Bilateral impairments in task-dependent modulation of the long-latency stretch reflex following stroke

• Type of Material: Article
• Authors: Randy D. Trumbower, Emory University; James M. Finley, Johns Hopkins University; Jonathan B. Shemmell, University of Otago; Claire F. Honeycutt, Northwestern University; Eric J. Perreault, Northwestern University
• Language: English
• Date: 2013-07
• Publisher: Elsevier: 12 months
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.
• License: Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1016/j.clinph.2013.01.013
• Title of Journal or Parent Work: Clinical Neurophysiology
• ISSN: 1388-2457
• Volume: 124
• Issue: 7
• Start Page: 1373
• End Page: 1380
• Grant/Funding Information: This work was supported by NIH Grants R01-NS053813 and T32 HD07418.
• Keywords: brain; stroke; stretch reflex; modulation; long-latency; arm
• Research Categories: Health Sciences, Rehabilitation and Therapy

Abstract

Objective Modulation of the long-latency reflex (LLR) is important for sensorimotor control during interaction with different mechanical loads. Transcortical pathways usually contribute to LLR modulation, but the integrity of pathways projecting to the paretic and non-paretic arms of stroke survivors is compromised. We hypothesize that disruption of transcortical reflex pathways reduces the capacity for stroke survivors to appropriately regulate the LLR bilaterally. Methods Elbow perturbations were applied to the paretic and non-paretic arms of persons with stroke, and the dominant arm of age-matched controls as subjects interacted with Stiff or Compliant environments rendered by a linear actuator. Reflexes were quantified using surface electromyograms, recorded from biceps. Results LLR amplitude was significantly larger during interaction with the Compliant load compared to the Stiff load in controls. However, there was no significant change in LLR amplitude for the paretic or non-paretic arm of stroke survivors. Conclusions Modulation of the LLR is altered in the paretic and non-paretic arms after stroke. Significance Our results are indicative of bilateral sensorimotor impairments following stroke. The inability to regulate the LLR may contribute to bilateral deficits in tasks that require precise control of limb mechanics and stability.