Error-augmented bimanual therapy for stroke survivors.

BACKGROUND: Stroke recovery studies have shown the efficacy of bimanual training on upper limb functional recovery and others have shown the efficacy of feedback technology that augments error. OBJECTIVE: In a double-blinded randomized controlled study (N = 26), we evaluated the short-term effects of bilateral arm training to foster functional recovery of a hemiparetic arm, with half of our subjects unknowingly also receiving error augmentation (where errors were visually and haptically enhanced by a robot). METHODS: Twenty-six individuals with chronic stroke were randomly assigned to practice an equivalent amount of bimanual reaching either with or without error augmentation. Participants were instructed to coordinate both arms while reaching to two targets (one for each arm) in three 45-minute treatments per week for two weeks, with a follow-up visit after one week without treatment. RESULTS: Subjects' 2-week gains in Fugl-Meyer score averaged 2.92, and we also observed improvements Wolf Motor Functional Ability Scale average 0.21, and Motor Activity Log of 0.58 for quantity and 0.63 for quality of life scores. The extra benefit of error augmentation over the three weeks became apparent in Fugl-Meyer score only after removing an outlier from consideration. CONCLUSIONS: This modest advantage of error augmentation was detectable over a short interval encouraging further research in interactive self-rehabilitation systems that can enhance error motor recovery.

Robot Training With Vector Fields Based on Stroke Survivors' Individual Movement Statistics.

The wide variation in upper extremity motor impairments among stroke survivors necessitates more intelligent methods of customized therapy. However, current strategies for characterizing individual motor impairments are limited by the use of traditional clinical assessments (e.g., Fugl-Meyer) and simple engineering metrics (e.g., goal-directed performance). Our overall approach is to statistically identify the range of volitional movement capabilities, and then apply a robot-applied force vector field intervention that encourages under-expressed movements. We investigated whether explorative training with such customized force fields would improve stroke survivors' (n = 11) movement patterns in comparison to a control group that trained without forces (n = 11). Force and control groups increased Fugl-Meyer UE scores (average of 1.0 and 1.1, respectively), which is not considered clinically meaningful. Interestingly, participants from both groups demonstrated dramatic increases in their range of velocity during exploration following only six days of training (average increase of 166.4% and 153.7% for the Force and Control group, respectively). While both groups showed evidence of improvement, we also found evidence that customized forces affected learning in a systematic way. When customized forces were active, we observed broader distributions of velocity that were not present in the controls. Second, we found that these changes led to specific changes in unassisted motion. In addition, while the shape of movement distributions changed significantly for both groups, detailed analysis of the velocity distributions revealed that customized forces promoted a greater proportion of favorable changes. Taken together, these results provide encouraging evidence that patient-specific force fields based on individuals' movement statistics can be used to create new movement patterns and shape them in a customized manner. To the best of our knowledge, this paper is the first to directly link engineering assessments of stroke survivors' exploration movement behaviors to the design of customized robot therapy.

Use of a Portable Assistive Glove to Facilitate Rehabilitation in Stroke Survivors With Severe Hand Impairment.

Treatment options for stroke survivors with severe hand impairment are limited. Active task practice can be restricted by difficulty in voluntarily activating finger muscles and interference from involuntary muscle excitation. We developed a portable, actuated glove-orthosis, which could be employed to address both issues. We hypothesized that combining passive cyclical stretching (reducing motoneuronal hyperexcitability) imposed by the device with active-assisted, task-oriented training (rehabilitating muscle activation) would improve upper extremity motor control and task performance post-stroke. Thirteen participants who experienced a stroke 2-6 months prior to enrollment completed 15 treatment sessions over five weeks. Each session involved cyclically stretching the long finger flexors (30 min) followed by active-assisted task-oriented movement practice (60 min). Outcome measures were completed at six intervals: three before and three after treatment initiation. Overall improvement in post-training scores was observed across all outcome measures, including the Graded Wolf Motor Function Test, Action Research Arm Test, and grip and pinch strength (p ≤ 0.02), except finger extension force. No significant change in spasticity was observed. Improvement in upper extremity capabilities is achievable for stroke survivors even with severe hand impairment through a novel intervention combining passive cyclical stretching and active-assisted task practice, a paradigm which could be readily incorporated into the clinic.

Quantification of a single score (1+) in the Modified Ashworth Scale (MAS), a clinical assessment of spasticity.

The Modified Ashworth Scale (MAS) is an assessment that is often used by clinicians to grade spasticity in the affected limbs of stroke survivors. The MAS is a function of the angle at which the clinician perceives a resistance to stretch and/or a `catch' during a passive joint rotation. The qualitative nature of the assessment in combination with the low resolution of the scale could result in varied grouping of spastic patients, even for a single score. The objective of this pilot study was to develop a method for the quantification of the MAS, which could provide greater resolution and could eventually guide better informed therapeutic interventions. The MAS assessment at the elbow joint for four stroke survivors with the same clinical MAS score of 1+ was performed by a clinician and quantified using signals from surface electromyography (EMG) and an electrogoniometer. The subjects were tested on both the affected and contralateral upper limbs. The findings from this study show a varied set of signal outputs across four stroke survivors, all graded at 1+. The quantification provides insight as to the mechanisms underlying the passive resistance.

Training finger individuation with a mechatronic-virtual reality system leads to improved fine motor control post-stroke.

BACKGROUND: Dexterous manipulation of the hand, one of the features of human motor control, is often compromised after stroke, to the detriment of basic functions. Despite the importance of independent movement of the digits to activities of daily living, relatively few studies have assessed the impact of specifically targeting individuated movements of the digits on hand rehabilitation. The purpose of this study was to investigate the impact of such finger individuation training, by means of a novel mechatronic-virtual reality system, on fine motor control after stroke. METHODS: An actuated virtual keypad (AVK) system was developed in which the impaired hand controls a virtual hand playing a set of keys. Creation of individuated digit movements is assisted by a pneumatically actuated glove, the PneuGlove. A study examining efficacy of the AVK system was subsequently performed. Participants had chronic, moderate hand impairment resulting from a single stroke incurred at least 6 months prior. Each subject underwent 18 hour-long sessions of extensive therapy (3x per week for 6 weeks) targeted at finger individuation. Subjects were randomly divided into two groups: the first group (Keypad: N = 7) utilized the AVK system while the other group (OT: N = 7) received a similarly intensive dose of occupational therapy; both groups worked directly with a licensed occupational therapist. Outcome measures such as the Jebsen-Taylor Hand Function Test (JTHFT), Action research Arm Test (ARAT), Fugl-Meyer Upper Extremity Motor Assessment/Hand subcomponent (FMUE/FMH), grip and pinch strengths were collected at baseline, post-treatment and one-month post-treatment. RESULTS: While both groups exhibited some signs of change after the training sessions, only the Keypad group displayed statistically significant improvement both for measures of impairment (FMH: p = 0.048) and measures of task performance (JTHFT: p = 0.021). Additionally, the finger individuation index - a measure of finger independence - improved only for the Keypad group after training (p = 0.05) in the subset (Keypad: N = 4; OT: N = 5) of these participants for which it was measured. CONCLUSIONS: Actively assisted individuation therapy comprised of non task-specific modalities, such as can be achieved with virtual platforms like the AVK described here, may prove to be valuable clinical tools for increasing the effectiveness and efficiency of therapy following stroke.