Electroencephalography and Clinical Neurophysiology/Electromyography and Motor Control
Magnetic transcranial stimulation: dissociation of excitatory and inhibitory mechanisms in acute strokes
Introduction
Cortical stimulation during voluntary target muscle contraction evokes an EMG potential followed by a pause of the muscle activity (Calancie et al., 1987; Mills, 1988; Fuhr et al., 1991). This silent period following a motor evoked potential (MEP) is supposed to be of inhibitory origin (Calancie et al., 1987; Holmgren et al., 1990; Fuhr et al., 1991; Uozumi et al., 1992; Inghilleri et al., 1993; Wasserman et al., 1993) and has been evaluated in various clinical conditions. In normal subjects, silent period duration (SPD) is rather constant, increasing with the intensity of the magnetic brain stimulation (Holmgren et al., 1990), while it was found to be shorter in the rigid limbs of patients suffering from asymmetrical Parkinson's disease (Cantello et al., 1991) or from upper motor neuron disorders (Uozumi et al., 1991).
In order to assess the clinical value of this technique in cerebral ischaemic disorders, we analysed the results obtained in 24 patients suffering from an acute stroke within the first week of the onset, with magnetic brain stimulation performed at rest and during various intensities of voluntary isometric contraction (VIC), while the stimulus intensity was gradually upgraded from a subthreshold level to the maximum (100%) of the stimulator output.
Section snippets
Patients
Thirty patients were included in this study. Twenty-four patients (Table 1) suffering from a 1st ischaemic stroke were investigated within the first week of the onset (mean time 7 days; range, 4–9 days). The diagnosis of stroke was made by clinical history and examination, and confirmed by CT scan performed 5–11 days following the cerebral insult.
All cases presented a sharp edged radiolucent area in the middle cerebral artery territory (11 left and 13 right hemispheres). Cases with a mass
Results
Results are expressed as mean values±SD.
Demographic data are summarised in Table 1. No significant difference was observed between the controls and the patients.
There was no statistical difference between the controls and the patients for the F-waves mean values (controls: 26.5±2.8 ms; group 1: 25.2±3.2 ms; and group 2: 24.7±3.2 ms).
Discussion
In control and in hemiparetic patients, the amplitude of the MEPs increases with augmenting intensity of the magnetic transcranial stimulation (Rossini and Caramia, 1988; Rossini et al., 1988; Caramia et al., 1989; Bridgers, 1990; Caramia et al., 1991; Rothwell et al., 1991; Escudero et al., 1992; Heald et al., 1993a; Heald et al., 1993b; Catano et al., 1995). Such reinforcement of the response is readily attributed to neuronal recruitment and obviously points out excitatory influence flowing
Acknowledgements
We acknowledge Drs. G. Caruso, P.M. Rossini, J.C. Rothwell and E.M. Wassermann. Thanks to Mr. Frédéric Noël for his technical assistance.
References (36)
- Amassian, V.E., Cracco, R.Q., Maccabee, P.J., Cracco, J.B., Rudell, A. and Eberle, L. Suppression of visual perception...
- Ashworth, B. Preliminary trial of carisoprodol in multiple sclerosis. Practitioner, 1964, 192:...
- Boniface, S.J., Schubert, M. and Mills, K.R. Suppression and long latency excitation of single spinal motoneurons by...
- Bridgers, S.L. Magnetic cortical stimulation in stroke patients with hemiparesis. In: S. Chokroverty (Ed.), Magnetic...
- Calancie, B., Nordin, M., Wallin, U. and Habgarth, K.E. Motor-unit responses in human wrist flexor and extensor muscles...
- Cantello, R., Gianelli, M., Bettucci, D., Civardi, C., De Angelis, M.S. and Mutani, R. Parkinson's disease rigidity:...
- Cantello, R., Gianelli, M., Civardi, C. and Mutani, R. Magnetic brain stimulation: the silent period after the motor...
- Caramia, M.D., Pardal, A.M., Zarola, F. and Rossini, P.M. Electric vs magnetic trans-cranial stimulation of the brain...
- Caramia, M.D., Cicinelli, P., Paradiso, C., Mariorenzi, R., Zarola, F., Bernardi, G. and Rossini, P.M. Excitability...
- Catano, A., Houa, M., Caroyer, J.M., Ducarne, H. and Noël, P. Magnetic transcranial stimulation in non-haemorrhagic...
Cited by (32)
Primary motor cortex excitability during recovery after stroke: Implications for neuromodulation
2015, Brain StimulationCitation Excerpt :At the sub-acute stage, ipsilesional corticomotor excitability (CME) is suppressed compared to the contralesional M1 and healthy adults [19–26], and usually increases in patients who experience an improvement in paretic upper-limb strength [23,24]. However, contralesional CME is typically not different to healthy adults [20,23–27] and is stable over time [23,24,27]. Interhemispheric inhibition (IHI) is reduced from ipsilesional to contralesional M1 [26,28], but normal from contralesional to ipsilesional M1 [26].
Stimulus-response characteristics of motor evoked potentials and silent periods in proximal and distal upper-extremity muscles
2009, Journal of Electromyography and KinesiologyCitation Excerpt :Partly because of these differences, it has been suggested that the facilitatory mechanisms involved in the MEP are physiologically different from the inhibitory mechanisms contributing to the SP (Wehrhahn et al., 2007; Lo and Fook-Chong, 2005; Chen et al., 1999; Cantello et al., 1992). Both the MEP and the SP have been used to predict post-stroke motor recovery (Hendricks et al., 2003, 2002; Nardone and Tezzon, 2002; Byrnes et al., 2001; Catano et al., 1997a,b; Braune and Fritz, 1995). In stroke patients with an initial paralysis of the upper extremity, the presence of an early MEP within the first weeks after stroke showed good positive predictive value (PPV = 1; 35 patients) for regaining hand motor function at 6 months after stroke.
Central motor conduction and its clinical application
2005, Magnetic Stimulation in Clinical NeurophysiologyMotor evoked potentials following transcranial magnetic stimulation after middle cerebral artery and/or basilar artery occlusions in rats
2003, Journal of Clinical Neuroscience