Motor imagery training promotes motor learning and brain plasticity without fatigability in people with progressive...

Fatigability, defined as the activity-induced decline in performance, is common in people with multiple sclerosis (PwMS), particularly among those with progressive courses of the disease. There is a pressing need to focus on this population to identify the most appropriate rehabilitation strategies, tailored to individual characteristics, including their susceptibility to fatigability. A key objective is to develop new interventions that maximize therapeutic effectiveness while simultaneously reducing task-related fatigability.

This study investigated whether motor imagery training (MIT) could enhance motor learning and cortical plasticity without causing fatigability in progressive PwMS.

Randomized cross-over study.

Outpatient clinics.

PwMS and healthy individuals.

The study consisted of two experiments. Experiment 1 - Motor Training (MT): Both healthy individuals and people with multiple sclerosis (PwMS) performed motor training involving thumb-to-index opposition movements. The primary outcome was pinch strength. Secondary outcomes included finger-opposition movement rate, motor evoked potential (MEP) amplitude, and motor and cognitive Visual Analogue Scale (VAS) scores assessing fatigability. Experiment 2 investigated the effects of MIT, consisting of kinesthetically imagining thumb-to-index opposition movements, and Active Control using a cross-over design. Both groups (PwMS and healthy individuals) underwent these interventions in a controlled randomized order (using the RAND() function in Excel), with a one-week washout period between sessions to minimize carryover effects. Pinch strength was the primary outcome, while finger-opposition movement rate, MEP amplitude, the score of the trials making test, motor and cognitive VAS scores and the score evaluating MI ability were secondary outcome parameters. All outcome measures were assessed before, immediately after and 60 minutes after the training in both experiments.

MT improved motor performance and increased cortical excitability in healthy individuals, but not in PwMS, where it instead induced fatigability. Conversely, MIT enhanced motor learning and cortical plasticity in both groups without increasing fatigability. Notably, PwMS with lower motor fatigability showed greater motor learning gains.

MIT effectively promoted motor skill improvements and cortical plasticity without causing fatigability in progressive PwMS.

These findings support MIT as a promising, low-fatigability strategy to complement traditional rehabilitation, helping to enhance motor function in progressive PwMS while minimizing fatigue-related barriers.