Use of a Foot-Induced Digitally Controlled Resistance Device for Functional Magnetic Resonance Imaging Evaluation in Patients with Foot Paresis

Summary

Chronic stroke patients' insured rehabilitation is generally time limited. Imaging-based study of brain activity from walking-related motor tasks can lead to establishing biomarkers to measure improved outcomes and justify extending tailored therapy. A novel, magnetic resonance-compatible, variable-resistance foot motion device and a protocol for use during functional magnetic resonance imaging are presented.

Abstract

Neurological deficits from a stroke can result in long-term motor disabilities, including those that affect walking gait. However, extensive rehabilitation following stroke is typically time limited. Establishing predictive biomarkers to identify patients who may meaningfully benefit from additional physical therapy and demonstrate improvement is important to improve the patients' quality of life. Detection of neuroplastic remodeling of the affected region and changes in the activity patterns excited while performing suitable motor tasks could have valuable implications for chronic stroke recovery. This protocol describes the use of a digitally controlled, magnetic resonance-compatible foot-induced robotic device (MR_COFID) to present a personalized foot-motor task involving trajectory following to stroke-affected subjects with gait impairment during functional magnetic resonance imaging (fMRI). In the task, foot flexion is performed against bi-directional resistive forces, which are tuned to the subject's strength in both the dorsiflexion and plantar flexion directions, while following a visual metronome. fMRI non-invasively uses endogenous deoxyhemoglobin as a contrast agent to detect blood oxygenation level-dependent (BOLD) changes between the active and resting periods during testing. Repeated periodic testing can detect therapy-related changes in excitation patterns during task performance. The use of this technique provides data to identify and measure biomarkers that may indicate the likelihood of an individual benefitting from rehabilitation beyond that which is currently provided to stroke patients.

Introduction

The use of quantitative metrics derived from functional and structural brain imaging may be more useful and effective for tracking progress and predicting the outcomes of stroke therapy than assessing clinical scores, and these quantitative metrics could be useful in designing and improving individualized therapy plans^1,2. Developing effective, personalized strategies that relate motor training to a measurable reorganization of neural activity and/or improvements in motor function remains challenging. In prior work, insights have been developed regarding how functional neuroimaging methods and brain mapping in....

Protocol

All the experiments were approved by the Institutional Review Board at Massachusetts General Hospital and performed as approved at the Athinoula A. Martinos Center for Biomedical Imaging. Subject consent for the use and sharing of de-identified data was obtained.

NOTE: In the current study, the inclusion criteria were as follows: (1) right or left hemiparesis with residual leg movement from an ischemic/MCA stroke incurred ≥6 months earlier; (2) a Functional Ambulation Category (FAC) scor.......

Discussion

Critical steps
The pre-testing of a subject's ability to generate at least minimal motion of the foot pedal with their paretic foot is crucial. An FAC score of 4 or 5 and the ability to stand for a minimal period reflect a subject's combined ability between their unaffected and paretic limbs and do not reflect the ability to move the paretic foot alone. In the current study, a primary goal was the stimulation of neuroplastic changes about the region of the injury through intensive therapy i.......

Materials

Name	Company	Catalog Number	Comments
3T MRI scanner	Siemens Medical Solutions USA, Inc., Malvern, PA	Magnetom Skyra	https://www.siemens-healthineers.com/en-us/magnetic-resonance-imaging/3t-mri-scanner/magnetom-skyra
Data acquisition unit (DAQ)	LabJack Corp., Lakewood, CO	T4	https://labjack.com/news/labjack-t4
High voltage amplifier	Trek, Inc., Lockport, NY	Model 609C-6	https://www.manualsdir.com/manuals/268654/trek-609e-6-high-voltage-power-amplifier.html?page=2&original=1
Matlab	The Mathworks, Ltd., Natick, MA	n/a	https://www.mathworks.com/
USB repeater cable	Tripp Lite, Chicago, IL	U026-10M	https://assets.tripplite.com/product-pdfs/en/u02610m.pdf