Stroke-induced synergistic phase shifting and its possible implications for recovery mechanisms

Biofeedback interventions for short term upper limb function following stroke: A systematic review with meta-analysis

BACKGROUND

Biofeedback has been used by rehabilitation professionals in the treatment of poststroke function impairments.

PURPOSE

Investigate the efficacy of any type of biofeedback intervention for the treatment of upper limb function in individuals following stroke.

STUDY DESIGN

Systematic review of literature with meta-analysis.

METHODS

Literature searches were conducted using MESH terms and text words in PubMed, Lilacs, Scielo, Scopus, PEDro, and Web of Science databases. The main outcome was improvement in upper limb's motor function and motor function in activities of daily living. We calculated the Mean Difference and Standardized Mean Difference for the assessment scales reported as primary outcome. The methodological quality of included studies was assessed using PEDro scale. The overall quality of the evidence was assessed using GRADE system.

RESULTS

From 1360 articles identified, 16 were included in the review (09 in the meta-analysis). Three forest plots of hemiparesis and one of hemiplegia showed that biofeedback therapy associated with conventional therapy has a greater improvement in participants upper limb motor function when compared to isolated conventional therapy. Two forest plots of hemiparesis and one of hemiplegia showed no superiority in participants improvement for biofeedback associated with conventional therapy when compared to isolated conventional therapy.

CONCLUSION

Biofeedback therapy associated with conventional therapy showed a small clinical effect when associated to conventional therapy and very low quality of evidence. Although further research with higher quality evidence is needed.

Motor Control System for Adaptation of Healthy Individuals and Recovery of Poststroke Patients: A Case Study on Muscle Synergies

Understanding the complex neuromuscular strategies underlying behavioral adaptation in healthy individuals and motor recovery after brain damage is essential for gaining fundamental knowledge on the motor control system. Relying on the concept of muscle synergy, which indicates the number of coordinated muscles needed to accomplish specific movements, we investigated behavioral adaptation in nine healthy participants who were introduced to a familiar environment and unfamiliar environment. We then compared the resulting computed muscle synergies with those observed in 10 moderate-stroke survivors throughout an 11-week motor recovery period. Our results revealed that computed muscle synergy characteristics changed after healthy participants were introduced to the unfamiliar environment, compared with those initially observed in the familiar environment, and exhibited an increased neural response to unpredictable inputs. The altered neural activities dramatically adjusted through behavior training to suit the unfamiliar environment requirements. Interestingly, we observed similar neuromuscular behaviors in patients with moderate stroke during the follow-up period of their motor recovery. This similarity suggests that the underlying neuromuscular strategies for adapting to an unfamiliar environment are comparable to those used for the recovery of motor function after stroke. Both mechanisms can be considered as a recall of neural pathways derived from preexisting muscle synergies, already encoded by the brain's internal model. Our results provide further insight on the fundamental principles of motor control and thus can guide the future development of poststroke therapies.

A physiologically based hypothesis for learning proprioception and in approximating inverse kinematics

A long-standing problem in muscle control is the "curse of dimensionality". In part, this problem relates to the fact that coordinated movement is only achieved through the simultaneous contraction and extension of multitude muscles to specific lengths. Couched in robotics terms, the problem includes the determination of forward and inverse kinematics. Of the many neurophysiological discoveries in cortex is the existence of position gradients. Geometrically, position gradients are described by planes in Euclidean space whereby neuronal activity increases as the hand approaches locations that lie in a plane. This work demonstrates that position gradients, when coupled with known physiology in the spinal cord, allows for a way to approximate proprioception (forward kinematics) and to specify muscle lengths for goal-directed postures (inverse kinematics). Moreover, position gradients provide a means to learn and adjust kinematics as animals learn to move and grow. This hypothesis is demonstrated using computer simulation of a human arm. Finally, experimental predictions are described that might confirm or falsify the hypothesis.

A functional magnetic resonance imaging study on the effect of acupuncture at GB34 (Yanglingquan) on motor-related network in hemiplegic patients

BACKGROUND

Functional disability of stroke patients, especially limb motor function, seriously impacts the quality of life. Although acupuncture at GB34 (Yang-ling-quan) has been shown to be effective on the recovery of motor function, the underlying mechanism has not been well explored.

OBJECTIVE

To explore the central mechanisms of immediate effect of acupuncture at GB34 on motor-related network of stroke patients with hemiplegia.

METHODS

A repeated measures ANOVA method was employed to investigate the effect of acupuncture at GB34 on functional connectivity of motor-related network. Six stroke patients with left hemiplegia were recruited. A left hand motor task fMRI experiment was performed before and right after acupuncture. Sham point acupuncture was taken as control. The most significant fMRI signal changes during motor task in the right precentral gyrus were identified, which was selected as a seed point for connectivity analysis. Then the functional connectivity of this seed point was compared between verum and sham point acupuncture.

RESULTS

Compared to sham, acupuncture at GB34 showed positive interaction effect at right temporal pole, left lingual gyrus, and left cerebellum. While negative interaction effect mainly occurred at contralateral motor cortex and ipsilateral motor cortex of lower limb.

CONCLUSIONS

Acupuncture at GB34 may increase motor-cognition connectivity meanwhile decrease compensation of unaffected motor cortex and homolateral synkinesis, which can definitely promote the rehabilitation of hemiplegia and spasm.