Modified head shake sensory organization test: Sensitivity and specificity

Normative Values for the Head Shake Sensory Organization Test in an Active Duty Military Cohort

INTRODUCTION

The Head Shake Sensory Organization Test (HS-SOT) assesses postural stability while the head is moving and may also identify deficits in attention associated with the dual task conditions of moving the head at a specified speed while maintaining balance. Normative values for the HS-SOT have not been established in a healthy military population or other highly trained populations such as athletes. Establishing normative values in a military population will enable clinicians to compare the scores of patients with medical conditions that affect postural stability and sensory integration such as concussion or traumatic brain injury, vestibular dysfunction, or migraine to those of a healthy population to determine a need for intervention and for return to duty considerations. The purposes of this cross-sectional study were to establish normative values for the HS-SOT within the military population, to determine whether HS-SOT scores differed between men and women or among age groups, and to determine whether HS-SOT scores differed from scores on similar conditions of the Sensory Organization Test (SOT).

MATERIALS AND METHODS

Active duty service members (n = 237, 54 female) at Joint Base Lewis-McChord, Washington, Fort Campbell, Kentucky, and the National Capitol Region (Washington, D.C, Maryland, and Virginia) completed the SOT and HS-SOT on the NeuroCom® Balance Master™. Parametric and non-parametric comparisons were analyzed for the equilibrium scores for the SOT and HS-SOT conditions 2 (SOT-2, HS-SOT-2, respectively) and 5 (SOT-5, HS-SOT-5, respectively) and the equilibrium score ratios (ESRs) for HS-SOT-2 and HS-SOT-5 for the total sample, men and women, and age group categories (18-26 years, 27-35 years, and 36-45 years).

RESULTS

There were no differences in HS-SOT-2 or HS-SOT-5 equilibrium ratio scores between men (0.99 ±.029 and 0.83 ±0.25, respectively) and women (1.00 ±0.03 and 0.81 ±0.21, respectively). There were no differences in the SOT-2 equilibrium scores (F = 2.29, P = 0.10) or SOT-5 equilibrium scores (Kruskal-Wallis H = 3.26, P = 0.20) among the different age groups. SOT-2 equilibrium scores were higher than the HS-SOT-2 equilibrium scores (Z = -4.10, P < 0.001). SOT-5 equilibrium scores were also higher than HS-SOT-5 equilibrium scores (Z = -12.22, P < 0.001), and the HS-SOT-2 and HS-SOT-5 equilibrium scores differed from each other (Z = -13.26, P < 0.001).

CONCLUSIONS

This study established normative values for the HS-SOT in a military population. Equilibrium scores did not differ between men and women or among age groups, suggesting that these values can be used as reference points for most service members. Postural stability was found to be significantly challenged during head motion, indicating the HS-SOT is a valuable tool for identifying subtle impairments in postural stability. These findings have important implications for early detection and intervention in individuals with medical conditions affecting balance, particularly concussions or vestibular disorders.

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.

A modified two-dimensional sensory organization test that assesses both anteroposterior and mediolateral postural control

Background

The Sensory Organization Test (SOT) was designed to measure changes in postural control in response to unreliable visual and/or proprioceptive feedback. However, secondary to the manipulation of sensory cues in only the sagittal plane, the SOT is capable of only describing postural control in a single direction. The present study aimed to characterize postural responses to a modified SOT designed to concurrently challenge both anteroposterior and mediolateral postural control.

Methods

Twenty-one healthy adult volunteers (30.6 ± 10.2 years) completed the standard anteroposterior one-dimensional (1D) SOT, in addition to a modified SOT with the support surface sway-referenced to both anteroposterior and mediolateral postural sway (two-dimensional, 2D). Our primary analysis concerned a comparison of mediolateral, as well as anteroposterior postural sway measured during the standard one-dimensional (i.e., pitch tilt) and the novel two-dimensional (i.e., roll and pitch tilt) sway-referenced paradigms. Here, postural sway was quantified by calculating the root mean square distance (RMSD) of the center of pressure (CoP) during each trial.

Results

Our data showed that the 2D sway-referenced conditions yielded a selective increase in mediolateral postural sway relative to the standard 1D conditions for both wide (η2 = 0.66) and narrow (η2 = 0.78) stance conditions, with anteroposterior postural sway being largely unaffected (η2 = 0.001 to 0.103, respectively). The ratio between mediolateral postural sway in the sway-referenced conditions and postural sway in the corresponding stable support surface conditions was greater for the 2D (2.99 to 6.26 times greater) compared to 1D paradigms (1.25 to 1.84 times greater), consistent with a superior degradation of viable proprioceptive feedback in the 2D paradigm.

Conclusion

A modified 2D version of the SOT was shown to provide a greater challenge to mediolateral postural control relative to the standard 1D SOT protocol, putatively as a result of a superior capacity to degrade proprioceptive feedback in the mediolateral direction. Given these positive findings, future studies should investigate the clinical utility of this modified SOT as a means by which to better characterize sensory contributions to postural control in the presence of various sensorimotor pathologies, including vestibular hypofunction.

Investigation of Head Shake Sensory Organization Test (HS-SOT) in three planes: Test-retest reliability and age-related differences

BACKGROUND

In recent years, it has been determined that SOT sensitivity is insufficient in patients who develop vestibular compensation and therefore the Head Shake Sensory Organization Test (HS-SOT) has been developed.

RESEARCH QUESTION

How differs the balance performance of healthy adults that is tested with HS-SOT according to age and test planes? What is the test-retest reliability level of the HS-SOT in three planes?

METHODS

Our prospective study, which has a methodological research design, included 80 participants divided into three groups by age range (Group 1: 20-39 years (n = 30); Group 2: 40-49 years (n = 30) and Group 3: 50-64 years (n = 20)). SOT and HSSOT ( yaw, pitch, roll) were performed to all participants. To investigate the testretest reliability of the HS-SOT, a total of 27 participants were re-evaluated one week later. The HS-SOT performance of the participants was compared between age groups and test planes. Intra-class correlation coefficient and minimum detectable change values (MDC) was calculated to test-retest reliability of HS-SOT.

RESULTS

HS-SOT scores (HS-2 and HS-5) did not differ significantly between age groups. The balance performance of individuals for the pitch plane was lower than other planes. Only the HS-5 score showed a significant difference between the sessions. HS-5 scores were higher in the re-test; for the first group in the pitch plane and for the third group in the yaw plane. The test-retest reliability level of these conditions was "moderate-good" for both groups. The corresponding MDC value was highest (14.01) for the HS-5 (yaw) score of the elderly group.

SIGNIFICANCE

The findings from this study demonstrated that the test plane influences the HS-SOT, a learning/practice effect may occur because of repeated HS-SOT evaluation, and this effect is more explicit in the elderly. This study provides a perspective for the evaluation and follow-up processes of patients with balance problems.

Conversational head movement decreases close-contact exposure to expired respiratory droplets

People constantly move their heads during conversation, as such movement is an important non-verbal mode of communication. Head movement alters the direction of people's expired air flow, therefore affecting their conversational partners' level of exposure. Nevertheless, there is a lack of understanding of the mechanism whereby head movement affects people's exposure. In this study, a dynamic meshing method in computational fluid dynamics was used to simulate the head movement of a human-shaped thermal manikin. Droplets were released during the oral expiration periods of the source manikin, during which it was either motionless, was shaking its head or was nodding its head, while the head of a face-to-face target manikin remained motionless. The results indicate that the target manikin had a high level of exposure to respiratory droplets when the source manikin was motionless, whereas the target manikin's level of exposure was significantly reduced when the source manikin was shaking or nodding its head. The source manikin had the highest level of self-exposure when it was nodding its head and the lowest level of self-exposure when its head was motionless. People's level of exposure during close contact is highly variable, highlighting the need for further investigations in more realistic conversational scenarios.

Postural control in Chiari I malformation: protocol for a paediatric prospective, observational cohort - potential role of posturography for surgical indication

INTRODUCTION

Chiari I malformation (CM1) is an anatomical abnormality characterised by the cerebellar tonsils descending at least 5 mm below the foramen magnum. CM1 causes obstruction of cerebrospinal fluid (CSF) circulation as well as direct compression on the brainstem, thus causing typical consequences (syringomyelia), and typical clinical features (characteristic headaches and neurological impairment). Surgery is the only available treatment, indicated when symptomatology is present. However, sometimes patients have atypical complaints, which are often suggestive of otolaryngological (ears, nose and throat, ENT) involvement. This may be difficult for a neurosurgeon to explain. Our study aims to investigate the relationship between one of these atypical symptoms, for example, postural instability, in a paediatric population using a Computerised Dynamic Posturography (Equitest, NeuroCom, Clackamas, OR). To our knowledge, there are no previously published studies carried out on children with CM1, using dynamic posturography.

METHODS AND ANALYSIS

Forty-five children aged 6-18 years old presenting with radiologically confirmed CM1 and presenting ENT clinical complaints will be included in the study for a duration of 3 years. As primary endpoint, posturographic results will be described in the population study. Second, posturographic results will be compared between patients with and without indication for surgery. Finally, preoperative and postoperative posturographic results, as well as CSF circulation quality at foramen magnum level, syringomyelia, sleep apnoea syndrome, scoliosis and behaviour will be compared in the operated patient group.

ETHICS AND DISSEMINATION

This protocol received ethical approval from the Clinical Research Delegation of Nancy University Hospital, in accordance with the National Commission on Informatics and Liberties (Commission Nationale de l'Informatique et des Libertés) (protocol number 2019PI256-107). Our data treatment was in accordance with the Methodology of reference Methodology Reference-004 specification for data policy. The study findings will be disseminated via peer-reviewed publications and conference presentations, especially to the Neurosphynx's rare disease healthcare network.

TRIAL REGISTRATION NUMBER

NCT04679792; Pre-results.

Test-Retest Reliability of Postural Control Assessment on Biodex BioSway™

Background

Recent protocols for posturographic assessment of postural control and balance have included head shake test conditions to challenge the vestibular contributions of postural control in an effort to increase the diagnostic accuracy of identifying individuals with impaired balance. However, evidence is limited regarding the test-retest reliability of such assessment protocols.

Purpose

The purpose of this study was twofold: to determine the test-retest reliability of postural control assessment on the Biodex Biosway™, an accessible and field expedient tool for posturographic assessment, and to determine the test-retest reliability of the Head Shake Sensory Interaction and Balance Test (HS-SIB), an adaptation of the modified Clinical Test of Sensory Interaction and Balance (mCTSIB) which adds two head shake conditions to challenge the vestibular contributions to postural control. Study Design. This was a correlational time series cohort study completed in a biomechanics laboratory.

Methods

The sample consisted of nineteen healthy adults (10 females, 9 males). Sway Index, Equilibrium Score, and the area of the ellipse enclosing 95% of the anterior-posterior (AP) and medial-lateral (ML) center of gravity (COG) displacement (AREA₉₅) are the 3 summary variables. Standard Error of Measurement (SEM) and Minimum Detectable Change (MDC) are also reported.

Results

Test-retest reliability was generally poor with limited exceptions. Moderate to good reliability was observed for the more challenging stance conditions (ICC range 0.58-0.81), including those with head shake.

Conclusions

Field-expedient systems, such as the Biodex BioSway™, may offer reliable posturographic testing where gold-standard methods are not available. Clinicians should be aware that less demanding test conditions have limited reliability; however, test-retest reliability of this assessment tool is improved with more challenged stance conditions and the inclusion of a head shake task.

Vestibular Rehabilitation for Peripheral Vestibular Hypofunction: An Updated Clinical Practice Guideline From the Academy of Neurologic Physical Therapy of the American Physical Therapy Association

Background:

Uncompensated vestibular hypofunction can result in symptoms of dizziness, imbalance, and/or oscillopsia, gaze and gait instability, and impaired navigation and spatial orientation; thus, may negatively impact an individual's quality of life, ability to perform activities of daily living, drive, and work. It is estimated that one-third of adults in the United States have vestibular dysfunction and the incidence increases with age. There is strong evidence supporting vestibular physical therapy for reducing symptoms, improving gaze and postural stability, and improving function in individuals with vestibular hypofunction. The purpose of this revised clinical practice guideline is to improve quality of care and outcomes for individuals with acute, subacute, and chronic unilateral and bilateral vestibular hypofunction by providing evidence-based recommendations regarding appropriate exercises.

Methods:

These guidelines are a revision of the 2016 guidelines and involved a systematic review of the literature published since 2015 through June 2020 across 6 databases. Article types included meta-analyses, systematic reviews, randomized controlled trials, cohort studies, case-control series, and case series for human subjects, published in English. Sixty-seven articles were identified as relevant to this clinical practice guideline and critically appraised for level of evidence.

Results:

Based on strong evidence, clinicians should offer vestibular rehabilitation to adults with unilateral and bilateral vestibular hypofunction who present with impairments, activity limitations, and participation restrictions related to the vestibular deficit. Based on strong evidence and a preponderance of harm over benefit, clinicians should not include voluntary saccadic or smooth-pursuit eye movements in isolation (ie, without head movement) to promote gaze stability. Based on moderate to strong evidence, clinicians may offer specific exercise techniques to target identified activity limitations and participation restrictions, including virtual reality or augmented sensory feedback. Based on strong evidence and in consideration of patient preference, clinicians should offer supervised vestibular rehabilitation. Based on moderate to weak evidence, clinicians may prescribe weekly clinic visits plus a home exercise program of gaze stabilization exercises consisting of a minimum of: (1) 3 times per day for a total of at least 12 minutes daily for individuals with acute/subacute unilateral vestibular hypofunction; (2) 3 to 5 times per day for a total of at least 20 minutes daily for 4 to 6 weeks for individuals with chronic unilateral vestibular hypofunction; (3) 3 to 5 times per day for a total of 20 to 40 minutes daily for approximately 5 to 7 weeks for individuals with bilateral vestibular hypofunction. Based on moderate evidence, clinicians may prescribe static and dynamic balance exercises for a minimum of 20 minutes daily for at least 4 to 6 weeks for individuals with chronic unilateral vestibular hypofunction and, based on expert opinion, for a minimum of 6 to 9 weeks for individuals with bilateral vestibular hypofunction. Based on moderate evidence, clinicians may use achievement of primary goals, resolution of symptoms, normalized balance and vestibular function, or plateau in progress as reasons for stopping therapy. Based on moderate to strong evidence, clinicians may evaluate factors, including time from onset of symptoms, comorbidities, cognitive function, and use of medication that could modify rehabilitation outcomes.

Discussion:

Recent evidence supports the original recommendations from the 2016 guidelines. There is strong evidence that vestibular physical therapy provides a clear and substantial benefit to individuals with unilateral and bilateral vestibular hypofunction.

Limitations:

The focus of the guideline was on peripheral vestibular hypofunction; thus, the recommendations of the guideline may not apply to individuals with central vestibular disorders. One criterion for study inclusion was that vestibular hypofunction was determined based on objective vestibular function tests. This guideline may not apply to individuals who report symptoms of dizziness, imbalance, and/or oscillopsia without a diagnosis of vestibular hypofunction.

Disclaimer:

These recommendations are intended as a guide to optimize rehabilitation outcomes for individuals undergoing vestibular physical therapy. The contents of this guideline were developed with support from the American Physical Therapy Association and the Academy of Neurologic Physical Therapy using a rigorous review process. The authors declared no conflict of interest and maintained editorial independence.

Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A369).

A comparison of head movements tests in force plate and accelerometer based posturography in patients with balance problems due to vestibular dysfunction

This study compares HS posturography on inertial sensors (MediPost) with force platform posturography in patients with unilateral vestibular dysfunction. The study group included 38 patients (age 50.6; SD 11.6) with unilateral vestibular weakness (UV) and 65 healthy volunteers (48.7; SD 11.5). HS tests were performed simultaneously on the force plate and with MediPost sensor attached at L4. Four conditions applied: eyes open/closed, firm/foam. The tests were performed twice, with the head moving at the frequency of 0.3 Hz (HS 0.3) and 0.6 Hz (HS 0.6). Mean sway velocity was significantly lower for MediPost than force plate in 4th condition both in UV and healthy group. For HS 0.3 the differences between devices were marginal; the highest sensitivity (87%) and specificity (95%) were in 4th condition. For HS 0.6 MediPost revealed lower sensitivity than force plate although the surface parameter improved results. MediPost IMU device and force platform posturography revealed a similar ability to differentiate between patients with balance problems in course of vestibular pathology and healthy participants, despite the differences observed between measuring methods. In some tests surface parameter may be more appropriate than sway velocity in improving MediPost sensitivity.

Compensatory image of the stability of people with multiple sclerosis and atrial vertigo based on posturography examination

Pathophysiology of balance disorders due to multiple sclerosis (MS) and atrial vertigo (AV) is different. We evaluated posture stability when maintaining balance in people with MS presenting symptoms of ataxia and those with AV. We included 45 women (15 with MS; 15 with AV; 15 controls). A posturography platform was used to measure balance parameters. To characterize the image of stability and the compensation of balance disorders, the surface area of the stabilogram (SAS), vision control index (VCI) and the vision-motion control index (VMCI) were used. The stability image of people with MS and AV with eyes open (p = 0.002), with eyes closed (p = 0.080) and with visual biofeedback (p = 0.0008) differed significantly. SAS depended on visual biofeedback regardless of the occurrence of balance disorders and was the basis for determining the compensatory share of vision-motor coordination. Differences in VCI between groups were insignificant. VMCI was significantly higher in people with balance disorders than in those without, but similar in the MS and AV groups. The image of stability is different in people with MS and AV. Thanks to visual biofeedback, it becomes possible to launch effective vision-motor coordination when compensating balance disorders. VCI may become the measure of compensation for balance disorders.

Posturography with head movements in the assessment of balance in chronic unilateral vestibular lesions

The aim of our study was to validate the method of head-shake static posturography (HS-posturography) in healthy individuals and to establish the value of this novel method in the diagnostics of patients with unilateral vestibular lesion (UV). The study included 202 participants divided into two groups, one consisting of 133 patients with canal paresis CP > 19% and one of 69 healthy subjects. Participant was tested according to the standard protocol of static posturography (SP), and with head movements of 0.3 Hz (HS 40), 0.6 Hz (HS 70) in random order controlled by a metronome. HS-posturography revealed a similar repeatability and internal consistency as the standard posturography. In patients with UV, 4th condition revealed higher sensitivity (74%) and specificity (71%) in HS 40 than in the standard posturography (67%, 65% respectively) and HS 70 (54%, 70% respectively). Static posturography and HS- posturography revealed a high reliability of the testing method. The head movements added to static posturography improve the sensitivity and specificity of the method in group with vestibular impairment. The most important test for that purpose seems to be the one on unstable surface with the eyes closed, with low frequency of head movements.

Measuring Vestibular Contributions to Age-Related Balance Impairment: A Review

Aging is associated with progressive declines in both the vestibular and human balance systems. While vestibular lesions certainly contribute to imbalance, the specific contributions of age-related vestibular declines to age-related balance impairment is poorly understood. This gap in knowledge results from the absence of a standardized method for measuring age-related changes to the vestibular balance pathways. The purpose of this manuscript is to provide an overview of the existing body of literature as it pertains to the methods currently used to infer vestibular contributions to age-related imbalance.

The Nintendo® Wii Fit Balance Board can be used as a portable and low-cost posturography system with good agreement compared to established systems

Background

Almost all epidemiological studies over the past 40 years have determined that the incidence of fragility fractures is increasing. Therefore, the assessment of postural stability and monitoring any progress during balance training for geriatric patients to prevent falls are becoming more important. The Nintendo^® Wii Fit Balance Board, with its integrated software and scoring system, might be a cheap and easily accessible tool for this purpose.

Methods

This prospective study analyzed the diagnostic value of the Wii Fit Balance Board in 41 healthy subjects using two measurements: the yoga task “tree,” which is performed in one-leg stance; and the balance game “table tilt.” Our investigation compared these tasks to two established, regularly used systems, the MFT-S3 Check and the Posturomed, by looking for correlation and agreement, using Bland–Altman plots, as well as for differences to demographic data. All measurement tools were also compared to the Sensory Organization Test—the gold standard for detecting impaired balance.

Results

We found a moderate correlation between the yoga exercise “tree” and the Sensory Organization Test (correlation coefficient r = 0.514, p = 0.001) as well as the MFT-S3 Check (r = 0.356–0.472, p = 0.002–0.022) and the Posturomed (r = 0.345, p = 0.027). However, results from the balance game “table tilt” did not show a significant correlation with those of the systems to which we compared it (p = 0.301–0.953).

Conclusions

According to the literature, the raw data from the Wii Fit Balance Board are comparable to that obtained by laboratory-grade force platforms. We have found, however, that the yoga pose “tree,” as integrated into the Nintendo^® Wii Fit Balance Board with its own scoring system, also correlates with the gold-standard Sensory Organization Test. It also correlates with two frequently used diagnostic and therapeutic devices. We, therefore, conclude that the Wii Fit Balance Board is suitable for the evaluation of postural stability and may be useful in preventing falls among the geriatric population.

Level of evidence

2b.

Preliminary study on an added vestibular-ocular reflex visual conflict task for postural control

BACKGROUND

Using the modified-Clinical Test of Sensory Integration and Balance (m-CTSIB), clinicians can assess sensory feedback systems of the visual, vestibular, and somatosensory systems on postural control. However, with growing vestibulo-ocular reflex (VOR) assessment, the addition of a VOR task, for sensory feedback on postural control has yet to be investigated.

AIM

The aim of the study was to examine the preliminary effect of an added VOR visual conflict task during postural control conditions of the m-CTSIB at baseline and re-test reliability.

METHODS

Seventeen healthy college-aged individuals completed a baseline m-CTSIB with an added VOR visual conflict condition consisting of a lateral headshake and follow-up assessment occurring 72-h after baseline. Measures consisted of m-CTSIB sway scores on individual conditions of eyes open and eyes closed tasks on firm and foam surfaces. A series of Wilcoxon matched-pairs signed-rank tests were conducted to determine the differences between the VOR condition and the m-CTSIB conditions. A Spearman Rank Order correlation was used to examine the retest reliability.

RESULTS

The VOR visual conflict task condition produced worse sway index scores than eyes-open firm and foam (p<0.001), but better scores than eyes-closed foam (P=0.01) conditions at baseline. VOR tasks on their respective firm (r_s=0.81) and foam surface (r_s=0.83) were strongly correlated at 72-h retest.

CONCLUSIONS

The addition of a VOR visual conflict task condition differed from the other conditions of the m-CTSIB, further targeting the vestibular-ocular system from the vestibular-spinal system during postural control. Incorporating a VOR task during postural stability may create greater postural control deficits in individuals with vestibular-ocular dysfunction. Test-retest correlations at 72-h were clinically acceptable.

RELEVANCE FOR PATIENTS

Addition of a VOR task as visual conflict condition of the m-CTSIB may assist in additional sensory system feedback for concussion assessment.

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.

Vestibular training promotes adaptation of multisensory integration in postural control

BACKGROUND

Postural stability depends on the integration of the multisensory system to produce motor outputs. When visual and somatosensory input is reliable, this reduces reliance on the vestibular system. Despite this, vestibular loss can still cause severe postural dysfunction. Training one or more of the three sensory systems through vestibular habituation and adaptation can alter sensory weighting and change postural behavior.

AIM

The purpose of this study was to assess sensory reweighting of postural control processing after combined vestibular activation with voluntary weight shift training in healthy adults.

METHODS

Thirty-three healthy individuals (18-35 y.o.) were randomly assigned to one of three groups: No training (control), visual feedback weight shift training (WST) coupled with an active horizontal headshake (HS) activity to elicit a vestibular perturbation, or the same WST without HS (NoHS). Training was performed 2x/day, every other day (M, W, F), totaling six sessions. Pre- and post- assessments on the Sensory Organization Test (SOT) were performed. Separate between- and within- repeated measures ANOVAs were used to analyze the six SOT equilibrium scores, composite scores, sensory ratios and center of pressure (COP) variables by comparing baseline to post-training. Alpha level was set at p < .05.

RESULTS

There was a significant group x session x condition change (p = .012) in the COP multiscale entropy (MSE) velocity sway in the HS group during SOT conditions 5 and 6. Similarly, COP medio-lateral standard deviation sway (ML Std) showed group x session x visual condition (p = .028), due to HS in condition 6 relative to other two groups.

CONCLUSION

Postural training can alter sensory organization after a visual feedback-vestibular activation training protocol, suggesting a possible sensory reweighting through vestibular adaptation and/or habituation.

SIGNIFICANCE

Translating these findings into a vestibular-impaired population can stimulate the design of a rehabilitation balance protocol.

Critical Role of Somatosensation in Postural Control Following Spaceflight: Vestibularly Deficient Astronauts Are Not Able to Maintain Upright Stance During Compromised Somatosensation

The free-fall of orbital spaceflight effectively removes the gravitational vector used as a primary spatial orientation reference on Earth. Sustained absence of this reference drives adaptive changes in the internal perception-action models of the central nervous system (CNS), most notably in the processing of the vestibular otolith inputs. Upon landing, the return of the gravitational signal triggers a re-adaptation that restores terrestrial performance; however, during this period, the individual suffers from a functional vestibular deficiency. Here we provide evidence of a transient increase of the weighting of somatosensory inputs in postural control while the CNS resolves these vestibular deficiencies. Postural control performance was measured before and after spaceflight in 11 Shuttle astronauts and 11 matched controls and nine elderly who did not experience spaceflight. A quiet-stance paradigm was used that eliminated vision, modulated the lower extremity somatosensory cues by subtly modulating the orientation of the support surface beneath feet of subjects in all groups. Additionally, in astronauts and matched controls, we challenged the vestibular system with dynamic head tilts. Postural stability on the landing day (R+0) was substantially decreased for trials with absent visual and altered somatosensory cues, especially those also requiring dynamic head tilts ( ± 5° @ 0.33 Hz) during which 20/22 trials ended prematurely with a fall. In contrast, none of the astronauts fell during eyes-closed, dynamic head tilt trials with unaltered somatosensory cues, and only 3/22 trials resulted in falls with eyes-closed and altered somatosensory cues, but static upright head orientation. Furthermore, postural control performance of astronauts was either statistically not different or worse than that of healthy elderly subjects during the most challenging vestibular conditions on R+0. Overall, our results demonstrate a transient reweighting of sensory cues associated with microgravity-induced vestibular deficiencies, with a significant increase in reliance on somatosensory cues, which can provide an effective reference even without vision and with dynamic vestibular challenges. The translation of these results to aging population suggests that elderly individuals with visual and vestibular deficits may benefit from therapeutic interventions enhancing sensorimotor-integration to improve balance and reduce the risk of falling.

Association between the Unterberger-Fukuda test and vectoelectronystagmography

ABSTRACT Purpose: to study and characterize anteroposterior and angular deviations in the Unterberger-Fukuda Test (UFT) in relation to the results of the caloric tests in patients complaining of dizziness or vertigo. Methods: 44 subjects-men and women between 20 and 79 years of age-who had symptoms of vertigo or dizziness and had been referred for vectoelectronystagmography were examined. The exclusion criteria were gait difficulties arising from orthopedic and/or spinal disorders, and syndromes or neurological diseases that affect balance. Two procedures were performed: vectoelectronystagmography and UFT. Results: the caloric test showed that 25.00% of the patients had hyporeflexia-the most frequent result. In the open-eyes UFT, only 2.30% presented altered results in anteroposterior displacement. In the closed-eyes test, the equivalent value was 31.80%. Anteroposterior deviation showed a greater correlation with age than the angular one. Abnormal results in the caloric test were associated with the UFT. Conclusion: the results of the closed-eyes UFT were associated with the caloric test. Anteroposterior deviation was correlated with age, while angular deviation was not.