Motor evoked potentials with magnetic stimulation: correlations with height

doi:10.1016/0168-5597(89)90039-7

Electroencephalography and Clinical Neurophysiology/Evoked Potentials Section

Volume 74, Issue 6, November–December 1989, Pages 481-485

https://doi.org/10.1016/0168-5597(89)90039-7 Get rights and content

Abstract

The relationship between height and motor evoked potentials (MEPs) was studied in 52 healthy young subjects. Evoked responses from the abductor digiti minimi and tibialis anterior muscles were obtained following magnetic stimulation over the vertex and the cervical and lumbar regions. The latencies of MEPs were highly correlated with height. The conduction time from the motor cortex to the lumbar region was also correlated with height, but that from the motor cortex to the cervical region was not. It is concluded that height is an important variable in defining the MEP normality.

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Interhemispheric differences in time-frequency representation of motor evoked potentials in brain tumor patients
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We hypothesize, that time-frequency results might be less prone to intra- and inter-subject co-variates and, thus, have a higher reliability and sensitivity for detecting disturbed corticospinal transmission. In fact, conventional time-series parameters have been shown to be susceptible to several individual factors (e.g., age, height, weight, AED intake) (Cantone et al., 2019; Chu, 1989; Jung et al., 2010; Sollmann et al., 2017; Tobimatsu et al., 1998). Time-frequency measures, however, were not affected by these co-variates in the present study.
Conventional time-series parameters are unreliable descriptors of motor-evoked potentials (MEPs) in brain tumor patients. Frequency domain analysis is suggested to provide additional information about the status of the cortico-spinal motor system. Aim of the present study was to describe the time-frequency representation of MEPs and its relation to the motor performance.
This study enrolled 17 consecutive brain tumor patients with impaired dexterity. After brain mapping of the affected (AH) and non-affected (NAH) hemisphere, TMS was applied to the hotspots of the abductor pollicis brevis muscles (APB). Using a Morlet wavelet approach, event-related spectral perturbation (ERSP) and inter-trial coherence (ITC) of the MEPs were calculated and compared to the Grooved Pegboard Test (GPT). Additionally, inter- and intra-subject reliability was assessed by the intraclass correlation coefficient (ICC).
MEPs were projecting to a frequency band between 30 and 400 Hz with a local maximum between 100 and 150 Hz. There was a significant ERSP and ITC reduction of the AH in comparison to the NAH. In contrast, no interhemispheric differences were depicted in the conventional time-series analysis. ERSP and ITC values correlated significantly with GPT results (r = 0.35 and r = 0.50). Time-frequency MEP description had good inter-and intra-subject reliability (ICC = 0.63).
Brain tumors affect corticospinal transmission resulting in a reduction of temporal and spectral MEP synchronization correlating with the dexterity performance.
Time-frequency representation of MEPs provide additional information beyond conventional time-domain features.
Relationship Between Motor Function, DTI, and Neurophysiological Parameters in Patients with Stroke in the Recovery Rehabilitation unit
2021, Journal of Stroke and Cerebrovascular Diseases
Citation Excerpt :
The F-wave latency was measured as the period from the stimulation to the onset of each F-wave, and the shortest latency was used for the analysis. The CMCT was calculated using the following formula:35-39 CMCT = MEP latency − (F-wave latency + M-wave latency − 1)/2
We investigated the relationship between pyramidal tract evaluation indexes (i.e., diffusion tensor imaging, transcranial magnetic stimulation (TMS)-induced motor-evoked potential (MEP), and central motor conduction time (CMCT) on admission to the recovery rehabilitation unit) and motor functions at discharge in patients with ischemic or hemorrhagic stroke.
Seventeen patients were recruited (12 men; 57.9 ± 10.3 years). The mean fractional anisotropy (FA) values of the right and left posterior limbs of the internal capsule were estimated using a computer-automated method. We determined the ratios of FA values in the affected and unaffected hemispheres (rFA), TMS-induced MEP, and the ratios of CMCT in the affected and unaffected hemispheres (rCMCT) and examined their association with motor functions (Fugl–Meyer Assessment (FMA) and Action Research Arm Test (ARAT)) at discharge.
Higher rFA values of the posterior limb of the internal capsule on admission to the recovery rehabilitation unit led to a better recovery of upper limb function (FMA: r = 0.78, p < 0.001; ARAT: r = 0.74, p = 0.001). Patients without MEP had poorer recovery of upper limb function than those with MEP (FMA: p < 0.001; ARAT: p = 0.001). The higher the rCMCT, the poorer the recovery of upper limb function (ARAT: r = −0.93, p < 0.001). However, no association was observed between the pyramidal tract evaluation indexes and recovery of lower limb motor function.
Evaluating the pyramidal tract is useful for predicting upper limb function prognosis, but not for lower limb function prognosis.
Non-invasive electrical and magnetic stimulation of the brain, spinal cord, roots and peripheral nerves: Basic principles and procedures for routine clinical and research application: An updated report from an I.F.C.N. Committee
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Citation Excerpt :
In this method, CMCT includes the time taken for at least one synaptic delay and the time in proximal motor root in the spinal canal, in addition to the true CMCT (time needed for conduction in the CST) (Cowan et al., 1984; Mills and Murray, 1985; Hess et al., 1987; Rossini et al., 1987a; Ugawa et al., 1988a,b, 1989a, 1990). The second approach is the use of F-waves (Rossini et al., 1987a; Chu, 1989; Eisen and Shtybel, 1990; Claus, 1990). The F wave latency measures antidromic conduction in motor axons to the spinal motoneuronal pool, the “turn-around” time at the motoneuron pool (generally considered to be 1 ms) and then orthodromic conduction from the motoneuron pool to the muscle.
These guidelines provide an up-date of previous IFCN report on “Non-invasive electrical and magnetic stimulation of the brain, spinal cord and roots: basic principles and procedures for routine clinical application” (Rossini et al., 1994). A new Committee, composed of international experts, some of whom were in the panel of the 1994 “Report”, was selected to produce a current state-of-the-art review of non-invasive stimulation both for clinical application and research in neuroscience.
Since 1994, the international scientific community has seen a rapid increase in non-invasive brain stimulation in studying cognition, brain–behavior relationship and pathophysiology of various neurologic and psychiatric disorders. New paradigms of stimulation and new techniques have been developed. Furthermore, a large number of studies and clinical trials have demonstrated potential therapeutic applications of non-invasive brain stimulation, especially for TMS. Recent guidelines can be found in the literature covering specific aspects of non-invasive brain stimulation, such as safety (Rossi et al., 2009), methodology (Groppa et al., 2012) and therapeutic applications (Lefaucheur et al., 2014).
This up-dated review covers theoretical, physiological and practical aspects of non-invasive stimulation of brain, spinal cord, nerve roots and peripheral nerves in the light of more updated knowledge, and include some recent extensions and developments.
Transcranial magnetic motor evoked potentials in Great Danes with and without clinical signs of cervical spondylomyelopathy: Association with neurological findings and magnetic resonance imaging
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Citation Excerpt :
A longer neuronal path length means that the impulse will need to travel a larger distance before reaching the muscle and generating a motor evoked potential; thus, yielding longer latencies. The influence of body size on TMMEP latencies has also been reported in humans and horses (Chu, 1989; Nollet et al., 2004). These results indicate that reference ranges for TMMEP latency will likely be different across dog breeds with different body sizes.
Transcranial magnetic motor evoked potentials (TMMEPs) assess the functional integrity of the descending motor pathways, which are typically compromised in canine cervical spondylomyelopathy (CSM). The objective of this prospective study was to establish the reference ranges of TMMEP latency and amplitude in clinically normal (control) Great Danes (GDs), compare TMMEPs obtained in GDs with and without CSM, and determine whether there is any association between TMMEP data and severity of neurological signs or magnetic resonance imaging (MRI) findings. Twenty-nine client-owned GDs were enrolled (15 controls, 14 CSM-affected). All dogs underwent TMMEPs under sedation, and latencies and amplitudes were recorded from the extensor carpi radialis (ECR) and cranial tibial (CT) muscles. MRI of the cervical vertebral column was performed to evaluate the presence and severity of spinal cord (SC) compression, and the presence of SC signal changes.
ECR and CT latencies were significantly longer in CSM-affected than control GDs. No significant differences between groups were found for amplitudes or neuronal path lengths. For the CT TMMEPs, CSM-affected GDs with moderate and severe clinical signs had significantly longer latencies than those with mild clinical signs. Significantly longer CT latencies were found in dogs with moderate and severe SC compression compared with dogs with mild compression. CT TMMEPs could not be recorded in 7/9 CSM-affected GDs with SC signal changes. These results provide a reference range for TMMEPs of clinically normal GDs. The use of TMMEPs is a valid ancillary test to assess the integrity of motor pathways in GDs with CSM.
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Transcranial magnetic stimulation (TMS) is an established neurophysiological tool to examine the integrity of the fast-conducting corticomotor pathways in a wide range of diseases associated with motor dysfunction. This includes but is not limited to patients with multiple sclerosis, amyotrophic lateral sclerosis, stroke, movement disorders, disorders affecting the spinal cord, facial and other cranial nerves. These guidelines cover practical aspects of TMS in a clinical setting. We first discuss the technical and physiological aspects of TMS that are relevant for the diagnostic use of TMS. We then lay out the general principles that apply to a standardized clinical examination of the fast-conducting corticomotor pathways with single-pulse TMS. This is followed by a detailed description of how to examine corticomotor conduction to the hand, leg, trunk and facial muscles in patients. Additional sections cover safety issues, the triple stimulation technique, and neuropediatric aspects of TMS.

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Short communicationMotor evoked potentials with magnetic stimulation: correlations with height

Abstract

Electroenceph. clin. Neurophysiol.

Lancet

Lancet

Electroenceph. clin. Neurophysiol.

Neurosci. Lett.

Electroenceph. clin. Neurophysiol.

Electroenceph. clin. Neurophysiol.

Brain Res.

Evoked Potentials in Clinical Medicine

Short communication
Motor evoked potentials with magnetic stimulation: correlations with height