scholarly journals Comparison of low frequency repetitive transcranial magnetic stimulation parameters on motor cortex excitability in normal subjects

2016 ◽  
Vol 03 (01) ◽  
pp. 002-006
Author(s):  
Lara Schrader ◽  
Sima Sadeghinejad ◽  
Jalleh Sadeghinejad ◽  
Movses Kazanchyan ◽  
Lisa Koski ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Low Frequency ◽  
Motor Threshold ◽  
Motor Cortex Excitability ◽  
Resting Motor Threshold

Abstract Background/objectives Optimal low frequency repetitive transcranial magnetic stimulation (LF-rTMS) parameters for treating epilepsy and other brain disorders are unknown. To address this question, a systematic study of the effects of LF-rTMS frequency and intensity on cortical excitability was performed. Methods Using a four-period crossover design, subjects were scheduled for four LF-rTMS sessions that were at least four weeks apart. LF-rTMS was delivered as 900 pulses directed at primary motor cortex using four protocols: 0.5 Hz at 90% resting motor threshold (RMT), 0.5 Hz at 110% RMT, 1 Hz at 90% RMT, and 1 Hz at 110% RMT. Motor evoked potential (MEP) amplitude, resting motor threshold (RMT), and cortical silent period (CSP) were measured before, immediately after, and 60 min after LF-rTMS. Each of the four protocols was analyzed separately to compare baseline measurements to those after LF-rTMS. Results None of the four LF-rTMS protocols produced a trend or significant change in MEP amplitude, RMT, or CSP. Conclusion The lack of significant effect from the four LF-rTMS protocols indicates that none produced evidence for alteration of cortical excitability. The direct comparison of four LF-rTMS protocols is distinct to this investigation, as most similar studies were exploratory and studied only one or two protocols. The negative result relates only to the methods used in this investigation and does not indicate that LF-rTMS does not alter cortical excitability with other parameters. These results may be useful when designing additional investigations into the effect of LF-rTMS on epilepsy, other disorders, and cortical excitability.

Low-intensity repetitive transcranial magnetic stimulation decreases motor cortical excitability in humans

2006 ◽  
Vol 101 (2) ◽  
pp. 500-505 ◽  
Author(s):  
Gabrielle Todd ◽  
Stanley C. Flavel ◽  
Michael C. Ridding
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Cortical Excitability ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Motor Threshold ◽  
Sham Stimulation ◽  
Motor Cortical Excitability ◽  
Resting Motor Threshold ◽  
Active Motor ◽  
Motor Cortical

Repetitive transcranial magnetic stimulation of the motor cortex (rTMS) can be used to modify motor cortical excitability in human subjects. At stimulus intensities near to or above resting motor threshold, low-frequency rTMS (∼1 Hz) decreases motor cortical excitability, whereas high-frequency rTMS (5–20 Hz) can increase excitability. We investigated the effect of 10 min of intermittent rTMS on motor cortical excitability in normal subjects at two frequencies (2 or 6 Hz). Three low intensities of stimulation (70, 80, and 90% of active motor threshold) and sham stimulation were used. The number of stimuli were matched between conditions. Motor cortical excitability was investigated by measurement of the motor-evoked potential (MEP) evoked by single magnetic stimuli in the relaxed first dorsal interosseus muscle. The intensity of the single stimuli was set to evoke baseline MEPs of ∼1 mV in amplitude. Both 2- and 6-Hz stimulation, at 80% of active motor threshold, reduced the magnitude of MEPs for ∼30 min ( P < 0.05). MEPs returned to baseline values after a weak voluntary contraction. Stimulation at 70 and 90% of active motor threshold and sham stimulation did not induce a significant group effect on MEP magnitude. However, the intersubject response to rTMS at 90% of active motor threshold was highly variable, with some subjects showing significant MEP facilitation and others inhibition. These results suggest that, at low stimulus intensities, the intensity of stimulation may be as important as frequency in determining the effect of rTMS on motor cortical excitability.

scholarly journals Efficacy of Repetitive Transcranial Magnetic Stimulation for Acute Central Post-stroke Pain: A Case Study

2021 ◽  
Vol 12 ◽  
Author(s):  
Calogero Malfitano ◽  
Angela Rossetti ◽  
Stefano Scarano ◽  
Chiara Malloggi ◽  
Luigi Tesio
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Thermal Sensation ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
The Body ◽  
Post Stroke ◽  
Thalamic Stroke ◽  
Motor Cortex Excitability

Although rare, central post-stroke pain remains one of the most refractory forms of neuropathic pain. Repetitive transcranial magnetic stimulation (rTMS) has been reported to be effective in chronic cases. However, there are no data on the effects in the acute and subacute phases after stroke. In this study, we present a case of a patient with thalamic stroke with acute onset of pain and paresthesia who was responsive to rTMS. After a right thalamic stroke, a 32-year-old woman presented with drug-resistant pain and paresthesia on the left side of the body. There were no motor or sensory deficits, except for blunted thermal sensation and allodynia on light touch. Ten daily sessions were performed, where 10 Hz rTMS was applied to the hand area of the right primary motor cortex, 40 days after stroke. Before rTMS treatment (T0), immediately after treatment conclusion (T1), and 1 month after treatment (T2), three pain questionnaires were administered, and cortical responses to single and paired-pulse TMS were assessed. Eight healthy participants served as controls. At T0, when the patient was experiencing the worst pain, the excitability of the ipsilesional motor cortex was reduced. At T1 and T2, the pain scores and paresthesia' spread decreased. The clinical improvement was paralleled by the recovery in motor cortex excitability of the affected hemisphere, in terms of both intra- and inter-hemispheric connections. In this subacute central post-stroke pain case, rTMS treatment was associated with decreased pain and motor cortex excitability changes.

scholarly journals Repetitive Transcranial Magnetic Stimulation for Dysesthesia Caused by Subacute Myelo-Optico-Neuropathy: A Case Report

2020 ◽  
Vol 12 (2) ◽  
pp. 169-174
Author(s):  
Tomoo Mano ◽  
Satoshi Kuru
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Lower Limbs ◽  
Antibacterial Drug ◽  
Motor Threshold ◽  
Neuromuscular Dysfunction ◽  
Resting Motor Threshold ◽  
Sensory Disturbances

Subacute myelo-optico-neuropathy (SMON) is caused by the ingestion of clioquinol (5-chloro-7-iodo-8-hydroxyquinoline), which is an intestinal antibacterial drug. Patients with SMON typically suffer from abnormal dysesthesia in the lower limbs, which cannot explain the mechanism only in pathology and electrophysiology. Neuromodulation therapies are increasingly being investigated as a means of alleviating abnormal sensory disturbances. We report here the response to repetitive transcranial magnetic stimulation (rTMS) for dysesthesia in a patient with SMON. The patient underwent rTMS treatment once per week for 12 weeks. rTMS was administered at 10 Hz, 90% of the resting motor threshold over the bilateral primary motor cortex foot area, for a total of 1,500 stimuli per day. After the treatment had finished at 12 weeks, the abnormal dysesthesia gradually declined. At first, there were improvements only in the area with a feeling of adherence. Later, this sensation was eliminated. Three months following the application, most of the feeling of adherence had disappeared and the feeling of tightness was slightly reduced. In contrast, the throbbing feeling had not changed during this period. Dysesthesia may indicate a process of central sensitization, which would contribute to chronic neuromuscular dysfunction. This case suggests that rTMS is a promising therapeutic application for dysesthesia.

scholarly journals Low-Frequency Repetitive Transcranial Magnetic Stimulation for Stroke-Induced Upper Limb Motor Deficit: A Meta-Analysis

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Lan Zhang ◽  
Guoqiang Xing ◽  
Shiquan Shuai ◽  
Zhiwei Guo ◽  
Huaping Chen ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Upper Limb ◽  
Magnetic Stimulation ◽  
Cortical Excitability ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Meta Analysis ◽  
Low Frequency ◽  
Motor Evoked Potential ◽  
Motor Deficit ◽  
Resting Motor Threshold

Background and Purpose. This meta-analysis aimed to evaluate the therapeutic potential of low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) over the contralesional hemisphere on upper limb motor recovery and cortex plasticity after stroke.Methods. Databases of PubMed, Medline, ScienceDirect, Cochrane, and Embase were searched for randomized controlled trials published before Jun 31, 2017. The effect size was evaluated by using the standardized mean difference (SMD) and a 95% confidence interval (CI). Resting motor threshold (rMT) and motor-evoked potential (MEP) were also examined.Results. Twenty-two studies of 1 Hz LF-rTMS over the contralesional hemisphere were included. Significant efficacy was found on finger flexibility (SMD = 0.75), hand strength (SMD = 0.49), and activity dexterity (SMD = 0.32), but not on body function (SMD = 0.29). The positive changes of rMT (SMD = 0.38 for the affected hemisphere and SMD = −0.83 for the unaffected hemisphere) and MEP (SMD = −1.00 for the affected hemisphere and SMD = 0.57 for the unaffected hemisphere) were also significant.Conclusions. LF-rTMS as an add-on therapy significantly improved upper limb functional recovery especially the hand after stroke, probably through rebalanced cortical excitability of both hemispheres. Future studies should determine if LF-rTMS alone or in conjunction with practice/training would be more effective.Clinical Trial Registration Information. This trial is registered with unique identifierCRD42016042181.

scholarly journals Motor demand-dependent improvement in accuracy following low-frequency transcranial magnetic stimulation of left motor cortex

2011 ◽  
Vol 106 (4) ◽  
pp. 1614-1621 ◽  
Author(s):  
Cathrin M. Buetefisch ◽  
Benjamin Hines ◽  
Linda Shuster ◽  
Paola Pergami ◽  
Adam Mathes
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Motor Performance ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Motor Task ◽  
Low Frequency ◽  
Afferent Input ◽  
Low Frequency Rtms

The role of primary motor cortex (M1) in the control of voluntary movements is still unclear. In brain functional imaging studies of unilateral hand performance, bilateral M1 activation is inconsistently observed, and disruptions of M1 using repetitive transcranial magnetic stimulation (rTMS) lead to variable results in the hand motor performance. As the motor tasks differed qualitatively in these studies, it is conceivable that M1 contribution differs depending on the level of skillfulness. The objective of the present study was to determine whether M1 contribution to hand motor performance differed depending on the level of precision of the motor task. Here, we used low-frequency rTMS of left M1 to determine its effect on the performance of a pointing task that allows the parametric increase of the level of precision and thereby increase the level of required precision quantitatively. We found that low-frequency rTMS improved performance in both hands for the task with the highest demand on precision, whereas performance remained unchanged for the tasks with lower demands. These results suggest that the functional relevance of M1 activity for motor performance changes as a function of motor demand. The bilateral effect of rTMS to left M1 would also support the notion of M1 functions at a higher level in motor control by integrating afferent input from nonprimary motor areas.

Potentiation of Short-Latency Cortical Responses by High-Frequency Repetitive Transcranial Magnetic Stimulation

2010 ◽  
Vol 104 (3) ◽  
pp. 1578-1588 ◽  
Author(s):  
Domenica Veniero ◽  
Claudio Maioli ◽  
Carlo Miniussi
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
High Frequency ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Indirect Evidence ◽  
Direct Demonstration ◽  
Resting Motor Threshold ◽  
On Line

It is generally accepted that low- and high-frequency repetitive transcranial magnetic stimulation (rTMS) induces changes in cortical excitability, but there is only indirect evidence of its effects despite a large number of studies employing different stimulation parameters. Typically the cortical modulations are inferred through indirect measurements, such as recording the change in electromyographic responses. Recently it has become possible to directly evaluate rTMS-induced changes at the cortical level using electronencephalography (EEG). The present study investigates the modulation induced by high-frequency rTMS via EEG by evaluating changes in the latency and amplitude of TMS-evoked responses. In this study, rTMS was applied to the left primary motor cortex (MI) in 16 participants while an EEG was simultaneously acquired from 29 scalp electrodes. The rTMS consisted of 40 trains at 20 Hz with 10 stimuli each (a total of 400 stimuli) that were delivered at the individual resting motor threshold. The on-line modulation induced by the high-frequency TMS was characterized by a sequence of EEG responses. Two of the rTMS-induced responses, P5 and N8, were specifically modulated according to the protocol. Their latency decreased from the first to the last TMS stimuli, while the amplitude values increased. These results provide the first direct, on-line evaluation of the effects of high-frequency TMS on EEG activity. In addition, the results provide a direct demonstration of cortical potentiation induced by rTMS in humans.

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