Stride Length Variability Research Articles

Visual-Somatosensory Integration and Quantitative Gait Performance in Aging.

Background: The ability to integrate information across sensory modalities is an integral aspect of mobility. Yet, the association between visual-somatosensory (VS) integration and gait performance has not been well-established in aging.Methods: A total of 333 healthy older adults (mean age 76.53 ± 6.22; 53% female) participated in a visual-somatosensory simple reaction time task and underwent quantitative gait assessment using an instrumented walkway. Magnitude of VS integration was assessed using probability models, and then categorized into four integration classifications (superior, good, poor, or deficient). Associations of VS integration with three independent gait factors (Pace, Rhythm, and Variability derived by factor analysis method) were tested at cross-section using linear regression analyses. Given overlaps in neural circuitry necessary for both multisensory integration and goal-directed locomotion, we hypothesized that VS integration would be significantly associated with pace but not rhythm which is a more automatic process controlled mainly through brainstem and spinal networks.Results: In keeping with our hypothesis, magnitude of VS integration was a strong predictor of pace (β = 0.12, p < 0.05) but not rhythm (β = −0.01, p = 0.83) in fully-adjusted models. While there was a trend for the association of magnitude of VS integration with variability (β = −0.11, p = 0.051), post-hoc testing of individual gait variables that loaded highest on the variability factor revealed that stride length variability (β = −0.13, p = 0.03) and not swing time variability (β = −0.08, p = 0.15) was significantly associated with magnitude of VS integration. Of the cohort, 29% had superior, 26% had good, 29% had poor, and 16% had deficient VS integration effects.Conclusions: Worse VS integration in aging is associated with worse spatial but not temporal aspects of gait performance.

Study on the influence of variable stride scale change on image recognition in CNN

After the research based on the progressing image classification recognition method of CNN, the paper aims at the problem that the size of feature size of output map of image with different complexity cannot be well solved by the constant value stride. We bring up the idea which based on the variable stride length for constraint parameters to selectively select the size of the stride. It is helpful to improve the efficiency of selective extraction and recognition of important features. Later studies have proved that the deficiency issue of complex image characteristic extraction due to the large stride size could be averted by adopting the variable stride length method based on constraint parameters. In the meantime, the method also avoids low recognition efficiency due to the image complexity is sparse and, also, the stride size of the image is too small. The theoretically calculated results are in good agreement with the experimental results.

Gait adaptations during overground walking and multidirectional oscillations of the visual field in a virtual reality headset

BackgroundVirtual reality (VR) has been used to study locomotor adaptability during balance-demanding tasks by exploring how humans react and adapt to the virtual environment (VE) and discordant sensorimotor stimulations. Previous research primarily focused on treadmill walking and little is known regarding the propensity for gait adaptations during overground walking and over time. Research questionTo what extent healthy young adults modify and adapt gait during overground walking in a VE and with continuous multidirectional perturbations of the visual field while wearing a VR headset? MethodsTwelve healthy young adults walked for 6 min on an instrumented walkway in four different conditions: RE, VE, and VE with antero-posterior (AP) and medio-lateral (ML) pseudo-random oscillations of the visual field. For each condition, stride length (SL), stride width (SW), stride time (ST) and their variability (SLV, SWV, and STV) were calculated using one-minute walking intervals. A 2-way repeated-measures ANOVA was performed to determine the main and interaction effects of the walking conditions and time. ResultsParticipants took shorter SL and showed higher SWV while walking in the VE. Perturbations of the visual field resulted in reduced SL, larger SW, and higher stride variability (i.e., SLV, SWV, and STV). The response was anisotropic, such that effects were more pronounced during the ML compared to AP perturbations. Over time, participants adapted to the VE and the visual perturbations by increasing SL and reducing SW, SLV, STV, and ST (only during VE and ML conditions). SWV did not adapt over time. SignificanceThe paper provided first evidence for visuomotor adaptations during unperturbed overground walking and during visual perturbations while wearing a VR headset. It represents an initial investigation that may help the development of new VR methods for early detection and remediation of gait deficits in more ecological conditions.

Pain, balance, grip strength and gait parameters of older adults with and without post-chikungunya chronic arthralgia.

To compare the levels of pain, grip strength, balance and gait in older adults with and without post-Chikungunya chronic arthralgia (PCCA). Sixty-two older adults, 30 with and 32 without PCCA participated in the study. Pain level was assessed using a Visual Analogue Scale (VAS). Gait during a 10-m walk was assessed using inertial sensors. Semi-static balance was assessed during an eyes-closed bipedal balance test on a force platform, and grip strength was assessed using a hand dynamometer. Participants with PCCA presented severe levels of pain (VAS>7.5), poorer balance, lower grip strength, walked slower, with lower cadence and stride length and higher stride time and stride length variability than participants without PCCA (P<0.001 for all variables). Older adults with PCCA had high levels of pain, impaired balance and gait and lower grip strength compared to older adults without PCCA.

Gait Variability and Energy Cost of Oveground Walking in Persons With Multiple Sclerosis: A Cross-Sectional Study.

This study examined the associations between gait variability based on common spatiotemporal parameters and energetic cost of walking in persons with multiple sclerosis. Eighty-six persons with multiple sclerosis underwent the 6-min walk while wearing a portable metabolic unit. The cost of walking was generated by dividing the net steady-state VO2 (milliliter per kilogram per minute) by walking speed during the 6-min walk. Participants further completed two trials of walking on the GAITRite mat at a self-selected pace for measuring spatiotemporal parameters. Variability of step length, step time, stride length, swing time, stance time, stride velocity, and single- and double-support time was indexed by the coefficient of variation. Variability in the spatiotemporal variables and Expanded Disability Status Scale scores were significantly correlated with cost of walking (i.e., ρ = 0.25-0.36). Multivariate analysis revealed that disability (Expanded Disability Status Scale: β = 0.186), stance time variability (β = 1.446), and step length variability (β = -1.216) explained significant variance (R(2) = 0.38, P < 0.001) in cost of walking. We provide evidence of the positive association between gait variability and cost of walking during overground walking in persons with multiple sclerosis. The findings highlight the need for interventions aiming to reduce gait variability, thereby reducing the energetic demands of walking in this population.

Changes in postural sway and gait characteristics as a consequence of anterior load carriage

BackgroundAnterior load carriage represents a common daily and occupational activity. Carrying loads in front of the body could potentially increase instability during standing and walking. Research questionThis study examined the effects of anterior load carriage on postural sway and gait parameters in healthy adults. MethodsTwenty-nine participants (19 males, 10 females, age = 33.8 ± 12.7 years, height = 1.73 ± 0.07 m, mass = 75.1 ± 13.7 kg) were assessed in four conditions; (1) carrying no load (CON), (2) carrying a load with no added weight (i.e. empty box), (3) carrying a load with 5% body mass, and (4) carrying a load with 10% body mass. Anteroposterior and mediolateral centre of pressure (COP) displacement (cm) and the mean COP velocity (cm s-1) were used to characterise postural sway. Coefficient of variation of the stride length, stride time and double support time were calculated from 1 min of treadmill walking at a preferred pace for gait assessment. ResultsThe addition of the 10% load elicited an increase in anteroposterior COP displacement when compared to CON (d = 1.59), 0% (d = 1.50), and 5% (d = 0.75) (P < 0.001). The addition of the 10% load increased stride time (d = 1.71) and stride length (d = 1.20) variability when compared to CON (P < 0.001). SignificanceIn summary, the increase in postural sway and gait variability with added weight is dependent on the magnitude of the load, where the greater the load, the greater the effect on static and dynamic stability. Anterior load carriage potentially increases the risk of fall-related injuries.

What affects gait performance during walking while texting? A comparison of motor, visual and cognitive factors

Texting on a cell phone disrupts walkers’ gait performance. The performance decrement has been attributed to increased motor demand, decreased visual information and increased cognitive load. However, relative contributions of motor, visual and cognitive factors are poorly understood. Here we quantitatively estimated the relative contributions of these factors by comparing multiple walking conditions. Thirty-two adults walked for 20 m, with or without a dual task on the phone. The dual task was either a cognitively demanding digit ordering task or a casual tapping task. Gait performance was assessed using gait speed, stride length, stride time and stride time variability. Results showed that texting negatively impacted gait performance. Importantly, we found that cognitive factor contributed the most, visual factor the least, and motor factor in between. Our findings resolve the inconsistency in the literature and unambiguously show that motor, visual and cognitive factors caused by simultaneous phone use all contribute to gait alterations.Practitioner Summary: Walking performance is typically worsened when a concurrent phone use task such as texting is performed. We found that visual, motor and cognitive factors contributed to this performance decrement with increasing importance. Besides resolving inconsistency among previous reports, we also raised theoretical and practical concerns for phone use during walking.

The impact of age-related hearing loss and lateralized auditory attention on spatiotemporal parameters of gait during dual-tasking among community dwelling older adults.

This investigation assessed the impact of hearing loss and lateralized auditory attention on spatiotemporal parameters of gait during overground dual-tasking by the use of the dichotic listening task. Seventy-eight right-handed, healthy older adults between 60 and 88 years were assigned to a Young-Old (<70 years) or an Old-Old (>71 years) group. Cognitive assessment and pure tone audiometry were conducted. Spatiotemporal parameters of gait quantified by mean (M), and coefficient of variations (CoV) were evaluated with the OptoGait system during 3 dichotic listening conditions: Non-Forced, Forced-Right and Forced-Left. Factorial analyses of variance and covariance were used to assess group differences and the moderating effects of hearing status, respectively. Results demonstrated that three of the gait parameters assessed were affected asymmetrically by the dual-task paradigm after controlling for hearing status. Asymmetries existed on step width, gait speed and variability of stride length. Finally, correlations between gait outcomes and dichotic listening results showed that M and CoVs in gait parameters during right-ear responses were longer compared with left-ear. Left-ear responses were related to increased variability on stride length, which indicates higher difficulty level. Hearing status varying from normal to mild levels of hearing loss modulates spatiotemporal gait outcomes measured during dichotic listening execution. Findings suggest that attending to left side stimuli relates to increased gait variability, while focusing on right-side assures a safe walk. Results demonstrated that attending to right-ear stimuli is an adaptive strategy for older adults that compensates for limited sensorimotor and cognitive resources during walking.

Greater Stance Time Variability is Associated with Lower Step Activity in Older Adults

Previous research has shown that older adults with greater gait variability are at a higher risk for falling. Falls increase fear of falling and may subsequently result in mobility disability manifesting as decreased physical activity. Physical activity is commonly gauged from continuous step activity monitoring. While decreased step activity has been associated with impaired gait, the associations between gait variability and step activity are not understood. PURPOSE: To examine the relationship between gait variability and step activity in older adults. METHODS: Spatiotemporal gait parameters were recorded for 19 healthy older adults (mean age 74.5 ± 6.3 years; 9 males/ 10 females) walking at a normal walking speed across a GAITRite walkway for 5 trials. Step activity (# of steps) was collected using a research-grade step activity monitor for 7 consecutive days. Average number of steps for the 7 days was used. Coefficient of variation (defined as % of SD over mean) of gait speed, stride length, step width, swing time, stance time and double support time were calculated. Pearson’s and Spearman’s correlation coefficients were used based on normality to determine the relationship between gait variability and step activity. RESULTS: Stance time variability showed significant moderate inverse correlation with step activity (rho = -0.482, p = 0.036). Swing time variability showed moderate inverse correlation with step activity with a trend towards significance (r = -0.451, p = 0.052). Variability of gait speed (rho = -0.349, p = 0.143), stride length (r = -0.3, p = 0.212), step width (rho = -0.088, p = 0.721), and double support time (rho = -0.249, p = 0.304) showed weak inverse but not significant correlation with step activity. CONCLUSION: In general, gait variability seems to be inversely related to step activity in older adults meaning those with greater gait variability showed lower step activity. In particular, stance time variability has earlier shown to be critical in identifying older adults with mobility disability and those older adults at risk for future disability. Our finding of decreased step activity in those older adults with increased stance time variability suggests that step activity monitoring could provide surrogate and complimentary measures to identify mobility disability in older adults.

Increased foot strike variability in Parkinson's disease patients with freezing of gait

IntroductionFreezing of gait (FOG) is a debilitating, late motor complication of Parkinson's disease (PD) that occurs in 50–80% of patients. Gait freezing significantly worsens quality of life by decreasing mobility and increasing falls. Studies have shown that patients with episodic freezing episodes also have deficits in continuous gait. We evaluated whether there was an objective gait correlate to the increased stumbling reported by many patients with gait freezing. MethodsPD subjects and healthy controls (HC) were enrolled after IRB approval. Subjects with more than 1 fall/day or a Montreal Cognitive Assessment score <10 were excluded. Subjects walked at their normal pace, 8 lengths of a 20 × 4 foot pressure-sensor mat. Data was collected and analyzed using PKMAS software (Protokinetics) and statistical analysis performed using SPSS 22 (IBM). Results72 age matched subjects (22 PD FOG, 27 PD no-FOG, and 23 HC) were enrolled. Disease duration and Hoehn & Yahr scores were not significantly different between the PD groups. Mean dimensions of foot strike were not significantly different between groups, but PD FOG subjects had increased step-to-step variability in foot strike as measured by the percent coefficient of variation (%CV) in foot strike length compared to PD no-FOG and HC, independent of stride velocity. In PD no-FOG subjects, fallers also had higher variability in foot strike length compared to non-fallers. ConclusionPD subjects with FOG had increased variability in foot strike suggesting that in addition to stride length variability, foot strike variability could contribute to imbalance leading to falls.

Peripheral neuropathy is associated with more frequent falls in Parkinson's disease

IntroductionPeripheral neuropathy is a common condition in the elderly that can affect balance and gait. Postural imbalance and gait difficulties in Parkinson's disease (PD), therefore, may stem not only from the primary neurodegenerative process but also from age-related medical comorbidities. Elucidation of the effects of peripheral neuropathy on these difficulties in PD is important to provide more targeted and effective therapy. The purpose of this study was to investigate the association between lower-limb peripheral neuropathy and falls and gait performance in PD while accounting for disease-specific factors. MethodsFrom a total of 140 individuals with PD, 14 male participants met the criteria for peripheral neuropathy and were matched 1:1 for Hoehn & Yahr stage and duration of disease with 14 male participants without peripheral neuropathy. All participants underwent fall (retrospectively) and gait assessment, a clinical evaluation, and [11C]dihydrotetrabenazine and [11C]methylpiperidin-4-yl propionate PET imaging to assess dopaminergic and cholinergic denervation, respectively. ResultsThe presence of peripheral neuropathy was significantly associated with more falls (50% vs. 14%, p = 0.043), as well as a shorter stride length (p = 0.011) and greater stride length variability (p = 0.004), which resulted in slower gait speed (p = 0.016) during level walking. There was no significant difference in nigrostriatal dopaminergic denervation, cortical and thalamic cholinergic denervation, and MDS-UPDRS motor examination scores between groups. ConclusionLower-limb peripheral neuropathy is significantly associated with more falls and gait difficulties in PD. Thus, treating such neuropathy may reduce falls and/or improve gait performance in PD.

Cerebral microhemorrhages impair gait coordination in mice

Impairment in gait coordination and the consequent risk of falling are important problems in the rapidly aging population of the Western world: clinically diagnosable gait abnormalities affect approximately 35% of adults over age 70. While musculoskeletal mechanisms and processes have been extensively studied, factors affecting central neural control of gait coordination in older adults without overt neurological diseases are much less understood. Recent studies raise the possibility that in addition to causing cognitive decline, age‐associated cerebromicrovascular pathologies also contribute to mobility disability. However, the specific microvascular mechanisms underlying the loss of gait coordination in aging are not completely understood. Cerebral microhemorrhages (CMHs) are associated with rupture of small intracerebral vessels and cause focal disruption of neuronal networks. While there is growing evidence that CMHs predict cognitive impairment, the association between CMHs and gait abnormalities have not been investigated. The present study was designed to provide proof‐of‐concept that CMHs are causally linked to progressive gait dysfunction. To achieve this goal, we adapted a model of hypertension‐induced CMHs in mice (treatment with angiotensin II plus the NO synthase inhibitor L‐NAME). Computerized gait analysis was performed daily (Noldus CatWalk). CMHs were verified histologically. Mice with CMHs showed significantly altered gait function as measured by stride length, stride time and stride length variability, changes in phase‐dispersion and gait speed. CMH burden also correlated changes in the regularity index (a measure of inter‐paw coordination). Collectively, hypertension‐induced CMHs result in detectable impairment of gait function in mice. Further studies to analyze association of CMHs with gait abnormalities in human patients are warranted.Support or Funding InformationThis work was supported by grants from the American Heart Association, the National Center for Complementary and Alternative Medicine, and the National Institute on AgingThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Spatiotemporal gait characteristics in patients with COPD during the Gait Real-time Analysis Interactive Lab-based 6-minute walk test.

Background and aimOverground gait assessment is limited by the analysis of multiple strides or both spatiotemporal gait characteristics, while fixed speed treadmill walking restricts natural gait speed variations. The Gait Real-time Analysis Interactive Lab (GRAIL)-based 6-minute walk test (6MWT) enables 3D motion analysis and self-paced treadmill walking, and could provide insight in gait alterations in patients with chronic obstructive pulmonary disease (COPD). The aim of this study is to compare spatiotemporal gait characteristics between patients with COPD and healthy elderly during the GRAIL-based 6MWT.Materials and methodsEighty COPD patients (60% male; 62±7 years; FEV1:56±19% predicted) and 38 healthy elderly (63% male; 62±6 years; FEV1:119±17% predicted) performed two GRAIL-based 6MWTs. Mean differences and coefficient of variation of spatiotemporal gait characteristics were calculated using the trial with the largest walk distance. Sub-analyses were conducted to account for walking speed differences between groups, and muscle strength and COPD severity within the patient group.ResultsCOPD patients showed increased temporal gait characteristics, decreased stride and step lengths, and increased gait variability compared to healthy elderly (p<0.01). Stride length variability remained increased in COPD after correction for walking speed (MD:0.98%, CI:0.36–1.61, p = 0.003). Reduced quadriceps strength did not translate into altered gait characteristics, while COPD severity is associated with stride time (left MD:-0.02s, CI:-0.04–0.01, p = 0.003; right MD:-0.02s, CI:-0.04–0.01, p = 0.003).DiscussionCOPD patients performed the GRAIL-based 6MWT differently compared to healthy elderly. Further research should use other variability measures to investigate gait characteristics in COPD, to assess subtle alterations in gait and to enable development of rehabilitation strategies to improve gait, and possibly balance and fall risk in COPD. Other lower limb muscle groups should be considered when investigating gait alterations in COPD.ConclusionCOPD patients have different gait characteristics compared to healthy elderly. Independent of walking speed, COPD patients demonstrate increased stride length variability during the GRAIL-based 6MWT compared to healthy elderly.

Study of the association between gait variability and physical activity

BackgroundGait variability can be considered an indirect measure of gait stability, in particular regarding temporal or spatial variability assessment. Physical activity, such as walking, is advised for the elderly and can be improved by gait stability. The aim of this study was to investigate the associations between gait stability and physical activity in women of different age ranges.MethodsForty-two healthy women of different age ranges (18-40 yrs. and 65-75 yrs.) were recruited in the study. To assess physical activity, the subjects wore a multi-sensor activity monitor for a whole week, inferring the time spent in moderate to vigorous physical activity (MVPA). MVPA were analysed in bouts of at least 10 subsequent minutes (MVPAbouts) and in overall minutes (MVPAtot). A kinematic analysis was performed with an optoelectronic system to calculate gait variability - expressed as standard deviation (SD) and coefficient of variability (CV) of step width, stride length, stance and swing time (during treadmill walking at different speeds).ResultsElderly women, with high walking speed (5 km/h), and moderate step width variability (CV = 8–27%), met the recommended levels of physical activity (MVPAtot and MVPAbouts). Furthermore, gait variability, adjusted for age and number of falls, was significantly and negatively associated with MVPAtot only at 3.5 km/h, and with MVPAbouts only at 4 km/h.ConclusionsIn a population of healthy elderly women, gait variability was significantly and negatively associated with the level of physical activity. Healthy elderly women, with moderate gait variability (step width variability), and high preferred walking speed, seem to be able to meet the recommended levels of physical activity.

Fractal fluctuations in spatiotemporal variables when walking on a self-paced treadmill

This study investigated the fractal dynamic properties of stride time (ST), stride length (SL) and stride speed (SS) during walking on a self-paced treadmill (STM) in which the belt speed is automatically controlled by the walking speed. Twelve healthy young subjects participated in the study. The subjects walked at their preferred walking speed under four conditions: STM, STM with a metronome (STM+met), fixed-speed (conventional) treadmill (FTM), and FTM with a metronome (FTM+met). To compare the fractal dynamics between conditions, the mean, variability, and fractal dynamics of ST, SL, and SS were compared. Moreover, the relationship among the variables was examined under each walking condition using three types of surrogates. The mean values of all variables did not differ between the two treadmills, and the variability of all variables was generally larger for STM than for FTM. The use of a metronome resulted in a decrease in variability in ST and SS for all conditions. The fractal dynamic characteristics of SS were maintained with STM, in contrast to FTM, and only the fractal dynamic characteristics of ST disappeared when using a metronome. In addition, the fractal dynamic patterns of the cross-correlated surrogate results were identical to those of all variables for the two treadmills. In terms of the fractal dynamic properties, STM walking was generally closer to overground walking than FTM walking. Although further research is needed, the present results will be useful in research on gait fractal dynamics and rehabilitation.

Multitasking in older adults with type 2 diabetes: A cross-sectional analysis.

Background and purposeDeficits in the ability to multitask contribute to gait abnormalities and falls in many at-risk populations. However, it is unclear whether older adults with type 2 diabetes mellitus (DM) also demonstrate impairments in multitasking. The purpose of this study was to compare multitasking performance in cognitively intact older adults with and without DM and explore its relationship to measures of gait and functional ability.MethodsWe performed a cross-sectional analysis of 40 individuals aged 60 and older with type 2 DM and a matched group of 40 cognitively intact older adults without DM. Multitasking was examined via the ambulatory Walking and Remembering Test (WART) and seated Pursuit Rotor Test (PRT). Self-selected normal and fast walking speed and stride length variability were quantitatively measured, and self-reported functional ability was assessed via the Late Life Function and Disability Index (LLFDI).ResultsParticipants with DM walked slower and took more steps off path when multitasking during the WART. No between-group differences in multitasking performance were observed on the PRT. Multitasking performance demonstrated little correlation with gait and functional ability in either group.Discussion and conclusionsOlder adults with DM appear to perform poorly on an ambulatory measure of multitasking. However, we analyzed a relatively small, homogenous sample of older adults with and without type 2 DM and factors such as peripheral neuropathy and the use of multiple comparisons complicate interpretation of the data. Future research should explore the interactions between multitasking and safety, fall risk, and function in this vulnerable population. Clinicians should recognize that an array of factors may contribute to gait and physical dysfunction in older adults with type 2 diabetes, and be prepared to assess and intervene appropriately.

Effects of Subthalamic and Nigral Stimulation on Gait Kinematics in Parkinson’s Disease

Conventional subthalamic deep brain stimulation for Parkinson’s disease (PD) presumably modulates the spatial component of gait. However, temporal dysregulation of gait is one of the factors that is tightly associated with freezing of gait (FOG). Temporal locomotor integration may be modulated differentially at distinct levels of the basal ganglia. Owing to its specific descending brainstem projections, stimulation of the substantia nigra pars reticulata (SNr) area might modulate spatial and temporal parameters of gait differentially compared to standard subthalamic nucleus (STN) stimulation. Here, we aimed to characterize the differential effect of STN or SNr stimulation on kinematic gait parameters. We analyzed biomechanical parameters during unconstrained over ground walking in 12 PD patients with subthalamic deep brain stimulation and FOG. Patients performed walking in three therapeutic conditions: (i) Off stimulation, (ii) STN stimulation (alone), and (iii) SNr stimulation (alone). SNr stimulation was achieved by stimulating the most caudal contact of the electrode. We recorded gait using three sensors (each containing a tri-axial accelerometer, gyroscope, and magnetometer) attached on both left and right ankle, and to the lumbar spine. STN stimulation improved both the spatial features (stride length, stride length variability) and the temporal parameters of gait. SNr stimulation improved temporal parameters of gait (swing time asymmetry). Correlation analysis suggested that patients with more medial localization of the SNr contact associated with a stronger regularization of gait. These results suggest that SNr stimulation might support temporal regularization of gait integration.

The Effect of Hearing Aids and Cochlear Implants on Balance During Gait.

Auditory input in people with hearing impairment will improve balance while walking. Auditory input is increasingly recognized as an additional input for balance. Several studies have found auditory cues to improve static balance measured on a sway platform. The effect of audition on gait, a dynamic task also linked to fall risk, has not been fully examined. If a positive effect were shown between audition and balance, it would further indicate that improving hearing could also improve balance. Inertial sensors quantified gait parameters of 13 bilateral hearing aid users and 12 bilateral cochlear implant (CI) users with their hearing devices on and off. Outcome measures included gait velocity, stride length variability, swing time variability, and double support phase. Group analysis of each of the gait outcomes showed no significant differences between the aided and unaided conditions in both the hearing aid and CI groups. Gait velocity, an outcome most strongly linked to fall risk had 95% confidence interval differences of -2.16 to 1.52 and -1.45 to 4.17 cm/s in hearing aid and CI users, respectively (aided versus unaided condition). There was considerable variation among participants with some individuals improving in all four parameters. The overall findings were not statistically significant, however, a small subset of our population improved clinically across several outcomes. This demonstrates that audition may have a clinically beneficial effect on balance in some patients.

P 73 Shorter pulse width reduces gait ataxia associated with VIM-DBS

Background Limb and gait ataxia following chronic VIM-DBS is a frequent and clinically relevant phenomenon ( Hwynn et al., 2011 ), which is likely caused by disruption of physiological cerebello-thalamic signaling and inadvertent cerebellar activation ( Reich et al., 2016 ). Ataxia dramatically improves after a pause of stimulation for more than 72 h. At the same time, tremor will reoccur, leaving the patient disabled. To date, no effective therapeutic option for stimulation-induced gait ataxia has been identified. Shorter pulse width than 60 μs have been suggested to broaden the therapeutic windows as fiber tracts involved in tremor suppression and induction of ataxia have differential electrophysiological properties ( Reich et al., 2015 , Groppa et al., 2014 ). Here, we explore the therapeutic value of 40 μs pulse width in treatment of stimulation-induced gait ataxia. Methods 5 patients received special access codes that allowed their neurostimulators to be programmed beyond regular limits. Spatiotemporal gait parameters were measured using an accelerometer-based kinematic motion analysis system (Mobility Lab, APDM). Measurements were repeated (1) ON best stimulation for tremor suppression (2) after 4 days of withdrawal of stimulation (3) after more than 6 weeks of adjusted stimulation with 40 μs pulse width. Clinical assessment of gait ataxia and tremor was done using Score for Assessment and Rating of Ataxia (SARA) items 1–3 and the Tremor-Rating-Score (TRS). Patients were asked to self-report their global impression of change (GIC-S). Results 4 of 5 patients self-reported an improvement of gait performance off stimulation and at DBS at short pulse width. Tremor scores were reduced with VIM-DBS similar for 40 μs (9.2 ± 3.8) and 60 μs (9.6 ± 4.0) pulse width compared to OFF DBS (21.4 ± 5.5; p = 0.065) and SARA axial items (1–3) decreased with stimulation OFF (2.8 ± 0.86) and 40 μs VIM-DBS (2.4 ± 0.74;) compared to 60 μs VIM-DBS (6.0 ± 0.89; p = 0.065). Coefficient of variability (CoV) of stride length and of shank range of motion were significantly reduced both OFF DBS and with 40 μs VIM-DBS (p Conclusions Our results add further evidence to the growing number of studies pointing to gait ataxia as a severe yet reversible side effect of thalamic stimulation rather than disease progression. Shorter pulsewidths may therefore be a promising approach to target stimulation-induced side effects while maintaining desired clinical efficacy of tremor suppression.

Effects of cognitive versus motor dual-task on spatiotemporal gait parameters in healthy controls and multiple sclerosis patients with and without fall history

BackgroundThe purpose of the current study was to compare the effects of cognitive or motor tasks on gait performance between healthy controls and multiple sclerosis (MS) patients with and without fall history. MethodsThe investigation included MS patients with fall history (n = 25) and without fall history (n = 25) and matched healthy controls (n = 25). Participants walked at their preferred speed on a motorized treadmill under three walking conditions in a randomized order: walking only, walking while performing a concurrent cognitive task (counting backward aloud by 3s), and walking while performing a concurrent motor task (carrying a tray with glasses). ResultsThe findings showed that in patients with MS, regardless of fall history, spatiotemporal gait parameters were different compared to healthy controls. In contrast to average gait parameters, variability in stride length and stride time could discriminate between MS fallers and non-fallers. Simultaneous performance of cognitive task and walking resulted in higher dual-task costs (DTC) in gait performance compared to the motor dual-task. However, the pattern of change was not different among the three groups. All participants responded to the cognitive task challenges by increasing stride length and decreasing cadence and stride length variability while maintaining cognitive task performance. ConclusionsThe findings may reflect successful adaptation of locomotor system to preserve cognitive task performance under cognitive dual-task condition. Future studies should examine more complex concurrent cognitive and motor tasks to better understand the dual-task-related gait changes and their contribution to falls in patients with MS.