Bilateral Coordination Of Gait Research Articles

Variability, asymmetry and bilateral coordination of gait during single- and dual-task walking of patients with cerebral small vessel disease

Objective We investigated coefficient of variation (CV), gait asymmetry (GA) and phase coordination index (PCI) in cerebral small vessel disease (CSVD) patients during single-task walking (STW) and dual-task walking (DTW) and explored the relationship between above parameters with disease severity and cognitive function. Methods This cross-sectional study collected cognitive function indices and gait parameters from 23 healthy controls and 94 patients with CSVD during STW and DTW. According to the Fazekas scales, the severity of CSVD valued by white matter hyperintensity (WMH) were divided into control, mild, moderate, severe and control group. MRIs were analyzed for WMHs, CMB, lacunes, etc. Results The control group showed lower PCI than CSVD patients during STW; no differences were detected among the disease severity groups. During DTW, all four groups exhibited significant differences in PCI and CV. For the moderate and severe groups, coordination and variation significantly differed between the two walking methods. There were correlations between the PCI and GA in the moderate and severe groups (R = 0.376, R = 0.573 during DTW; R = 0.414, R = 0.643 during STW) and no correlations in the control group and mild CSVD group. Conclusion PCI and CV may be vital for detecting the symptoms in the early stage of CSVD disease. We also verified that the PCI could become the bridge across the cognition and motor disorder in CSVD, which was helpful for evaluating clinical symptoms comprehensively.

Bilateral coordination of gait at self-selected and fast speed in patients with multiple sclerosis: a case-control study.

Multiple sclerosis (MS) is characterized by progressive demyelinating deterioration of nervous tissues in the brain and cord, leading to a disruption in the ability of parts of the nervous system to transmit signals. Although dorsal column pathways are compromised in neuropathological studies, gait control assessments, especially on speed effects, have been understudied in MS. This study aimed to compare bilateral coordination of gait in subjects with MS at self-selected and fast speed and to relate these findings to disease severity (Expanded Disability Status Scale (EDSS)) and age. An age-matched and sex-matched case-control study was performed to assess the bilateral coordination of gait of 26 MS subjects by evaluating the gait spatiotemporal parameters captured by an inertial measurement unit sensor. The bilateral variability, accuracy, and overall coordination (the sum of variability and accuracy) were assessed at a self-selected and fast speed, and correlated with disease severity and age. All gait control parameters improved at the fast speed compared to the self-selected walking speed (p<0.05 for all comparisons). The bilateral coordination of gait was moderately related to disease severity and age (p<0.05), and the gait spatiotemporal parameters were related to disease severity (p<0.001, from R=0.66 to R=0.70). Patients with MS showed significant impairment in the bilateral coordination of gait at self-selected compared to fast speed. Functional mobility tests and locomotor interventions should be cautious when analyzed at different paces. Interventions aiming to increase speed can be a proper and safe strategy in locomotor studies.

Age related changes in gait variability, asymmetry, and bilateral coordination – When does deterioration starts?

BackgroundGait pattern coordination is affected by several factors (e.g., neurodegeneration), while aging is known to have a significant negative impact. Various gait parameters, such as gait asymmetry (GA) and stride time coefficient of variation (CV), are widely used in both research and clinical settings in order to evaluate human locomotion. Another parameter is the phase coordination index (PCI), which specifically assesses bilateral coordination of gait (BCG), by quantifying the consistency and accuracy of the anti-phased stepping pattern. ObjectiveIn this study we hypothesized that there is a steady deterioration in the bilateral coordination of walking through ageing, and in gait rhythmicity, which would be evident by an increase in the values of the coordination parameters which are examined. MethodsWe analyzed gait cycles of 66 healthy participants in ages between 40 and 85 years which were divided into five age groups (40–44; 45–54; 55–64; 75 +). The participants performed corridor walking (i.e., back and forth) wearing a computerized motion sensor-based gait analysis system. PCI, CV and GA parameters were calculated for the straight-line walking segments. ResultsPCI values remained relatively stable between the ages of 40–75 (3.16 ± 1.11%), while in the age group of 75 + years old we observed a significant increase (i.e., deterioration in BCG) in PCI values (5.68 ± 2.01%, p < 0.047). Same pattern was seen for the CV parameter. However, GA was not statistically significantly different between all age groups. ConclusionIt appears that PCI and CV are more sensitive measures to detect changes in gait through the aging process. The results suggest that potential screening to detect salient gait deterioration should start from the age of 70. On the other hand, GA may be used to identify neurological impairments if found increased at any age.

A passive exoskeleton can assist split-belt adaptation.

An exoskeletal device can assist walking in those with gait deficits. A passive exoskeleton can be a favorable choice for local or home rehabilitation settings because it is affordable, light weight, and less complex to utilize. While there is research that investigates the effects of exoskeleton on gait research examining the effects of such devices on gait adaptation, is rare. This is important because in diseases like stroke, the ability to flexibly adapt is affected, such that functional recovery becomes difficult. The purpose of this study was to characterize gait adaptation patterns that result from exoskeleton usage during a split-belt adaptation task. Healthy young participants were randomly assigned to a unilateral exoskeleton or a no-exoskeleton group. Each participant performed the specific split-belt adaptation tasks on the treadmill, where the speed of each belt could be controlled independently. Symmetry indices of spatiotemporal variables were calculated to quantify gait adaptation. To analyze the adaptation, trials were divided into early and late adaptation. We also analyzed degree of adaptation, and transfer effects. We also measured the symmetry of the positive power generated by the individual legs during the split-belt task to determine if using exoskeleton assistance reduced power in the exoskeleton group versus the no-exoskeleton group. Use of a passive exoskeleton device altered gait adaptation during a split-belt treadmill task in comparison to the control group. Such adaptation was found to be largely restricted to the temporal domain. Changes in the gait coordination patterns consisted of both early and late adaptive changes, especially in intra-limb patterns like stance time rather than inter-limb patterns like step time. Although the symmetry of the positive power generated during the split-belt task was found to be reduced for the exoskeleton-assistance group, it was shown that this was primarily the result of increased positive power generated by the side not receiving exoskeletal assistance. An unpowered assistive device can provide a unique solution for coordinating the lower limbs during different gait tasks. Such a solution could reduce the neural burden of adaptation consequently resulting in a reduction of the mechanical burden of walking during the bilateral gait coordination task. This may be useful for accelerating gait rehabilitation in different patient populations. However, balance control is important to consider during unilateral exoskeletal assistance.

Gait characteristics under single-/dual-task walking conditions in elderly patients with cerebral small vessel disease: Analysis of gait variability, gait asymmetry and bilateral coordination of gait

BackgroundDual-task walking (DTW) is common in daily life and represents an ideal paradigm for elucidating gait irregularity. Under single-task walking (STW) and DTW conditions, the symmetric and bilaterally coordinated human gait pattern found in healthy individuals is absent in individuals with neurological ailments such as Parkinson’s disease, Alzheimer’s disease and post-stroke issues. Cerebral small vessel disease (CSVD) is a neuropathological and radiological issue that has been reported to be associated with cognitive and motor disorders. However, few gait analyses have focused on elderly individuals with CSVD under DTW conditions. Research questionAre parameters of gait analysis helpful in elucidating gait abnormalities in elderly patients with CSVD under DTW conditions? MethodsA total of 46 elderly patients with CSVD (CSVD group) and 22 healthy, age-matched individuals (HE group) were recruited. Gait data were collected from both groups under STW and DTW conditions. Direct parameters and metrics reflecting gait variability, gait asymmetry, and bilateral coordination of gait in the two groups were compared. ResultsUnder STW conditions, elderly individuals with CSVD showed markedly shorter stride length, were slower, and had higher gait asymmetry (GA) and phase coordination index (PCI) than healthy controls after adjusting for age, sex and level of education. Under DTW conditions, there were statistically significant differences between the two groups in stride time, stride length, cadence, stride time variability, GA and PCI after adjusting for age, sex, and level of education. SignificanceReanalysis-generated parameters, such as gait variability, GA, and PCI, are biomarkers for gait dysfunction in elderly patients with CSVD. In this study, elderly individuals with CVSD showed abnormal gait features under both STW and DTW conditions.

Adaptation of bilateral coordination of gait during split belt walking as reflected by the phase coordination index.

The Split belt treadmill (SBTM) has recently been used in research and rehabilitation to study and utilize gait adaptations. The Phase coordination index (PCI) is useful in assessing bilateral coordination of gait by quantifying the consistency and accuracy in generating the anti-phased left-right stepping pattern. Recently we proposed that 23 strides are sufficient to reliably characterize PCI values from regular over ground and treadmill walking RESEARCH QUESTION: Can we detect the effect of SBTM on PCI using only 23 gait cycles also from SBTM walking? Young healthy participants (n = 13) with right side motor dominance performed SBTM walking trials. Experiment protocol began by walking in tied belt (TB) mode, followed by an incremental speed increase of one of the belts by 50 % - split belt (SB) mode. This was performed for each side. Two 1-minute segments were analyzed per participant, TB and SB. PCI analysis was carried out upon fewer strides (n = 23) and compared to PCI that was obtained based on all available strides (n = 56 ± 5). Clear SBTM walking effects on PCI were seen in both experiments, for example, PCI increased from 4.46 ± 1.5 % (TB) to 10.07 ± 3.6 % (SB) for left belt speed increase. Twenty three strides from each trail were sufficient to demonstrate the effect. PCI can be a useful metric to characterize changes in bilateral coordination of gait during SBTM gait adaptations. The fact that 23 strides are sufficient for its reliable estimation, contribute to the continued monitoring through the adaptation process (i.e., by using time windows).

A temporal analysis of bilateral gait coordination in people with multiple sclerosis

Background: Gait performance often dictates an individual's ability to navigate the dynamic environments of everyday living. With each stride, the lower extremities move through phases of stance, swing, and double support. Coordinating these motions with high accuracy and consistency is imperative to constraining the center of mass within the base of support, thereby maintaining balance. Gait abnormalities accompany neurodegeneration, impeding stride to stride cohesion and increasing the likelihood of a fall. This study sought to identify the temporal actions underlying bilateral coordination in people with multiple sclerosis (PwMS) and furthermore, how bilateral coordination is affected by gait speed augmentation in these individuals. Methods: The Phase Coordination Index (PCI), a temporal analysis of left-right step pattern generations throughout the gait cycle was used to quantify bilateral coordination in twenty-nine neurotypical (21 females and 8 males) and twenty-seven PwMS (20 females and 7 males). PCI was acquired with inertial monitoring units while performing two-minute over ground gait trials while walking at a self-selected pace and at a fast pace. Results: PwMS displayed significantly worse bilateral coordination compared to neurotypical adults regardless of gait speed. The poorer left-right stepping patterns generated by PwMS were derived from significant decreases in both phase (step) generation accuracy and consistency. In addition to demonstrating poorer bilateral coordination, PwMS walked more slowly than their neurotypical peers during each walking condition. Conclusion: PwMS exhibited poorer left-right coordinated stepping patterns during gait compared to neurotypical peers across walking conditions. Beyond the novelty of this examination, this assessment highlights PCI as a potential target for future rehabilitative interventions for PwMS and individualized rehabilitation strategies aimed at improving the health span and overall quality of life for PwMS.

Gait asymmetry, and bilateral coordination of gait during a six-minute walk test in persons with multiple sclerosis

Gait impairments in persons with multiple sclerosis (pwMS) leading to decreased ambulation and reduced walking endurance remain poorly understood. Our objective was to assess gait asymmetry (GA) and bilateral coordination of gait (BCG), among pwMS during the six-minute walk test (6MWT), and determine their association with disease severity. We recruited 92 pwMS (age: 46.6 ± 7.9; 83% females) with a range of clinical disability, who completed the 6MWT wearing gait analysis system. GA was assessed by comparing left and right swing times, and BCG was assessed by the phase coordination index (PCI). Several functional and subjective gait assessments were performed. Results show that gait is more asymmetric and less coordinated as the disease progresses (p < 0.0001). Participants with mild MS showed significantly better BCG as reflected by lower PCI values in comparison to the other two MS severity groups (severe: p = 0.001, moderate: p = 0.02). GA and PCI also deteriorated significantly each minute during the 6MWT (p < 0.0001). GA and PCI (i.e., BCG) show weaker associations with clinical MS status than associations observed between functional and subjective gait assessments and MS status. Similar to other neurological cohorts, GA and PCI may be important parameters to assess and target in interventions among pwMS.

Soft-Material-Based Smart Insoles for a Gait Monitoring System.

Spatiotemporal analysis of gait pattern is meaningful in diagnosing and prognosing foot and lower extremity musculoskeletal pathologies. Wearable smart sensors enable continuous real-time monitoring of gait, during daily life, without visiting clinics and the use of costly equipment. The purpose of this study was to develop a light-weight, durable, wireless, soft-material-based smart insole (SMSI) and examine its range of feasibility for real-time gait pattern analysis. A total of fifteen healthy adults (male: 10, female: 5, age 25.1 ± 2.64) were recruited for this study. Performance evaluation of the developed insole sensor was first executed by comparing the signal accuracy level between the SMSI and an F-scan. Gait data were simultaneously collected by two sensors for 3 min, on a treadmill, at a fixed speed. Each participant walked for four times, randomly, at the speed of 1.5 km/h (C1), 2.5 km/h (C2), 3.5 km/h (C3), and 4.5 km/h (C4). Step count from the two sensors resulted in 100% correlation in all four gait speed conditions (C1: 89 ± 7.4, C2: 113 ± 6.24, C3: 141 ± 9.74, and C4: 163 ± 7.38 steps). Stride-time was concurrently determined and R2 values showed a high correlation between the two sensors, in both feet (R2 ≥ 0.90, p < 0.05). Bilateral gait coordination analysis using phase coordination index (PCI) was performed to test clinical feasibility. PCI values of the SMSI resulted in 1.75 ± 0.80% (C1), 1.72 ± 0.81% (C2), 1.72 ± 0.79% (C3), and 1.73 ± 0.80% (C4), and those of the F-scan resulted in 1.66 ± 0.66%, 1.70 ± 0.66%, 1.67 ± 0.62%, and 1.70 ± 0.62%, respectively, showing the presence of a high correlation (R2 ≥ 0.94, p < 0.05). The insole developed in this study was found to have an equivalent performance to commercial sensors, and thus, can be used not only for future sensor-based monitoring device development studies but also in clinical setting for patient gait evaluations.

Reshaping of Bilateral Gait Coordination in Hemiparetic Stroke Patients After Early Robotic Intervention

Hemiparetic gait is a common condition after stroke which alters importantly the quality of life of stroke survivors. In recent years, several robotic interventions have been developed to support and enhance rehabilitation strategies for such population. The Hybrid Assistive Limb® (HAL) robot suit is a unique device able to collect in real time bioelectric signals from the patient to support and enhance voluntary gait. HAL has been used before in early stages of stroke showing gait improvement after the intervention. However, evaluation of the coordination of gait has not been done yet. Coordination is a key factor for an adequate gait performance; consequently, its changes may be closely related to gait recovery. In this study, we used planar covariation to evaluate coordination changes in hemiparetic stroke patients after early HAL intervention. Before starting, impaired intersegmental coordination for the paretic and non-paretic side was evident. HAL intervention was able to induce recovery of the covariation loop shape and deviation from the covariation plane improving intersegmental coordination. Also, there was a tendency of recovery for movement range evidenced by comparison of peak elevation angles of each limb segment of the patients before and after HAL intervention, and also when compared to healthy volunteers. Our results suggest that early HAL intervention contributed to the improvement of gait coordination in hemiparetic stroke patients by reinforcing central pattern generators and therefore reshaping their gait pattern.Trial registration: UMIN000022410 2016/05/23.

Gender differences in patients with fibromyalgia: a gait analysis.

This study analysed the spatio-temporal parameters, asymmetry, variability and bilateral coordination of gait in women and men with fibromyalgia and healthy subjects walking at their usual velocity and at a faster walking velocity. Fifty-five women and 12 men with fibromyalgia were analysed. A healthy group of 44 women and 17 men was analysed as the control group. A GAITRite system was used to obtain the spatio-temporal gait parameters for the participants when walking at their usual velocity and at a faster velocity. Coefficients of variation, bilateral coordination and gait asymmetry indexes were calculated. All groups exhibited a significant increase (p &lt; 0.001) in spatio-temporal parameters when walking fast. The fibromyalgia groups showed increased bilateral coordination, asymmetry and variability of stance phase when walking fast. The fibromyalgia women showed significant spatio-temporal, variability and bilateral coordination of gait differences compared with the healthy women. The fibromyalgia men reported significant differences in velocity, cadence, stride length, swing time variability and stance gait asymmetry indices compared with the healthy men. No significant differences were observed between the men and women in the fibromyalgia groups. The findings of the present study did not support gender-specific differences in walking variables and indices in FM patients. The differences found between both genders of FM patients and healthy subjects in walking indices at fast velocities could be a useful tool for diagnoses and evaluation of male and female patients with FM during short-term fast walking tests.

How many strides are required for a reliable estimation of temporal gait parameters? Implementation of a new algorithm on the phase coordination index.

BackgroundThe Phase coordination index (PCI), a temporal gait measure that quantifies consistency and accuracy in generating the anti-phased left-right stepping pattern, assesses bilateral coordination of gait in various cohorts (e.g., Parkinson's disease, post stroke). As PCI is based on mean values calculated across a series of gait cycles, individuals are required to perform lengthy walking trials, prolonging gait assessments which cause discomfort to some of them. This study introduces an algorithm to identify the required number of strides to obtain a reliable, characteristic PCI value.MethodsSimulated data sets, as well as physiological data (obtained from healthy elderly and young persons, from over ground and treadmill trials) were used in this research. A series of N-1 PCI values was calculated for i = 2,3,4…N gait cycles for each participant. There is a value i = k, representing certain number of cycles, for which no significant change in PCI occurs as additional cycles are added, termed point of stabilization (POS). The algorithm presented here uses a 2-stage iterative process to determine POS. Stage 1 searches for the gross location of the interval of PCI values containing the POS. In stage 2, the algorithm performs a high-resolution recursive, iterative process within this interval to find the exact point. The criterion for defining stability within a window of PCI values is a coefficient of variation (CV) of ≤ 5%.ResultsOur recursive, iterative algorithm indicates that ~23 strides on average should be captured to attain a characteristic PCI.ConclusionsGait trials with at least 23 strides on average should suffice to obtain a reliable estimation of PCI in healthy young adults. While this methodology may be considered generic, future studies should obtain POS values based on additional cohorts (e.g., disabled participants, fixed walking speeds).

Gait Coordination Deteriorates in Independent Old-Old Adults.

Human gait is symmetric and bilaterally coordinated in young healthy persons. In this study, we aimed to explore the differences in bilateral coordination of gait as measured by the phase coordination index (PCI), gait asymmetry, and stride time variability of gait between four age groups. A total of 44 older adults were recruited: nine young-old (age 70-74 years), 26 old (age 75-84 years), nine old-old (>85 years and older), and 13 young adults (age 20-30 years). Subjects walked on a treadmill; walking speed was systematically increased from 0.5 to 0.9m/s in steps of 0.1m/s. There were marginal effects of age on PCI, significant main effects of walking speeds without interaction between walking speeds and age group. A difference in PCI could distinguish between young's and late aging group, and only during their preferred treadmills walking speed. This study explicitly shows that bilateral coordination of walking is modified by gait speed, and deteriorates only at a very old age.

The effect of uphill and downhill walking on gait parameters: A self-paced treadmill study

It has been shown that gait parameters vary systematically with the slope of the surface when walking uphill (UH) or downhill (DH) (Andriacchi et al., 1977; Crowe et al., 1996; Kawamura et al., 1991; Kirtley et al., 1985; McIntosh et al., 2006; Sun et al., 1996). However, gait trials performed on inclined surfaces have been subject to certain technical limitations including using fixed speed treadmills (TMs) or, alternatively, sampling only a few gait cycles on inclined ramps. Further, prior work has not analyzed upper body kinematics. This study aims to investigate effects of slope on gait parameters using a self-paced TM (SPTM) which facilitates more natural walking, including measuring upper body kinematics and gait coordination parameters.Gait of 11 young healthy participants was sampled during walking in steady state speed. Measurements were made at slopes of +10°, 0° and −10°. Force plates and a motion capture system were used to reconstruct twenty spatiotemporal gait parameters. For validation, previously described parameters were compared with the literature, and novel parameters measuring upper body kinematics and bilateral gait coordination were also analyzed.Results showed that most lower and upper body gait parameters were affected by walking slope angle. Specifically, UH walking had a higher impact on gait kinematics than DH walking. However, gait coordination parameters were not affected by walking slope, suggesting that gait asymmetry, left-right coordination and gait variability are robust characteristics of walking. The findings of the study are discussed in reference to a potential combined effect of slope and gait speed. Follow-up studies are needed to explore the relative effects of each of these factors.

Variability of gait, bilateral coordination, and asymmetry in women with fibromyalgia

PurposeTo analyze how fibromyalgia affected the variability, asymmetry, and bilateral coordination of gait walking at comfortable and fast speeds. Methods65 fibromyalgia (FM) patients and 50 healthy women were analyzed. Gait analysis was performed using an instrumented walkway (GAITRite system). Average walking speed, coefficient of variation (CV) of stride length, swing time, and step width data were obtained and bilateral coordination and gait asymmetry were analyzed. ResultsFM patients presented significantly lower speeds than the healthy group. FM patients obtained significantly higher values of CV_StrideLength (p=0.04; p<0.001), CV_SwingTime (p<0.001; p<0.001), CV_StepWidth (p=0.004; p<0.001), phase coordination index (p=0.01; p=0.03), and p_CV (p<0.001; p=0.001) than the control group, walking at comfortable or fast speeds. Gait asymmetry only showed significant differences in the fast condition. ConclusionFM patients walked more slowly and presented a greater variability of gait and worse bilateral coordination than healthy subjects. Gait asymmetry only showed differences in the fast condition. The variability and the bilateral coordination were particularly affected by FM in women. Therefore, variability and bilateral coordination of gait could be analyzed to complement the gait evaluation of FM patients.

Poster 1 Arm Movement Manipulations Affect Bilateral Coordination of Gait During Self-Paced Treadmill Walking

Poster 1 Arm Movement Manipulations Affect Bilateral Coordination of Gait During Self-Paced Treadmill Walking

Side by side treadmill walking reduces gait asymmetry induced by unilateral ankle weight

Asymmetric gait is a hallmark of many neurological and musculoskeletal conditions. This behavior is often the result of a decrease in the stability of interlimb coordination, and synchronization to external signals such as auditory cuing or another walking individual may be helpful for altering abnormal movement patterns. The purpose of this study was to investigate the interaction between interlimb coordination and unintentional, interpersonal synchronization of gait in healthy individuals in response to unilateral ankle loading. Fifty participants completed four trials while walking on a motorized treadmill: (1) by themselves, (2) with a partner on an adjacent treadmill, (3) by themselves with additional weight applied unilaterally to their right ankle, and (4) with both a partner and unilateral weight. As expected, the addition of unilateral weight increased asymmetry according to several spatiotemporal measures of gait, but the presence of a partner on an adjacent treadmill significantly reduced this effect. Further, the amount of unintentional, interpersonal synchronization among pairings was relatively unaffected by the addition of ankle weight to one of the partners. All pairings realized a beneficial effect on asymmetrical gait but this effect was greater for pairings that consistently synchronized unintentionally. These results suggest that side by side walking might be an effective approach for influencing bilateral coordination of gait and may hold insight for understanding gait asymmetry and interlimb movement variability.

Effects of walking speed on asymmetry and bilateral coordination of gait

The mechanisms regulating the bilateral coordination of gait in humans are largely unknown. Our objective was to study how bilateral coordination changes as a result of gait speed modifications during over ground walking. 15 young adults wore force sensitive insoles that measured vertical forces used to determine the timing of the gait cycle events under three walking conditions (i.e., usual-walking, fast and slow). Ground reaction force impact (GRFI) associated with heel-strikes was also quantified, representing the potential contribution of sensory feedback to the regulation of gait. Gait asymmetry (GA) was quantified based on the differences between right and left swing times and the bilateral coordination of gait was assessed using the phase coordination index (PCI), a metric that quantifies the consistency and accuracy of the anti-phase stepping pattern. GA was preserved in the three different gait speeds. PCI was higher (reduced coordination) in the slow gait condition, compared to usual-walking (3.51% vs. 2.47%, respectively, p=0.002), but was not significantly affected in the fast condition. GRFI values were lower in the slow walking as compared to usual-walking and higher in the fast walking condition (p<0.001). Stepwise regression revealed that slow gait related changes in PCI were not associated with the slow gait related changes in GRFI. The present findings suggest that left–right anti-phase stepping is similar in normal and fast walking, but altered during slow walking. This behavior might reflect a relative increase in attention resources required to regulate a slow gait speed, consistent with the possibility that cortical function and supraspinal input influences the bilateral coordination of gait.

Is Freezing of Gait in Parkinson's Disease a Result of Multiple Gait Impairments? Implications for Treatment

Several gait impairments have been associated with freezing of gait (FOG) in patients with Parkinson's disease (PD). These include deteriorations in rhythm control, gait symmetry, bilateral coordination of gait, dynamic postural control and step scaling. We suggest that these seemingly independent gait features may have mutual interactions which, during certain circumstances, jointly drive the predisposed locomotion system into a FOG episode. This new theoretical framework is illustrated by the evaluation of the potential relationships between the so-called “sequence effect”, that is, impairments in step scaling, and gait asymmetry just prior to FOG. We further discuss what factors influence gait control to maintain functional gait. “Triggers”, for example, such as attention shifts or trajectory transitions, may precede FOG. We propose distinct categories of interventions and describe examples of existing work that support this idea: (a) interventions which aim to maintain a good level of locomotion control especially with respect to aspects related to FOG; (b) those that aim at avoiding FOG “triggers”; and (c) those that merely aim to escape from FOG once it occurs. The proposed theoretical framework sets the stage for testable hypotheses regarding the mechanisms that lead to FOG and may also lead to new treatment ideas.

Modulation of gait coordination by subthalamic stimulation improves freezing of gait

The effect of subthalamic deep brain stimulation on gait coordination and freezing of gait in patients with Parkinson's disease is incompletely understood. The purpose of this study was to investigate the extent to which modulation of symmetry and coordination between legs by subthalamic deep brain stimulation alters the frequency and duration of freezing of gait in patients with Parkinson's disease. We recruited 13 post-subthalamic deep brain stimulation patients with Parkinson's disease with off freezing of gait and evaluated them in the following 4 conditions: subthalamic deep brain stimulation on (ON) and stimulation off (OFF), 50% reduction of stimulation voltage for the leg with shorter step length (worse side reduction) and for the leg with longer step length (better side reduction). Gait analysis was performed on a treadmill and recorded by an optoelectronic analysis system. We measured frequency and duration of freezing of gait episodes. Bilateral coordination of gait was assessed by the Phase Coordination Index, quantifying the ability to generate antiphase stepping. From the OFF to the ON state, freezing of gait improved in frequency (2.0 ± 0.4 to 1.4 ± 0.5 episodes) and duration (12.2 ± 2.6 to 2.6 ± 0.8 seconds; P = .005). Compared with the ON state, only better side reduction further reduced freezing of gait frequency (0.2 ± 0.2) and duration of episodes (0.2 ± 0.2 seconds; P = .03); worse side reduction did not change frequency (1.3 ± 0.4) but increased freezing of gait duration (5.2 ± 2.1 seconds). The better side reduction-associated improvements were accompanied by normalization of gait coordination, as measured by phase coordination index (16.5% ± 6.0%), which was significantly lower than in the other 3 conditions. Reduction of stimulation voltage in the side contralateral to the leg with longer step length improves frequency and duration of freezing of gait through normalization of gait symmetry and coordination in subthalamic deep brain stimulation patients with Parkinson's disease. This identifies poor leg coordination as a risk factor for causing freezing of gait.