Inter-limb coordination in bimanual reach-to-grasp following stroke

Purpose. To determine the extent to which inter-limb coordination in the execution of unimanual and bimanual tasks was impaired following stroke.

Methods. Thirteen stroke survivors aged 55 - 77 years and 13 healthy, neurologically intact participants aged 57 - 86 years performed a unimanual and two bimanual tasks involving the relocation of single and paired objects. Movements were recorded using electromagnetic sensors attached to the wrists and a series of micro switches placed under the objects. Main outcome measures included time to complete components of the tasks; comparison between sides; deviation of the hands from a linear trajectory; coordination of the two sides as indicated by relative phase angle.

Results. Stroke survivors took longer to complete the bimanual tasks, but did not deviate from the optimal trajectories more than the healthy participants. Both groups performed unimanual tasks faster than bimanual and stroke participants were only slightly less synchronised when performing bimanual tasks.

Conclusions. In conclusion, in a group of stroke patients with reasonable strength, inter-limb coordination was mildly impaired. This impairment in coordination was not due to lateral deviation of the impaired limb.     

Network activation during bimanual movements in humans

The coordination of movement between the upper limbs is a function highly distributed across the animal kingdom. How the central nervous system generates such bilateral, synchronous movements, and how this differs from the generation of unilateral movements, remain uncertain. Electrophysiologic and functional imaging studies support that the activity of many brain regions during bimanual and unimanual movement is quite similar. Thus, the same brain regions (and indeed the same neurons) respond similarly during unimanual and bimanual movements as measured by electrophysiological responses. How then are different motor behaviors generated? To address this question, we studied unimanual and bimanual movements using fMRI and constructed networks of activation using Structural Equation Modeling (SEM). Our results suggest that (1) the dominant hemisphere appears to initiate activity responsible for bimanual movement; (2) activation during bimanual movement does not reflect the sum of right and left unimanual activation; (3) production of unimanual movement involves a network that is distinct from, and not a mirror of, the network for contralateral unimanual movement; and (4) using SEM, it is possible to obtain robust group networks representative of a population and to identify individual networks which can be used to detect subtle differences both between subjects as well as within a single subject over time. In summary, these results highlight a differential role for the dominant and non-dominant hemispheres during bimanual movements, further elaborating the concept of handedness and dominance. This knowledge increases our understanding of cortical motor physiology in health and after neurological damage.     

Integrity of white matter in the corpus callosum correlates with bimanual co-ordination skills

Variation in brain structure may reflect variation in functional properties of specific brain systems. Structural variation may therefore reflect variation in behavioural performance. Here, we use diffusion-weighted magnetic resonance imaging to show that variation in white matter integrity in a specific region in the body of the corpus callosum is associated with variation in performance of a bimanual co-ordination task. When the callosal region showing this association is used as a seed for probabilistic tractography, inter-hemispheric pathways are generated to the supplementary motor area and caudal cingulate motor area. This provides further evidence for the role of medial wall motor areas in bimanual co-ordination and supports the idea that variation in brain structure reflects inter-individual differences in skilled performance.     

Development of the assisting hand assessment for adults following stroke: a Rasch-built bimanual performance measure

Aims: To describe the development of a new test of bimanual performance for adults following Stroke, the Adult-Assisting Hand Assessment Stroke, and to report the evidence of internal and external validity.

Methods: Scale development included: (i) establishing the test situation; (ii) constructing test items; (iii) evaluating internal construct validity by use of Rasch measurement analysis on 144 assessments of adults with hemiparesis, mean age 53?years (SD11.45); and (iv) investigating external validity by correlation to the Jebsen and Taylor Test of Hand Function and the ABILHAND Stroke.

Results: The Adult-Assisting Hand Assessment Stroke scale, scored on 19 items using a four-point rating scale, provided a valid measure of bimanual performance. The rating scale structure, goodness of fit, and principal component analysis demonstrated evidence of a unidimensional construct. The strong reliability and high person separation ratio indicated high probability for the scale to be responsive to change. Correlation to outcomes of the Jebsen and Taylor Test of Hand Function and the ABILHAND Stroke indicated strong external validity.

Conclusion: Using two hands together is a critical aspect for performance of most daily life tasks. However, assessments of hand function commonly focus on measuring aspects of unimanual function. The Adult-Assisting Hand Assessment Stroke has the potential to contribute new and clinically important knowledge to stroke rehabilitation by providing an observation-based valid functional measure of bimanual performance.

• Implications for rehabilitation

• Hand function assessments commonly focus on unimanual aspects, although the use of two hands together is critical to perform most daily life tasks.

• The Adult-Assisting Hand Assessment Stroke measures how effectively a patient with a hemiparesis uses his/her affected hand together with the unaffected hand to perform bimanual tasks.

• The Adult-Assisting Hand Assessment Stroke contributes a new and clinically important aspect to stroke rehabilitation by providing a valid bimanual observation-based measure to guide intervention and measure change over time.

     

Information processing in human parieto-frontal circuits during goal-directed bimanual movements

It is known that, in macaques, movements guided by somatosensory information engage anterior parietal and posterior precentral regions. Movements performed with both visual and somatosensory feedback additionally activate posterior parietal and anterior precentral areas. It remains unclear whether the human parieto-frontal circuits exhibit a similar functional organization. Here, we employed a directional interference task requiring a continuous update of sensory information for the on-line control of movement direction, while brain activity was measured by functional magnetic resonance imaging (fMRI). Directional interference arises when bimanual movements occur along different directions in joint space. Under these circumstances, the presence of visual information does not substantially alter performance, such that we could vary the amount and type of sensory information used during on-line guidance of goal-directed movements without affecting motor output. Our results confirmed that in humans, as in macaques, movements guided by somatosensory information engages anterior parietal and posterior precentral regions, while movements performed with both visual and somatosensory information activate posterior parietal and anterior precentral areas. We provide novel evidence on how the interaction of specific portions of the dorsal parietal and precentral cortex in the right hemisphere might generate spatial representations by integrating different sensory modalities during goal-directed movements.     

The role of the medial wall and its anatomical variations for bimanual antiphase and in-phase movements

The medial wall of the frontal cortex is thought to play an important role for bimanual coordination. However, there is uncertainty regarding the exact neuroanatomical regions involved. We compared the activation patterns related to bimanual movements using functional magnetic resonance imaging in 12 healthy right-handed subjects, paying special attention to the anatomical variability of the frontal medial wall. The subjects performed unimanual right and left and bimanual antiphase and in-phase flexion and extension movements of the index finger. Activation of the right supplementary motor area (SMA) proper, right and left caudal cingulate motor area (CMA), and right and left premotor cortices was significantly stronger during bimanual antiphase than bimanual in-phase movements, indicating an important function of these areas with bimanual coordination. A frequent anatomical variation is the presence of the paracingulate sulcus (PCS), which might be an anatomical landmark to determine the location of activated areas. Seven subjects had a bilateral, three a unilateral right, and two a unilateral left PCS. Because the area around the PCS is functionally closer coupled to the CMA than to the SMA, activation found in the area around the PCS should be attributed to the CMA. With anatomical variations such as the presence of a PCS or a vertical branch of the cingulate sulcus, normalization and determination of the activation with the help of stereotaxic coordinates can cause an incorrect shift of CMA activation to the SMA. This might explain some of the discrepancies found in previous studies.     

Changes in prefrontal cortical behaviour depend upon familiarity on a bimanual co-ordination task: an fNIRS study

To investigate neurocognitive mechanisms associated with task-related expertise development, this paper investigates serial changes in prefrontal activation patterns using functional near infrared spectroscopy (fNIRS). We evaluate cortical function in 62 healthy subjects with varying experience during serial evaluations of a knot-tying task. All tasks were performed bimanually and self paced, with fixed episodes of motor rest for five repetitions. Improvements in technical skill were evaluated using dexterity indices to quantify time, total movements and pathlength required to complete trials. Significant improvements in technical skills were observed in novices between the 2nd and 3rd trials, associated with increasing task familiarity. In trained subjects, minimal fluctuation in task-related oxyhaemoglobin (HbO(2)) and deoxyhaemoglobin (HHb) changes were observed in association with more stable task performance. In contrast, two significant transitions in prefrontal haemodynamic change were observed in novices. Greater task-related increases in HbO(2) and decreases in HHb were identified on the second trial compared to the first. Relative decreases in HbO(2) and increases in HHb change were observed between the third and fourth, and fourth and fifth trials respectively. These data suggest that prefrontal processing across five knot-tying trials is influenced by the level of experience on a task. Modifications in prefrontal activation appear to confer technical performance adaptation in novices.     

Disablement following stroke

Purpose: Stroke is the most disabling chronic condition, newly affecting 35000 persons in Canada each year. Because of declining fatality, a growing number of persons will have to cope with stroke-related disability. The purpose of this paper is to describe the disabilities experienced by persons with stroke during the first year and explore the evolution of impairment, disability, handicap and health-related quality of life. Subjects: The data for this paper come from a series of longitudinal and cross-sectional studies, collectively known as the McGill Stroke Rehabilitation Research Program. Results: Within the first week post-stroke, getting out of bed and walking over a short distance, even with assistance, was a strong predictor of discharge home. Most of the improvement in measures of impairment and disability occurred during the first month and, by 3 months, there was still considerable room for improvement in all measures : 85% of persons were still impaired on gait speed, 78% had not reached age-specific norms for upper extremity function, 68% still demonstrated slow physical mobility, 37% needed some assistance with basic activities of daily living and 29% were still impaired on balance. By 1 year, 73% of persons scored the maximum for basic activities of daily living but 51 and 67% of persons reported their physical health and mental health to be lower than expected. Among a hardy group of stroke survivors, still living in the community 1 year post-stroke, the most striking area of difficulty was endurance, as measured by the 6 minute walk test. Those subjects well enough to complete this task (50% of sample) were able to walk, on average, only 250 metres, equivalent to 40% of their predicted ability. This series of snapshots taken at different points in time suggests that much of the improvement in impairment and disability occurs during the first month and then reaches a plateau. Handicap and quality of life continue to be issues later. Rehabilitation strategies need to consider the multifaceted nature of disablement, which in itself changes with time post-stroke.     

Rehabilitation following stroke

Rehabilitation following stroke begins as soon as the patient is medically stable and continues after discharge from hospital. This article describes the processes involved.     

Outcome following stroke

A community study based on an age-stratified sample of those aged 55 years and older in a northern health district in the United Kingdom has been used to consider the implications for purchasing health-care services for those who have survived a stroke. The study showed that while almost a quarter of those reporting a stroke had made a full recovery, a wide range of impairments and disabilities persisted. Almost half reported needing help at least daily. A logistic regression model to predict this level of dependency found that impairments, disabilities and other factors, such as locality, were also predictive of dependency. A second model predicting mobility handicap (dwelling restricted) was found to have a similar mix of predictors. These results show how purchasers must consider the broad outcome in terms of a continuum of impairment, disability and handicap. The results also show that handicap is a distinct concept that draws together many influences which act upon the individual.     

Self-management following stroke

This article defines the concept of self-management and describes psychological theories and emerging behaviour change techniques that nurses can use to promote positive self-care in patients who have had a stroke. A sample of interventions used in stroke care to effect behaviour change are presented and challenges that may arise for nurses when trying to encourage self-management are discussed.     

Disablement following stroke

Purpose: Stroke is the most disabling chronic condition, newly affecting 35000 persons in Canada each year. Because of declining fatality, a growing number of persons will have to cope with stroke-related disability. The purpose of this paper is to describe the disabilities experienced by persons with stroke during the first year and explore the evolution of impairment, disability, handicap and health-related quality of life. Subjects: The data for this paper come from a series of longitudinal and cross-sectional studies, collectively known as the McGill Stroke Rehabilitation Research Program. Results: Within the first week post-stroke, getting out of bed and walking over a short distance, even with assistance, was a strong predictor of discharge home. Most of the improvement in measures of impairment and disability occurred during the first month and, by 3 months, there was still considerable room for improvement in all measures : 85% of persons were still impaired on gait speed, 78% had not reached age-specific norms for upper extremity function, 68% still demonstrated slow physical mobility, 37% needed some assistance with basic activities of daily living and 29% were still impaired on balance. By 1 year, 73% of persons scored the maximum for basic activities of daily living but 51 and 67% of persons reported their physical health and mental health to be lower than expected. Among a hardy group of stroke survivors, still living in the community 1 year post-stroke, the most striking area of difficulty was endurance, as measured by the 6 minute walk test. Those subjects well enough to complete this task (50% of sample) were able to walk, on average, only 250 metres, equivalent to 40% of their predicted ability. This series of snapshots taken at different points in time suggests that much of the improvement in impairment and disability occurs during the first month and then reaches a plateau. Handicap and quality of life continue to be issues later. Rehabilitation strategies need to consider the multifaceted nature of disablement, which in itself changes with time post-stroke.