Neuroimaging Technology in Exercise Neurorehabilitation Research in Persons with MS: A Scoping Review

Effects of rhythmic-cued gait training on gait-like task related brain activation in people with multiple sclerosis

BACKGROUND

Walking impairment is one of the most debilitating symptoms of multiple sclerosis (MS). A better understanding of brain mechanisms underlying successful gait training could help to improve development of targeted therapy. We therefore investigated changes in brain activation associated with improvements in walking function after rhythmic-cued gait training.

METHODS

Thirty-one people with MS (pwMS; median EDSS = 2.5, range:2.0-5.0) and 17 age- and sex-matched healthy controls (HC) completed behavioural and MRI assessments at baseline and post-intervention (four weeks after baseline). All included pwMS received a four-week actual and/or imagined gait training with rhythmic-auditory cueing, while HC received no intervention. All participants performed a bipedal ankle plantar- and dorsiflexion and a corresponding motor-imagery task during fMRI. PwMS displaying a > 5 % walking distance increase in the 2-Minute Walk Test (2MWT) from baseline to post-intervention were defined as responders.

RESULTS

Responders did not differ from non-responders in terms of demographics, clinical variables, and walking function at baseline. Responders, non-responders, and HC showed similar movement-related brain activation at baseline. At post-intervention, responders showed decreased brain activation within the premotor cortex, precuneus, and middle frontal gyrus during the movement task. Stronger decreases within these areas were associated with higher walking function improvements in all pwMS after controlling for potential confounders. No association was observed between walking function and motor imagery-related brain activation changes.

CONCLUSION

Improved walking function after rhythmic-cued gait training was associated with reduced brain activation in motor planning and attention areas. This suggests a more efficient recruitment of areas subserving motor function after successful training.

Associations between connectivity in functional brain networks and gait speed in older adults with and without multiple sclerosis

OBJECTIVE

To assess whether resting-state functional connectivity (RSFC) brain networks are associated with gait speed in a sample of older adults with and without multiple sclerosis (MS).

METHODS

Older adults with MS (OAMS: n = 82, mean age = 64.4 ± 4.1 years) and controls (n = 85, mean age = 68.6 ± 7.1 years) underwent brain MRI, cognitive assessment, and motor testing. RSFC brain networks were computed from resting-state functional scans based on a data-driven approach. The timed-25-foot-walk test (T25FW), an established measure of disability in aging and clinical populations, served as the outcome measure.

RESULTS

Analyses adjusted for confounders revealed that faster gait speed was significantly associated with higher RSFC in left fronto-parietal (p = 0.002) network in the full cohort. Among OAMS, significant associations between faster gait speed and higher RSFC were found in left fronto-parietal (p = 0.002), cerebellar (p = 0.023), and language (p = 0.046) networks. In contrast, among control participants, there were no significant associations between RSFC and gait speed.

CONCLUSION

In aging, greater functional brain support of walking speed, operationalized using RSFC in empirically derived networks, is required in MS compared to healthy control participants.

Exercise as a Therapeutic Intervention in Multiple Sclerosis

The role of exercise as a therapeutic intervention in multiple sclerosis (MS) has shifted over time. Early views surrounding exercise in MS advocated for caution against participation. With increasing evidence, perspectives shifted to promote exercise as a therapeutic approach for symptom management. Recent efforts have focused on understanding the potential disease-modifying effects of exercise in MS, although this work is still in its infancy. While efforts continue to optimize exercise prescriptions and unravel underlying mechanisms of exercise effects, current knowledge and implementation gaps limit the accessibility of exercise as therapy for all people living with MS. This topical review is based on an invited presentation on 'Exercise as a Therapeutic Intervention in MS' delivered at the ACTRIMS Forum 2024. The review summarizes current evidence for the role of exercise as a therapeutic intervention in MS from symptomatic to disease-modifying potential. We highlight directions for future research efforts to advance our understanding of potential exercise benefits and translate findings into real-world contexts for people living with MS.

Focusing on neural mechanisms of exercise training benefits in multiple sclerosis

Exercise training (ET) should be a mainstay of comprehensive care in multiple sclerosis (MS), yet there is reluctance regarding its implementation among healthcare providers. This reluctance has its roots in the lack of evidence from randomized controlled trials (RCTs) that provide a neurobiological mechanism for beneficial outcomes. We argue that ET training is efficacious for improving mobility and cognitive dysfunction as hallmark consequences of MS, and propose an experimental medicine framework for guiding research focusing on CNS mechanisms-of-action for ET benefits. The framework establishes three hierarchical pathways as preconditions for applying a mediation framework in a fourth pathway for fully testing mechanistic research questions using a RCT. This paper describes the conceptual basis of the pathways, and then reviews the existing evidence within the pathways of the framework for ET effects on the CNS, mobility, and cognition in MS. Lastly, this paper discusses future directions and challenges for testing the pathways of the framework for advancing the evidence regarding CNS mechanisms of ET benefits in this population. Our objective is guiding the field toward evidence that facilitates the prescription and promotion of ET as a neurorestorative approach within MS clinical practice.

Bridging the Gap between Basic Research and Clinical Practice: The Growing Role of Translational Neurorehabilitation

Translational neuroscience is intended as a holistic approach in the field of brain disorders, starting from the basic research of cerebral morphology and with the function of implementing it into clinical practice. This concept can be applied to the rehabilitation field to promote promising results that positively influence the patient's quality of life. The last decades have seen great scientific and technological improvements in the field of neurorehabilitation. In this paper, we discuss the main issues related to translational neurorehabilitation, from basic research to current clinical practice, and we also suggest possible future scenarios.