A four-week, task-specific neuroprosthesis program for a person with no active wrist or finger movement because of chronic stroke

Multi-contact functional electrical stimulation for hand opening: electrophysiologically driven identification of the optimal stimulation site

BACKGROUND

Functional Electrical Stimulation (FES) is increasingly applied in neurorehabilitation. Particularly, the use of electrode arrays may allow for selective muscle recruitment. However, detecting the best electrode configuration constitutes still a challenge.

METHODS

A multi-contact set-up with thirty electrodes was applied for combined FES and electromyography (EMG) recording of the forearm. A search procedure scanned all electrode configurations by applying single, sub-threshold stimulation pulses while recording M-waves of the extensor digitorum communis (EDC), extensor carpi radialis (ECR) and extensor carpi ulnaris (ECU) muscles. The electrode contacts with the best electrophysiological response were then selected for stimulation with FES bursts while capturing finger/wrist extension and radial/ulnar deviation with a kinematic glove.

RESULTS

The stimulation electrodes chosen on the basis of M-waves of the EDC/ECR/ECU muscles were able to effectively elicit the respective finger/wrist movements for the targeted extension and/or deviation with high specificity in two different hand postures.

CONCLUSIONS

A subset of functionally relevant stimulation electrodes could be selected fast, automatic and non-painful from a multi-contact array on the basis of muscle responses to subthreshold stimulation pulses. The selectivity of muscle recruitment predicted the kinematic pattern. This electrophysiologically driven approach would thus allow for an operator-independent positioning of the electrode array in neurorehabilitation.

Therapy incorporating a dynamic wrist-hand orthosis versus manual assistance in chronic stroke: a pilot study

BACKGROUND AND PURPOSE

The purpose of this study was to compare the effect of therapy using a wrist-hand orthosis (WHO) versus manual-assisted therapy (MAT) for individuals with chronic, moderate-to-severe hemiparesis. The relationship between the repetitions during therapy and functional change was also examined.

METHODS

Nineteen participants were randomly assigned to either the WHO group (n = 10) or the MAT group (n = 9). The WHO group performed therapy while wearing a dynamic WHO (SaeboFlex), the MAT group performed therapy with manual assistance of a therapist. Both groups participated in 1 hour of therapy per week for 6 weeks and were prescribed exercises to perform at home 4 days per week. Pre- and posttraining assessments included grip strength, the Action Research Arm Test (ARAT), Box and Blocks (B&B) test, and Stroke Impact Scale (SIS).

RESULTS

There were no significant between-group differences for any of the measures. Within-group differences showed that the WHO group had a significant improvement in the ARAT score (mean = 2.2; P = 0.04). The MAT group had a significant improvement on the percent recovery on the SIS (mean = 9.3%; P = 0.03) and approached a significant improvement on the ARAT (mean = 1.4; P = 0.08). When analyzing all participants together, the relationship between the number of exercise repetitions and functional improvement was moderate for the ARAT and the B&B test (r = 0.55, P = 0.02, and r = 0.30, P = 0.10, respectively).

DISCUSSION AND CONCLUSIONS

Small improvements in function and perception of recovery were observed in both groups, with no definite advantage of the WHO. This study adds to the evidence that individuals with chronic stroke can improve arm use with therapy incorporating functional hand training, and that there is a relationship between amount of change and amount of practice.

Improving poststroke recovery: neuroplasticity and task-oriented training

Neurorehabilitation is a critical part of the overall process to achieve optimal outcome after stroke. Presently, the field of neurorehabilitation is in transition. New research suggesting novel approaches to optimize functional recovery after stroke is on the horizon, but clear knowledge of the underlying mechanisms of this recovery is still being unraveled. In practice, many rehabilitation centers continue to provide traditional compensatory rehabilitation training while many others are practicing newer, "task-oriented" approaches. A few centers are incorporating new technology, such as computer-based training devices or robotics, into rehabilitation care. This transition is happening because neuroscientific research has shown that neuroplastic changes in the cerebral cortex and in other parts of the central nervous system (CNS) are necessarily linked to motor skill retraining in the affected limbs. Task-oriented training that focuses on the practice of skilled motor performance is the critical link to facilitating neural reorganization and "rewiring" in the CNS. Therefore, whenever possible, task-oriented training at an intense level should be incorporated into the rehabilitation program of any patient with stroke-related motor deficits. Two such task-oriented therapies that should be available at all neurorehabilitation centers are constraint-induced movement therapy and body weight-supported treadmill training. The optimal intensity of training (frequency and duration) is still not clear but is certainly greater than that available in clinical programs. Therefore, the incorporation of automated training devices will be necessary in the future. However, the engineering necessary to make these devices effective, easy to use, affordable, and portable remains a challenge for the next decade of neurologic bioengineering research.

Affected arm use and cortical change in stroke patients exhibiting minimal hand movement

BACKGROUND AND PURPOSE

Conventional electrical stimulation modalities are limited by their lack of opportunities for motor learning and, consequently, their impact on function. Other rehabilitative regimens necessitate affected hand and wrist movement for patients to be included, making them implausible for most patients. In light of these challenges, the current study examined the efficacy of a repetitive task-specific training (RTP) regimen using an electrical stimulation neuroprosthesis in stroke patients exhibiting no affected wrist or hand movement.

METHOD

Eight chronic stroke patients (mean = 46.5 months) with moderately affected arm motor deficits participated in 30-minute therapy sessions occurring every weekday for 8 weeks. During the sessions, they wore the neuroprosthesis to enable performance of valued activities identified largely by the patients. To ensure transfer to their real-world environments, most sessions were home based, with the patients coming to the clinic for "tune-up" sessions (eg, adjusting the stimulation parameters, exercises, and/or fit of the device) twice every other week (a total of 8 clinical visits). Outcomes were evaluated using the Action Research Arm Test (ARAT) and the upper extremity section of the Fugl-Meyer Assessment (FM), the amount of use scale of the Motor Activity Log (MAL), and high-field functional magnetic resonance imaging (fMRI).

RESULTS

Before the intervention, patients exhibited stable motor deficits. After the intervention, they exhibited ARAT and FM score increases (+2.85 and +2.2, respectively). Postintervention fMRI revealed significant increases in cortical activation, possibly brought about by markedly increased affected arm use patterns on the MAL (+0.97).

CONCLUSIONS

An affected arm RTP program incorporating NEURSTIM appears to increase affected arm use and elicit neural changes in more impaired patients. These factors may conspire to produce motor changes, although motor changes are smaller in this population than with less impaired patients. The program may act as a "bridge" to other promising regimens.