Plantarflexor PAS - Stroke

VA Office of Research and Development

Status

Completed

Conditions

Stroke

Hemiparesis

Gait Dysfunction

Treatments

Other: PAS - Walking

Other: PAS at Rest

Other: PAS - Active

Study type

Interventional

Funder types

Other U.S. Federal agency

Identifiers

NCT04515407

B3609-P

1I21RX003609-01 (U.S. NIH Grant/Contract)

Details and patient eligibility

About

The current project investigates a method called paired associative stimulation (PAS) which is known to influence nervous system function through a process called neuroplasticity. Here the investigators will target function of the ankle plantarflexor muscles because they are critically important to walking. The investigators will study adults who have walking dysfunction resulting from stroke. The study will test three ways of delivering PAS targeted towards brain-muscle connections serving the ankle plantarflexors. The overall goal is to improve functioning of the plantarflexors. The investigators believe that improving plantarflexor function will increase the likelihood of positive effects from gait retraining programs for people post-stroke. Participants will experience all three PAS methods in separate sessions. The investigators will compare differences in the size of these effects to identify the optimal method for delivery of PAS to the ankle plantarflexors. This study is a preliminary step to help us design a better clinical trial of combined PAS and gait retraining.

Full description

The current project builds on preliminary work in which the investigators have observed a relationship between efficacy of the corticospinal tract serving the plantarflexors and walking function, specifically ankle plantarflexor power, in individuals with chronic post-stroke hemiparesis. The investigators have observed robust associations between: i) PF corticospinal efficacy, and ii) modulation of corticospinal drive, and PF power, particularly in individuals poststroke. Importantly, clinical and demographic factors including: age, stroke chronicity, and lesion location, neither explain, nor modify, these associations. In combination, these findings lead to the investigators' central premise, that improved efficacy of the corticospinal tract serving the plantarflexors will enable augmentation of ankle PF power and contribute to improved walking function in individuals post-stroke. Here the team will investigate use of paired associative stimulation (PAS) to enhance corticospinal efficacy and to the plantarflexors through targeted neuroplasticity. Specifically the team will investigate three approaches to PAS to determine its efficacy for enhancing: i) neural responses, ii) biomechanical effects (A2), and iii) retention of neural and biomechanical effects.

Objectives. This SPiRE project focuses on methodological variables required to optimize efficacy of PAS on:

a) corticospinal efficacy to the plantarflexors, and b) walking function (quantified as A2) in Veterans and adults with poststroke walking dysfunction. By achieving the aims, data generated from this SPiRE will contribute to development of more focused and relevant hypotheses to be tested in future studies supported through competitive Merit Review. However, before motivating a larger study, the investigators first seek to determine the salience and magnitude of effects of PAS. In addition to exploring methodological issues related to PAS, data generated from the proposed SPiRE will enable us to determine the appropriate scope of a future project including sample size and dosing. The investigators seek to develop the methodology, determine feasibility, and generate preliminary/exploratory data for sake of determining effect sizes and computing statistical power for future large scale studies in human subjects. The investigators will compare effects of PAS targeting ankle plantarflexion when delivered: at rest, during submaximal activity, and during walking.

Enrollment

10 patients

Sex

All

Ages

18+ years old

Volunteers

No Healthy Volunteers

Inclusion criteria

hemiparesis resulting from stroke
single, unilateral, hemispheric stroke (cortical or sub-cortical areas)
stroke confirmed by neuroimaging (CT or MRI)
stroke 3 months prior to enrollment
ability to walk, independently at least 25' on level ground, even if requiring brace or assistive device (cane)
Veteran Status prioritized

Exclusion criteria

lower extremity pain affecting ability to bear weight on legs
contractures limiting normal range of motion in major lower extremity joints
other neurological conditions (e.g., Parkinson's Disease, Multiple Sclerosis, ALS), prior traumatic brain injury, severe osteoarthritis or prior pathological fracture
cardiovascular conditions contraindicative to walking or light exercise
severe hypertension (i.e., >200/110 at rest that cannot be controlled in resting range of 180/110 mmHg)
perceptual or cognitive deficits affecting ability to: comprehend, follow three step directions, or provide consent

Trial design

Primary purpose

Other

Allocation

N/A

Interventional model

Single Group Assignment

Masking

Double Blind

10 participants in 3 patient groups

Order 1

Other group

Description:

All participants will receive PAS in three experimental conditions, randomized to the order of condition. Experimental order will be counterbalanced across participants. Order 1 will be: Seated@Rest, Seated@Active, Walking.

Treatment:

Other: PAS - Active

Other: PAS at Rest

Other: PAS - Walking

Order 2

Other group

Description:

Treatment:

Other: PAS - Active

Other: PAS at Rest

Other: PAS - Walking

Order 3