Is posturography able to identify fallers in patients with Parkinson's disease?

The psychometric properties of the modified fear of falling avoidance behavior questionnaire in Parkinson's disease and older adults

Introduction

The Fear of Falling Avoidance Behavior Questionnaire (FFABQ) has good psychometric properties. However, we have recently modified the FFABQ (mFFABQ) to improve the clarity of the questions and Likert responses. This study aimed to examine the reliability and validity of this modified version in older adults and people with Parkinson's disease (PD).

Methods

A total of 88 participants, 39 with PD (age = 72.2 ± 9.5; 29 males, 10 females) and 49 older adults (age = 72.8 ± 5.0; 13 males, 36 females), answered the mFFABQ twice, separated by 1 week, for test-retest reliability. Construct validity was evaluated through correlational analyses with fall history, Activities-Specific Balance Confidence Scale (ABC), Berg Balance Scale (BBS), Timed Up and Go, 30-Second Sit to Stand, Sensory Organization Test, Zung Anxiety Scale, Beck Depression Inventory, Consequences of Falling Questionnaire (CoFQ), and average daily activity levels using an activity monitor.

Results

The mFFABQ had good overall test-retest reliability (intraclass correlational coefficient [ICC] = 0.822; older adult ICC = 0.781, PD ICC = 0.806). The mFFABQ correlated with fall history (r = -0.430) and exhibited high correlation with the ABC (rho = -0.804) and moderate correlations with CoFQ (rho = 0.582) and BBS (rho = -0.595). The mFFABQ also correlated with time stepping (rho = -0.298) and number of steps (rho = -0.358).

Conclusion

These results provide supportive evidence for the reliability and validity of the mFFABQ in older adults and people with PD, which supports its suitability as a clinical and research tool for the assessment of fear of falling avoidance behavior.

The reliability and validity of the 3-m backward walk test in people with Parkinson's disease

BACKGROUND

People with Parkinson's disease (PwPD) lose the ability in backward walking which is an important part of mobility in daily life. The 3-m backward walk test (3MBWT) evaluates backward walking; however, its reliability and validity have not been examined in PwPD yet.

AIMS

To examine (1) the test-retest reliability of the 3MBWT in PwPD; (2) the minimum detectable change in the 3MBWT times; (3) the concurrent and known-groups validity of the 3MBWT; and (4) the optimum cutoff time which best discriminates fallers from non-fallers with Parkinson's disease (PD).

METHODS

This cross-sectional study included 36 PwPD and 33 healthy people. The 3MBWT was conducted with the 10-m walk test, timed up and go test, Berg Balance Scale, four square step test, activity-specific balance confidence scale, Movement Disorders Society Sponsored Unified Parkinson's Disease Rating Scale, and Hoehn and Yahr Scale.

RESULTS

The 3MBWT demonstrated excellent test-retest reliability (ICC = 0.965). The MDC of 2.13 s was determined. The 3MBWT had moderate to high correlations with the other outcome measures (correlation coefficient ranged from -0.592 to 0.858). On the 3MBWT times, there were significant differences between PwPD and healthy people, and between fallers and non-fallers with PD (p < 0.001 and p < 0.001, respectively). A 3MBWT time of 10.31 s was found to best discriminate fallers from non-fallers with PD.

CONCLUSIONS

The 3MBWT is a reliable, valid, and easy to administer outcome measure to assess backward walking performance in PwPD, indicating it to be used in practice and research.

Predictors of balance in individuals with Parkinson's disease: A cross-sectional study

INTRODUCTION

Some previous studies investigated predictors of balance in individuals with Parkinson's Disease (PD). However, outcomes commonly evaluated in the rehabilitation of individuals with PD that could predict balance deficits have not yet been investigated.

OBJECTIVE

To determine whether the variables muscle strength, physical activity and depression are predictors of balance in individuals with PD.

MATERIAL AND METHODS

This is a cross-sectional study in which the investigated variables included: trunk and knee extensors' muscle strength (modified sphygmomanometer test - MST), physical activity level (Adjusted Human Activity Profile score) and depression (Patient Health Questionnaire-9 - PHQ-9). The outcome variable was balance, as assessed by the Mini-BESTest. Multiple regression analysis was used to determine which predictor variables explain the outcome variable.

RESULTS

A total of 50 individuals with PD, mean age 67 ± 8.8 years, 68% male, 40% HY 2.5 were included. The mean value of the dominant limb extensor muscle strength was 139 ± 45 mmHg, and the mean trunk extensor muscle strength value was 81.9 ± 19 mmHg. More than half of the sample (52%, n = 26) was classified as moderately active. Most of the sample (78%) had mild depression. The average Mini-BESTest score was 21 ± 5.4. The physical activity level explained 29% of the balance variance. When depression was included in the model, the explained variance increased to 35%. The other independent variables were not included in the model.

CONCLUSION

The findings of the present study showed that the physical activity level and depression were able to explain 35% of the balance variation.

Reliability and learning effects of repeated exposure to the Bertec Balance Advantage sensory organisation test in healthy individuals

BACKGROUND

The Sensory Organisation Test (SOT) of computerised dynamic posturography (CDP) is a well-established clinical test used to measure postural control. Advances in technology have enabled new CDP systems to use immersive virtual reality, such as the Bertec® Balance Advantage®. While the Bertec provides an innovative approach to posturography, the reliability and learning effects of the Bertec in administering the SOT has not been thoroughly investigated.

RESEARCH QUESTION

To evaluate the reliability and performance during repeated administration of the Bertec® Balance Advantage® SOT.

METHODS

Fourteen healthy adults (age 27.17 ± 5.5years; 10 females) participated. Each participant performed five SOTs over three sessions. The first two sessions were approximately two days apart and the third one month later. In the first two sessions, two SOTs were conducted, and in the third session, one was performed. Composite, equilibrium, and ratio scores were used for analysis.

RESULTS

Poor within-session reliability was found in the first session for the composite score (ICC: 0.73, 95% CI: 0.32-0.91), which improved by the second session (ICC: 0.84, 95% CI: 0.58-0.94). Poor within-session reliability (ICC <0.5) was found for all ratio and equilibrium scores, except for the equilibrium score of condition 3, which demonstrated moderate reliability (ICC: 0.84, 95% CI: 0.57-0.95). Poor between-session reliability was found for all outcomes. There was an increase in the composite and equilibrium scores for conditions 5 and 6 over the 5 tests, which plateaued after the fourth test, and were retained at 1 month.

SIGNIFICANCE

The data demonstrate a steady increase in performance with repeated exposure to the Bertec SOT, which was maintained one month later, indicating a learning effect. We recommend that a minimum of two familiarisation sessions should be administered to establish baseline performance and improve reliability.

Peripheral vestibular system: Age-related vestibular loss and associated deficits

Given the interdependence of multiple factors in age-related vestibular loss (e.g., balance, vision, cognition), it is important to examine the individual contributions of these factors with ARVL. While the relationship between the vestibular and visual systems has been well studied (Bronstein et al., 2015), little is known about the association of the peripheral vestibular system with neurodegenerative disorders (Cronin et al., 2017). Further, emerging research developments implicate the vestibular system as an opportunity for examining brain function beyond balance, and into other areas, such as cognition and psychological functioning. Additionally, the bidirectional impact of psychological functioning is understudied in ARVL. Recognition of ARVL as part of a multifaceted aging process will help guide the development of integrated interventions for patients who remain at risk for decline. In this review, we will discuss a wide variety of characteristics of the peripheral vestibular system and ARVL, how it relates to neurodegenerative diseases, and correlations between ARVL and balance, vision, cognitive, and psychological dysfunction. We also discuss clinical implications as well as future directions for research, with an emphasis on improving care for patients with ARVL.

Applications of Multivariate Statistical and Data Mining Analyses to the Search for Biomarkers of Sensorineural Hearing Loss, Tinnitus, and Vestibular Dysfunction

Disorders of sensory systems, as with most disorders of the nervous system, usually involve the interaction of multiple variables to cause some change, and yet often basic sensory neuroscience data are analyzed using univariate statistical analyses only. The exclusive use of univariate statistical procedures, analyzing one variable at a time, may limit the potential of studies to determine how interactions between variables may, as a network, determine a particular result. The use of multivariate statistical and data mining methods provides the opportunity to analyse many variables together, in order to appreciate how they may function as a system of interacting variables, and how this system or network may change as a result of sensory disorders such as sensorineural hearing loss, tinnitus or different types of vestibular dysfunction. Here we provide an overview of the potential applications of multivariate statistical and data mining techniques, such as principal component and factor analysis, cluster analysis, multiple linear regression, random forest regression, linear discriminant analysis, support vector machines, random forest classification, Bayesian classification, and orthogonal partial least squares discriminant analysis, to the study of auditory and vestibular dysfunction, with an emphasis on classification analytic methods that may be used in the search for biomarkers of disease.

Usefulness of Mobile Devices in the Diagnosis and Rehabilitation of Patients with Dizziness and Balance Disorders: A State of the Art Review

Objective

The gold standard for objective body posture examination is posturography. Body movements are detected through the use of force platforms that assess static and dynamic balance (conventional posturography). In recent years, new technologies like wearable sensors (mobile posturography) have been applied during complex dynamic activities to diagnose and rehabilitate balance disorders. They are used in healthy people, especially in the aging population, for detecting falls in the older adults, in the rehabilitation of different neurological, osteoarticular, and muscular system diseases, and in vestibular disorders. Mobile devices are portable, lightweight, and less expensive than conventional posturography. The vibrotactile system can consist of an accelerometer (linear acceleration measurement), gyroscopes (angular acceleration measurement), and magnetometers (heading measurement, relative to the Earth’s magnetic field). The sensors may be mounted to the trunk (most often in the lumbar region of the spine, and the pelvis), wrists, arms, sternum, feet, or shins. Some static and dynamic clinical tests have been performed with the use of wearable sensors. Smartphones are widely used as a mobile computing platform and to evaluate the results or monitor the patient during the movement and rehabilitation. There are various mobile applications for smartphone-based balance systems. Future research should focus on validating the sensitivity and reliability of mobile device measurements compared to conventional posturography.

Conclusion

Smartphone based mobile devices are limited to one sensor lumbar level posturography and offer basic clinical evaluation. Single or multi sensor mobile posturography is available from different manufacturers and offers single to multi-level measurements, providing more data and in some instances even performing sophisticated clinical balance tests.

Trunk Exercises Improve Balance in Parkinson Disease: A Phase II Randomized Controlled Trial

BACKGROUND AND PURPOSE

Trunk control is important for maintaining balance; hence, deficient trunk control may contribute to balance problems in people with Parkinson disease (PD). Unfortunately, this deficit is poorly managed with pharmacological therapies, emphasizing the need for alternative therapies for these patients. This randomized controlled trial sought to examine the effects of a 12-week trunk-specific exercise-based intervention on balance in people with PD.

METHODS

Twenty-four people with PD and with a history of falls completed assessments of motor symptom severity, balance confidence, mobility, quality of life, and quiet-standing balance. Participants were then randomized to receive either 12 weeks of exercise or education and reassessed after 12 and 24 weeks.

RESULTS

Linear mixed-models analyses showed no significant changes in clinical outcomes following the intervention. However, during quiet standing, sway area on a foam surface without vision was reduced for the exercise group at 12 (-6.9 ± 3.1 cm; 95% confidence interval [CI] = -13.1 to -0.7; P = 0.029; d = 0.66) and 24 weeks (-7.9 ± 3.1 cm; 95% CI = -14.1 to -1.7; P = 0.013; d = 0.76). Furthermore, the exercise group demonstrated reduced sway variability at 12 (-0.2 ± 0.1 cm; 95% CI = -0.4 to 0.0; P = 0.042; d = 0.62) and 24 weeks in the medial-lateral direction (-0.2 ± 0.1 cm; 95% CI = -0.4 to 0.0; P = 0.043; d = 0.62). No changes in quiet standing balance were recorded for the education group.

DISCUSSION AND CONCLUSIONS

The results of this study suggest that exercise-based interventions targeting trunk strength, endurance, and mobility may be effective for improving quiet-standing balance in people with PD. However, additional research is needed to determine whether these improvements are sufficient to reduce falls risk.Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A254).

Parkinson Disease and Orthostatic Hypotension in the Elderly: Recognition and Management of Risk Factors for Falls

Parkinson disease (PD) is often associated with postural instability and gait dysfunction that can increase the risk for falls and associated consequences, including injuries, increased burden on healthcare resources, and reduced quality of life. Patients with PD have nearly twice the risk for falls and associated bone fractures compared with their general population counterparts of similar age. Although the cause of falls in patients with PD may be multifactorial, an often under-recognized factor is neurogenic orthostatic hypotension (nOH). nOH is a sustained decrease in blood pressure upon standing whose symptomology can include dizziness/lightheadedness, weakness, fatigue, and syncope. nOH is due to dysfunction of the autonomic nervous system compensatory response to standing and is a consequence of the neurodegenerative processes of PD. The symptoms associated with orthostatic hypotension (OH)/nOH can increase the risk of falls, and healthcare professionals may not be aware of the real-world clinical effect of nOH, the need for routine screening, or the value of early diagnosis of nOH when treating elderly patients with PD. nOH is easily missed and, importantly, healthcare providers may not realize that there are effective treatments for nOH symptoms that could help lessen the fall risk resulting from the condition. This review discusses the burden of, and key risk factors for, falls among patients with PD, with a focus on practical approaches for the recognition, assessment, and successful management of OH/nOH. In addition, insights are provided as to how fall patterns can suggest fall etiology, thereby influencing the choice of intervention.

Does patient environment have any influence on balance?

BACKGROUND

Although patient environment is a factor to consider when planning a vestibular rehabilitation program, there are no studies correlating this factor to outcomes of balance assessment.

AIM

To evaluate whether there are differences in objective evaluation of balance in elderly patients at risk of falls according to the environment in which they live (urban or rural) and their lifestyle (considering cardiovascular risk factors).

METHODS

Cross-sectional study of a sample of 139 elderly patients with high risk of falls assessed with objective outcome measures: Computer Dynamic Posturography (CDP), and the modified Timed Up-and-Go (TUG) test; and subjective outcome measures: Dizziness Handicap Inventory (DHI) and short Falls Efficacy Scale-International (short FES-I). Rural or urban environment was defined according to administrative and legal criteria.

RESULTS

Elderly patients at risk of fall living in rural environment show better composite results in SOT with better scores in Condition 6 and fewer falls during the CDP. They also require fewer steps to perform the TUG test.

DISCUSSION

The present study provides evidence that patient environment has an influence in balance.

CONCLUSION

Patient environment should be considered when analyze tests evaluating static and dynamic balance.

Prognostic factors that modify outcomes of vestibular rehabilitation in elderly patients with falls

BACKGROUND

Our previous study has shown that vestibular rehabilitation (VR) is an effective technique to reduce falls in elderly patients. It would be interesting to establish patients' clinical characteristics in which vestibular rehabilitation is expected to be more effective.

AIMS

Evaluate factors that could modify rehabilitation outcomes in elderly patients with previous falls.

METHODS

Fifty-seven patients randomized to one of the intervention group (computerized dynamic posturography-CDP-training, optokinetic stimulus or exercise at home) and with previous falls were analyzed. Patients were assessed with objective outcome measures (sensorial organization test and limits of stability-LOS-of CDP, modified timed up and go test-TUG-and number of falls) and with subjective outcome measures (dizziness handicap inventory and Short falls efficacy scale-international-Short FES-I) during a 12-month follow-up period.

RESULTS

In the logistic regression model, a worse score in the maximum excursion (MXM), and a shorter time in the TUG significantly associated with a reduction > 50% of falls. Also, association with a higher score in the Short FES-I was close to a statistical significance. There was no statistical significance association with other covariables.

DISCUSSION

In patients with reduced limits of stability, VR seems to be more effective and they should be encouraged to perform it. But on the other hand, patients with longer time in the TUG show worse outcomes and may benefit more with gait training.

CONCLUSIONS

VR in elderly people with previous falls is effective regardless of their age and gender.

Postural Stability in Obese Preoperative Bariatric Patients Using Static and Dynamic Evaluation

INTRODUCTION

Globally, 300 million adults have clinical obesity. Heightened adiposity and inadequate musculature secondary to obesity alter bipedal stance and gait, diminish musculoskeletal tissue quality, and compromise neuromuscular feedback; these physiological changes alter stability and increase injury risk from falls. Studies in the field focus on obese patients across a broad range of body mass indices (BMI >30 kg/m2) but without isolating the most morbidly obese subset (BMI ≥40 kg/m2). We investigated the impact of obesity in perturbing postural stability in morbidly obese subjects elected for bariatric intervention, harboring a higher-spectrum BMI.

SUBJECTS AND METHODS

Traditional force plate measurements and stabilograms are gold standards employed when measuring center of pressure (COP) and postural sway. To quantify the extent of postural instability in subjects with obesity before bariatric surgery, we assessed 17 obese subjects with an average BMI of 40 kg/m2 in contrast to 13 nonobese subjects with an average BMI of 30 kg/m2. COP and postural sway were measured from static and dynamic tasks. Involuntary movements were measured when patients performed static stances, with eyes either opened or closed. Two additional voluntary movements were measured when subjects performed dynamic, upper torso tasks with eyes opened.

RESULTS

Mean body weight was 85% (p < 0.001) greater in obese than nonobese subjects. Following static balance assessments, we observed greater sway displacement in the anteroposterior (AP) direction in obese subjects with eyes open (87%, p < 0.002) and eyes closed (76%, p = 0.04) versus nonobese subjects. Obese subjects also exhibited a higher COP velocity in static tests when subjects' eyes were open (47%, p = 0.04). Dynamic tests demonstrated no differences between groups in sway displacement in either direction; however, COP velocity in the mediolateral (ML) direction was reduced (31%, p < 0.02) in obese subjects while voluntarily swaying in the AP direction, but increased in the same cohort when swaying in the ML direction (40%, p < 0.04).

DISCUSSION AND CONCLUSION

Importantly, these data highlight obesity's contribution towards increased postural instability. Obese subjects exhibited greater COP displacement at higher AP velocities versus nonobese subjects, suggesting that clinically obese individuals show greater instability than nonobese subjects. Identifying factors contributory to instability could encourage patient-specific physical therapies and presurgical measures to mitigate instability and monitor postsurgical balance improvements.

Destroyed non-dopaminergic pathways in the early stage of Parkinson's disease assessed by posturography

BACKGROUND

The early stage of Parkinson's disease (PD) (Hoehn-Yahr (HY) I-II stages) is characterized by a negative pull test, which clinically excludes postural instability. Previous studies with dynamic posturography detected balance disturbances even at the onset of the disease but the age dependency or prediction of dyskinesia with dynamic posturography are not known.

OBJECTIVE/HYPOTHESIS

We hypothesized that the postural instability evoked by dynamic posturography was part of the early stage of PD. Furthermore, we studied how we can provoke dyskinesia.

METHODS

Postural instability with static and dynamic posturography (passing balls with different weights around the body) was studied in 45 patients with PD in their HY I, II stages. They were compared with 35 age-matched healthy controls. Eighteen patients with dyskinesia were involved in the study. Fourteen patients were followed for two years.

RESULTS

The pathway and velocity of the movement assessed by static and the dynamic posturography were significantly higher in the group >65 years than that of age-matched healthy controls, while the group ≤65 years showed a significant increment only in the antero-posterior sway during dynamic posturography. The imbalance of patients with dyskinesia was significantly (p < 0.05) provoked by dynamic posturography compared to patients with PD without dyskinesia. The results were independent of age.

CONCLUSION

Postural instability is part of the early symptoms of PD. Non-dopaminergic pathways may be involved in the early stage of PD.

Quiet standing: The Single Inverted Pendulum model is not so bad after all

In the study of balance and postural control the (Single) Inverted Pendulum model (SIP) has been taken for a long time as an acceptable paradigm, with the implicit assumption that only ankle rotations are relevant for describing and explaining sway movements. However, more recent kinematic analysis of quiet standing revealed that hip motion cannot be neglected at all and that ankle-hip oscillatory patterns are characterized by complex in-phase and anti-phase interactions, suggesting that the SIP model should be substituted by a DIP (Double Inverted Pendulum) model. It was also suggested that DIP control could be characterized as a kind of optimal bi-axial active controller whose goal is minimizing the acceleration of the global CoM (Center of Mass). We propose here an alternative where active feedback control is applied in an intermittent manner only to the ankle joint, whereas the hip joint is stabilized by a passive stiffness mechanism. The active control impulses are delivered to the ankle joint as a function of the delayed state vector (tilt rotation angle + tilt rotational speed) of a Virtual Inverted Pendulum (VIP), namely a pendulum that links the ankle to the CoM, embedded in the real DIP. Simulations of such DIP/VIP model, with the hybrid control mechanism, show that it can reproduce the in-phase/anti-phase interaction patterns of the two joints described by several experimental studies. Moreover, the simulations demonstrate that the DIP/VIP model can also reproduce the measured minimization of the CoM acceleration, as an indirect biomechanical consequence of the dynamic interaction between the active control of the ankle joint and the passive control of the hip joint. We suggest that although the SIP model is literally false, because it ignores the ankle-hip coordination, it is functionally correct and practically acceptable for experimental studies that focus on the postural oscillations of the CoM.

Comparing Balance Performance on Force Platform Measures in Individuals with Parkinson's Disease and Healthy Adults

Introduction

Postural instability is a known contributing factor to balance dysfunction and increased fall risk in those with Parkinson's disease (PD). Computerized posturography employing a force platform system provides objective, quantitative assessments of postural control impairments. This study examines balance performance as measured by force platform (FP) tests in persons with PD compared to age-matched healthy adults. Secondarily, we examine if these FP measures provide diagnostic and clinically meaningful information about the underlying balance impairments in the PD population.

Methods

Participants-42 individuals with PD (Hoehn and Yahr stage = 2.33 ± 0.77) and 55 age-matched healthy adults-were assessed on three standardized balance measures on a computerized force platform system. Between groups, comparisons of FP performance were analyzed using independent t-test. Within the group, comparisons for the PD cohort were analyzed using ANOVA for comparing disease stage and Mann-Whitney U test for PD subtypes.

Results

The PD cohort demonstrated significantly greater postural instability on the sensory organization test (SOT) measures (P=0.013, CI-95% = 1.286 to 10.37) and slower movement velocity on the limits of stability (LOS) test (P=0.001, CI-95% = 0.597 to 1.595) than the healthy cohort, suggesting that these tests were sensitive to detect sensory integration and voluntary postural control deficits in the PD cohort. Within the PD group, the SOT differentiated between H&Y stages 1-3. The motor control test (MCT) detected changes in reactive postural control mainly in later disease stages. All three FP tests distinguished between PD subtypes, with the Posture Gait Instability subtype demonstrating poorer balance performance than Tremor Dominant subtype.

Conclusion

These findings suggest FP measures provide clinically meaningful, diagnostic information in the examination of balance impairments in individuals with PD. FP measures may inform clinicians regarding intrinsic balance deficits and guide them in designing targeted balance interventions to reduce fall risk in persons with PD.

Impairments in Postural Control and Retest Reliability of Dynamic Posturographic Measures After Lung Transplantation

OBJECTIVES

The aims of the study were to classify impairments in postural control using computerized posturography in lung transplant recipients undergoing subacute rehabilitation and to examine the retest reliability of these measures.

METHODS

In a prospective repeated-measures study, 50 lung transplant recipients underwent clinical and quantitative posturographic testing (SMART EquiTest), which included the sensory organization test, motor control test, and limits of stability test. Testing was repeated after 1 to 2 days and upon completion of rehabilitation, 2 mos later. Main outcome measures were the following: sensory organization test-composite score, motor control test-latency and amplitude scaling, limits of stability test-movement velocity, and endpoint excursion/maximum excursion.

RESULTS

At the beginning of rehabilitation, the mean sensory organization test-composite score and limits of stability test, but not the motor control test scores, were below normative reference values and and did not return to normal after rehabilitation. Intraclass correlation coefficients(2,1) yielded excellent relative reliability for all posturographic tests. The smallest detectable differences observed for the sensory organization test and limits of stability test exceeded the mean changes observed upon completion of rehabilitation.

CONCLUSIONS

Impairments in sensory and anticipatory postural control were insufficiently restored after subacute lung transplantation rehabilitation. The little sensitivity of the sensory organization test-composite score or limits of stability test scores to detect a minimal change in performance due to rehabilitation limits the clinical applicability of these tests as objective outcome measures in lung transplantation rehabilitation.

Modified dynamic gait index and limits of stability in myotonic dystrophy type 1

INTRODUCTION

The purpose of this study was to describe and compare the performance of balance and walking tests in relation to self-reported fall history in adults with myotonic dystrophy type 1 (DM1).

METHODS

Twenty-two (13 male) participants with DM1 completed, a 6-month fall history questionnaire, the modified Dynamic Gait Index (mDGI), limits of stability (LoS) testing, and 10-m walking tests.

RESULTS

Mean (SD) falls in 6 months was 3.7 (3.1), and 19 (86%) participants reported at least 1 fall. Significant differences in mDGI scores (P = 0.006) and 10-m fast walking gait velocity (P = 0.02) were found between those who had been classified as "fallers" and those who had been classified as "nonfallers." Significant correlations were found between mDGI scores and 10-m walking time.

DISCUSSION

Falls are common in DM1, and the mDGI may have potential to distinguish fallers from nonfallers, whereas the LoS failed to detect such impairment. Future studies should further explore use of the mDGI in DM1. Muscle Nerve 58: 694-699, 2018.

Relationship Between Posturography, Clinical Balance and Executive Function in Parkinson´s Disease

This study aimed to evaluate the relationship between posturography, clinical balance, and executive function tests in Parkinson´s disease (PD). Seventy-one people participated in the study. Static posturography evaluated the center of pressure fluctuations in quiet standing and dynamic posturography assessed sit-to-stand, tandem walk, and step over an obstacle. Functional balance was evaluated by Berg Balance Scale, MiniBESTest, and Timed Up and Go test. Executive function was assessed by Trail Making Test (TMT) and semantic verbal fluency test. Step over obstacle measures (percentage of body weight transfer and movement time) were moderately correlated to Timed Up and Go, part B of TMT and semantic verbal fluency (r > 0.40; p < 0.05 in all relationships). Stepping over an obstacle assesses the responses to internal perturbations. Participants with shorter movement times and higher percentage of body weight transfer (higher lift up index) on this task were also faster in Timed Up and Go, part B of TMT, and semantic verbal fluency. All these tasks require executive function (problem solving, sequencing, shifting attention), which is affected by PD and contribute to postural assessment.

Vestibular Deficits in Neurodegenerative Disorders: Balance, Dizziness, and Spatial Disorientation

The vestibular system consists of the peripheral vestibular organs in the inner ear and the associated extensive central nervous system projections—from the cerebellum and brainstem to the thalamic relays to cortical projections. This system is important for spatial orientation and balance, both of critical ecological importance, particularly for successful navigation in our environment. Balance disorders and spatial disorientation are common presenting features of neurodegenerative diseases; however, little is known regarding central vestibular processing in these diseases. A ubiquitous aspect of central vestibular processing is its promiscuity given that vestibular signals are commonly found in combination with other sensory signals. This review discusses how impaired central processing of vestibular signals—typically in combination with other sensory and motor systems—may account for the impaired balance and spatial disorientation in common neurodegenerative conditions. Such an understanding may provide for new diagnostic tests, potentially useful in detecting early disease while a mechanistic understanding of imbalance and spatial disorientation in these patients may enable a vestibular-targeted therapy for such problems in neurodegenerative diseases. Studies with state of the art central vestibular testing are now much needed to tackle this important topic.

Comparison of intraobserver single-task reliabilities of the Interactive Balance System (IBS) and Vertiguard in asymptomatic subjects

The intraobserver reliabilities of the Interactive Balance System (IBS) and Vertiguard were compared in 30 asymptomatic volunteers. Relative reliability for all IBS single tasks and parameters in the IBS was excellent (intraclass correlation coefficient, ICC ≥0.75). The ICC values ranged from 0.78 to 0.89. The ICC values of the Vertiguard system ranged from 0 to 0.75. The cumulative measure of injury risk of the Vertiguard system was highly reliable.

Posturographic limits of stability can predict the increased risk of falls in elderly patients with instability?

CONCLUSIONS

There was a difference in average score of the sensory organization test (SOT) of the case group (elderly instability) compared to the control group (healthy subjects). Cases had worse scores on the limits of stability (LOS) than controls, but were only able to confirm statistically significant differences in the movement velocity.

OBJECTIVE

To study the LOS of elderly patients with instability vs healthy subjects of the same age to try to explain the increased risk of falls in elderly patients with instability.

METHODS

Fifty individuals ≥65 years, 30 cases (at least one of the next inclusion criteria: ≥1 fall in the last 12 months, >15 s or some support in the timed up and go test, composite <68 in SOT, ≥1 fall during production of the SOT) compared to 20 controls. Postural study: SOT and LOS, Smart Equitest Neurocom^® platform.

STATISTICAL ANALYSIS

t-Student test (p < 0.05).

RESULT

Mean value of overall balance: patients with instability =56% vs controls =77.1% (p < 0.001). Movement velocity: cases =2243°/s vs controls =2860°/s (p = 0.029). The reaction time (cases =1217 s vs controls =1.077 s), excursion (56.95% vs 59.35%) and directional control (56.95% vs 59.35%) differences were not statistically significant.

What Could Posturography Tell Us About Balance Problems in Parkinson's Disease?

OBJECTIVE

Impaired balance in patients with Parkinson's disease (PD) leads to loss of balance and frequent falls. Computerized dynamic posturography allows the assessment of stance tasks whereas mobile posturography analyzes the balance in free-field conditions, where falls among PD patients commonly occur (e.g. sitting down or standing up). The aim of the present study is to assess postural stability in PD patients with both techniques.

STUDY DESIGN

Prospective study.

SETTING

University Hospitals, ambulatory care (outpatient clinic).

PATIENTS

Thirty-three patients diagnosed with idiopathic PD.

INTERVENTION

Balance assessment.

MAIN OUTCOME MEASURES

Dizziness handicap inventory (DHI), activities-specific balance confidence scale (ABC), composite score of sensory organization test (SOT), results of free-field body sway analysis (standard balance deficit test (SBDT)), or geriatric SBDT.

RESULTS

PD patients showed a significantly higher sway in the roll direction in almost all of the SBDT conditions. Also, pathological sway compared with normative values was more prominent in complex tasks. There is a significant correlation between the different objective variables of the postural study (SOT and SBDT) and the ABC, but not with the DHI. Finally, the percentage of PD patients with a pathological score in SOT-composite score was 54.5% whereas in SBDT-composite score it was significantly higher (93.9%).

CONCLUSION

Mobile posturography is more accurate in depicting the reality of balance impairment in PD patients than platform posturography. Also, ABC relates better than DHI to the significant psychological consequences of balance impairments. An increased lateral trunk sway seems to be a key factor of postural instability in PD patients.

Impact of obesity in elderly patients with postural instability

OBJECTIVE

The aim of the study is to assess whether obesity affects balance in elderly patients with postural instability.

STUDY DESIGN

It is a case-control study, with cases defined by BMI ≥30 kg/m(2), and developed in a third level university hospital.

METHODS

We included 135 patients aged 65 years old or more who presented postural instability. Balance assessment was through the sensory organisation test (SOT), limits of stability (LOS) and rhythmic weight shift (RWS) of computerised dynamic posturography (CDP) and the modified timed up-and-go (TUG) test. The patients also completed the Dizziness Handicap Inventory and short Falls Efficacy Scale-International questionnaire.

RESULTS

Patients with obesity took longer to perform the modified TUG and required more steps. Also these patients had poorer scores in the subjective tests. In the CDP there were no significant differences in the SOT nor the LOS, and only there was a statistical significant difference in the anterior-posterior directional control of the RWS. Obese patients have a higher risk of fallings compared to non-obese patients.

CONCLUSION

In essence, our results indicate that obesity interferes in the balance of elderly patients with postural instability, putting them at a greater risk of fallings, performing worse dynamic tasks and feeling more disabled. Although continued education on training balance may be useful in older population, since the obese group shows more rate of fallers, rehabilitation programmes focus on dynamic tasks in these patients could be useful to reduce their fall risk and improve their quality of life.

Postural sensory correlates of freezing of gait in Parkinson's disease

INTRODUCTION

To elucidate the unique patterns of postural sensory deficits contributing to freezing of gait (FOG) in patients with Parkinson's disease (PD) and to identify postural sensory modalities that correlate with FOG severity.

METHODS

Twenty-five PD patients with FOG, 22 PD patients without FOG, and 26 age-matched controls were evaluated using a sensory organization test and clinical measures including the Unified Parkinson's Disease Rating Scale motor score, Montreal Cognitive Assessment, Frontal Assessment Battery, Activities-specific Balance Confidence, Beck Anxiety Inventory, Beck Depression Inventory, and Berg Balance Scale. Multivariable logistic regression analysis was performed for posturographic parameters and possible confounders to determine postural sensory contributors to FOG. We also correlated FOG severity, measured using a New Freezing of Gait Questionnaire, with posturographic parameters.

RESULTS

PD patients with FOG showed worse postural sensory processing compared with those without FOG. In particular, the inability to use the vestibular information (odds ratio [OR] 1.447; 95% confidential interval [CI]: 1.120, 1.869) and poor control over the perturbed somatosensory inputs (OR 2.904; 95% CI: 1.028, 8.202) significantly contributed to FOG. Among PD patients with FOG, FOG severity was correlated with higher reliance on visual information (ρ = -0.432, p = 0.039).

CONCLUSIONS

Postural sensory deficits involving specific sensory modalities are strongly associated with FOG. Quantitative measurement of postural sensory deficits in PD patients with FOG may provide a better understanding of pathomechanisms of FOG and increase the efficacy of sensory cueing strategies for alleviating FOG, by more accurately identifying suitable patients for rehabilitative therapies.

Lighten Up: Specific Postural Instructions Affect Axial Rigidity and Step Initiation in Patients With Parkinson's Disease

BACKGROUND

Parkinson's disease (PD) is associated with stooped postural alignment, increased postural sway, and reduced mobility. The Alexander Technique (AT) is a mindfulness-based approach to improving posture and mobility by reducing muscular interference while maintaining upward intentions. Evidence suggests that AT can reduce disability associated with PD, but a mechanism for this effect has not yet been established.

OBJECTIVE

We investigated whether AT-based instructions reduce axial rigidity and increase upright postural alignment, and whether these instructions have different effects on postural alignment, axial rigidity, postural sway, and mobility than effort-based instructions regarding posture.

METHOD

Twenty subjects with PD practiced 2 sets of instructions and then attempted to implement both approaches (as well as a relaxed control condition) during quiet standing and step initiation. The "Lighten Up" instructions relied on AT principles of reducing excess tension while encouraging length. The "Pull Up" instructions relied on popular concepts of effortful posture correction. We measured kinematics, resistance to axial rotation, and ground reaction forces.

RESULTS

Both sets of experimental instructions led to increases in upright postural alignment relative to the control condition. Only the Lighten Up instructions led to reduced postural sway, reduced axial postural tone, greater modifiability of tone, and a smoother center of pressure trajectory during step initiation, possibly indicating greater movement efficiency.

CONCLUSION

Mindful movement approaches such as AT may benefit balance and mobility in subjects with PD by acutely facilitating increased upright postural alignment while decreasing rigidity.

Virtual Reality-Based Training to Improve Obstacle-Crossing Performance and Dynamic Balance in Patients With Parkinson's Disease

BACKGROUND

Obstacle crossing is a balance-challenging task and can cause falls in people with Parkinson's disease (PD). However, programs for people with PD that effectively target obstacle crossing and dynamic balance have not been established.

OBJECTIVE

To examine the effects of virtual reality-based exercise on obstacle crossing performance and dynamic balance in participants with PD.

METHODS

Thirty-six participants with a diagnosis of PD (Hoehn and Yahr score ranging 1 to 3) were randomly assigned to one of three groups. In the exercise groups, participants received virtual reality-based Wii Fit exercise (VRWii group) or traditional exercise (TE group) for 45 minutes, followed by 15 minutes of treadmill training in each session for a total of 12 sessions over 6 weeks. Participants in the control group received no structured exercise program. Primary outcomes included obstacle crossing performance (crossing velocity, stride length, and vertical toe obstacle clearance) and dynamic balance (maximal excursion, movement velocity, and directional control measured by the limits-of-stability test). Secondary outcomes included sensory organization test (SOT), Parkinson's Disease Questionnaire (PDQ39), fall efficacy scale (FES-I), and timed up and go test (TUG). All outcomes were assessed at baseline, after training, and at 1-month follow-up.

RESULTS

The VRWii group showed greater improvement in obstacle crossing velocity, crossing stride length, dynamic balance, SOT, TUG, FES-I, and PDQ39 than the control group. VRWii training also resulted in greater improvement in movement velocity of limits-of-stability test than TE training.

CONCLUSIONS

VRWii training significantly improved obstacle crossing performance and dynamic balance, supporting implementation of VRWii training in participants with PD.