A Music-Based Digital Therapeutic: Proof-of-Concept Automation of a Progressive and Individualized Rhythm-Based Walking Training Program After Stroke.

BACKGROUND: The rhythm of music can entrain neurons in motor cortex by way of direct connections between auditory and motor brain regions. OBJECTIVE: We sought to automate an individualized and progressive music-based, walking rehabilitation program using real-time sensor data in combination with decision algorithms. METHODS: A music-based digital therapeutic was developed to maintain high sound quality while modulating, in real-time, the tempo (ie, beats per minute, or bpm) of music based on a user's ability to entrain to the tempo and progress to faster walking cadences in-sync with the progression of the tempo. Eleven individuals with chronic hemiparesis completed one automated 30-minute training visit. Seven returned for 2 additional visits. Safety, feasibility, and rehabilitative potential (ie, changes in walking speed relative to clinically meaningful change scores) were evaluated. RESULTS: A single, fully automated training visit resulted in increased usual (∆ 0.085 ± 0.027 m/s, P = .011) and fast (∆ 0.093 ± 0.032 m/s, P = .016) walking speeds. The 7 participants who completed additional training visits increased their usual walking speed by 0.12 ± 0.03 m/s after only 3 days of training. Changes in walking speed were highly related to changes in walking cadence (R2 > 0.70). No trips or falls were noted during training, all users reported that the device helped them walk faster, and 70% indicated that they would use it most or all of the time at home. CONCLUSIONS: In this proof-of-concept study, we show that a sensor-automated, progressive, and individualized rhythmic locomotor training program can be implemented safely and effectively to train walking speed after stroke. Music-based digital therapeutics have the potential to facilitate salient, community-based rehabilitation.

Central Drive to the Paretic Ankle Plantarflexors Affects the Relationship Between Propulsion and Walking Speed After Stroke.

BACKGROUND AND PURPOSE: The ankle plantarflexor muscles are the primary generators of propulsion during walking. Impaired paretic plantarflexion is a key contributor to interlimb propulsion asymmetry after stroke. Poststroke muscle weakness may be the result of a reduced force-generating capacity, reduced central drive, or a combination of these impairments. This study sought to elucidate the relationship between the neuromuscular function of the paretic plantarflexor muscles and propulsion deficits across individuals with different walking speeds. METHODS: For 40 individuals poststroke, we used instrumented gait analysis and dynamometry coupled with supramaximal electrostimulation to study the interplay between limb kinematics, the neuromuscular function of the paretic plantarflexors (ie, strength capacity and central drive), propulsion, and walking speed. RESULTS: The strength capacity of the paretic plantarflexors was not independently related to paretic propulsion. Reduced central drive to the paretic plantarflexors independently contributed to paretic propulsion deficits. An interaction between walking speed and plantarflexor central drive was observed. Individuals with slower speeds and lower paretic plantarflexor central drive presented with the largest propulsion impairments. Some study participants with low paretic plantarflexor central drive presented with similarly fast speeds as those with near-normal central drive by leveraging a compensatory reliance on nonparetic propulsion. The final model accounted for 86% of the variance in paretic propulsion (R = 0.86, F = 33.10, P < 0.001). DISCUSSION AND CONCLUSIONS: Individuals poststroke have latent paretic plantarflexion strength that they are not able to voluntarily access. The magnitude of central drive deficit is a strong indicator of propulsion impairment in both slow and fast walkers.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A298).

Reducing The Cost of Transport and Increasing Walking Distance After Stroke: A Randomized Controlled Trial on Fast Locomotor Training Combined With Functional Electrical Stimulation.

Background Neurorehabilitation efforts have been limited in their ability to restore walking function after stroke. Recent work has demonstrated proof-of-concept for a functional electrical stimulation (FES)-based combination therapy designed to improve poststroke walking by targeting deficits in paretic propulsion. Objectives To determine the effects on the energy cost of walking (EC) and long-distance walking ability of locomotor training that combines fast walking with FES to the paretic ankle musculature (FastFES). Methods Fifty participants >6 months poststroke were randomized to 12 weeks of gait training at self-selected speeds (SS), fast speeds (Fast), or FastFES. Participants' 6-minute walk test (6MWT) distance and EC at comfortable (EC-CWS) and fast (EC-Fast) walking speeds were measured pretraining, posttraining, and at a 3-month follow-up. A reduction in EC-CWS, independent of changes in speed, was the primary outcome. Group differences in the number of 6MWT responders and moderation by baseline speed were also evaluated. Results When compared with SS and Fast, FastFES produced larger reductions in EC (Ps ≤.03). FastFES produced reductions of 24% and 19% in EC-CWS and EC-Fast (Ps <.001), respectively, whereas neither Fast nor SS influenced EC. Between-group 6MWT differences were not observed; however, 73% of FastFES and 68% of Fast participants were responders, in contrast to 35% of SS participants. Conclusions Combining fast locomotor training with FES is an effective approach to reducing the high EC of persons poststroke. Surprisingly, differences in 6MWT gains were not observed between groups. Closer inspection of the 6MWT and EC relationship and elucidation of how reduced EC may influence walking-related disability is warranted.

Effects of repeated treadmill testing and electrical stimulation on post-stroke gait kinematics.

Improvements in task performance due to repeated testing have previously been documented in healthy and patient populations. The existence of a similar change in performance due to repeated testing has not been previously investigated at the level of gait kinematics in the post-stroke population. The presence of such changes may define the number of testing sessions necessary for measuring a stable baseline of pre-training gait performance, which is a necessary prerequisite for determining the effectiveness of gait interventions. Considering the emergence of treadmills as a popular tool for gait evaluation and retraining and the common addition of functional electrical stimulation (FES) to gait retraining protocols, the stability of gait kinematics during the repeated testing of post-stroke individuals on a treadmill, either with or without FES, needs to be determined. Nine individuals (age: 58.1±7.3 years), with hemi-paresis secondary to a stroke (onset: 7.3±6.0 years) participated in this study. An 8-camera motion analysis system was used to measure sagittal plane knee and ankle joint kinematics. Gait kinematics were compared across two (N=9) and five (N=5) testing sessions. No consistent changes in knee or ankle kinematics were observed during repeated testing. These findings indicate that clinicians and researchers may not need to spend valuable time and resources performing multiple testing and acclimatization sessions when assessing baseline gait kinematics in the post-stroke population for use in determining the effectiveness of gait interventions.