39. Cortical excitability in high-frequency repetitive transcranial magnetic stimulation for intractable neuropathic pain

Background: Increasing evidence supports an analgesic effect of repetitive transcranial magnetic stimulation (rTMS) for neuropathic pain (NP). However, the optimal parameters of rTMS (stimulation frequency and treatment sessions) for achieving long-term analgesic effects remain unknown. This study analyzed the current findings in the literature. Objective: The aim of this study was to assess the optimal parameters of rTMS for NP, including the rTMS sessions needed for inducing acute as well as long-term analgesic effects. Study Design: A meta-analysis of the analgesic effect of high frequency rTMS (HF- rTMS) for neuropathic patients. Setting: This meta-analysis examined all studies involving the analgesic efficacy of HF-rTMS for NP. Methods: PubMed, Embase, and the Cochrane library were searched for clinical studies of rTMS treatment on NP published before December 31, 2014. Crude standardized mean differences (SMD) with 95% confidence interval (CI) were calculated for pain intensity after different treatment sessions (from 1 to 10) and follow-up of one or 2 months after rTMS treatment using random effect models. Results: Twenty-five studies (including 32 trials and 589 patients) were selected for the metaanalysis according to the inclusion and exclusion criteria. All 3 HF-rTMS treatments (5, 10, and 20 Hz) produced pain reduction, while there were no differences between them, with the maximal pain reduction found after one and 5 sessions of rTMS treatment. Further, this significant analgesic effect remained forone month after 5 sessions of rTMS treatment. Limitations: There are limitations of this meta-analysis. For example, the long-term analgesic effects of different HF-rTMS and low frequency (LF) rTMS sessions, including the single session of rTMS on different NP of varying origins have yet not been evaluated; the full degree of pain relief is still unclear for many rTMS studies. Conclusions: HF-rTMS stimulation on primary motor cortex is effective in relieving pain in NP patients. Although 5 sessions of rTMS treatment produced a maximal analgesic effect and may be maintained for at least one month, further large-scale and well-controlled trials are needed to determine if this enhanced effect is specific to certain types of NP such as post-stroke related central NP. Key words: High frequency, repetitive transcranial magnetic stimulation, neuropathic pain, single stimulation, multiple stimulation, meta-analysis

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Changes in motor cortical excitability induced by high-frequency repetitive transcranial magnetic stimulation of different stimulation durations

Clinical Neurophysiology ◽

10.1016/j.clinph.2007.09.124 ◽

2008 ◽

Vol 119 (1) ◽

pp. 71-79 ◽

Cited By ~ 44

Author(s):

Se Hee Jung ◽

Jae Eun Shin ◽

Yong-Seol Jeong ◽

Hyung-Ik Shin

Keyword(s):

Transcranial Magnetic Stimulation ◽

High Frequency ◽

Magnetic Stimulation ◽

Cortical Excitability ◽

Repetitive Transcranial Magnetic Stimulation ◽

Motor Cortical Excitability ◽

Motor Cortical ◽

Stimulation Of

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

Journal of Neurophysiology ◽

10.1152/jn.00172.2010 ◽

2010 ◽

Vol 104 (3) ◽

pp. 1578-1588 ◽

Cited By ~ 25

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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High-Frequency Transcranial Magnetic Stimulation on Motor Cortex of Patients Affected by Migraine With Aura: A Way to Restore Normal Cortical Excitability?

Cephalalgia ◽

10.1111/j.1468-2982.2009.01870.x ◽

2009 ◽

Vol 30 (1) ◽

pp. 46-52 ◽

Cited By ~ 35

Author(s):

F Brighina ◽

A Palermo ◽

O Daniele ◽

A Aloisio ◽

B Fierro

Keyword(s):

Transcranial Magnetic Stimulation ◽

Motor Cortex ◽

Migraine With Aura ◽

High Frequency ◽

Magnetic Stimulation ◽

Cortical Excitability ◽

Repetitive Transcranial Magnetic Stimulation ◽

Motor Evoked Potential ◽

Intracortical Inhibition ◽

Healthy Controls

We showed reduced motor intracortical inhibition (ICI) and paradoxical increase of intracortical facilitation (ICF) to 1 Hz repetitive transcranial magnetic stimulation (rTMS) in patients affected by migraine with aura (MA). In conditions of enhanced excitability due to a reduced inhibition, high-frequency rTMS was found to potentiate intracortical inhibition. Here we explored the conditioning effects of high-frequency priming stimulation of motor cortex with the aim of normalizing excitability reverting paradoxical facilitation by 1 Hz rTMS in MA. Nine patients with MA and nine healthy controls underwent a paired-pulse TMS paradigm to evaluate motor intracortical excitability (ICI and ICF) before and after the following rTMS conditions: 1 Hz alone or preceded by a real or sham conditioning high-frequency (10 Hz) rTMS. Sham was used to control for rTMS specificity. In baseline, ICI was significantly lower in migraineurs with respect to controls. One hertz stimulation reduced motor evoked potential amplitude and ICF in healthy controls, while it caused a significant paradoxical ICF increase in migraineurs. High-frequency rTMS conditioning normalized excitability in migraine, increasing short ICI and so reversing the paradoxical effects of 1 Hz rTMS. These findings raise the possibility that the interictal reduced intracortical inhibition in migraine could be normalized by high-frequency rTMS. This would open perspectives for new treatment strategies in migraine prevention.

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