The triple stimulation technique to study central motor conduction to the lower limbs

Bühler, Robert; Magistris, Michel R.; Truffert, André; Heß, Christian; Rösler, Kai M.

doi:10.1016/s1388-2457(01)00506-5

Cited by 79 publications

(38 citation statements)

References 25 publications

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“…The TST eliminates inXuences of MN discharge desynchronization and of repMNDs on the response size (discussed in detail by Bühler et al 2001;Magistris et al 1998;Rösler et al 2002). It is thus well suited to quantify the Wrst MN discharges evoked by the brain stimulus.…”

Section: Discussionmentioning

confidence: 99%

Repetitive spinal motor neuron discharges following single transcranial magnetic stimulation: relation to dexterity

et al. 2008

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Transcranial magnetic stimulation allows to study the properties of the human corticospinal tract noninvasively. After a single transcranial magnetic stimulus, spinal motor neurons (MNs) sometimes Wre not just once, but repetitively. The biological signiWcance of such repetitive MN discharges (repMNDs) is unknown. To study the relation of repMNDs to other measures of cortico-muscular excitability and to physiological measures of the skill for Wnely tuned precision movements, we used a previously described quadruple stimulation (QuadS) technique (Z'Graggen et al. 2005) to quantify the amount of repMNDs in abductor digiti minimi muscles (ADMs) on both sides of 20 right-handed healthy subjects. Skillfulness for Wnger precision movements of both hands was assessed using a Wnger tapping task. In 16 subjects, a follow-up examination was performed after training of either precision movements (n = 8) or force (n = 8) of the left ADM. The size of the QuadS response (amplitude and area ratios) was greater in the dominant right hand than in the left hand (QuadS amplitude ratio: 47.1 § 18.1 versus 37.7 § 22.0%, Wilcoxon test: P < 0.05; QuadS area ratio: 49.7 § 16.2% versus 36.9 § 23.0%, Wilcoxon test: P < 0.05), pointing to a greater amount of repMNDs. Moreover, the QuadS amplitude and area increased signiWcantly after Wnger precision training, but not after force training. This increase of repMNDs correlated signiWcantly with the increase in performance in the Wnger tapping task. Our results demonstrate that repMNDs are related to handedness and therefore probably reXect supraspinal excitability diVerences. The increase of repMNDs after skills training but not after force training supports the hypothesis of a supraspinal origin of repMNDs.

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Section: Discussionmentioning

confidence: 99%

Repetitive spinal motor neuron discharges following single transcranial magnetic stimulation: relation to dexterity

et al. 2008

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“…Axonal loss may result in increased motor thresholds, small MEP size (amplitude and area) [14,35] and, in severe cases, in prolonged CMCT. Even so, there are several publications on CMCT alterations in the literature [17,23,27,28,29,41,42], but very few investigated amplitude and area alterations, especially in patients with low disability [8,13,30,38,37,42].The aim of the present study was to evaluate MEP amplitude alterations compared with CMCT in MS patients with low disability (EDSS 0-3.5) and to assess if the abnormalities increased in the group with higher EDSS.…”

Section: Introductionmentioning

confidence: 91%

Motor evoked potentials in multiple sclerosis patients without walking limitation: amplitude vs. conduction time abnormalities

et al. 2007

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We used Motor Evoked Potentials (MEPs), elicited by transcranial magnetic stimulation, for assessing a motor pathways dysfunction in a selected group of Multiple Sclerosis (MS) patients, without limitation in walking. We selected 32 Relapsing Remitting MS patients, in remission phase, with EDSS < or = 3.5 and 20 healthy individuals with similar height and age distribution. We measured the following MEP parameters: motor thresholds; central motor conduction time (CMCT); amplitude and area, both expressed as MEP/CMAP ratio. Patients were divided into two groups according to the EDSS score: non-disabled group (ND; EDSS 0-1.5) and disabled group (D; EDSS 2-3.5). Mean average MEP values were significantly different in the patients compared with the controls. Even in MS patients with no or minor neurological signs (ND group), MEP parameters showed differences from controls and furthermore all MEP parameters were significantly different in the D group compared with the ND group. The 75% of the patients had an amplitude or area alteration; this percentage was significantly higher than the percentage of patients with a CMCT alteration (56.2%). In addition, CMCT increase was always associated with reduced amplitude and area, but amplitude and area alterations were present also in patients with normal CMCT. In early stages of MS, the higher percentage shown in alteration of MEP amplitudes and areas as opposed to CMCTs has not previously been highlighted in the literature. Independently of its pathogenesis (demyelination or axonal loss), the amplitude or area decrease should be considered in clinical trials and in follow-up studies, as a marker of the motor pathways dysfunction, at least as much as CMCT increase.

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“…28,29 It is difficult to deduce the precise fraction of the knee extensor motor pool activated by TMS because of complications associated with comparisons of MEP and Mmax amplitudes due to phase cancellation of motor unit action potentials at the muscle membrane. 2,12 For example, MEP amplitude and, to a lesser extent, area can be considerably smaller than Mmax, even if TMS activates all of the motoneurons in a motor pool. 2,12 Nevertheless, the TMS stimuli activated a sufficiently large proportion of the knee extensor motor pool to evoke extra force even at MVC, and they yielded ERTs of comparable magnitude to the RT elicited by supramaximal femoral nerve stimulation.…”

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confidence: 99%

“…2,12 For example, MEP amplitude and, to a lesser extent, area can be considerably smaller than Mmax, even if TMS activates all of the motoneurons in a motor pool. 2,12 Nevertheless, the TMS stimuli activated a sufficiently large proportion of the knee extensor motor pool to evoke extra force even at MVC, and they yielded ERTs of comparable magnitude to the RT elicited by supramaximal femoral nerve stimulation. Thus, the data demonstrate that a large proportion of the knee extensor motoneuron pool was activated by TMS, as is required for accurate measurement of VA.…”

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confidence: 99%

Cortical voluntary activation of the human knee extensors can be reliably estimated using transcranial magnetic stimulation

2008

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The objective of this study was to determine if a transcranial magnetic stimulation (TMS) method of quantifying the degree to which the motor cortex drives the muscles during voluntary efforts can be reliably applied to the human knee extensors. Although the technique for estimating "cortical" voluntary activation (VA) is valid and reliable for elbow flexors and wrist extensors, evidence that it can be applied to muscles of the lower limb is necessary if twitch interpolation with TMS is to be widely used in research or clinical practice. Eight subjects completed two identical test sessions involving brief isometric knee extensions at forces ranging from rest to maximal voluntary contraction (MVC). Electromyographic (EMG) responses to TMS of the motor cortex and electrical stimulation of the femoral nerve were recorded from the rectus femoris (RF) and biceps femoris (BF) muscles, and knee extension twitch forces evoked by stimulation were measured. The amplitude of TMS-evoked twitch forces decreased linearly between 25% and 100% MVC (r(2) > 0.9), and produced reliable estimations of resting twitch and VA (ICC(2,1) > 0.85). The reliability and size of cortical measures of VA were comparable to those derived from motor nerve stimulation when the resting twitches were estimated on the basis of as few as three TMS trials. Thus, TMS measures of VA may provide a reliable and valid tool in studies investigating central fatigue due to exercise and neurological deficits in neural drive in the lower limbs.

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The triple stimulation technique to study central motor conduction to the lower limbs

Cited by 79 publications

References 25 publications

Repetitive spinal motor neuron discharges following single transcranial magnetic stimulation: relation to dexterity

Repetitive spinal motor neuron discharges following single transcranial magnetic stimulation: relation to dexterity

Motor evoked potentials in multiple sclerosis patients without walking limitation: amplitude vs. conduction time abnormalities

Cortical voluntary activation of the human knee extensors can be reliably estimated using transcranial magnetic stimulation

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