Date Presented 04/06/19
OTs commonly treat persons with varying degrees of hemiplegia. This study explored two strategies (limb dominance and cognitive loading) that would either facilitate or inhibit upper-extremity motor control. In a healthy population, limb dominance had much more of an inhibiting effect upon bimanual motor control than cognitive loading. This may be an important consideration when teaching persons with hemiplegia during upper-extremity bimanual functional activities.
Primary Author and Speaker: Martin Rice
Additional Authors and Speakers: Joseph Sharaya
Contributing Authors: Hannah Esperanza, Robert Breneman
PURPOSE AND RATIONALE: Occupational therapists commonly treat persons with varying degrees of hemiplegia. Whatever the cause, it is often challenging for the individual to control both limbs during functional bimanual motions; hence the rationale for this study. It has been shown that bimanual coordination in persons with hemiplegia is often limited by being ‘too coupled’(Gosser and Rice, 2015; Rice and Newell, 2004). That is, it is relatively difficult for the hemiplegic limb to move in a way that is independent from the motions of the unaffected limb. This is termed interlimb coupling. The purpose of this study is to observe patterns of upper extremity bimanual motor control while performing a reaching activity with and without a cognitive load.
DESIGN: This study used a repeated measures counterbalanced design.
PARTICIPANTS: Fifty-two healthy adult participants aged 18 and older were recruited from the community by flyers to participate in this study, seven of whom were left handed.
METHOD: Data were collected at 120 hertz using a 12-camera Max Pro Motion Capture System (Innovision Systems Inc, Columbiaville, MI).
PROCEDURE: Prior to any data collection, informed consent was obtained. Participants were randomly assigned to one of the four order-of-presentation groups with the factor of cognitive load nested with the factor of limb. Reflective markers were placed over the third metacarpal of both hands. Participants were asked to sit in a chair at a table with both hands placed on the table directly in front of the upper body. The participant was asked to move his or her upper extremities simultaneously so that one hand tapped two separate Jelly Bean switches while the other hand tapped one switch. The switches were placed 18 cm apart and the furthest switch was placed 35 cm away on the table. During the High Cognitive conditions, the participant was asked to read prose projected on a screen located in front of the table. During the Low Cognitive condition, the participant was not asked to read anything and no prose was projected on the screen. Each trial lasted 20 seconds and participants were offered a practice trial for each of the four different conditions.
ANALYSIS AND RESULTS: A Shapiro-Wilk test determined that the data were not normal. Therefore, the subsequent analyses used non-parametric statistics. A Friedman test for repeated measures revealed a significant difference among the four conditions (X2=33.83, p = <.001).
A follow-up multi-comparison analysis using Wilcoxon revealed no significant difference among the comparisons within level of cognition. There was, however, a significant difference between all of the Dominance versus Non-Dominance comparisons (p-value < .008).
CONCLUSION: Interlimb coupling increased when the non-dominant hand performed the more complex task in a bimanual movement. Complex bilateral movements in everyday occupations require decoupled movements of the upper extremity to complete tasks. These complex tasks are particularly difficult for those with hemplipegia. As such, occupational therapists may want to consider limb dominance when performing bimanual tasks. However, this needs to be the subject of future research. Additionally, factors that assist in decoupling limbs should be continued to be researched in order to improve occupational therapy efficiency and treatment goals.
IMPACT: This study’s findings will be potentially helpful in guiding occupational therapy clinical reasoning when teaching persons with hemiplegia during upper extremity bimanual functional activities.
RELATES TO RESEARCH PRIORITIES: This basic research will help inform clinical reasoning for bimanual motor control for persons with hemiplegia.
References
Gosser, S. M., & Rice, M. S. (2015) Efficiency of unimanual and bimanual reach in persons with and without stroke, Topics in Stroke Rehabilitation, 22:1, 56-62, DOI: 10.1179/1074935714Z.0000000002
Rice, M. S., & Newell, K. M. (2001). Interlimb Coupling and Left Hemiplegia Because of Right Cerebral Vascular Accident. The Occupational Therapy Journal of Research, 21(1), 12-28. doi:10.1177/153944920102100102
Rice, M. S., & Newell, K. M. (2004). Upper-extremity interlimb coupling in persons with left hemiplegia due to stroke. Archives of Physical Medicine and Rehabilitation, 85(4), 629-634. doi:http://dx.doi.org/10.1016/j.apmr.2003.08.084
