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

Abstract

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 walking tasks 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 walking in 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 walking tasks 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).

Trial registration: ClinicalTrials.gov NCT02132650.

Conflict of interest statement

Conflicts of interest: none

Figures

Figure 1.

Equipment and set up for recording skin conductance.

Figure 2.. Change in skin conductance level (ΔSCL) and skin conductance response (ΔSCR) for the stroke and young groups.

Panels A, B, C and D show the change in skin conductance (i.e., ΔSCL and ΔSCR) from the resting to the walking period of each task. The stroke group is shown in black and the young group is shown in light grey. The error bars denote the standard error.

Figure 3.. Change in skin conductance level (ΔSCL) and skin conductance response (ΔSCR) for the stroke group pre-intervention and post-intervention.

Panels A and B show the change in skin conductance (i.e., ΔSCL and ΔSCR, respectively) from the resting to the walking period of each task pre-intervention and post-intervention. Skin conductance at pre-intervention is shown in light grey and post-intervention is shown in black. The error bars denote the standard error.

Figure 4.. Example raw skin conductance data during the walking tasks.

Panels A and B show example skin conductance level (SCL) and skin conductance response (SCR) recorded during the walking tasks. Each black dot on the raw data plot indicates a point in time at which a SCR was detected by the analysis algorithm.