Upper-limb motor control in patients after stroke: attentional demands and the potential beneficial effects of arm support.

The goal of this study was to investigate the attentional load of using the upper limb in moderately and mildly affected patients after stroke, with and without arm support. Ten patients with stroke (4 mild and 6 moderate paresis) and ten healthy, gender- and age-matched control subjects performed a dual-task experiment that consisted of a circle drawing task and an auditive Stroop task. Complexity of the motor task was manipulated by supporting the arm against gravity. Individual motor (area×speed) and cognitive (accuracy/reaction time) scores during the dual-task conditions were converted into percentage scores relative to the respective single-task scores and then combined in a single measure of net dual-task performance. Without arm support, only moderately affected patients showed significantly greater side differences in dual-task performance to the detriment of the affected upper limb. With arm support, no side differences were found for any of the three groups. Thus, the hypothesis that patients with moderate upper-limb paresis suffer from a lack of automaticity of motor control was substantiated by the dual-task condition. Furthermore, supporting the arm reduced the attentional load of using the affected side.

Assessment of upper-limb capacity, performance, and developmental disregard in children with cerebral palsy: validity and reliability of the revised Video-Observation Aarts and Aarts module: Determine Developmental Disregard (VOAA-DDD-R).

AIM: To investigate the validity and reliability of the revised Video-Observation Aarts and Aarts module: Determine Developmental Disregard (VOAA-DDD-R). METHOD: Upper-limb capacity and performance were assessed in children with unilateral spastic cerebral palsy (CP) by measuring overall duration of affected upper-limb use and the frequency of specific behaviours during a task in which bimanual activity was demanded ('stringing beads') and stimulated ('decorating a muffin'). Developmental disregard was defined as the difference in duration of affected upper-limb use between both tasks. Raters were two occupational and one physical therapist who received 3 hours of training. Construct validity was determined by comparing children with CP with typically developing children. Intrarater, interrater, and test-retest reliability were determined using the intraclass correlation coefficient. Standard errors of measurement and smallest detectable differences were also calculated. RESULTS: Twenty-five children with CP (15 females, 10 males; mean age 4 y 9 mo [SD 1 y 7 mo], range 2 y 9 mo-8 y; Manual Ability Classification System levels I-III) scored lower on capacity (p=0.052) and performance (p<0.001), and higher on developmental disregard (p<0.001) than 46 age- and sex-matched typically developing children (23 males; mean age 5 y 3 mo [SD 1 y 5 mo], range 2 y 6 mo-8 y). The intraclass correlation coefficients (0.79-1.00) indicated good reliability. Absolute agreement was high, standard errors of measurement ranged from 4.5 to 6.8%, and smallest detectable differences ranged from 12.5 to 19.0%. INTERPRETATION: The VOAA-DDD-R can be reliably and validly used by occupational and physical therapists to assess upper-limb capacity, performance, and developmental disregard in children (2 y 6 mo-8 y) with CP.

Functional recovery of the paretic upper limb after stroke: who regains hand capacity?

OBJECTIVE: To describe recovery of upper limb capacity after stroke during inpatient rehabilitation based on the Stroke Upper Limb Capacity Scale (SULCS). DESIGN: Prospective observational study. SETTING: Inpatient department of a rehabilitation center. PARTICIPANTS: Patients with stroke (N=299) admitted to a specialized stroke rehabilitation center. INTERVENTION: Not applicable. MAIN OUTCOME MEASURES: Upper limb capacity was assessed at the start and end of the rehabilitation phase with the SULCS (range, 0-10). The following demographic and clinical characteristics were registered: age, sex, side of stroke, stroke type, time since stroke, and length of stay in the rehabilitation center. RESULTS: On admission, 125 patients had no hand capacity (SULCS score, 0-3), 58 had basic hand capacity (SULCS score, 4-7), and 116 had advanced hand capacity (SULCS score, 8-10). Of the patients without initial hand capacity, 41% regained some hand capacity (SULCS score, ≥4) at discharge. Of these, patients with SULCS scores of 2 and 3 had 29 and 97 times greater chance of regaining some hand capacity compared with patients with an initial SULCS score of 0, respectively. Of the patients with initial basic hand capacity, 78% regained advanced hand capacity at discharge. The SULCS score on admission explained 51% of the SULCS score variance at discharge, while time since stroke was negatively associated with upper limb recovery, explaining an additional 7% of the SULCS score variance at discharge. CONCLUSIONS: Even patients with minimal proximal shoulder and elbow control of the upper paretic limb on admission in a rehabilitation center have a fair chance of regaining some hand capacity in the long-term after stroke, whereas patients without such proximal arm control have a much poorer prognosis for regaining hand capacity.

The Rivermead Mobility Index allows valid comparisons between subgroups of patients undergoing rehabilitation after stroke who differ with respect to age, sex, or side of lesion.

OBJECTIVE: To investigate differential item functioning or item bias of the Rivermead Mobility Index (RMI) and its impact on the drawing of valid comparisons with the RMI between subgroups of patients after stroke who differ with respect to age, sex, or side of lesion. DESIGN: Cross-sectional study. SETTING: A rehabilitation center in the Netherlands and 2 stroke rehabilitation units and the wider community in the United Kingdom. PARTICIPANTS: The RMI was completed for patients undergoing rehabilitation after stroke (N=620; mean age ± SD, 69.2±12.5y; 297 [48%] men; 269 [43%] right hemisphere lesion, and 304 [49%] left hemisphere lesion). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Mokken scale analysis was used to investigate differential item functioning of the RMI between subgroups of patients who differed with respect to age (young vs older), sex (men vs women), and side of stroke lesion (right vs left hemisphere). RESULTS: No differential item functioning was found for any of the comparison subgroups. CONCLUSIONS: The RMI allows valid comparisons to be made between subgroups of patients undergoing rehabilitation after stroke who differ with respect to age, sex, or side of lesion.

Item hierarchy-based analysis of the Rivermead Mobility Index resulted in improved interpretation and enabled faster scoring in patients undergoing rehabilitation after stroke.

OBJECTIVE: To enable improved interpretation of the total score and faster scoring of the Rivermead Mobility Index (RMI) by studying item ordering or hierarchy and formulating start-and-stop rules in patients after stroke. DESIGN: Cohort study. SETTING: Rehabilitation center in the Netherlands; stroke rehabilitation units and the community in the United Kingdom. PARTICIPANTS: Item hierarchy of the RMI was studied in an initial group of patients (n=620; mean age ± SD, 69.2±12.5y; 297 [48%] men; 304 [49%] left hemisphere lesion, and 269 [43%] right hemisphere lesion), and the adequacy of the item hierarchy-based start-and-stop rules was checked in a second group of patients (n=237; mean age ± SD, 60.0±11.3y; 139 [59%] men; 103 [44%] left hemisphere lesion, and 93 [39%] right hemisphere lesion) undergoing rehabilitation after stroke. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Mokken scale analysis was used to investigate the fit of the double monotonicity model, indicating hierarchical item ordering. The percentages of patients with a difference between the RMI total score and the scores based on the start-and-stop rules were calculated to check the adequacy of these rules. RESULTS: The RMI had good fit of the double monotonicity model (coefficient H(T)=.87). The interpretation of the total score improved. Item hierarchy-based start-and-stop rules were formulated. The percentages of patients with a difference between the RMI total score and the score based on the recommended start-and-stop rules were 3% and 5%, respectively. Ten of the original 15 items had to be scored after applying the start-and-stop rules. CONCLUSIONS: Item hierarchy was established, enabling improved interpretation and faster scoring of the RMI.

Measuring upper limb capacity in patients after stroke: reliability and validity of the stroke upper limb capacity scale.

OBJECTIVE: To investigate the interrater reliability and construct validity of the Stroke Upper Limb Capacity Scale (SULCS). DESIGN: Cohort study. SETTING: Inpatient department of a rehabilitation center. PARTICIPANTS: Patients after stroke (N=21; mean age ± SD, 61.7 ± 7.9y; 57% men), undergoing inpatient rehabilitation. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The SULCS was administered by occupational therapists (OTs) within 6 weeks after stroke (t1), 3 months after t1 by the same OT (t2), and within 1 week after t2 by another OT (t3). Interrater reliability, the repeatability between different raters, was assessed by calculating the intraclass correlation coefficient (ICC) based on the scores at t2 and t3. Construct validity, indicating agreement with hypotheses concerning the construct that is being measured, was assessed with Spearman rank correlation coefficient (ρ). The SULCS scores were cross-sectionally correlated with those of the Action Research Arm Test (ARAT) and the Rivermead Motor Assessment (RMA) at t1, and longitudinally with the respective change scores between t1 and t2. RESULTS: The SULCS (range, 0-10) had a high ICC (.94; 95% confidence interval, .86-.97) and strong cross-sectional correlation with both the ARAT and the RMA (ρ=.91 and ρ=.85, respectively), while the respective change scores showed a strong correlation with the ARAT (ρ=.71) and a moderate correlation with the RMA (ρ=.48). CONCLUSIONS: The SULCS has good interrater reliability and construct validity.

A neurocognitive perspective on developmental disregard in children with hemiplegic cerebral palsy.

A common problem in children with hemiplegic cerebral palsy (CP) is the asymmetrical development of arm and hand capacity caused by the lack of use of the affected upper limb, or developmental disregard. In this paper, we provide a neuropsychological model that relates developmental disregard to attentional processes and motor learning. From this model, we hypothesize that high attentional demands associated with the use of the affected upper limb might hinder its use in daily life, and therefore may be a factor in developmental disregard. This can be assessed with a dual-task paradigm. However, until now, this has not been applied to children with CP. We provide recommendations for using a dual-task paradigm in children with CP based on empirical studies in typically developing children and children with developmental coordination disorder. Ultimately, these dual-task studies may be used to improve interventions aimed at reducing developmental disregard.

Circle drawing as evaluative movement task in stroke rehabilitation: an explorative study.

BACKGROUND: The majority of stroke survivors have to cope with deficits in arm function, which is often measured with subjective clinical scales. The objective of this study is to examine whether circle drawing metrics are suitable objective outcome measures for measuring upper extremity function of stroke survivors. METHODS: Stroke survivors (n = 16) and healthy subjects (n = 20) drew circles, as big and as round as possible, above a table top. Joint angles and positions were measured. Circle area and roundness were calculated, and synergistic movement patterns were identified based on simultaneous changes of the elevation angle and elbow angle. RESULTS: Stroke survivors had statistically significant lower values for circle area, roundness and joint excursions, compared to healthy subjects. Stroke survivors moved significantly more within synergistic movement patterns, compared to healthy subjects. Strong correlations between the proximal upper extremity part of the Fugl-Meyer scale and circle area, roundness, joint excursions and the use of synergistic movement patterns were found. CONCLUSIONS: The present study showed statistically significant differences in circle area, roundness and the use of synergistic movement patterns between healthy subjects and stroke survivors. These circle metrics are strongly correlated to stroke severity, as indicated by the proximal upper extremity part of the FM score.In clinical practice, circle area and roundness can give useful objective information regarding arm function of stroke survivors. In a research setting, outcome measures addressing the occurrence of synergistic movement patterns can help to increase understanding of mechanisms involved in restoration of post stroke upper extremity function.

Measuring upper limb capacity in poststroke patients: development, fit of the monotone homogeneity model, unidimensionality, fit of the double monotonicity model, differential item functioning, internal consistency, and feasibility of the stroke upper limb capacity scale, SULCS.

OBJECTIVES: To develop an easy-to-use scale that measures upper limb capacity, according to the International Classification of Functioning, Disability and Health definition, in patients after stroke, and to investigate certain psychometric properties of this scale. DESIGN: Cohort study. SETTING: Inpatient department of a rehabilitation center. PARTICIPANTS: Patients (N=546; mean age ± SD, 60.1±11.2y; 56% men) undergoing rehabilitation after stroke. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Mokken scale analysis was used to investigate the following psychometric properties: (1) fit of the monotone homogeneity model, indicating that the items form a scale; (2) unidimensionality, indicating that the items measure only 1 concept (or construct); (3) fit of the double monotonicity model, indicating invariant (hierarchical) item ordering; (4) differential item functioning (DIF), indicating the validity of comparison between subgroups; and (5) internal consistency, indicating the degree of interrelatedness of the items. The mean time needed to complete the scale was calculated to indicate (6) feasibility. RESULTS: The Stroke Upper Limb Capacity Scale (SULCS) was developed on the basis of interviews with experts. Ten of 15 items had (1) good fit of the monotone homogeneity model (coefficient H=.88), were (2) unidimensional, and had (3) good fit of the double monotonicity model (coefficient H(T)=.71), (4) absence of DIF (Crit-values <40), and (5) good internal consistency (coefficient ρ=.96). When applying start-and-stop rules, the (6) feasibility of the SULCS was good (6min). CONCLUSIONS: The SULCS is an easy-to-use, unidimensional, hierarchical, and internally consistent scale that assesses upper limb capacity in patients after stroke.

Providing training enhances the biomechanical improvements of an alternative computer mouse design.

OBJECTIVE: The purpose of this study is to determine if an alternative mouse promotes more neutral postures and decreases forearm muscle activity and if training enhances these biomechanical benefits. BACKGROUND: Computer mouse use is a risk factor for developing musculoskeletal disorders; alternative mouse designs can help lower these risks. Ergonomic training combined with alternative input devices could be even more effective than alternative designs alone. METHODS: Thirty healthy adults (15 males, 15 females) performed a set of computer mouse tasks with a standard mouse and an alternative mouse while an electromagnetic motion analysis system measured their wrist and forearm postures and surface electromyography measured the muscle activity of three wrist extensor muscles. Fifteen participants received no training on how to hold the alternative mouse, whereas the remaining 15 participants received verbal instructions before and during use of the alternative mouse. RESULTS: The alternative mouse was found to promote a more neutral forearm posture compared with the standard mouse (up to 11.5 degrees lower forearm pronation); however, pronation was further reduced when instructions on how to hold the mouse were provided. Wrist extensor muscle activity was reduced for the alternative mouse (up to 1.8% of maximum voluntary contraction lower) compared with the standard mouse, but only after participants received instructions. CONCLUSION: The alternative mouse design decreased biomechanical exposures; however, instructions enhanced this potential ergonomic benefit of the design. APPLICATION: User knowledge and training are important factors when effectively implementing an alternative ergonomic device.

Smaller external notebook mice have different effects on posture and muscle activity.

BACKGROUND: Extensive computer mouse use is an identified risk factor for computer work-related musculoskeletal disorders; however, notebook computer mouse designs of varying sizes have not been formally evaluated but may affect biomechanical risk factors. METHODS: Thirty adults performed a set of mouse tasks with five notebook mice, ranging in length from 75 to 105 mm and in width from 35 to 65 mm, and a reference desktop mouse. An electro-magnetic motion analysis system measured index finger (metacarpophalangeal joint), wrist and forearm postures, and surface electromyography measured muscle activity of three extensor muscles in the forearm and the first dorsal interosseus. FINDINGS: The smallest notebook mice were found to promote less neutral postures (up to 3.2 degrees higher metacarpophalangeal joint adduction; 6.5 degrees higher metacarpophalangeal joint flexion, 2.3 degrees higher wrist extension) and higher muscle activity (up to 4.1% of maximum voluntary contraction higher wrist extensor muscle activity). Participants with smaller hands had overall more non-neutral postures than participants with larger hands (up to 5.6 degrees higher wrist extension and 5.9 degrees higher pronation); while participants with larger hands were more influenced by the smallest notebook mice (up to 3.6 degrees higher wrist extension and 5.5% of maximum voluntary contraction higher wrist extensor values). Self-reported ratings showed that while participants preferred smaller mice for portability; larger mice scored higher on comfort and usability. INTERPRETATION: The smallest notebook mice increased the intensity of biomechanical exposures. Longer term mouse use could enhance these differences, having a potential impact on the prevention of work-related musculoskeletal disorders.