[Abstract] Mobility Function and Recovery After Stroke: Preliminary Insights From Sympathetic Nervous System Activity

Background and Purpose: Poststroke hemiparesis increases the perceived challenge of walking. Perceived challenge is commonly measured by self-report, which is susceptible to measurement bias. A promising approach to objectively assess perceived challenge is measuring sympathetic nervous system (SNS) activity with skin conductance to detect the physiological stress response. We investigated the feasibility of using skin conductance measurements to detect task-related differences in the challenge posed by complex walking tasks in adults poststroke.

Methods: Adults poststroke (n = 31) and healthy young adults (n = 8) performed walkingtasks including typical walking, walking in dim lighting, walking over obstacles, and dual-task walking. Measures of skin conductance and spatiotemporal gait parameters were recorded. Continuous decomposition analysis was conducted to assess changes in skin conductance level (ΔSCL) and skin conductance response (ΔSCR). A subset of participants poststroke also underwent a 12-week rehabilitation intervention.

Results: SNS activity measured by skin conductance (both ΔSCL and ΔSCR) was significantly greater for the obstacles task and dual-task walking than for typical walkingin the stroke group. Participants also exhibited “cautious” gait behaviors of slower speed, shorter step length, and wider step width during the challenging tasks. Following the rehabilitation intervention, SNS activity decreased significantly for the obstacles task and dual-task walking.

Discussion and Conclusions: SNS activity measured by skin conductance is a feasible approach for quantifying task-related differences in the perceived challenge of walkingtasks in people poststroke. Furthermore, reduced SNS activity during walking following a rehabilitation intervention suggests a beneficial reduction in the physiological stress response evoked by complex walking tasks.

Video Abstract available for more insights from the authors (See Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A234).

via Mobility Function and Recovery After Stroke: Preliminary In… : Journal of Neurologic Physical Therapy

[Abstract] Body Schema Plasticity after Stroke: Subjective and Neurophysiological Correlates of the Rubber Hand Illusion

Highlights

•Stroke could increase body-ownership and agency over an external limb.•Stroke could limit changes in galvanic skin response and skin temperature.•Illusion of ownership could decrease electromyographic activity in stroke subjects.•It is hypothesized that the premotor cortex could cause these effects.•Results could evidence a body schema plasticity promoted by stroke.

Abstract

Stroke can lead to motor impairments that can affect the body structure and restraint mobility. We hypothesize that brain lesions and their motor sequelae can distort the body schema, a sensorimotor map of body parts and elements in the peripersonal space through which human beings embody the reachable space and ready the body for forthcoming movements. Two main constructs have been identified in the embodiment mechanism: body-ownership, the sense that the body that one inhabits is his/her own, and agency, the sense that one can move and control his/her body. To test this, the present study simultaneously investigated different embodiment subcomponents (body-ownership, localization, and agency) and different neurophysiological measures (galvanic skin response, skin temperature, and surface electromyographic activity), and the interaction between them, in clinically-controlled hemiparetic individuals with stroke and in healthy subjects after the rubber hand illusion. Individuals with stroke reported significantly stronger body-ownership and agency and reduced increase of galvanic skin response, skin temperature, and muscular activity in the stimulated hand. We suggest that differences in embodiment could have been motivated by increased plasticity of the body schema and pathological predominance of the visual input over proprioception. We also suggest that differences in neurophysiological responses could have been promoted by a suppression of the reflex activity of the sympathetic nervous system and by the involvement of the premotor cortex in the reconfiguration of the body schema. These results could evidence a body schema plasticity promoted by the brain lesion and a main role of the premotor cortex in this mechanism.

Graphical abstract

Source: Body Schema Plasticity after Stroke: Subjective and Neurophysiological Correlates of the Rubber Hand Illusion