Construct Validity of the Upper-Limb Interlimb Coordination Test in Stroke

 If you can rotate your forearm you are high functioning in arm use already, not me. And you actually think this is an objective measurement?

Construct Validity of the Upper-Limb Interlimb Coordination Test in Stroke

Roni Molad, OT, MSc, Mindy F. Levin, PT, PhD

First Published October 29, 2021 Research Article Find in PubMed 

https://doi.org/10.1177/15459683211058092

Article information

Abstract

Background

Coordination impairments are under-evaluated in patients with stroke due to the lack of validated assessments resulting in an unclear relationship between coordination deficits and functional limitations.

Objective

Determine the construct validity of the new clinical upper-limb (UL) Interlimb Coordination test (ILC2) in individuals with chronic stroke.

Methods

Thirteen individuals with stroke, ≥40 years, with ≥30° isolated supination of the more-affected (MAff) arm, who could understand instructions and 13 healthy controls of similar age participated in a cross-sectional study. Participants performed synchronous bilateral anti-phase forearm rotations for 10 seconds in 4 conditions: self-paced internally-paced (IP1), fast internally-paced (IP2), slow externally-paced (EP1), and fast externally-paced (EP2). Primary (continuous relative phase-CRP, cross-correlation, lag) and secondary outcome measures (UL and trunk kinematics) were compared between groups.

Results

Participants with stroke made slower UL movements than controls in all conditions, except EP1. Cross-correlation coefficients were lower (i.e., closer to 0) in stroke in IP1, but CRP and lag were similar between groups. In IP1 and matched-speed conditions (IP1 for healthy and IP2 for stroke), stroke participants used compensatory trunk and shoulder movements. The synchronicity sub-scale and total scores of ILC2 were related to temporal coordination in IP2. Interlimb Coordination test total score was related to greater shoulder rotation of the MAff arm. Interlimb Coordination test scores were not related to clinical scores.

Conclusion

Interlimb Coordination test is a valid clinical measure that may be used to objectively assess UL interlimb coordination in individuals with chronic stroke. Further reliability testing is needed to determine the clinical utility of the scale.

Keywords

motor coordination, stroke, kinematics, assessment, bimanual

Introduction

Motor impairments are common following stroke and may result in limitations in the performance of daily activities, participation and quality of life.^1,2 Performance limitations may be related to impairments in interlimb coordination, an important aspect of skilled arm use^3-5 affected by stroke. However, this concept is neither well-defined nor well-measured clinically. This may be due to the focus of rehabilitation on improving unilateral performance, based on the assumption that reduced bimanual arm use results from deficits in the more-impaired upper-limb (UL).⁶ However, principles of interlimb coordination cannot be inferred from those of single-limb movements.^7-9 Complex interactions between task requirements, environmental constraints, lesion location, level of sensorimotor impairment, and interhemispheric connectivity may all affect bimanual task accomplishment following stroke.^10,11 The lack of consensus regarding the clinical definition of interlimb coordination makes it difficult to characterize. This has led to a poor understanding of the relationship between interlimb coordination deficits and limitations in functional recovery in stroke survivors.

Various perspectives on how the motor system controls and selects specific movement patterns despite its redundancy have been described, proposing different definitions of interlimb coordination.^12-15 In particular, the dynamical systems theory suggests that coordination arises from the entrainment of dynamically coupled oscillators, reducing the number of possible solutions to a motor task. The concept of dynamical coupling has been implemented in a recent operational definition of coordination for reaching and pointing as “a goal-oriented and context-dependent process of organizing movements in both space and time.”¹⁶ Although originally formulated for intralimb coordination, this definition is also applicable to bimanual and bilateral movements.

Clinical UL interlimb coordination assessments at the International Classification of Functioning (ICF) Body Function and Structure level¹⁷ include rhythmic and discrete hand movements made at different frequencies, spatio-temporal relationships (e.g., timing, direction, and phase relationships) or with different loads,^18-21 but their measurement properties have not been evaluated. At the ICF Activity level, assessments evaluating bimanual tasks, such as the Arm Motor Ability Test,²² rate task completion without objective description of how the task was performed and whether motor compensations were used.²³ To provide a comprehensive description of coordinated movements that can distinguish motor recovery from compensation, movement should be described at 2 levels: performance and movement quality.²⁴ The performance level describes the endpoint (i.e.,, hand) behavior using temporal and spatial variables. Movement quality refers to the joint rotations and displacements as well as motor compensations contributing to endpoint movement.²⁴

The Comprehensive Coordination Scale (CCS) is a newly-developed objective outcome measure of the coordination of multiple body segments at both levels of movement description in people with neurological injuries.²⁵ The CCS relies on observational kinematics for movement assessment and has 3 subscales with excellent intra-rater (ICC = .95-.98) and interrater (ICC = .95-.99) reliability.²⁶ One of the 6 CCS tests is the Interlimb Coordination Test (ILC2), assessing bilateral UL coordination, in which seated individuals perform alternating anti-phase forearm rotations (i.e., pronation-supination) on their knees for 10s. In the CCS, the ILC2 test of rhythmic bimanual anti-phase movement was chosen since, rather than being driven by a common neural generator as used for in-phase movement, anti-phase movement is driven by more independent pathways and involves stronger interhemispheric coupling between motor regions.^27,28 Anti-phase movement is less stable than in-phase movement, has higher variability and may involve more compensatory movement.^7,18,29 Performance and movement quality (i.e.,, presence of compensations) are scored on 0–3 pt subscales for a maximum of 6-pts. Although clinicians can assess UL movement characteristics by observation with moderate to high accuracy,³⁰ validity testing is needed.

Thus, this study aimed to determine the construct validity of the ILC2 by assessing interlimb coordination at 2 levels of movement description in healthy individuals and in individuals with stroke using highly accurate motion analysis. According to the COSMIN (COnsensus-based Standards for the selection of health status Measurement INstruments) panel definition, construct validity is the degree to which test scores are consistent with the hypotheses regarding internal relationships of scored items, relationships with other test scores, or differences between relevant groups.³¹ Based on this definition, we compared subjective scores of the total ILC2 and its sub-scales between healthy and stroke groups and within groups to objective kinematic measurements of coordination (i.e., cross correlation coefficient, lag and continuous relative phase; CRP) as well as to scores of clinical assessments at the ICF impairment and activity levels. We hypothesized that coordination and kinematic measures of anti-phase forearm rotations would differ between healthy and stroke participants. Since movement characteristics vary with frequency, we also evaluated movements at 2 different frequencies and matched frequencies between the stroke and healthy groups and hypothesized that higher movement frequencies would lead to a greater disruption in coordination and kinematic measures in the stroke group (Hypothesis 2). Our third hypothesis was that participants with stroke who had greater sensorimotor impairments would have greater disruption in coordination measures.

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