The effect of task symmetry on bimanual reach-to-grasp movements after cervical spinal cord injury

Laura Britten,S L Astill,F Jamil,W Raza,R O Coats,R M Ichiyama

doi:10.1007/s00221-018-5354-8

Laura Britten, S L Astill + Show 4 more

Open Access

https://doi.org/10.1007/s00221-018-5354-8

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Abstract

Injury to the cervical spinal cord results in deficits in bimanual control, reducing functional independence and quality of life. Despite this, little research has investigated the control strategies which underpin bimanual arm/hand movements following cervical spinal cord injury (cSCI). Using kinematics and surface electromyography this study explored how task symmetry affects bimanual control, in patients with an acute cSCI (< 6 m post injury), as they performed naturalistic bimanual reach-to-grasp actions (to objects at 50% and 70% of their maximal reach distance), and how this differs compared to uninjured age-matched controls. Twelve adults with a cSCI (mean age 69.25 years), with lesions at C3–C8, categorized by the American Spinal Injury Impairment Scale (AIS) at C or D and 12 uninjured age-matched controls (AMC) (mean age 69.29 years) were recruited. Participants with a cSCI produced reach-to-grasp actions which took longer, were slower, less smooth and had longer deceleration phases than AMC (p < 0.05). Participants with a cSCI were less synchronous than AMC at peak velocity and just prior to object pick up (p < 0.05), but both groups ended the movement in a synchronous fashion. Peak muscle activity occurred just prior to object pick up for both groups. While there seems to be a greater reliance on the deceleration phase of the movement, we observed minimal disruption of the more impaired limb on the less impaired limb and no additional effects of task symmetry on bimanual control. Further research is needed to determine how to take advantage of this retained bimanual control in therapy.

Highlights

Many activities of daily living require the use of both hands simultaneously, and given that injury to the cervical spinal cord often results in bilateral deficit (Spooren et al 2009), bimanual movements are often impaired
This study explored the effect of task symmetry on bimanual reach-to-grasp movements in individuals with cervical spinal cord injury (cSCI) and how this differs to age-matched controls (AMC)
Interlimb synchrony at movement onset and end of the movement did not differ between groups, but the participants with a cSCI were less synchronous than the AMC during the reach, no more affected by task symmetry (Fig. 4a–d)

Summary

Introduction

Many activities of daily living require the use of both hands simultaneously, and given that injury to the cervical spinal cord (cSCI) often results in bilateral deficit (Spooren et al 2009), bimanual movements are often impaired. Spared fibres of the CST, may be a mechanism for recovery as neuroplasticity in the CST have previously been shown to induce improvements in function (Rosenzweig et al 2009, 2010; Krajacic et al 2010). Spinal interneurons (Takei and Seki 2010) and propriospinal neurons (Sasaki et al 2004) have been shown to innervate upper limb muscles in bimanual movement and those spared fibres unaffected by the primary cSCI may act as a mechanism for recovery (Lemon 2008). Bimanual therapy after cSCI has been shown to improve bimanual upper limb function and these improvements have been in individuals with a chronic cSCI (Hoffman and Field-Fote 2010, 2013), suggesting that further

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