Operant Up-Conditioning of the Tibialis Anterior Motor-Evoked Potential in Multiple Sclerosis: Feasibility Case Studies

Neural Plasticity, 2018 · DOI: https://doi.org/10.1155/2018/4725393 · Published: July 15, 2018

Simple Explanation

This study explores whether a technique called MEP operant conditioning can help people with multiple sclerosis (MS) who have difficulty lifting their foot (foot drop). The goal was to see if strengthening the connection between the brain and the muscles that lift the foot could improve their walking ability. The participants underwent a training program where they tried to increase the size of the muscle response (MEP) when their leg muscle was stimulated. They received feedback to help them improve their muscle response. The study found that in most participants, this training led to improvements in muscle strength, walking ability, and muscle activity during walking. These results suggest that MEP operant conditioning might be a useful therapy for improving walking in people with MS and other conditions that affect the brain and spinal cord.

Study Duration

10 weeks, with follow-up sessions for one subject over 3 years

Participants

Four women with chronic foot drop due to secondary progressive MS

Evidence Level

Case Series

Key Findings

1
In 3 out of 4 subjects, TA MEP increased 32–75% after the conditioning sessions.
2
MVC increased 28–52% in 3 out of 4 subjects.
3
Locomotor EMG modulation improved in multiple leg muscles in 3 of 4 subjects, and foot drop became less severe.

Research Summary

This study investigated the feasibility of tibialis anterior (TA) motor-evoked potential (MEP) operant conditioning to enhance corticospinal excitability and alleviate locomotor problems in people with chronic stable multiple sclerosis (MS). The protocol consisted of 6 baseline and 24 up-conditioning sessions over 10 weeks, where participants were encouraged to increase MEP size with immediate feedback. The results showed that in most subjects, TA MEP and MVC increased, locomotor EMG modulation improved, and foot drop became less severe, suggesting a therapeutic possibility of MEP operant conditioning for improving locomotion in people with MS or other CNS disorders.

Practical Implications

Therapeutic Potential

MEP operant conditioning may offer a novel therapeutic approach for improving locomotion in individuals with MS and potentially other CNS disorders such as spinal cord injury and stroke.

Corticospinal Plasticity

The study supports the idea that corticospinal pathways in individuals with MS are capable of plasticity and can be strengthened through targeted training.

Long-term Maintenance

One subject maintained improvements in MEP, MVC, and voluntary ankle dorsiflexion over 3 years of follow-up sessions, indicating the potential for long-term benefits with periodic maintenance.

Study Limitations

1
Small sample size limits generalizability.
2
Feasibility study; wider applicability needs confirmation through larger clinical trials.
3
Potential for non-specific (psychological) effects of the procedures.

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