Abstract Details

Title A Methodological Reappraisal to Restrain Intra-Trial MEP Area Variability

Topic Clinical Neurophysiology

Presentation(s) P02 - (-)

Poster/Presentation
Number 236

Objective

Background BACKGROUND: Motor Evoked Potential (MEP) area could reflect motor conduction failure/axonal damage, but its reliability is affected by MEPs' variability.

Design/Methods DESIGN/METHODS: In 7 healthy volunteers and 4 multiple sclerosis patients MEPs to Transcranial Magnetic Stimulation using the double cone coil were bilaterally recorded from Vastus Medialis (VM), Tibialis Anterior (TA) and Flexor Hallucis Brevis (FHB). Ten stimuli were delivered in basal condition and 10 during standardized, controlled simultaneous muscle activation by means of a purpose made mechanical device. We quantified the advantage of MEP averaging on area variability by comparing 2 independent averaged MEPs (averaged-MEPs) obtained from 5 activated, rectified MEPs, drawn from the 10 responses. Area and latency of the averaged-MEPs, of the individual basal and activated MEPs were measured and parameters variability, expressed as the absolute value and percentage difference [(Val max-Val min) x 100/Val min] were evaluated. Paired T-Test was applied to compare intra-trial variability of MEPs' parameters.

Results RESULTS: Maximum area variability was observed in basal responses and, as expected, voluntary facilitation lowered percentage area difference to 78%, 48% and 64 % for VM, TA and FHB respectively. The comparison between the 2 averaged-MEPs dramatically reduced MEP area variability to satisfactory values in all muscle districts: the percentage area difference averaged dropped to 10.5 %, 6.4 % and 6.6 % for VM, TA and FHB respectively. Moreover, MEPs averaging also allowed increasing likelihood of detecting a reliable MEP latency, less biased by the background voluntary activity.

Conclusions CONCLUSIONS: Intra-trial MEP area variability can be significantly restrained, if the averaging of only few MEPs is combined with an objectively controlled voluntary activation, making MEP area an acceptable parameter to assess central motor conduction failure.

Authors/Disclosures
Alessia Di Sapio, MD PRESENTER	No disclosure on file
Jacqueline Montes, PT, EdD, NCS (Columbia University Medical Center)	Ms. Montes has received personal compensation in the range of $10,000-$49,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Biogen. Ms. Montes has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for F. Hoffman LaRoche. Ms. Montes has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Scholar Rock. Ms. Montes has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Sarepta. The institution of Ms. Montes has received research support from NIH/NICHD. The institution of Ms. Montes has received research support from Muscular Dystrophy Association. The institution of Ms. Montes has received research support from Cure SMA.
	No disclosure on file
Simona Malucchi	No disclosure on file
Antonio Bertolotto, MD, FAAN (Ospedale Koelliker)	Dr. Bertolotto has nothing to disclose.
Valter Troni, MD (Ospedale San Luigi Gonzaga)	No disclosure on file

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