Obstacle Avoidance and Dual-Tasking During Reaching While Standing in Patients With Mild Chronic Stroke

I have zero reaching ability mainly because I have no grasping ability, can't open my hand due to spasticity.  Can't straighten my arm either due to spasticity.

Obstacle Avoidance and Dual-Tasking During Reaching While Standing in Patients With Mild Chronic Stroke

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Aditi A. Mullick, MSc, Melanie C. Baniña, PhD, Yosuke Tomita, PhD, ...

First Published August 30, 2021 Research Article 

https://doi.org/10.1177/15459683211023190

Article information

Abstract

Background. 

Poststroke individuals use their paretic arms less often than expected in daily life situations, even when motor recovery is scored highly in clinical tests. Real-world environments are often unpredictable and require the ability to multitask and make decisions about rapid and accurate arm movement adjustments.  

Objective. 

To identify whether and to what extent cognitive–motor deficits in well-recovered individuals with stroke affect the ability to rapidly adapt reaching movements in changing cognitive and environmental conditions.  

Methods. 

Thirteen individuals with mild stroke and 11 healthy controls performed an obstacle avoidance task in a virtual environment while standing. Subjects reached for a virtual juice bottle with their hemiparetic arm as quickly as possible under single- and dual-task conditions. In the single-task condition, a sliding glass door partially obstructed the reaching path of the paretic arm. A successful trial was counted when the subject touched the bottle without the hand colliding with the door. In the dual-task condition, subjects repeated the same task while performing an auditory–verbal working memory task. 

Results. 

Individuals with stroke had significantly lower success rates than controls in avoiding the moving door in single-task (stroke: 51.8 ± 21.2%, control: 70.6 ± 12.7%; P = .018) and dual-task conditions (stroke: 40.0 ± 27.6%, control: 65.3 ± 20.0%; P = .015). Endpoint speed was lower in stroke subjects for successful trials in both conditions. Obstacle avoidance deficits were exacerbated by increased cognitive demands in both groups. Individuals reporting greater confidence using their hemiparetic arm had higher success rates.  

Conclusion. 

Clinically well-recovered individuals with stroke may have persistent deficits performing a complex reaching task.

Keywords

stroke, upper limb, kinematics, obstacle avoidance, dual-tasking, cognition

Introduction

Upper limb (UL) motor deficits following stroke affect a large proportion of acute stroke survivors with only a limited number regaining effective functional arm use.¹ There is a strong relationship between UL function and the ability to perform activities of daily living (ADL), with the caveat that even if motor recovery is scored highly on clinical tests, use of the paretic arm in daily life situations is diminished.^2-4 The discrepancy between clinical measures of motor and real-world functional arm use after stroke may arise from deficits in the ability to adapt movement in unpredictable real-world environments. Sudden changes in the environment often require rapid and accurate motor adaptations to interact effectively with objects. In a previous study, well-recovered individuals with stroke were less successful than healthy age-matched controls in making online corrective endpoint trajectories to avoid an obstacle in the reaching path when seated.⁵ This was due to delayed initiation of corrective movements in response to sudden obstacle appearance. Several stroke-related and sensorimotor impairments, including spasticity, sensory deficits, abnormal muscle recruitment patterns, decreased range of motion, and difficulty dealing with interjoint interaction torques affect UL movement production and adaptation.^6-10 A decrease in overall motor abundance (i.e., ability to combine joint movements in different ways to achieve the same motor goal—termed motor equivalence)¹¹ is reflected in the altered adaptability of UL movement.^5,12 Adaptability also depends on mental flexibility or the ability to change the movement plan according to task demands.^13,14 Cognitive processes such as attention, information processing speed, and executive function (planning, task flexibility, reasoning, decision-making, and problem-solving), crucial for online movement correction, are often impaired after stroke.^15-18

In addition to the ability to react to unexpected situations, real-world environments often require doing more than one task at a time (i.e., dual-tasking).¹⁹ Competing attentional demands when dual-tasking may lead to performance decrements, especially when the attentional demand is high or attentional capacity is reduced. As poststroke individuals often have impaired cognition (including reduced attention),¹⁹ dual-tasking may be diminished, such as that reported for gait and balance activities^19-21 and pointing during standing.¹² For example, locomotor parameters were affected when a cognitive task (CT) was performed while walking.²² Performing a CT in standing was associated with a decrease in anteroposterior and mediolateral sway and increased weight-bearing asymmetry.²² To date, research in healthy subjects and neurological patients has focused on the effects of adding a CT during motor tasks such as walking or maintaining balance. Despite its potential importance for ADLs, there is relatively less information about dual-task effects on UL motor activities, which are presumably more cognitively driven and less automatic than gross motor activities such as walking.^23,24 For example, Bank et al.²⁵ investigated the influence of on an auditory Stroop task on goal-directed UL movements. Healthy and stroke subjects controlled a virtual mouse to collect virtual pieces of cheese as fast as possible while avoiding a virtual cat (obstacle). Stroke subjects had greater difficulty avoiding the obstacle, were less successful, and moved slower than controls, suggesting differences between groups in capacity-sharing patterns. However, the study was limited by the heterogeneity of the stroke group, variability in dual-task performance and lack of kinematic outcomes.

While arm use may be limited by motor deficits in patients with greater stroke severity, well-recovered patients may have difficulties that remain undetected by conventional clinical tests. To optimally challenge cognitive–motor functions in well-recovered poststroke individuals, we used a reaching task requiring critical timing to avoid hitting a moving obstacle. To more accurately reflect everyday environments, we added a simple working memory task. Being able to detect complex arm motor function deficits and cognitive–motor interactions will allow clinicians and researchers to design rehabilitation programs that have the potential for greater carryover to everyday activities.

We sought to identify whether and to what extent motor and cognitive demands in well-recovered people with stroke affect the ability to avoid obstacles when reaching with the more-affected arm during standing. Since well-recovered patients with stroke may have subtle motor and cognitive deficits and motor problem-solving is involved in error correction, we hypothesized that (1) individuals with stroke would have greater difficulty in avoiding a moving obstacle during reaching while standing compared to healthy age-matched controls; (2) error correction ability would be more diminished in people with stroke than healthy individuals when cognitive demands are increased (i.e., dual-tasking); and (3) decreased success in avoiding obstacles would be related to lower clinical scores, patient-reported arm use, and self-efficacy. Preliminary results appeared in the abstract form.²⁶