Do alternate methods of analysing motor evoked potentials give comparable results?

Reliability of lower limb motor evoked potentials in stroke and healthy populations: How many responses are needed?

“…Phase cancellation does not occur when the data are rectified 15 prior to averaging and the response area or rms measured. Our finding that MEP measures from averaged responses were less reliable outcome measures contrasts with McDonnell and colleagues (McDonnell, Ridding, 2004), who did not find any consistent differences in reliability between ensemble average or individual MEP measures in healthy participants.…”

“…The minimum number of MEPs required to obtain reliable results has been recommended at five for intrasession (Bastani and Jaberzadeh, 2012, Christie, Fling, 2007, Doeltgen, Ridding, 2009) and ten for intersession comparisons (Bastani andJaberzadeh, 2012, Doeltgen, Ridding, 2009). Only one study has investigated the effect of different MEP processing and analysis procedures and showed no difference in reliability between the use of MEP area and MEP amplitude outcome measures to represent the magnitude of the MEP (McDonnell, Ridding, 2004). This study was undertaken in the upper limb and the findings may be 5 different in lower limb muscles where there is less synchronisation of the descending cortical volley and polyphasic MEPs are often obtained (Marchand-Pauvert et al, 1999, Soto et al, 2006.…”

“…Previous studies examining the reliability of MEPs have mainly focused on hand and forearm muscles (Bastani and Jaberzadeh, 2012, Carroll et al, 2001, Christie et al, 2007, Kamen, 2004, Livingston and Ingersoll, 2008, McDonnell et al, 2004, Mortifee et al, 1994, Ngomo et al, 2012, with a smaller number of studies examining muscles from the lower limb (Cacchio et al, 2009, Cacchio et al, 2011, Tallent et al, 2012, van Hedel et al, 2007, Wheaton et al, 2009). Most authors have reported good or excellent reliability of MEP amplitude measurements within and between sessions but this is not always consistent (Livingston andIngersoll, 2008, McDonnell, Ridding, 2004).…”

Method for Assessing Brain Changes Associated With Gluteus Maximus Activation

“…3,7,17,32 Because surface electromyography (EMG) is used to measure changes in corticomotor excitability of the target muscle, TMS measures may also vary between test sessions, due to differences in electrode placement and/ or skin impedance. Though reliability of TMS has been established for upper extremity muscles such as the biceps and first dorsal interosseus, 17,[20][21][22] measurement error may be magnified when measuring corticomotor excitability of the gluteus maximus, a large muscle with a small M1 representational area. In addition, the use of surface EMG to assess activation of the gluteus maximus can be challenging due to the large amount of subcutaneous tissue that typically surrounds this muscle.…”

The amplitude of lower leg motor evoked potentials is a reliable measure when controlled for torque and motor task

“…Inclusion of MEP amplitude might provide additional information about CS transmission, as it reflects not only the integrity of the CS tract, but also the excitability of motor cortex (especially without activation of the target muscle) and subcortical (brain stem to spinal motoneuron pools) structures. However, MEP amplitudes vary considerably from trial-to-trial [6][7][8].…”