Upper limb motor evoked potentials as outcome measure in progressive multiple sclerosis

Area of Science:

• Neuroscience
• Clinical Neurology
• Biomedical Engineering

Background:

• Multiple Sclerosis (MS) is a progressive neurodegenerative disease impacting the central nervous system.
• Assessing motor impairment in people with progressive MS (PwPMS) is crucial for monitoring disease progression and treatment efficacy.
• Current outcome measures may be limited by the frequent absence of lower extremity motor evoked potentials (LE-MEPs) in PwPMS.

Purpose of the Study:

• To evaluate the utility of upper limb (UE) motor evoked potentials (MEPs) as a biomarker for motor impairment in PwPMS.
• To compare UE-MEP characteristics with established clinical and functional assessments.

Main Methods:

• Fifty PwPMS with an Expanded Disability Status Scale (EDSS) of 4.0-6.5 were assessed.
• Evaluated parameters included UE and LE MEPs, 6-minute walk-test (6MWT), 10-meter walk-test (10MWT), EDSS, 9-hole peg-test (9HPT), and Manual Muscle Testing (MRC) and Modified Ashworth Scale (MAS) for UE and LE.

Main Results:

• LE-MEPs were absent in 74% of participants, correlating with poorer 10MWT and 6MWT performance.
• UE-MEPs were rarely absent (8%) but frequently delayed (74%).
• Abnormal UE-MEPs correlated with worse 9-hole peg-test performance, and UE-MEP latency showed significant correlations with 10MWT, 6MWT, and EDSS scores.

Conclusions:

• UE-MEPs can serve as a clinically relevant measure of corticospinal tract integrity in PwPMS, particularly when LE-MEPs are unmeasurable.
• This finding supports the use of UE-MEPs for monitoring disease progression and therapeutic responses in MS.