mean experience +/- standard deviation, 7.2+/-7.2 y) were compared with 20 elderly non-Tai Chi practitioners and 20 young, healthy university students.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The amplitude of anteroposterior body sway under different somatosensory, visual, and vestibular conditions was measured using computerized dynamic posturography, whereby subjects underwent 6 combinations of visual and support surface conditions.

RESULTS

The Tai Chi practitioners had significantly better balance control than the non-Tai Chi subjects in the visual and vestibular ratios, but not in the somatosensory ratio. Furthermore, there were no significant differences in any of these 3 sensory ratios when the Tai Chi practitioners were compared with those of the young, healthy subjects.

CONCLUSIONS

Long-term Tai Chi practice improved balance control in the elderly population when there was an increased reliance on the visual and vestibular systems during stance. Of particular interest is that our elderly Tai Chi practitioners attained the same level of balance control performance as did young, healthy subjects when standing under reduced or conflicting somatosensory, visual, and vestibular conditions.

Vestibular rehabilitation: useful but not universally so

OBJECTIVE

Although vestibular rehabilitation (VR) is gaining popularity, few data support its utility in improving locomotor stability, and no good predictors exist of whom will benefit most.

STUDY DESIGN AND SETTING

A double-blind, placebo-controlled randomized trial of vestibular rehabilitation was conducted at a large tertiary care hospital on 124 patients (59 +/- 18 years old) with unilateral (n = 51) or bilateral (n = 73) vestibular hypofunction, of whom 86 completed a 12-week intervention. Of these 86, 27 returned for long-term (1-year) follow-up testing. The primary outcome measure was locomotor stability.

RESULTS

Group A (6 weeks of VR) significantly (P < 0.01) increased their gait velocity and stability compared with group B (6 weeks of strengthening exercise), but there was a smaller difference (P = 0.05) between groups at 12 weeks, when both had had VR; there were no group differences at 1 year. Of the 86 who completed the intervention, 52 (61%) had clear locomotor gains.

CONCLUSION AND SIGNIFICANCE

VR is helpful for most patients in providing locomotor stability, but further work is needed to determine the factors that prevent VR from being effective for all patients with vestibulopathy.

Trunk sway measures of postural stability during clinical balance tests: effects of a unilateral vestibular deficit

This research evaluated whether quantified measures of trunk sway during clinical balance tasks are sensitive enough to identify a balance disorder and possibly specific enough to distinguish between different types of balance disorder. We used a light-weight, easy to attach, body-worn apparatus to measure trunk angular velocities in the roll and pitch planes during a number of stance and gait tasks similar to those of the Tinetti and CTSIB protocols. The tasks included standing on one or two legs both eyes-open and closed on a foam or firm support-surface, walking eight tandem steps, walking five steps while horizontally rotating or pitching the head, walking over low barriers, and up and down stairs. Tasks were sought, which when quantified might provide optimal screening for a balance pathology by comparing the test results of 15 patients with a well defined acute balance deficit (sudden unilateral vestibular loss (UVL)) with those of 26 patients with less severe chronic balance problems caused by a cerebellar-pontine-angle-tumour (CPAT) prior to surgery, and with those of 88 age- and sex-matched healthy subjects. The UVL patients demonstrated significantly greater than normal trunk sway for all two-legged stance tasks especially those performed with eyes closed on a foam support surface. Sway was also greater for walking while rotating or pitching the head, and for walking eight tandem steps on a foam support surface. Interestingly, the patients could perform gait tasks such as walking over barriers almost normally, however took longer. CPAT patients had trunk sway values intermediate between those of UVL patients and normals. A combination of trunk sway amplitude measurements (roll angle and pitch velocity) from the stance tasks of standing on two legs eyes closed on a foam support, standing eyes open on a normal support surface, as well as from the gait tasks of walking five steps while rotating, or pitching the head, and walking eight tandem steps on foam permitted a 97% correct recognition of a normal subject and a 93% correct recognition of an acute vestibular loss patient. Just over 50% of CPAT patients could be classified into a group with intermediate balance deficits, the rest were classified as normal. Our results indicate that measuring trunk sway in the form of roll angle and pitch angular velocity during five simple clinical tests of equilibrium, four of which probe both stance and gait control under more difficult sensory conditions, can reliably and quantitatively distinguish patients with a well defined balance deficit from healthy controls. Further, refinement of these trunk sway measuring techniques may be required if functions such as preliminary diagnosis rather than screening are to be attempted.

Balance control near the limit of stability in various sensory conditions in healthy subjects and patients suffering from vertigo or balance disorders: impact of sensory input on balance control

The large inter-individual variability within the normal population, the limited reproducibility due to habituation or fatigue, and the impact of instruction and the subject's motivation, all constitute a major problem in posturography. These aspects hinder reliable evaluation of the changes in balance control in the case of disease and complicate objectivation of the impact of therapy and sensory input on balance control. In this study, we examine whether measurement of balance control near individualized limits of stability and under very challenging sensory conditions might reduce inter- and intra-individual variability compared to the well-known Sensory Organization Test (SOT). To do so, subjects balance on a platform on which instability increases automatically until body orientation or body sway velocity surpasses a safety limit. The maximum tolerated platform instability is then used as a measure for balance control under 10 different sensory conditions. Ninety-seven healthy subjects and 107 patients suffering from chronic dizziness (whiplash syndrome (n = 25), Meniere's disease (n = 28), acute (n = 28) or gradual (n = 26) peripheral function loss) were tested. In both healthy subjects and patients this approach resulted in a low intra-individual variability (< 14.5(%). In healthy subjects and patients, balance control was maximally affected by closure of the eyes and by vibration of the Achilles' tendons. The other perturbation techniques applied (sway referenced vision or platform, cooling of the foot soles) were less effective. Combining perturbation techniques reduced balance control even more, but the effect was less than the linear summation of the effect induced by the techniques applied separately. The group averages of healthy subjects show that vision contributed maximum 37%, propriocepsis minimum 26%, and labyrinths maximum 44% to balance control in healthy subjects. However, a large inter-individual variability was observed. Balance control of each patient group was less than in healthy subjects in all sensory conditions. Similar to healthy subjects, patients also show a large inter-individual variability, which results in a low sensitivity of the test. With the exception of some minor differences between Whiplash and Meniere patients, balance control did not differ between the four patient groups. This points to a low specificity of the test. Balance control was not correlated with the outcome of the standard vestibular examination. This study strengthens our notion that the contribution of the sensory inputs to balance control differs considerably per individual and may simply be due to differences in the vestibular function related to the specific pathology, but also to differences in motor learning strategies in relation to daily life requirements. It is difficult to provide clinically relevant normative data. We conclude that, like the SOT, the current test is merely a functional test of balance with limited diagnostic value.