Was failure to induce motor changes because the extra 45 minutes 5 times a week for 3 weeks wasn't intensive enough? WHOM is going to answer that simple question?
Behavioral and neurophysiological effects of an intensified robot-assisted therapy in subacute stroke: a case control study
Journal of NeuroEngineering and Rehabilitation volume 18, Article number: 6 (2021)
Abstract
Background
Physical training is able to induce changes at neurophysiological and behavioral level associated with performance changes for the trained movements. The current study explores the effects of an additional intense robot-assisted upper extremity training on functional outcome and motor excitability in subacute stroke patients.
Methods
Thirty moderately to severely affected patients < 3 months after stroke received a conventional inpatient rehabilitation. Based on a case–control principle 15 patients were assigned to receive additional 45 min of robot-assisted therapy (Armeo®Spring) 5 times per week (n = 15, intervention group, IG). The Fugl-Meyer Assessment for the Upper Extremity (FMA-UE) was chosen as primary outcome parameter. Patients were tested before and after a 3-week treatment period as well as after a follow-up period of 2 weeks. Using transcranial magnetic stimulation motor evoked potentials (MEPs) and cortical silent periods were recorded from the deltoid muscle on both sides before and after the intervention period to study effects at neurophysiological level. Statistical analysis was performed with non-parametric tests. Correlation analysis was done with Spearman´s rank correlation co-efficient.
Results
Both groups showed a significant improvement in FMA-UE from pre to post (IG: + 10.6 points, control group (CG): + 7.3 points) and from post to follow-up (IG: + 3.9 points, CG: + 3.3 points) without a significant difference between them. However, at neurophysiological level post-intervention MEP amplitudes were significantly larger in the IG but not in the CG. The observed MEP amplitudes changes were positively correlated with FMA-UE changes and with the total amount of robot-assisted therapy.
Conclusion
The additional robot-assisted therapy induced stronger excitability increases in the intervention group. However, this effect did not transduce to motor performance improvements at behavioral level.
Trial registration The trial was registered in German Clinical Trials Register. Clinical trial registration number: DRKS00015083. Registration date: September 4th, 2018. https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00015083. Registration was done retrospectively
Introduction
Stroke patients frequently suffer from motor deficits [1]. The prognosis in severely affected individuals is poor with about 60% failing to achieve at least some dexterity at 6 months after stroke [2]. Thus, further reduction of these deficits is a major challenge for rehabilitation. Various techniques as constraint-induced movement therapy, mirror therapy, virtual reality, neuro-muscular electrical stimulations, task-oriented training and the use of (electro)-mechanical devices to support motor rehabilitation have been recommended so far [3, 4]. Lately, electro-mechanical and robot-driven devices were shown to be effective regarding activities of daily living as well as arm and hand function [5]. However, the authors pointed out that intensity, duration, amount and type of training, device type, participants´ characteristics varied in studies included in their meta-analysis leading to lower evidence quality [5, 6]. Other authors also emphasized that detailed recommendations regarding training intensity and frequency are missing [7]. However, some evidence is available indicating that more movement practice leads to better outcomes [8, 9]. Furthermore, it was recommended to increase exercise intensity by making the tasks more difficult and/or increasing the number of repetitions [10, 11]. Presumably, robot-assisted therapy is effective because it allows to deliver both: high-dosage and high-intensity training [12].
Most studies that evaluated an intense training program have been conducted in chronic stroke patients [13,14,15,16,17,18]. Much less is known about the impact of robot-assisted therapy as well as the dosage for the paretic upper limb within the first 3 months after the stroke [7].
Moreover, the results of rehabilitation are usually presented as improvements in motor function using behavioral measures. Our understanding of the pathophysiology of motor dysfunction and recovery is still limited [19]. In order to optimally design the rehabilitation program, a more complete understanding of the physiological processes of recovery is required [19]. Transcranial magnetic stimulation (TMS) as a suitable tool for safe and painless examination of cortical and corticospinal physiology could help to clarify these processes [20]. Previous studies in stroke patients have shown an enlargement of motor cortex representations after exercises as well as due to spontaneous functional recovery [21,22,23].
To address some of the raised topics, we investigated the effects of an additional robot-assisted training of the upper extremity in subacute stroke patients. For the training we used an upper extremity exoskeleton that provides an adjustable arm support and allows gravity-supported and computer-enhanced arm exercises (Armeo®Spring). Several studies using this device have already demonstrated improvements in motor functions, including increases of strength, as well as reductions of spasticity and pain [24,25,26].
The present study was performed in patients who received a multidisciplinary inpatient rehabilitation. It was designed to answer three questions:
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1
Does this intensified treatment lead to clinical improvements?
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2
Does the additional training induce motor excitability changes and how do these relate to improvements of motor functions?
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3
Is it feasible to increase the amount of motor training relatively early after a severe stroke or would patients discontinue their participation, e.g. due to too much fatigue?(Well, what about action observation and mirror therapy? Or is that also too fatiguing?)
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