CHECGAIT: A Functional Electrical Stimulation Clinical Pathway to Reduce Foot Drop during Walking in Adult Patients with Upper Motor Neuron Lesions.

Foot drop during the swing phase of gait and at initial foot contact is a current kinematic abnormality that can occur following an upper motor neuron (UMN) lesion. Functional electrical stimulation (FES) of the common peroneal nerve through an assistive device is often used in neuro-rehabilitation to help patients regain mobility. Although there are FES-specific guideline recommendations, it remains a challenge for clinicians to appropriately select patients eligible for the daily use of FES devices, as very few health insurance systems cover its cost in Europe. In Luxembourg, since 2018, successfully completing an FES clinical pathway called CHECGAIT is a prerequisite to receiving financial coverage for FES devices from the national health fund (Caisse Nationale de Santé-CNS). This study describes the structure and steps of CHECGAIT and reports our experience with a cohort of 100 patients enrolled over a three-year period. The clinical and gait outcomes of all patients were retrospectively quantified, and a specific analysis was performed to highlight differences between patients with and without an FES device prescription at the end of a CHECGAIT. Several significant gait differences were found between these groups. These results and CHECGAIT may help clinicians to better select patients who can most benefit from this technology in their daily lives. In addition, CHECGAIT could provide significant savings to public health systems by avoiding unnecessary deliveries of FES devices.

Classification of Stiff-Knee Gait Kinematic Severity after Stroke Using Retrospective k-Means Clustering Algorithm.

Nowadays, a classification system for unilateral stiff-knee gait (SKG) kinematic severity in hemiparetic adult patients after stroke does not exist. However, such classification would be useful to the clinicians. We proposed the use of the k-means method in order to define unilateral SKG severity clusters in hemiparetic adults after stroke. A retrospective k-means cluster analysis was applied to five selected knee kinematic parameters collected during gait in 96 hemiparetic adults and 19 healthy adults from our clinical gait analysis database. A total of five discrete knee kinematic clusters were determined. Three clusters of SKG were identified, based on which a three-level severity classification was defined: unbend-knee gait, braked-knee gait, and frozen-limb gait. Preliminary construct validity of the classification was obtained. All selected knee kinematic parameters defining the five clusters and the majority of usual kinematic parameters of the lower limbs showed statistically significant differences between the different clusters. We recommend diagnosing SKG for values strictly below 40° of knee flexion during the swing phase. Clinicians and researchers are now able to specify the level of kinematic severity of SKG in order to optimize treatment choices and future clinical trial eligibility criteria.

Metabolic Energy Expenditure and Accelerometer-Determined Physical Activity Levels in Post-Stroke Hemiparetic Patients.

BACKGROUND: Assessment of metabolic energy expenditure in post-stroke patients using accelerometers is clinically important. However, understanding of the best placement of accelerometers on the body and methods for calculating activity counts are limited. METHODS: Thirty hemiparetic post-stroke patients participated in this cross-sectional study. Four triaxial accelerometers were attached to the hemiplegic and contralateral sides of the waist and ankles during various activities: lying, sitting, standing, stepping in place, and walking on a treadmill (1-5 kmh-1). Activity counts and metabolic energy expenditure of the patients were recorded simultaneously. Simple linear regression analyses were performed between the activity counts and energy expenditure. Activities were classified according to their intensity, using the definition of energetic sedentary behavior of post-stroke patients and a low fitness level group. RESULTS: The best estimate of energy expenditure was obtained when the accelerometer was worn on the contralateral ankle and the activity counts was calculated using the vertical and anteroposterior axes (R2=0.812). Six classes of activity intensity (sedentary: ≤1.5 METs, very light: 1.51-1.79, light: 1.80-2.59, moderate: 2.60-3.39, hard: 3.40-4.39, and very hard: ≥4.40) and corresponding activity counts cut-off points are presented. CONCLUSION: A triaxial accelerometer worn on the contralateral ankle and a method of calculating activity counts that includes at least the vertical and anteroposterior axes are recommended for estimating metabolic energy expenditure in post-stroke patients. The new activity counts cut-off points provide a significant advance in the interpretation of post-stroke monitoring in patients outside the hospital or rehabilitation center.

Asymptomatic Genu Recurvatum reshapes lower limb sagittal joint and elevation angles during gait at different speeds.

BACKGROUND: Kinematic characteristics of walking with an asymptomatic genu recurvatum are currently unknown. The objective of this study is to characterize the lower limb sagittal joint and elevation angles during walking in participants with asymptomatic genu recurvatum and compare it with control participants without knee deformation at different speeds. METHODS: The spatio-temporal parameters and kinematics of the lower limb were recorded using an optoelectronic motion capture system in 26 participants (n = 13 with genu recurvatum and n = 13 controls). The participants walked on an instrumented treadmill during five minutes at three different speeds: slow, medium and fast. RESULTS: Participants with genu recurvatum showed several significant differences with controls: a narrower step width, a greater maximum hip joint extension angle, a greater knee joint extension angle at mid stance, a lower maximum knee joint flexion angle during the swing phase, and a greater ankle joint extension angle at the end of the gait cycle. Participants with genu recurvatum had a greater minimum thigh elevation angle, a greater maximum foot elevation angle, and a change in the orientation of the covariance plane. Walking speed had a significant effect on nearly all lower limb joint and elevation angles, and covariance plane parameters. CONCLUSION: Our findings show that genu recurvatum reshapes lower limb sagittal joint and elevation angles during walking at different speeds but preserves the covariation of elevation angles along a plane during both stance and swing phases and the rotation of this plane with increasing speed.

A multimodal dataset of human gait at different walking speeds established on injury-free adult participants.

Human motion capture is used in various fields to analyse, understand and reproduce the diversity of movements that are required during daily-life activities. The proposed dataset of human gait has been established on 50 adults healthy and injury-free for lower and upper extremities in the most recent six months, with no lower and upper extremity surgery in the last two years. Participants were asked to walk on a straight level walkway at 5 speeds during one unique session: 0-0.4 m.s-1, 0.4-0.8 m.s-1, 0.8-1.2 m.s-1, self-selected spontaneous and fast speeds. Three dimensional trajectories of 52 reflective markers spread over the whole body, 3D ground reaction forces and moment, and electromyographic signals were simultaneously recorded. For each participants, a minimum of 3 trials per condition have been made available in the dataset for a total of 1143 trials. This dataset could increase the sample size of similar datasets, lead to analyse the effect of walking speed on gait or conduct unusual analysis of gait thanks to the full body markerset used.

Influence of normative data's walking speed on the computation of conventional gait indices.

The pathology's impact on gait pattern may be overestimated by conventional gait indices (Gillette Gait Index - GGI, Gait Deviation Index - GDI, Gait Profile Score - GPS), since impairments' consequences on kinematics may be amplified by a change in walking speed. The objectives of this study were to evaluate the influence of walking speed on the computation of gait indices and to propose a corrective method to cancel the effects of walking speed. Spatiotemporal parameters and kinematics of fifty-four asymptomatic participants (30 M/24 W, 37.9 ±â€¯13.7 years, 72.8 ±â€¯13.3 kg, 1.74 ±â€¯0.10 m) were collected at four speed conditions (C1:[0,0.4] m s-1, C2:[0.4,0.8] m s-1, C3:[0.8,1.2] m s-1, C4:spontaneous). Four values of each index were computed for each trial using successively the four conditions as normative data repository. Mean values over all participants were statistically compared (paired t-tests, 95% confidence level). Indices values computed with normative at equivalent walking speed were not statistically different from reference values. Meanwhile, deviations appeared when the walking speed discrepancy between conditions and normative increased. These drifts related to walking speed mismatch have been quantified and fitting functions proposed. A correction was applied to indices. GGI was efficiently adjusted while GDI and GPS remain different from their reference values for C1 and C2. Gait indices must be interpreted cautiously in function of the normative data repository's walking speed used for computation. Furthermore, a coupled use of conventional and corrected gait indices could lead to a better comprehension of the contribution of impairments and walking speed on gait deviations and overall gait quality.

Brain plasticity after implanted peroneal nerve electrical stimulation to improve gait in chronic stroke patients: Two case reports.

BACKGROUND: Recent studies have shown that stimulation of the peroneal nerve using an implantable 4-channel peroneal nerve stimulator could improve gait in stroke patients. OBJECTIVES: To assess structural cortical and regional cerebral metabolism changes associated with an implanted peroneal nerve electrical stimulator to correct foot drop related to a central nervous system lesion. METHODS: Two stroke patients presenting a foot drop related to a central nervous system lesion were implanted with an implanted peroneal nerve electrical stimulator. Both patients underwent clinical evaluations before implantation and one year after the activation of the stimulator. Structural magnetic resonance imaging (MRI) and [18F]-fluorodeoxyglucose-positron emission tomography (FDG-PET) were acquired before and one year after the activation of the stimulator. RESULTS: Foot drop was corrected for both patients after the implantation of the stimulator. After one year of treatment, patient 1 improved in three major clinical tests, while patient 2 only improved in one test. Prior to treatment, FDG-PET showed a significant hypometabolism in premotor, primary and supplementary motor areas in both patients as compared to controls, with patient 2 presenting more widespread hypometabolism. One year after the activation of the stimulator, both patients showed significantly less hypometabolism in the damaged motor cortex. No difference was observed on the structural MRI. CONCLUSION: Clinical improvement of gait under peroneal nerve electrical stimulation in chronic stroke patients presenting foot drop was paralleled to metabolic changes in the damaged motor cortex.

Influence of a rhythmic auditory stimulation on asymptomatic gait.

The direct effects of a rhythmic auditory stimulation (RAS) on the gait of asymptomatic subjects are not clear. Previous studies only showed modifications in the gastrocnemius activity, inconsistent effects on temporal parameters, and no modification of spatial parameters. Furthermore, the influence of RAS on kinematics and kinetics has only been reported in pathological gait. The objective of this study was to perform a full comparison of gait characteristics in asymptomatic subjects at preferred and reduced walking speed between without and with RAS conditions. Spatiotemporal parameters, kinematics, kinetics and EMG signals datasets were collected for each condition. RAS conditions were obtained by asking subjects to walk on metronomic beats. 17 asymptomatic subjects were included in the study (12M/5W, 37.4±15.7years, 74.0±14.8kg, 1.77±0.09m). Comparisons between without and with RAS conditions were then performed using the Statistical Parametric Mapping method. For all combined subjects, the effect of RAS was limited whatever the walking speed. Meanwhile, global effects were observed for kinematics, kinetics and EMG at both spontaneous and reduced walking speed, which can only be explained by covariances (i.e., no effect on individual time-series). The use of RAS to impose a specific cadence matching the desired walking speed (e.g., to collect normative data) appears thus possible, as none parameters were modified individually. However, RAS should be used with caution taking into account covariances (i.e., muscle synergy or joint coordination patterns). This study has to be extended to a larger number of subjects to confirm these observations.

Proposition of a Classification of Adult Patients with Hemiparesis in Chronic Phase.

BACKGROUND: Patients who have developed hemiparesis as a result of a central nervous system lesion, often experience reduced walking capacity and worse gait quality. Although clinically, similar gait patterns have been observed, presently, no clinically driven classification has been validated to group these patients' gait abnormalities at the level of the hip, knee and ankle joints. This study has thus intended to put forward a new gait classification for adult patients with hemiparesis in chronic phase, and to validate its discriminatory capacity. METHODS AND FINDINGS: Twenty-six patients with hemiparesis were included in this observational study. Following a clinical examination, a clinical gait analysis, complemented by a video analysis, was performed whereby participants were requested to walk spontaneously on a 10m walkway. A patient's classification was established from clinical examination data and video analysis. This classification was made up of three groups, including two sub-groups, defined with key abnormalities observed whilst walking. Statistical analysis was achieved on the basis of 25 parameters resulting from the clinical gait analysis in order to assess the discriminatory characteristic of the classification as displayed by the walking speed and kinematic parameters. Results revealed that the parameters related to the discriminant criteria of the proposed classification were all significantly different between groups and subgroups. More generally, nearly two thirds of the 25 parameters showed significant differences (p<0.05) between the groups and sub-groups. However, prior to being fully validated, this classification must still be tested on a larger number of patients, and the repeatability of inter-operator measures must be assessed. CONCLUSIONS: This classification enables patients to be grouped on the basis of key abnormalities observed whilst walking and has the advantage of being able to be used in clinical routines without necessitating complex apparatus. In the midterm, this classification may allow a decision-tree of therapies to be developed on the basis of the group in which the patient has been categorised.

Control of Stroke-Related Genu Recurvatum With Prolonged Timing of Dorsiflexor Functional Electrical Stimulation: A Case Study.

BACKGROUND AND PURPOSE: Abnormal knee hyperextension during the stance phase (genu recurvatum) is a common gait abnormality in persons with hemiparesis due to stroke. While ankle-foot orthoses (AFOs) are often used to prevent genu recurvatum by maintaining ankle dorsiflexion during the stance phase, AFOs reduce ankle joint mobility. Functional electrical stimulation (FES) is an alternative to the use of AFO for producing appropriately timed ankle dorsiflexion and with prolonged timing may also have value for reducing genu recurvatum. CASE DESCRIPTION: A 51-year-old man with chronic stroke was the subject of this case study. The patient had excessive plantarflexion during stance phase (ie, dynamic equinus foot), with associated genu recurvatum. INTERVENTION: Evaluation included clinical examination, instrumented gait analysis, 10-meter walk test, and 6-minute walk test. The patient underwent a trial of botulinum toxin to the plantarflexor muscles that was not effective for controlling the genu recurvatum. A subsequent trial with surface FES to elicit dorsiflexion during gait was effective, and he subsequently received an implanted FES system. OUTCOMES: Stimulation-induced contraction of the dorsiflexors during terminal swing phase resulted in improved ankle dorsiflexion at initial contact. Moreover, extension of stimulation into the loading phase ensured tibial advancement, which limited knee hyperextension. The patient was reevaluated 12 months following implantation with continued positive outcomes. DISCUSSION: This case study illustrates the potential value of prolonged timing of dorsiflexor FES to manage genu recurvatum attributed to a dynamic equinus foot in a stroke survivor.

Asynchrony between position and motion signals in the saccadic system.

The influence of position and motion signals on saccades was studied in two dimensions (2D) using a double step-ramp paradigm. We showed the presence of a predictive component in 2D catch-up saccade programming that is based on motion signals and influences both saccade amplitude and orientation. Interestingly, a significant proportion of catch-up saccades was characterized by a large curvature or a sudden change of direction in midflight for large values of retinal slip. For these saccades, a quantitative analysis showed that their trajectory could be explained by an asynchrony between position and motion signals in saccade programming. When the saccade trajectory was not straight, position error was always available first and influenced the initial orientation of the saccade, whereas retinal slip determined the final orientation. This new paradigm could be used in electrophysiological experiments, where it should prove to be very useful to study position and motion pathways separately in catch-up saccades.