The association between impaired turning and normal straight walking in Parkinson's disease

Foot-Floor Contact Sequences: A Metric for Gait Assessment in Parkinson's Disease after Deep Brain Stimulation

Digital gait monitoring is increasingly used to assess locomotion and fall risk. The aim of this work is to analyze the changes in the foot-floor contact sequences of Parkinson's Disease (PD) patients in the year following the implantation of Deep Brain Stimulation (DBS). During their best-ON condition, 30 PD patients underwent gait analysis at baseline (T0), at 3 months after subthalamic nucleus DBS neurosurgery (T1), and at 12 months (T2) after subthalamic nucleus DBS neurosurgery. Thirty age-matched controls underwent gait analysis once. Each subject was equipped with bilateral foot-switches and a 5 min walk was recorded, including both straight-line and turnings. The walking speed, turning time, stride time variability, percentage of atypical gait cycles, stance, swing, and double support duration were estimated. Overall, the gait performance of PD patients improved after DBS, as also confirmed by the decrease in their UPDRS-III scores from 19.4 ± 1.8 to 10.2 ± 1.0 (T0 vs. T2) (p < 0.001). In straight-line walking, the percentages of atypical cycles of PD on the more affected side were 11.1 ± 1.5% (at T0), 3.1 ± 1.5% (at T1), and 5.1 ± 2.4% (at T2), while in controls it was 3.1 ± 1.3% (p < 0.0005). In turnings, this percentage was 13.7 ± 1.1% (at T0), 7.8 ± 1.1% (at T1), and 10.9 ± 1.8% (at T2), while in controls it was 8.1 ± 1.0% (p < 0.001). Therefore, in straight-line walking, the atypical cycles decreased by 72% at T1, and by 54% at T2 (with respect to baseline), while, in turnings, atypical cycles decreased by 43% at T1, and by 20% at T2. The percentage of atypical gait cycles proved an informative digital biomarker for quantifying PD gait changes after DBS, both in straight-line paths and turnings.

Basal ganglia-spinal cord pathway that commands locomotor gait asymmetries in mice

The basal ganglia are essential for executing motor actions. How the basal ganglia engage spinal motor networks has remained elusive. Medullary Chx10 gigantocellular (Gi) neurons are required for turning gait programs, suggesting that turning gaits organized by the basal ganglia are executed via this descending pathway. Performing deep brainstem recordings of Chx10 Gi Ca2+ activity in adult mice, we show that striatal projection neurons initiate turning gaits via a dominant crossed pathway to Chx10 Gi neurons on the contralateral side. Using intersectional viral tracing and cell-type-specific modulation, we uncover the principal basal ganglia-spinal cord pathway for locomotor asymmetries in mice: basal ganglia → pontine reticular nucleus, oral part (PnO) → Chx10 Gi → spinal cord. Modulating the restricted PnO → Chx10 Gi pathway restores turning competence upon striatal damage, suggesting that dysfunction of this pathway may contribute to debilitating turning deficits observed in Parkinson's disease. Our results reveal the stratified circuit architecture underlying a critical motor program.

The effect of deep brain stimulation on lower extremity dexterity in people with Parkinson's disease

PURPOSE

To examine the effect of deep brain stimulation (DBS) on lower extremity dexterity in people with Parkinson's disease (PwPD) and to investigate the relationship between this effect and the effect of DBS on measures of different walking characteristics, and other features of Parkinson's disease.

MATERIALS AND METHODS

Thirty-six PwPD were included. Assessment was performed twice with DBS "on" and DBS "off" state.

RESULTS

The LEDT scores of both extremities, the Unified Parkinson Disease Rating Scale-motor section (UPDRS-III), the 10-Meter Walk Test (TMWT), the Timed Up and Go Test (TUG), the Figure-of-Eight Walk Test (FEWT), and the Three-Meter Backward Walk Test (TMBWT) scores were significantly better in "on" DBS condition than "off" DBS condition. The effect of DBS on lower extremity dexterity is related to age and levodopa equivalent daily dosage (LEDD). The effect of DBS on lower extremity dexterity and the effect of DBS on the bradykinesia, TUG, the FEWT, and the TMBWT were also related.

CONCLUSIONS

DBS has a positive effect on lower extremity dexterity. Clinical characteristics such as age and LEDD and the effect of DBS on bradykinesia, walking with turning, curved walking, and backward walking is related with the effect of DBS on lower extremity dexterity.

Quantifying Turning Tasks With Wearable Sensors: A Reliability Assessment

OBJECTIVE

The aim of this study was to establish the test-retest reliability of metrics obtained from wearable inertial sensors that reflect turning performance during tasks designed to imitate various turns in daily activity.

METHODS

Seventy-one adults who were healthy completed 3 turning tasks: a 1-minute walk along a 6-m walkway, a modified Illinois Agility Test (mIAT), and a complex turning course (CTC). Peak axial turning and rotational velocity (yaw angular velocity) were extracted from wearable inertial sensors on the head, trunk, and lumbar spine. Intraclass correlation coefficients (ICCs) were established to assess the test-retest reliability of average peak turning speed for each task. Lap time was collected for reliability analysis as well.

RESULTS

Turning speed across all tasks demonstrated good to excellent reliability, with the highest reliability noted for the CTC (45-degree turns: ICC = 0.73-0.81; 90-degree turns: ICC = 0.71-0.83; and 135-degree turns: ICC = 0.72-0.80). The reliability of turning speed during 180-degree turns from the 1-minute walk was consistent across all body segments (ICC = 0.74-0.76). mIAT reliability ranged from fair to excellent (end turns: ICC = 0.52-0.72; mid turns: ICC = 0.50-0.56; and slalom turns: ICC = 0.66-0.84). The CTC average lap time demonstrated good test-retest reliability (ICC = 0.69), and the mIAT average lap time test-retest reliability was excellent (ICC = 0.91).

CONCLUSION

Turning speed measured by inertial sensors is a reliable outcome across a variety of ecologically valid turning tasks that can be easily tested in a clinical environment.

IMPACT

Turning performance is a reliable and important measure that should be included in clinical assessments and clinical trials.

A biomechanical analysis of turning during gait in individuals with different subtypes of Parkinson's disease

BACKGROUND

Turning while walking is a complex component of locomotor capacity, which can be challenging in the daily lives of people with Parkinson's disease. The aim of the study was to compare biomechanical strategies during turning of gait in individuals with Parkinson's disease and its different clinical subtypes.

METHODS

A cross-sectional study, comprising of 43 individuals with idiopathic Parkinson's disease, divided in subgroups: akineto-rigid, dominant tremor and mixed. Motor impairment was assessed using the Unified Parkinson's Disease Rating Scale. The gait biomechanical parameters (number of steps, step length, cadence, amplitude, velocity and radius of the turn) were analyzed during turning in a kinematics laboratory. In the statistical analysis, a comparison was made between subgroups, and correlations between biomechanical parameters.

FINDINGS

There was no statistically significant difference between the subgroups. In the correlation analysis, notable correlations were found between the anticipatory step length and the following variables: number of steps (r = -0.418), step length while turning (r = 0.805), step length after turning (r = 0.644), average velocity (r = 0.830), average velocity while turning (r = 0.755), and maximum velocity (rho = 0.835).

INTERPRETATION

The difficulties primarily occur during the anticipatory phase of the turn, which affects the entire task. The greater the length of the anticipatory step, the greater the length of the step taken to turn as well as the step taken after turning. And the greater the velocity, the greater the step length, and to fewer steps taken to perform the task.

Beyond timing and step counting in 360° turning-in-place assessment: a scoping review

BACKGROUND

Turning in place is a challenging motor task and is used as a brief assessment test of lower limb function and dynamic balance. This review aims to examine how research of instrumented analysis of turning in place is implemented. In addition to reporting the studied population, we covered acquisition systems, turn detection methods, quantitative parameters, and how these parameters are computed.

METHODS

Following the development of a rigorous search strategy, the Web of Science and Scopus were systematically searched for studies involving the use of turning-in-place. From the selected articles, the study population, types of instruments used, turn detection method, and how the turning-in-place characteristics were calculated.

RESULTS

Twenty-one papers met the inclusion criteria. The subject groups involved in the reviewed studies included young, middle-aged, and older adults, stroke, multiple sclerosis and Parkinson's disease patients. Inertial measurement units (16 studies) and motion camera systems (5 studies) were employed for gathering measurement data, force platforms were rarely used (2 studies). Two studies used commercial software for turn detection, six studies referenced previously published algorithms, two studies developed a custom detector, and eight studies did not provide any details about the turn detection method. The most frequently used parameters were mean angular velocity (14 cases, 7 studies), turn duration (13 cases, 13 studies), peak angular velocity (8 cases, 8 studies), jerkiness (6 cases, 5 studies) and freezing-of-gait ratios (5 cases, 5 studies). Angular velocities were derived from sensors placed on the lower back (7 cases, 4 studies), trunk (4 cases, 2 studies), and shank (2 cases, 1 study). The rest (9 cases, 8 studies) did not report sensor placement. Calculation of the freezing-of-gait ratio was based on the acceleration of the lower limbs in all cases. Jerkiness computation employed acceleration in the medio-lateral (4 cases) and antero-posterior (1 case) direction. One study did not reported any details about jerkiness computation.

CONCLUSION

This review identified the capabilities of turning-in-place assessment in identifying movement differences between the various subject groups. The results, based on data acquired by inertial measurement units across studies, are comparable. A more in-depth analysis of tests developed for gait, which has been adopted in turning-in-place, is needed to examine their validity and accuracy.

A Comparison of Walking Behavior during the Instrumented TUG and Habitual Gait

The timed up and go test (TUG) is a common clinical functional balance test often used to complement findings on sensorimotor changes due to aging or sensory/motor dysfunction. The instrumented TUG can be used to obtain objective postural and gait measures that are more sensitive to mobility changes. We investigated whether gait and body coordination during TUG is representative of walking. We examined the walking phase of the TUG and compared gait metrics (stride duration and length, walking speed, and step frequency) and head/trunk accelerations to normal walking. The latter is a key aspect of postural control and can also reveal changes in sensory and motor function. Forty participants were recruited into three groups: young adults, older adults, and older adults with visual impairment. All performed the TUG and a short walking task wearing ultra-lightweight wireless IMUs on the head, chest, and right ankle. Gait and head/trunk acceleration metrics were comparable across tasks. Further, stride length and walking speed were correlated with the participants' age. Those with visual impairment walked significantly slower than sighted older adults. We suggest that the TUG can be a valuable tool for examining gait and stability during walking without the added time or space constraints.

Lower Limb Muscle Fatigue Alters Spatiotemporal Gait Parameters and Turning Difficulty Characteristics in Parkinson's Disease

OBJECTIVE

To determine the effects of lower limb muscle fatigue on spatiotemporal gait parameters and turning difficulty characteristics during the extended Timed Up and Go (extended TUG) test in individuals with different severity stages of Parkinson's disease (PD).

METHODS

Forty individuals with PD, classified as Hoehn and Yahr (H&Y) stages 2 and 3 participated in this pre- and post-experimental study design. The participants performed a continuous sit-to-stand task from a chair based on 30 cycles/min set-up to induce lower limb muscle fatigue. They performed extended TUG test immediately before and after completing the fatigue protocol. Spatiotemporal gait parameters and turning difficulty characteristics were recorded using two GoPro® Hero 4 Silver cameras. Data were subjected to a repeated-measure ANOVA.

RESULTS

Individuals with PD experience significant changes in spatiotemporal gait parameters, specifically stride velocity and length, under conditions of lower limb muscle fatigue (p=0.001). These changes were more pronounced in individuals with PD in the H&Y stage 3 group. Additionally, both PD groups exhibited difficulty with turning, requiring more than five steps to complete a 180° turn and taking more than 3 seconds to accomplish it.

CONCLUSION

These findings highlight the impact of muscle fatigue on gait performance in PD and suggest that individuals in later stages of the disease may be particularly affected. Further research is needed to explore interventions that can mitigate these gait impairments and improve mobility in individuals with PD.

Neurophysiology of cerebellar ataxias and gait disorders

There are numerous forms of cerebellar disorders from sporadic to genetic diseases. The aim of this chapter is to provide an overview of the advances and emerging techniques during these last 2 decades in the neurophysiological tests useful in cerebellar patients for clinical and research purposes. Clinically, patients exhibit various combinations of a vestibulocerebellar syndrome, a cerebellar cognitive affective syndrome and a cerebellar motor syndrome which will be discussed throughout this chapter. Cerebellar patients show abnormal Bereitschaftpotentials (BPs) and mismatch negativity. Cerebellar EEG is now being applied in cerebellar disorders to unravel impaired electrophysiological patterns associated within disorders of the cerebellar cortex. Eyeblink conditioning is significantly impaired in cerebellar disorders: the ability to acquire conditioned eyeblink responses is reduced in hereditary ataxias, in cerebellar stroke and after tumor surgery of the cerebellum. Furthermore, impaired eyeblink conditioning is an early marker of cerebellar degenerative disease. General rules of motor control suggest that optimal strategies are needed to execute voluntary movements in the complex environment of daily life. A high degree of adaptability is required for learning procedures underlying motor control as sensorimotor adaptation is essential to perform accurate goal-directed movements. Cerebellar patients show impairments during online visuomotor adaptation tasks. Cerebellum-motor cortex inhibition (CBI) is a neurophysiological biomarker showing an inverse association between cerebellothalamocortical tract integrity and ataxia severity. Ataxic gait is characterized by increased step width, reduced ankle joint range of motion, increased gait variability, lack of intra-limb inter-joint and inter-segmental coordination, impaired foot ground placement and loss of trunk control. Taken together, these techniques provide a neurophysiological framework for a better appraisal of cerebellar disorders.

Effect of Levodopa and Environmental Setting on Gait and Turning Digital Markers Related to Falls in People with Parkinson's Disease

Background

It is unknown whether medication status (off and on levodopa) or laboratory versus home settings plays a role in discriminating fallers and non-fallers in people with Parkinson's disease (PD).

Objectives

To investigate which specific digital gait and turning measures, obtained with body-worn sensors, best discriminated fallers from non-fallers with PD in the clinic and during daily life.

Methods

We recruited 34 subjects with PD (17 fallers and 17 non-fallers based on the past 6 month's falls). Subjects wore three inertial sensors attached to both feet and the lumbar region in the laboratory for a 3-minute walking task (both off and on levodopa) and during daily life activities for a week. We derived 24 digital (18 gait and 6 turn) measures from the 3-minute walk and from daily life.

Results

In clinic, none of the gait and turning measures collected during on levodopa state were significantly different between fallers and non-fallers. In contrast, digital measures collected in the off levodopa state were significantly different between groups, (average turn velocity, average number of steps to complete a turn, and variability of gait speed, P < 0.03). During daily life, the variability of average turn velocity (P = 0.023) was significantly different in fallers than non-fallers. Last, the average number of steps to complete a turn was significantly correlated with the patient-reported outcomes.

Conclusions

Digital measures of turning, but not gait, were different in fallers compared to non-fallers with PD, in the laboratory when off medication and during a daily life.

Association of 7-Day Profiles of Motor Activity in Marital Dyads with One Component Affected by Parkinson's Disease

(1) Background: A noticeable association between the motor activity (MA) profiles of persons living together has been found in previous studies. Social actigraphy methods have shown that this association, in marital dyads composed of healthy individuals, is greater than that of a single person compared to itself. This study aims at verifying the association of MA profiles in dyads where one component is affected by Parkinson's disease (PD). (2) Methods: Using a wearable sensor-based social actigraphy approach, we continuously monitored, for 7 days, the activities of 27 marital dyads including one component with PD. (3) Results: The association of motor activity profiles within a marital dyad (cross-correlation coefficient 0.344) is comparable to the association of any participant with themselves (0.325). However, when considering the disease severity quantified by the UPDRS III score, it turns out that the less severe the symptoms, the more associated are the MA profiles. (4) Conclusions: Our findings suggest that PD treatment could be improved by leveraging the MA of the healthy spouse, thus promoting lifestyles also beneficial for the component affected by PD. The actigraphy approach provided valuable information on habitual functions and motor fluctuations, and could be useful in investigating the response to treatment.

The psychometric properties of the figure-of-eight walk test in people with Parkinson's disease

PURPOSE

To investigate: (1) the interrater, and test-retest reliability of the figure-of-eight walk test (F8WT) in people with Parkinson's disease (PwPD); (2) the minimum detectable change in the F8WT times; (3) the concurrent and known-groups validity of the F8WT times; and (4) the cut-off times that best discriminate PwPD from healthy people and fallers from non-fallers with PD.

METHODS

This was a cross-sectional study. Forty-three PwPD and 34 healthy people were recruited. The F8WT was performed along with the timed up and go test, 10 m walk test, Berg Balance Scale, Activities-Specific Balance Confidence Scale, Unified Parkinson's disease Rating Scale, and Hoehn and Yahr Scale.

RESULTS

The F8WT showed good interrater and test-retest reliability (ICC = 0.964-0.978 and ICC = 0.905-0.920, respectively). The MDC was 2.77 s. The F8WT was correlated with other outcome measures. Significant differences in the F8WT times were found between PwPD and healthy people and between fallers and non-fallers with PD (p < 0.001 and p < 0.001, respectively). The cut-off times of 8.43 s best discriminated PwPD from healthy people, while 11.19 s best discriminated fallers from non-fallers with PD.

CONCLUSIONS

The F8WT is a reliable, valid, and easy-to-administer tool in assessing the walking skill of PwPD.Implications for rehabilitationThe figure-of-eight walk test (F8WT) is a reliable, valid, and clinically available tool for assessing walking skill in Parkinson's disease (PD).The minimal detectable change of the F8WT is 2.77 s, which may help to determine any real change in walking skill after any intervention.The F8WT correlated with functional mobility, gait speed, balance, balance confidence, and severity and stage of PD.The F8WT times may detect impaired walking skill between people with PD and healthy people, and between fallers and non-fallers with PD.

Suitability of a Low-Cost Wearable Sensor to Assess Turning in Healthy Adults

Background: Turning is a complex measure of gait that accounts for over 50% of daily steps. Traditionally, turning has been measured in a research grade laboratory setting, however, there is demand for a low-cost and portable solution to measure turning using wearable technology. This study aimed to determine the suitability of a low-cost inertial sensor-based device (AX6, Axivity) to assess turning, by simultaneously capturing and comparing to a turn algorithm output from a previously validated reference inertial sensor-based device (Opal), in healthy young adults. Methodology: Thirty participants (aged 23.9 ± 4.89 years) completed the following turning protocol wearing the AX6 and reference device: a turn course, a two-minute walk (including 180° turns) and turning in place, alternating 360° turn right and left. Both devices were attached at the lumbar spine, one Opal via a belt, and the AX6 via double sided tape attached directly to the skin. Turning measures included number of turns, average turn duration, angle, velocity, and jerk. Results: Agreement between the outcomes from the AX6 and reference device was good to excellent for all turn characteristics (all ICCs > 0.850) during the turning 360° task. There was good agreement for all turn characteristics (all ICCs > 0.800) during the two-minute walk task, except for moderate agreement for turn angle (ICC 0.683). Agreement for turn outcomes was moderate to good during the turns course (ICCs range; 0.580 to 0.870). Conclusions: A low-cost wearable sensor, AX6, can be a suitable and fit-for-purpose device when used with validated algorithms for assessment of turning outcomes, particularly during continuous turning tasks. Future work needs to determine the suitability and validity of turning in aging and clinical cohorts within low-resource settings.

Gait Initiation Impairment in Patients with Parkinson's Disease and Freezing of Gait

Freezing of gait (FOG) is a sudden episodic inability to produce effective stepping despite the intention to walk. It typically occurs during gait initiation (GI) or modulation and may lead to falls. We studied the anticipatory postural adjustments (imbalance, unloading, and stepping phase) at GI in 23 patients with Parkinson's disease (PD) and FOG (PDF), 20 patients with PD and no previous history of FOG (PDNF), and 23 healthy controls (HCs). Patients performed the task when off dopaminergic medications. The center of pressure (CoP) displacement and velocity during imbalance showed significant impairment in both PDNF and PDF, more prominent in the latter patients. Several measurements were specifically impaired in PDF patients, especially the CoP displacement along the anteroposterior axis during unloading. The pattern of segmental center of mass (SCoM) movements did not show differences between groups. The standing postural profile preceding GI did not correlate with outcome measurements. We have shown impaired motor programming at GI in Parkinsonian patients. The more prominent deterioration of unloading in PDF patients might suggest impaired processing and integration of somatosensory information subserving GI. The unaltered temporal movement sequencing of SCoM might indicate some compensatory cerebellar mechanisms triggering time-locked models of body mechanics in PD.

Visual Cues for Turning in Parkinson's Disease

Turning is a common impairment of mobility in people with Parkinson’s disease (PD), which increases freezing of gait (FoG) episodes and has implications for falls risk. Visual cues have been shown to improve general gait characteristics in PD. However, the effects of visual cues on turning deficits in PD remains unclear. We aimed to (i) compare the response of turning performance while walking (180° and 360° turns) to visual cues in people with PD with and without FoG; and (ii) examine the relationship between FoG severity and response to visual cues during turning. This exploratory interventional study measured turning while walking in 43 participants with PD (22 with self-reported FoG) and 20 controls using an inertial sensor placed at the fifth lumbar vertebrae region. Participants walked straight and performed 180° and 360° turns midway through a 10 m walk, which was done with and without visual cues (starred pattern). The turn duration and velocity response to visual cues were assessed using linear mixed effects models. People with FoG turned slower and longer than people with PD without FoG and controls (group effect: p < 0.001). Visual cues reduced the velocity of turning 180° across all groups and reduced the velocity of turning 360° in people with PD without FoG and controls. FoG severity was not significantly associated with response to visual cues during turning. Findings suggest that visual cueing can modify turning during walking in PD, with response influenced by FoG status and turn amplitude. Slower turning in response to visual cueing may indicate a more cautious and/or attention-driven turning pattern. This study contributes to our understanding of the influence that cues can have on turning performance in PD, particularly in freezers, and will aid in their therapeutic application.

The Effects of Constraining Head Rotation on Eye and Whole-Body Coordination During Standing Turns at Different Speeds

A limitation of the ability to rotate the head with respect to the upper body has been associated with turning problems; however, the extent of head constraints on whole-body coordination has not been fully determined. The aim of this study was to limit head on body rotation and observe the effects on whole-body coordination during standing turns at various speeds. Twelve participants completed standing turns at 180°. A Vicon motion system and a BlueGain Electrooculography system were used to record movement kinematics and measure horizontal eye movements, respectively. All participants were tested at 3 randomized speeds, and under 2 conditions with or without their head constrained using a head, neck, and chest brace which restricted neck movement. A repeated-measures analysis of variance found a significant main effect of turning speed on the onset latency of all segments, peak head-thorax angular separation, and step characteristics. Constraining the head rotation had multiple significant effects including delayed onset latency and decreased intersegmental coordination defined as peak head segmental angular separations, increased total step and step duration, and decreased step size. This indicates the contribution of speed, head, and neck constraints, which have been associated with falls during turning and whole-body coordination.

Reliability and validity of the Roche PD Mobile Application for remote monitoring of early Parkinson's disease

Digital health technologies enable remote and therefore frequent measurement of motor signs, potentially providing reliable and valid estimates of motor sign severity and progression in Parkinson’s disease (PD). The Roche PD Mobile Application v2 was developed to measure bradykinesia, bradyphrenia and speech, tremor, gait and balance. It comprises 10 smartphone active tests (with ½ tests administered daily), as well as daily passive monitoring via a smartphone and smartwatch. It was studied in 316 early-stage PD participants who performed daily active tests at home then carried a smartphone and wore a smartwatch throughout the day for passive monitoring (study NCT03100149). Here, we report baseline data. Adherence was excellent (96.29%). All pre-specified sensor features exhibited good-to-excellent test–retest reliability (median intraclass correlation coefficient = 0.9), and correlated with corresponding Movement Disorder Society–Unified Parkinson's Disease Rating Scale items (rho: 0.12–0.71). These findings demonstrate the preliminary reliability and validity of remote at-home quantification of motor sign severity with the Roche PD Mobile Application v2 in individuals with early PD.

Turning when using a smartphone in persons with and without neurologic conditions: an observational study (Preprint)

BACKGROUND

Turning during walking is a relevant and common everyday movement and it depends on a correct top-down intersegmental coordination. This could be reduced in several conditions (en bloc turning), and an altered turning kinematics has been linked to increased risk of falls. Smartphone use has been associated with poorer balance and gait; however, its effect on turning-while-walking has not been investigated yet. This study explores turning intersegmental coordination during smartphone use in different age groups and neurologic conditions.

OBJECTIVE

This study aims to evaluate the effect of smartphone use on turning behavior in healthy individuals of different ages and those with various neurological diseases.

METHODS

Younger (aged 18-60 years) and older (aged >60 years) healthy individuals and those with Parkinson disease, multiple sclerosis, subacute stroke (<4 weeks), or lower-back pain performed turning-while-walking alone (single task [ST]) and while performing 2 different cognitive tasks of increasing complexity (dual task [DT]). The mobility task consisted of walking up and down a 5-m walkway at self-selected speed, thus including 180° turns. Cognitive tasks consisted of a simple reaction time test (simple DT [SDT]) and a numerical Stroop test (complex DT [CDT]). General (turn duration and the number of steps while turning), segmental (peak angular velocity), and intersegmental turning parameters (intersegmental turning onset latency and maximum intersegmental angle) were extracted for head, sternum, and pelvis using a motion capture system and a turning detection algorithm.

RESULTS

In total, 121 participants were enrolled. All participants, irrespective of age and neurologic disease, showed a reduced intersegmental turning onset latency and a reduced maximum intersegmental angle of both pelvis and sternum relative to head, thus indicating an en bloc turning behavior when using a smartphone. With regard to change from the ST to turning when using a smartphone, participants with Parkinson disease reduced their peak angular velocity the most, which was significantly different from lower-back pain relative to the head (P<.01). Participants with stroke showed en bloc turning already without smartphone use.

CONCLUSIONS

Smartphone use during turning-while-walking may lead to en bloc turning and thus increase fall risk across age and neurologic disease groups. This behavior is probably particularly dangerous for those groups with the most pronounced changes in turning parameters during smartphone use and the highest fall risk, such as individuals with Parkinson disease. Moreover, the experimental paradigm presented here might be useful in differentiating individuals with lower-back pain without and those with early or prodromal Parkinson disease. In individuals with subacute stroke, en bloc turning could represent a compensative strategy to overcome the newly occurring mobility deficit. Considering the ubiquitous smartphone use in daily life, this study should stimulate future studies in the area of fall risk and neurological and orthopedic diseases.

TRIAL REGISTRATION

German Clinical Trials Register DRKS00022998; https://drks.de/search/en/trial/DRKS00022998.

An Algorithm for Accurate Marker-Based Gait Event Detection in Healthy and Pathological Populations During Complex Motor Tasks

There is growing interest in the quantification of gait as part of complex motor tasks. This requires gait events (GEs) to be detected under conditions different from straight walking. This study aimed to propose and validate a new marker-based GE detection method, which is also suitable for curvilinear walking and step negotiation. The method was first tested against existing algorithms using data from healthy young adults (YA, n = 20) and then assessed in data from 10 individuals from the following five cohorts: older adults, chronic obstructive pulmonary disease, multiple sclerosis, Parkinson’s disease, and proximal femur fracture. The propagation of the errors associated with GE detection on the calculation of stride length, duration, speed, and stance/swing durations was investigated. All participants performed a variety of motor tasks including curvilinear walking and step negotiation, while reference GEs were identified using a validated methodology exploiting pressure insole signals. Sensitivity, positive predictive values (PPV), F1-score, bias, precision, and accuracy were calculated. Absolute agreement [intraclass correlation coefficient (ICC2,1)] between marker-based and pressure insole stride parameters was also tested. In the YA cohort, the proposed method outperformed the existing ones, with sensitivity, PPV, and F1 scores ≥ 99% for both GEs and conditions, with a virtually null bias (&lt;10 ms). Overall, temporal inaccuracies minimally impacted stride duration, length, and speed (median absolute errors ≤1%). Similar algorithm performances were obtained for all the other five cohorts in GE detection and propagation to the stride parameters, where an excellent absolute agreement with the pressure insoles was also found (ICC2,1=0.817− 0.999). In conclusion, the proposed method accurately detects GE from marker data under different walking conditions and for a variety of gait impairments.

Troubleshooting Gait Disturbances in Parkinson's Disease With Deep Brain Stimulation

Deep brain stimulation (DBS) of the subthalamic nucleus or the globus pallidus is an established treatment for Parkinson's disease (PD) that yields a marked and lasting improvement of motor symptoms. Yet, DBS benefit on gait disturbances in PD is still debated and can be a source of dissatisfaction and poor quality of life. Gait disturbances in PD encompass a variety of clinical manifestations and rely on different pathophysiological bases. While gait disturbances arising years after DBS surgery can be related to disease progression, early impairment of gait may be secondary to treatable causes and benefits from DBS reprogramming. In this review, we tackle the issue of gait disturbances in PD patients with DBS by discussing their neurophysiological basis, providing a detailed clinical characterization, and proposing a pragmatic programming approach to support their management.

Detection of balance disorders using rotations around vertical axis and an artificial neural network

Vestibular impairments affect patients' movements and can result in difficulties with daily life activities. The main aim of this study is to answer the question whether a simple and short test such as rotation about a vertical axis can be an objective method of assessing balance dysfunction in patients with unilateral vestibular impairments. A 360˚ rotation test was performed using six MediPost devices. The analysis was performed in three ways: (1) the analytical approach based only on data from one sensor; (2) the analytical approach based on data from six sensors; (3) the artificial neural network (ANN) approach based on data from six sensors. For approaches 1 and 2 best results were obtained using maximum angular velocities (MAV) of rotation and rotation duration (RD), while approach 3 used 11 different features. The following sensitivities and specificities were achieved: for approach 1: MAV—80% and 60%, RD—69% and 74%; for approach 2: 61% and 85% and RD—74% and 56%; for approach 3: 88% and 84%. The ANN-based six-sensor approach revealed the best sensitivity and specificity among parameters studied, however one-sensor approach might be a simple screening test used e.g. for rehabilitation purposes.

Turning reveals the characteristics of gait freezing better than walking forward and backward in Parkinson's disease

BACKGROUNDS

People with Parkinson's disease (PD) experiences walking disturbances and freezing of gait (FoG) is one of the most distressing symptoms.

RESEARCH QUESTION

This study aimed to comprehensively analyze the walking characteristics of patients with PD, including forward and backward walking and turning, in order to define the characteristics of FoG.

METHODS

A total of 68 patients with PD and 14 control subjects were enrolled in this study. Forward and backward walking and 360-degree turning were recorded at preferred speed in "off" state using three-dimensional motion analysis system.

RESULTS

PD patients showed a narrower step length, slower walking speed, and higher asymmetry index (AI) of step length during forward and backward walking. During turning, the PD patients had more turning steps, longer turning time, and shorter step length than the control subjects. No difference was observed in the characteristics of forward walking according to the FoG status, but the freezer group showed a narrower step length and decreased range of motion in the ankle joints during backward walking. Freezer group showed longer step time and higher AI of step length at turning. The severity of FoG was correlated with step length and walking speed during forward and backward walking, total step count, total step time, and walking speed during turning.

SIGNIFICANCE

The characteristics and impacts of FoG in PD were most prominent during turning, followed by backward and forward walking. Further comprehensive analyses of walking including turning might contribute to the understanding of the pathophysiology of walking disturbances in PD.

Task-related trunk training on balance, trunk control, pulmonary function and quality of life in patients with Parkinson's disease. A randomised controlled trial

Background/Aims

Stooped posture and ‘en-bloc’ movement of the trunk in people with Parkinson's disease are related to balance issues, pulmonary dysfunction and difficulty in daily tasks. The primary objective of this study was to examine the effects of task-related trunk training on balance in people with Parkinson's disease. The secondary objective was to observe whether trunk control, thoracic rotation range, pulmonary function and quality of life would change for patients with Parkinson's disease after trunk training.

Methods

A total of 32 individuals participated in this randomised controlled trial. They had a mean age of 70.8 years, with a modified Hoehn and Yahr Scale grade of 1.5–3, could take more than six steps in the 360° turn test, were scored as grade I or II on the retropulsion test and had an absence of severe cognitive deficits. Task-related trunk training emphasised the thoracic spine's extension and rotation in prone position on elbows, hands and knees and in kneeling, sitting and standing positions. Standard physiotherapy included breathing exercises, stretching of shoulder and neck muscles, balance and walking training. Both groups practised for 1 hour a day, 3 days a week over 6 weeks. The primary outcome measure was the Mini-Balance Evaluation Systems Test. The secondary outcome measures were the Trunk Control Test, thoracic rotation range of movement, Pulmonary Function Test and Parkinson's Disease Questionnaire-39.

Results

Repeated measure analysis of variance revealed significant group by time interaction for the Mini-Balance Evaluation Systems Test and thoracic rotation range (P<0.05), but not for the pulmonary function test and quality of life measures.

Conclusions

Task-related trunk training appears to be more beneficial in the balance capacity of individuals with Parkinson's disease than standard physiotherapy, but does not have any significant effects for pulmonary function and health-related quality of life.

Effects of curved path walking compared to straight path walking in older adults with cognitive deficits: A systematic review and network meta-analysis

OBJECTIVE

To determine whether the existing literature provides evidence that curved path walking time can be a reliable marker of cognitive impairment among older adults using a network meta-analysis (NMA).

DATA SOURCES

PubMed, Web of Science, ScienceDirect, Scopus, and Korean Studies Information Service System (KSISS) electronic databases were searched in December 2019.

STUDY SELECTION

Studies that included the following variables were selected: (P): patients with cognitive impairment, (I): straight path versus curved path walking, (C): control group without cognitive impairment, (O): walking time, and (S): cross-sectional or longitudinal study design. In total, 21 studies were selected for the NMA, which was performed to compare the standardized mean difference (SMD) of walking time on curved and straight paths.

RESULTS

Older adults with dementia had significantly longer walking times than older adults with mild cognitive impairment (MCI) for both straight path walking and curved path walking. The SMD of straight path walking time was 0.59 (95% credible interval [CrI]: 0.39, 0.81) for older adults with MCI and 0.90 (95% CrI: 0.65, 1.16) for older adults with dementia. The SMD of walking time on a curved path was 0.52 (95% CrI: -0.22, 1.26) for older adults with MCI and 1.98 (95% CrI: 1.20, 2.92) for those with dementia. In older adults with dementia, the correlation coefficient of the Fisher's z value was higher for curved path walking than for straight path walking.

CONCLUSION

The way people with dementia walk exhibits signs of cognitive impairments. NMA confirmed that older adults with dementia requires significantly longer time to walk the same distance than healthy controls or older adults with MCI for both curved and straight path walking.

Efficacy of C-Mill gait training for improving walking adaptability in early and middle stages of Parkinson's disease

BACKGROUND

Walking adaptability is an obvious manifestation of Parkinson's disease (PD). Augmented reality technologies such as interactive walkways may improve walking adaptability in patients with Parkinson's Disease (PWP).

RESEARCH QUESTION

How effective is C-Mill gait adaptability training in the early and middle stages of PD for improving walking adaptability in motor subtypes of the disease?

METHODS

Fifty-two patients with early- or middle-stage PD were divided into two groups according to motor subtype (postural instability/gait disorder [PIGD] and non-PIGD) and received 7 days of training (0.5 h every day, 2 h after medication) on an augmented reality treadmill with built-in visual targets and obstacles. Functional assessments were performed before and after intervention, including posture control and walking, C-gait assessment, and participant experience. The Parkinson Disease Quality of Life questionnaire was administered at 3-month follow-up.

RESULTS

Both the PIGD (n = 29) and non-PIGD (n = 23) groups showed improved tandem walking, obstacle avoidance, and overall score in C-gait assessment and Timed Up and Go test after C-Mill training. However, there were no differences between the two groups. The PIGD group showed improvement in visually guided stepping and Speed adaptations, whereas the non-PIGD group did not improve. The non-PIGD group reported they could complete the training with less exertion after the intervention and at the 3-month follow-up, these patients reported improvement in quality of life.

SIGNIFICANCE

C-Mill gait adaptation training in the early and middle stages of PD improves walking adaptability in both motor subtypes. Cue strategies are the probable mechanism and may decrease fall risk after training. There was no difference between the groups in the improvements of perceived exertion and quality of life at follow-up. Although PIGD patients showed statistic improvements in visually guided stepping compared with non-PIGD patients, but the difference was not likely to be clinically meaningful. Specific effects of C-mill training for different types of PD were not observed in our study.

Persons with Parkinson's disease show impaired interlimb coordination during backward walking

INTRODUCTION

Although there is growing literature supporting the implementation of backward walking as a potential rehabilitation tool, moving backwards may precipitate falls for persons with Parkinson's disease. We sought to better understand interlimb coordination during backward walking in comparison to forward walking in persons with Parkinson's disease and healthy controls.

METHODS

We assessed coordination using point estimate of relative phase at each participant's preferred walking speed.

RESULTS

Persons with Parkinson's disease demonstrated impaired interlimb coordination between the more affected arm and each leg compared to controls, which worsened during backward walking.

CONCLUSION

For those with Parkinson's disease, inability to output smooth coordinated movement of the more affected shoulder may impair coordination during forward and, especially, backward walking. Our findings provide new information about backward walking that can allow clinicians to make safer, more effective therapeutic recommendations for persons with Parkinson's disease.

Classification of Parkinson's disease with freezing of gait based on 360° turning analysis using 36 kinematic features

BACKGROUND

Freezing of gait (FOG) is a sensitive problem, which is caused by motor control deficits and requires greater attention during postural transitions such as turning in people with Parkinson's disease (PD). However, the turning characteristics have not yet been extensively investigated to distinguish between people with PD with and without FOG (freezers and non-freezers) based on full-body kinematic analysis during the turning task. The objectives of this study were to identify the machine learning model that best classifies people with PD and freezers and reveal the associations between clinical characteristics and turning features based on feature selection through stepwise regression.

METHODS

The study recruited 77 people with PD (31 freezers and 46 non-freezers) and 34 age-matched older adults. The 360° turning task was performed at the preferred speed for the inner step of the more affected limb. All experiments on the people with PD were performed in the "Off" state of medication. The full-body kinematic features during the turning task were extracted using the three-dimensional motion capture system. These features were selected via stepwise regression.

RESULTS

In feature selection through stepwise regression, five and six features were identified to distinguish between people with PD and controls and between freezers and non-freezers (PD and FOG classification problem), respectively. The machine learning model accuracies revealed that the random forest (RF) model had 98.1% accuracy when using all turning features and 98.0% accuracy when using the five features selected for PD classification. In addition, RF and logistic regression showed accuracies of 79.4% when using all turning features and 72.9% when using the six selected features for FOG classification.

CONCLUSION

We suggest that our study leads to understanding of the turning characteristics of people with PD and freezers during the 360° turning task for the inner step of the more affected limb and may help improve the objective classification and clinical assessment by disease progression using turning features.

Approach to the Patient with Gait Disturbance

The assessment of patients presenting with disorders of gait can be a daunting task for neurologists given the broad potential localization and differential diagnosis. However, gait disorders are extremely common in outpatient neurology, and all neurologists should be comfortable with the assessment, triage, and management of patients presenting with difficulty walking. Here, we aim to present a manageable framework for neurologists to approach the assessment of patients presenting with gait dysfunction. We suggest a chief complaint-based phenomenological characterization of gait, using components of the neurological history and examination to guide testing and treatment. We present the framework to mirror the outpatient visit with the patient, highlighting (1) important features of the gait history, including the most common gait-related chief complaints and common secondary (medical) causes of gait dysfunction; (2) gait physiology and a systematic approach to the gait examination allowing appropriate characterization of gait phenomenology; (3) an algorithmic approach to ancillary testing for patients with gait dysfunction based on historical and examination features; and (4) definitive and supportive therapies for the management of patients presenting with common neurological disorders of gait.

Functional gait assessment in early and advanced Parkinson’s disease

Background

Postural instability and balance problems in patients with Parkinson’s disease (PD) can seriously affect the quality of life and lead to falls with a subsequent increase in the morbidity and mortality. Early identification of gait dysfunction in early stages of PD establishes an effective therapy, prevention of the falls and reducing health care costs. This work aimed to detect gait disorders in patients with PD using the functional gait assessment (FGA) scale and to correlate it with the disease severity in Egyptian PD patients. This is a case–control study in which 40 patients with PD were recruited from the Involuntary Movement Clinic at Alexandria University El-Hadara Hspoital; 20 patients had early stages of PD (Hoehn Yahr stages 1 and 2) and 20 patients had advanced PD (Hoehn Yahr stages 3 and 4). Another 20 subjects were recruited as controls. All recruited subjects underwent gait assessment using FGA scale.

Results

Gait analysis using FGA showed significant differences (P < 0.001) between the recruited PD patients and the control group. Upon comparing the early and advanced PD patients’ groups, certain items in the FGA (gait with pivot turn, step over obstacle, gait with eyes closed and backward gait) together with time consumed for 6-m walk with eyes open and close showed significant statistical differences between early and advanced PD patients. The patients’ duration of illness with PD was reversely correlated with the total FGA score.

Conclusion

The FGA scale was strongly influenced by the duration of PD among the Egyptian patients and can potentially detect early stages of PD.

The starting distance of obstacle circumvention did not affect intersegmental coordination in individuals with Parkinson's disease

BACKGROUND

Obstacle circumvention is a challenging task in Parkinson's disease (PD). Body segments adjustments, such as changing the direction of the trunk, followed by a change in the direction of the head, and modifications in the positioning of the feet, are necessary to circumvent an obstacle during walking. For that, individuals need to identify the distance to the obstacle, its characteristics (such as its dimension), and perform well-coordinated movements. However, PD is characterized by rigidity, which may be increased in the axial axis and compromise the task execution. Also, worsening sensory integration in PD may increase the time to perform these body segments adjustments, thus impairing the movement coordination when starting obstacle circumvention near to the obstacle.

AIM

To determine if the starting distance (1.5 m, 3 m, or 5 m) from the obstacle could modify the intersegmental coordination (specifically, the coordination between head, trunk, and pelvis) during the obstacle circumvention steps in individuals with PD.

METHODS

Fourteen individuals with a diagnosis of idiopathic PD and 15 neurologically healthy individuals (CG) from the community were included in this study. The participants were evaluated in three different gait conditions, according to the starting distance from the obstacle: 1.5 m, 3 m, and 5 m away from the obstacle. Vector coding technique was employed to establish the coupling between head, trunk, and pelvis in the steps immediately before and during obstacle circumvention. Three-way ANOVA's (group, distance, and step) were calculated with the level of significance at p < 0.05.

RESULTS

For all couplings of coordination, there were no effects of distance. However, significant main effects of group and steps (p < 0.05) were found for all couplings with different patterns of coordination: head/pelvis (group: in-phase and anti-phase variables; steps: anti-phase variable), head/trunk (group: trunk variable; steps: in-phase and anti-phase variables) and trunk/pelvis (group: anti-phase; steps: trunk and pelvis). Finally, only head/trunk coupling showed an interaction between group*steps. Individuals with PD showed 7.95% lower head movement (p < 0.024) and 14.85% greater trunk movement than CG (p < 0.002). Also, individuals with PD performed 17.56% greater head movement in the step before the circumvention compared to the step during circumvention (p < 0.044).

CONCLUSION

The starting distance from the obstacle did not influence the pattern of axial intersegmental coordination in both groups. However, how these segments interact in the preparation and during the obstacle circumvention are opposite in individuals with PD. While on the previous step to obstacle circumvention, the head movement was greater than the trunk, during the obstacle circumvention step, individuals with PD rotated the trunk more.

Evaluation of movement and brain activity

Clinical neurophysiology studies can contribute important information about the physiology of human movement and the pathophysiology and diagnosis of different movement disorders. Some techniques can be accomplished in a routine clinical neurophysiology laboratory and others require some special equipment. This review, initiating a series of articles on this topic, focuses on the methods and techniques. The methods reviewed include EMG, EEG, MEG, evoked potentials, coherence, accelerometry, posturography (balance), gait, and sleep studies. Functional MRI (fMRI) is also reviewed as a physiological method that can be used independently or together with other methods. A few applications to patients with movement disorders are discussed as examples, but the detailed applications will be the subject of other articles.

Between-site equivalence of turning speed assessments using inertial measurement units

BACKGROUND

Turning is a component of gait that requires planning for movement of multiple body segments and the sophisticated integration of sensory information from the vestibular, visual, and somatosensory systems. These aspects of turning have led to growing interest to quantify turning in clinical populations to characterize deficits or identify disease progression. However, turning may be affected by environmental differences, and the degree to which turning assessments are comparable across research or clinical sites has not yet been evaluated.

RESEARCH QUESTION

The aim of this study was to determine the extent to which peak turning speeds are equivalent between two sites for a variety of mobility tasks.

METHODS

Data were collected at two different sites using separate healthy young adult participants (n = 47 participants total), but recruited using identical inclusion and exclusion criteria. Participants at each site completed three turning tasks: a one-minute walk (1 MW) along a six-meter walkway, a modified Illinois Agility Test (mIAT), and a custom clinical turning course (CCTC). Peak yaw turning speeds were extracted from wearable inertial sensors on the head, trunk, and pelvis. Between-site differences and two one-sided tests (TOST) were used to determine equivalence between sites, based on a minimum effect size reported between individuals with mild traumatic brain injury and healthy control subjects.

RESULTS

No outcomes were different between sites, and equivalence was determined for 6/21 of the outcomes. These findings suggest that some turning tasks and outcome measures may be better suited for multi-site studies. The equivalence results are also dependent on the minimum effect size of interest; nearly all outcomes were equivalent across sites when larger minimum effect sizes of interest were used.

SIGNIFICANCE

Together, these results suggest some tasks and outcome measures may be better suited for multi-site studies and literature-based comparisons.

Modifications in Prefrontal Cortex Oxygenation in Linear and Curvilinear Dual Task Walking: A Combined fNIRS and IMUs Study

Increased oxygenated hemoglobin concentration of the prefrontal cortex (PFC) has been observed during linear walking, particularly when there is a high attention demand on the task, like in dual-task (DT) paradigms. Despite the knowledge that cognitive and motor demands depend on the complexity of the motor task, most studies have only focused on usual walking, while little is known for more challenging tasks, such as curved paths. To explore the relationship between cortical activation and gait biomechanics, 20 healthy young adults were asked to perform linear and curvilinear walking trajectories in single-task and DT conditions. PFC activation was assessed using functional near-infrared spectroscopy, while gait quality with four inertial measurement units. The Figure-of-8-Walk-Test was adopted as the curvilinear trajectory, with the "Serial 7s" test as concurrent cognitive task. Results show that walking along curvilinear trajectories in DT led to increased PFC activation and decreased motor performance. Under DT walking, the neural correlates of executive function and gait control tend to be modified in response to the cognitive resources imposed by the motor task. Being more representative of real-life situations, this approach to curved walking has the potential to reveal crucial information and to improve people' s balance, safety, and life's quality.

Footsteps and walking trajectories during the Timed Up and Go test in young, older, and Parkinson's disease subjects

BACKGROUND

Footsteps and walking trajectories during the Timed Up and Go test (TUG), and their relationships with spatiotemporal gait parameters during turning in people with Parkinson's disease (PD) and older people have not been clarified.

RESEARCH QUESTION

We investigated the footsteps, walking trajectories, and spatiotemporal parameters during the TUG in PD, healthy older (HO), and healthy young (HY) subjects and the associations between the parameters of footsteps or walking trajectories and the spatiotemporal parameters during turning.

METHODS

Twenty-six PD, 20 HO, and 20 HY subjects participated. They performed the TUG at self-selected speed and underwent evaluations of spatiotemporal parameters in the forward, turning, and return phases and parameters of footsteps and walking trajectories by a system using laser range sensors to measure the two-dimensional distance data of the legs. Foot placement for each foot was measured as the estimated position when the leg speed of movement reached the minimum between foot-contact and foot-off. We calculated the minimum distance from a TUG marker to footsteps and the maximum anterior distance from the start to the footsteps. Step length was calculated using a method for non-linear walking.

RESULTS

The PD subjects showed significantly smaller step lengths in all phases. The minimum distance from the marker to the footsteps in PD subjects was significantly smaller than in HO subjects and was significantly positively correlated only with the turning-phase step length. The maximum anterior distance from the start to footsteps in HO subjects was significantly larger than in PD and HY subjects and was not correlated with any spatiotemporal parameters.

SIGNIFICANCE

This study demonstrated that people with PD turn close to the TUG marker, and this turning strategy may be associated with the decreased step length when turning. These findings could help in providing instructions which prevent the exaggeration of step-length reduction when turning.

A Clinically Interpretable Computer-Vision Based Method for Quantifying Gait in Parkinson's Disease

Gait is a core motor function and is impaired in numerous neurological diseases, including Parkinson's disease (PD). Treatment changes in PD are frequently driven by gait assessments in the clinic, commonly rated as part of the Movement Disorder Society (MDS) Unified PD Rating Scale (UPDRS) assessment (item 3.10). We proposed and evaluated a novel approach for estimating severity of gait impairment in Parkinson's disease using a computer vision-based methodology. The system we developed can be used to obtain an estimate for a rating to catch potential errors, or to gain an initial rating in the absence of a trained clinician-for example, during remote home assessments. Videos (n=729) were collected as part of routine MDS-UPDRS gait assessments of Parkinson's patients, and a deep learning library was used to extract body key-point coordinates for each frame. Data were recorded at five clinical sites using commercially available mobile phones or tablets, and had an associated severity rating from a trained clinician. Six features were calculated from time-series signals of the extracted key-points. These features characterized key aspects of the movement including speed (step frequency, estimated using a novel Gamma-Poisson Bayesian model), arm swing, postural control and smoothness (or roughness) of movement. An ordinal random forest classification model (with one class for each of the possible ratings) was trained and evaluated using 10-fold cross validation. Step frequency point estimates from the Bayesian model were highly correlated with manually labelled step frequencies of 606 video clips showing patients walking towards or away from the camera (Pearson's r=0.80, p<0.001). Our classifier achieved a balanced accuracy of 50% (chance = 25%). Estimated UPDRS ratings were within one of the clinicians' ratings in 95% of cases. There was a significant correlation between clinician labels and model estimates (Spearman's ρ=0.52, p<0.001). We show how the interpretability of the feature values could be used by clinicians to support their decision-making and provide insight into the model's objective UPDRS rating estimation. The severity of gait impairment in Parkinson's disease can be estimated using a single patient video, recorded using a consumer mobile device and within standard clinical settings; i.e., videos were recorded in various hospital hallways and offices rather than gait laboratories. This approach can support clinicians during routine assessments by providing an objective rating (or second opinion), and has the potential to be used for remote home assessments, which would allow for more frequent monitoring.

Atypical Gait Cycles in Parkinson's Disease

It is important to find objective biomarkers for evaluating gait in Parkinson's Disease (PD), especially related to the foot and lower leg segments. Foot-switch signals, analyzed through Statistical Gait Analysis (SGA), allow the foot-floor contact sequence to be characterized during a walking session lasting five-minutes, which includes turnings. Gait parameters were compared between 20 PD patients and 20 age-matched controls. PDs showed similar straight-line speed, cadence, and double-support compared to controls, as well as typical gait-phase durations, except for a small decrease in the flat-foot contact duration (-4% of the gait cycle, p = 0.04). However, they showed a significant increase in atypical gait cycles (+42%, p = 0.006), during both walking straight and turning. A forefoot strike, instead of a "normal" heel strike, characterized the large majority of PD's atypical cycles, whose total percentage was 25.4% on the most-affected and 15.5% on the least-affected side. Moreover, we found a strong correlation between the atypical cycles and the motor clinical score UPDRS-III (r = 0.91, p = 0.002), in the subset of PD patients showing an abnormal number of atypical cycles, while we found a moderate correlation (r = 0.60, p = 0.005), considering the whole PD population. Atypical cycles have proved to be a valid biomarker to quantify subtle gait dysfunctions in PD patients.

Action Observation and Motor Imagery Improve Dual Task in Parkinson's Disease: A Clinical/fMRI Study

BACKGROUND

Action observation training and motor imagery may improve motor learning in Parkinson's disease (PD).

OBJECTIVES

The objectives of this study were to assess mobility and balance (performing motor and dual tasks) and brain functional reorganization following 6 weeks of action observation training and motor imagery associated with dual-task gait/balance exercises in PD patients with postural instability and gait disorders relative to dual-task training alone.

METHODS

Twenty-five PD-postural instability and gait disorder patients were randomized into 2 groups: the DUAL-TASK+AOT-MI group performed a 6-week gait/balance training consisting of action observation training-motor imagery combined with practicing the observed-imagined exercises; the DUAL-TASK group performed the same exercises combined with watching landscape videos. Exercises were increasingly difficult to include the dual task. At baseline and at 6 weeks, patients underwent: mobility, gait, and balance evaluations (also repeated 2 months after training), cognitive assessment, and functional MRI, including motor and dual tasks.

RESULTS

Dual-task gait/balance training enhanced mobility, during both single- and dual-task conditions, and executive functions in PD-postural instability and gait disorders, with a long-lasting effect at 14 weeks. When exercises were preceded by action observation training-motor imagery, PD-postural instability and gait disorders showed greater improvement of balance and gait velocity both with and without the dual task, particularly during the turning phase. After training, the DUAL-TASK+AOT-MI group showed reduced recruitment of frontal areas and increased activity of cerebellum during functional-MRI motor and dual task, correlating with balance/turning velocity and executive improvements, respectively. The DUAL-TASK group showed reduced activity of supplementary motor area and increased recruitment of temporo-parietal areas during the dual task and decreased cerebellar activity during the motor task correlating with faster turning velocity. Functional MRI results were not corrected for multiple comparisons and should be interpreted carefully.

CONCLUSIONS

Adding action observation training-motor imagery to dual-task gait/balance training promotes specific functional reorganization of brain areas involved in motor control and executive-attentive abilities and more long-lasting effects on dual-task mobility and balance in PD-postural instability and gait disorders. © 2021 International Parkinson and Movement Disorder Society.

Effectiveness of a Community-Based Muscle Strengthening Exercise Program to Increase Muscle Strength Among Pre-frail Older Persons in Malaysia: A Pilot Study

Deterioration in muscle mass and muscle strength is common among the frail older persons, cause functional dependence and decrease in the quality of life. Therefore, the identification of cost-effective interventions to prevent or ameliorate frailty is crucially needed. The aim of this study is to determine the effectiveness of a Community-based Muscle Strengthening Exercise (COME) program to increase muscle strength among pre-frail older persons. This study was a quasi-experimental study. A total of 32 older persons aged 60 years and older with pre-frail symptoms were recruited from the community center. The COME was developed based on the Growing Stronger program and the Otago Home Exercise Program. COME was designed to strengthen all of the major muscle groups in the upper and lower extremities. The exercise program was conducted for 12 weeks and divided into 3 parts; (1) to strengthen the body slowly and gently, using only body weight, (2) to introduce dumbbells and ankle weights to increase strength and (3) to add various new ways to boost strength even more. Functional tests were measured before and after the intervention. The results revealed non-significant p-value for pre- and post-intervention comparison for all study outcomes. Observing the values of mean difference, the study intervention was shown to have slightly improved the time up and go (Mean difference = -0.25), and sit-to-stand duration (Mean difference = -0.41) as well as the handgrip strength (Mean difference = 0.68) among the participants. On the assessment of Cohen ES, all three improvements exhibited small effect sizes. Sit-to-stand duration was shown to have most benefited from the intervention with highest ES among the outcome variables (ES = 0.20). COME intervention program among pre-frail older persons showed favorable trend toward improvement of upper and lower extremities muscle strength. This study should be further tested in randomized control trial to confirm its effectiveness.

Differentiating between Parkinson's disease patients and controls using variability in muscle activation during walking

Surface electromyography (sEMG) of the lower limb muscles has been proposed to evaluate motor dysfunctions in Parkinson's disease (PD) patients. Variability in the sEMG could be used as an indicator of poor muscle coordination, but previous studies have reported conflicting results. This study has examined the variability of muscle using the coefficients of variance of Tibialis anterior (TA) and Medial gastrocnemius (MG) lower limb muscles for 24 PD, 24 age matched controls (CO), and 24 young controls (YC), during different phases of the gait cycle. The gait intervals were measured using the inertial measurement unit (IMU). We observed a statistically significant difference between PD and control for the variability of lower limb muscle when comparing the sub-phases of the gait. It was also found that the difference was more pronounced for the TA muscle.

Turning Detection During Gait: Algorithm Validation and Influence of Sensor Location and Turning Characteristics in the Classification of Parkinson's Disease

Parkinson's disease (PD) is a common neurodegenerative disorder resulting in a range of mobility deficits affecting gait, balance and turning. In this paper, we present: (i) the development and validation of an algorithm to detect turns during gait; (ii) a method to extract turn characteristics; and (iii) the classification of PD using turn characteristics. Thirty-seven people with PD and 56 controls performed 180-degree turns during an intermittent walking task. Inertial measurement units were attached to the head, neck, lower back and ankles. A turning detection algorithm was developed and validated by two raters using video data. Spatiotemporal and signal-based characteristics were extracted and used for PD classification. There was excellent absolute agreement between the rater and the algorithm for identifying turn start and end (ICC ≥ 0.99). Classification modeling (partial least square discriminant analysis (PLS-DA)) gave the best accuracy of 97.85% when trained on upper body and ankle data. Balanced sensitivity (97%) and specificity (96.43%) were achieved using turning characteristics from the neck, lower back and ankles. Turning characteristics, in particular angular velocity, duration, number of steps, jerk and root mean square distinguished mild-moderate PD from controls accurately and warrant future examination as a marker of mobility impairment and fall risk in PD.

The Effect of a Secondary Task on Kinematics during Turning in Parkinson’s Disease with Mild to Moderate Impairment

Patients with Parkinson’s disease (PD) show typical gait asymmetries. These peculiar motor impairments are exacerbated by added cognitive and/or mechanical loading. However, there is scarce literature that chains these two stimuli. The aim of this study was to investigate the combined effects of a dual task (cognitive task) and turning (mechanical task) on the spatiotemporal parameters in mild to moderate PD. Participants (nine patients with PD and nine controls (CRs)) were evaluated while walking at their self-selected pace without a secondary task (single task), and while repeating the days of the week backwards (dual task) along a straight direction and a 60° and 120° turn. As speculated, in single tasking, PD patients preferred to walk with a shorter stride length (p < 0.05) but similar timing parameters, compared to the CR group; in dual tasking, both groups walked slower with shorter strides. As the turn angle increased, the speed will be reduced (p < 0.001), whereas the ground–foot contact will become greater (p < 0.001) in all the participants. We showed that the combination of a simple cognitive task and a mechanical task (especially at larger angles) could represent an important training stimulus in PD at the early stages of the pathology.

The Figure-of-8 Walk Test used to detect the loss of motor skill in walking among persons with Parkinson's disease

BACKGROUND

The Figure-of-8 Walk Test (F8W) is a valid measure of walking skill in older adults with a mobility disability. Use of the F8W in assessing walking skill in persons with Parkinson's disease (PWP) is unknown.

PURPOSE

We examined the validity of the F8W by associations with mobility, and cognitive and physical function, and determined the ability of the F8W to discriminate the motor skill of walking in PWP from that of older adults (OA).

METHODS

Participants, PWP (n = 60) and OA (n = 34) performed the F8W, usual straight path walking, the Montreal Cognitive Assessment (MoCA), and the Late-Life Function and Disability Instrument (LLFDI).

RESULTS

Among PWP, F8W time and steps related to: usual gait speed (r = -0.660, -0.650); stride time variability (r = 0.377, 0.438); cognition (r = -0.293, time only); and physical function (r = -0.532, - 0.619), all p < .05. Area under the curve (AUC) analyses demonstrated greater sensitivity and specificity of F8W performance (0.811, 0.790) compared to usual gait speed (0.729) to recognize the motor skill of walking in PWP from that of OA.

CONCLUSION

The F8W is a valid indicator of the motor skill of walking in PWP. Use of the F8W may uncover walking difficulties not identified by usual gait speed.

Turn Characteristics During Gait Differ With and Without a Cognitive Demand Among College Athletes

CONTEXT

Sports often involve complex movement patterns, such as turning. Although cognitive load effects on gait patterns are well known, little is known on how it affects biomechanics of turning gait among athletes. Such information could help evaluate how concussion affects turning gait required for daily living and sports.

OBJECTIVE

To determine the effect of a dual task on biomechanics of turning while walking among college athletes.

DESIGN

Cross-sectional study.

SETTING

University laboratory.

PARTICIPANTS

Fifty-three participants performed 5 trials of a 20-m walk under single- and dual-task conditions at self-selected speed with a 180° turn at 10-m mark. The cognitive load included subtraction, spelling words backward, or reciting the months backward.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Turn duration, turning velocity, number of steps, SD of turn duration and velocity, and coefficient of variation of turn duration and velocity.

RESULTS

Participants turned significantly slower (155.99 [3.71] cm/s vs 183.52 [4.17] cm/s; P < .001) and took longer time to complete the turn (2.63 [0.05] s vs 2.33 [0.04] s; P < .001) while dual tasking, albeit taking similar number of steps to complete the turn. Participants also showed more variability in turning time under the dual-task condition (SD of turn duration = 0.39 vs 0.31 s; P = .004).

CONCLUSIONS

Overall, college athletes turned slower and showed more variability during turning gait while performing a concurrent cognitive dual-task turning compared with single-task turning. The slower velocity increased variability may be representative of specific strategy of turning gait while dual tasking, which may be a result of the split attention to perform the cognitive task. The current study provides descriptive values of absolute and variability turning gait parameters for sports medicine personnel to use while they perform their concussion assessments on their college athletes.

The Effects of Augmented Reality Visual Cues on Turning in Place in Parkinson's Disease Patients With Freezing of Gait

Background: Turning in place is particularly bothersome for patients with Parkinson's disease (PD) experiencing freezing of gait (FOG). Cues designed to enforce goal-directed turning are not yet available.

Objectives: Assess whether augmented reality (AR) visual cues improve FOG and turning in place in PD patients with FOG.

Methods: Sixteen PD patients with FOG performed a series of 180° turns under an experimental condition with AR visual cues displayed through a HoloLens and two control conditions (one consisting of auditory cues and one without any cues). FOG episodes were annotated by two independent raters from video recordings. Motion data were measured with 17 inertial measurement units for calculating axial kinematics, scaling, and timing of turning.

Results: AR visual cues did not reduce the percent time frozen (p = 0.73) or the number (p = 0.73) and duration (p = 0.78) of FOG episodes compared to the control condition without cues. All FOG parameters were higher with AR visual cues than with auditory cues [percent time frozen (p = 0.01), number (p = 0.02), and duration (p = 0.007) of FOG episodes]. The AR visual cues did reduce the peak angular velocity (visual vs. uncued p = 0.03; visual vs. auditory p = 0.02) and step height (visual vs. uncued p = 0.02; visual vs. auditory p = 0.007), and increased the step height coefficient of variation (visual vs. uncued p = 0.04; visual vs. auditory p = 0.01) and time to maximum head–pelvis separation (visual vs. uncued p = 0.02; visual vs. auditory p = 0.005), compared to both control conditions.

Conclusions: The AR visual cues in this study did not reduce FOG, and worsened some measures of axial kinematics, and turn scaling and timing. Stimulating goal-directed turning might, by itself, be insufficient to reduce FOG and improve turning performance.

Trial Registration: This study was registered in the Dutch trial registry (NTR6409; 2017-02-16).

Assessing the Relationship between the Enhanced Gait Variability Index and Falls in Individuals with Parkinson's Disease

Gait impairment and increased gait variability are common among individuals with Parkinson's disease (PD) and have been associated with increased risk for falls. The development of composite scores has gained interest to aggregate multiple aspects of gait into a single metric. The Enhanced Gait Variability Index (EGVI) was developed to compare an individual's gait variability to the amount of variability in a healthy population, yet the EGVI's individual parts may also provide important information that may be lost in this conversion. We sought to contrast individual gait measures as predictors of fall frequency and the EGVI as a single predictor of fall frequency in individuals with PD. 273 patients (189M, 84F; 68 ± 10 yrs) with idiopathic PD walked over an instrumented walkway and reported fall frequency over three months (never, rarely, monthly, weekly, or daily). The predictive ability of gait velocity, step length, step time, stance time, and single support time and the EGVI was assessed using regression techniques to predict fall frequency. The EGVI explained 15.1% of the variance in fall frequency (p < 0.001, r = 0.389). Although the regression using the combined spatiotemporal measures to predict fall frequency was significant (p=0.002, r = 0.264), none of the components reached significance (gait velocity: p=0.640, step length: p=0.900, step time: p=0.525, stance time: p=0.532, single support time: p=0.480). The EGVI is a better predictor of fall frequency in persons with PD than its individual spatiotemporal components. Patients who fall more frequently have more variable gait, based on the interpretation of the EGVI. While the EGVI provides an objective measure of gait variability with some ability to predict fall frequency, full clinical interpretations and applications are currently unknown.

Human kinematic, kinetic and EMG data during different walking and stair ascending and descending tasks

This paper reports the kinematic, kinetic and electromyographic (EMG) dataset of human locomotion during level walking at different velocities, toe- and heel-walking, stairs ascending and descending. A sample of 50 healthy subjects, with an age between 6 and 72 years, is included. For each task, both raw data and computed variables are reported including: the 3D coordinates of external markers, the joint angles of lower limb in the sagittal, transversal and horizontal anatomical planes, the ground reaction forces and torques, the center of pressure, the lower limb joint mechanical moments and power, the displacement of the whole body center of mass, and the surface EMG signals of the main lower limb muscles. The data reported in the present study, acquired from subjects with different ages, represents a valuable dataset useful for future studies on locomotor function in humans, particularly as normative reference to analyze pathological gait, to test the performance of simulation models of bipedal locomotion, and to develop control algorithms for bipedal robots or active lower limb exoskeletons for rehabilitation.

A turn for the worse: Turning performance in Parkinson's disease and Essential tremor

BACKGROUND

Turning is an activity of daily living known to elicit falls in older adults and particularly in persons with movement disorders. Specifically, those with Parkinson's disease have marked impairments in forward walking and turning. Although recent work has identified gait impairment in those with Essential tremor, turning has not been extensively evaluated. As the cerebellum is key in the pathophysiology of Essential tremor, complex tasks like turning, may be impaired for this population. The purpose of this study was to investigate turning behavior and falls in those with Essential tremor and Parkinson's disease.

METHODS

15 persons with Essential tremor and 15 persons with Parkinson's disease performed forward walking and turns on an instrumented walkway. t-tests compared groups and a regression was performed to predict fall frequency.

FINDINGS

During turning, those with Essential tremor had lower cadence (p = .042) and took more time (p = .05). No other variables, including forward walking variables, differed between groups. When pooling groups, the significant fall frequency predictor model (p = .003) included decreased forward cadence, increased turning cadence, and female sex. Overall, the model explained 40.7% of the variance.

INTERPRETATION

While forward gait performance was similar between groups, those with Essential tremor had increased turn time, a measure often associated with turning impairment. Together, these results suggest overall gait impairment in Essential tremor is more prevalent than recognized. Walking performance, both turning and forward, and sex were predictive of fall frequency. Therapeutic interventions in these populations should include both forward walking and turns to mitigate fall risk.

[Deep brain stimulation effect on postural instability and gait disorders in Parkinson's disease]

An effect of deep brain stimulation on postural instability and gait disorders in Parkinson's disease S.G. Sultanova, N.V. Fedorova, E.V. Bril, A.A. Gamaleya, A.A. Tomskiy During the last time, surgical treatment of patients with Parkinson's disease has firmly taken its place in the general algorithm for managing patients with this pathology. Deep brain electrostimulation is the most advanced and promising method, which allows the reduction in the severity of main clinical manifestations of the disease, including axial symptoms. It is noted that certain temporal aspects of parkinsonian gait disorder remain therapeutically resistant. Subthalamic nucleus stimulation was also reported to improve levodopa-responsive freezing of gait. In this review, the authors summarize the effects of deep brain stimulation on gait and postural symptoms.

The Association between Prefrontal Cortex Activity and Turning Behavior in People with and without Freezing of Gait

Turning elicits Freezing of Gait (FoG) episodes in people with Parkinson's disease (PD) and is thought to require higher cortical control compared to straight ahead gait. Functional near infrared spectroscopy (fNIRS) has been used to examine prefrontal cortex (PFC) activity while walking, but the relationship between PFC activity and turn performance remains unclear. The aim of this pilot study was to examine PFC activity during turning in PD and healthy controls, and to investigate the association between PFC activity and turning. Thirty-two subjects, 15 freezers (PD + FoG) and 17 non-freezers (PD - FoG), and 8 controls were asked to perform a 2-min turning-in-place test under single-task (ST) and dual-task (DT) conditions. Each participant wore an fNIRS system to measure changes in oxyhemoglobin, as measure of PFC activity, and inertial sensors to quantify turning. Our results show a significant group (p = .050), task (p = .039), and interaction (p = .047) for the PFC activity during turning. Specifically, PD + FoG show higher PFC during turning compared to the other groups; PFC activity during DT is overall different compared to ST with an opposite trend in PD + FoG compared to controls and PD - FoG. In addition, higher PFC is associated with worse FoG in PD + FoG (r = 0.57, p = .048) and with lower number of turns in PD - FoG (r = -0.70, p = .002). The increased PFC activity in PD and the association between higher PFC activity and poorer turning performance may be a sign of poor movement automaticity in PD. Although further investigations are required, these pilot findings may guide development of personalized treatments to improve motor automaticity in PD.