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S11-3 Repetitive transcranial magnetic stimulation (rTMS) for neuropathic pain
S22
Oral Presentations: Symposia
and safety of conventional TMS protocols, undesired effects and risks of emerging TMS interventions, the applications of TMS in patients with implanted electrodes in the central nervous system, safety aspects of TMS in neuroimaging environments, and emerging safety issues related to the use of deep coils for stimulation. S11-2 Combined TMS and fMRI for studying network effects of TMS 1
S. Bestmann Sobell Department, Institute of Neurology, University College London, United Kingdom
1
A detailed understanding of the distributed consequences elicited by TMS is critical in light of rise in studies attempting to use TMS to promote plasticity in basic neuroscience and therapeutic settings. In combination with neuroimaging, TMS can now be used to study the consequences of functional interactions between the stimulated region and other parts of the network. Two main issues are of relevance for studying representational plasticity as promoted by TMS: (a) Measures of targeted brain networks that identify the brain regions remote to the stimulation site on which TMS impacts, (b) higlighting degenerate brain systems that may explain the frequent lack of functional consequences to rTMS, despite their established physiological impact. We will illustrate this using combined TMS-fMRI as one approach to highlight state-dependent interregional interactions during TMS in the healthy brain and after stroke. Importantly, we illustrate how model-based approaches such as dynamic causal modelling (DCM) express testable hypotheses in terms of neural connectivity, and how rTMS exerts its local and remote influences that ultimately must occur to promote plasticity. Such approaches have lead to a reappraisal of strictly modular views of TMS research of brain function, that emphasize functional properties of single (directly stimulated) brain regions, towards new perspectives on how TMS can change functional interactions between remote but interconnected brain regions. Critically, combined TMS & neuroimaging provides a handle on how TMS-evoked changes trigger the network changes that may support and promote therapeutic effects. For understanding TMS-evoked plastic changes at a functional and systems level, the combination with neuroimaging is not an optional, but a necessary condition. S11-3 Repetitive transcranial magnetic stimulation (rTMS) for neuropathic pain Y. Saitoh1 , K. Hosomi1 , H. Kishima1 , T. Goto1 , T. Yoshimine1 1 Osaka University Graduate School of Medicine, Japan The precentral gyrus (M1) is a representative target for electrical stimulation therapy of intractable neuropathic pain (NP). According to recent reports, rTMS can provide an effect similar to that of electrical stimulation. We have already performed rTMS on M1 for 120 patients with NP. Therefore, we would like to report the results and discuss about the mechanism of pain reduction with M1 stimulation. The parameters of rTMS were 5 Hz (total 500 or 1500 pulses) and 90% resting motor threshold. Averaged rates of pain reduction with rTMS were 23.2% (VAS) and 34.6% (SF-MPQ), and effective rates (30% pain reduction) were 31% (VAS) and 49% (SF-MPQ). In comparison between real and sham stimulations, averaged rates of pain reduction in VAS were 28.6% (real) and 13.8% (sham), and effective rates were 43% (real) and 13% (sham). There were significant differences between real and sham stimulations. In PET study, significant rCBF increases were identified in the posterior thalamus, insula, anterior cingulate cortex and orbitofrontal cortex after the electrical stimulation of M1 (J Neurosurg, 2007). In the tractography study of post-stroke pain, the rTMS effective group had higher delineation ratio of the cortico-spinal tract (p = 0.02) and thalamo-cortical tract (p = 0.005) than the rTMS-ineffective group (Pain, 2008). NP is significantly reduced by 5 Hz rTMS in comparison with sham stimulation. rTMS is suggested to modulate the pathways from the insula and orbitpfrontal cortex to posterior thalamus to upregulate the pain threshold and pathways from the posterior insula to the anterior cingulate cortex to control emotional perception. Thalamo-cortical tract may play a role in pain reduction by rTMS of M1. rTMS of M1 may modulate pain threshold through thalamocortical tract and at the same time, control the emotional perception related with NP.
S11-4 Neuroanatomical correlates of therapeutic efficacy of transcranial magnetic stimulation in the treatment of depression S. Kito1 1 Department of Neuropsychiatry, Kyorin University School of Medicine, Tokyo, Japan Transcranial magnetic stimulation (TMS) is a potential tool for the treatment of neurological and psychiatric disorders, and there is growing evidence that TMS of the dorsolateral prefrontal cortex is effective in the treatment of depression. Most studies of TMS for depression have used high-frequency left prefrontal stimulation (HFLS) and a number of double-blind, randomized, sham-controlled trials support antidepressant effects of HFLS in depression. Several studies have indicated that low-frequency right prefrontal stimulation (LFRS) is also effective in depression. Brain imaging studies in depression have revealed that several brain regions, especially the prefrontal cortex, anterior cingulate, subgenual cingulate, and orbitofrontal cortex are involved in the pathophysiology of depression. According to earlier studies, patients with depression generally show decreased cerebral blood flow (CBF) in the prefrontal cortex and anterior cingulate, and increased CBF in the subgenual cingulate and orbitofrontal cortex. In addition, the abnormal perfusion is known to be changed with recovery from depression. Recent brain imaging studies using TMS have shown that HFLS increases CBF in the prefrontal cortex, and the therapeutic efficacy is correlated with increases in CBF in the prefrontal cortex and subcortical regions, whereas, LFRS decreases CBF in several brain regions with improvement of depression, and the therapeutic efficacy is correlated with decreases in the subgenual cingualte and orbitofrontal cortex. Therefore, it seems that HFLS normalize hypoperfusion in the prefrontal cortex, and LFRS alleviates hyperperfusion in the subgenual cingulate and orbitofrontal cortex. Recent studies suggest that these brain regions play a critical role in the treatment of depression using TMS and raise the possibility that both HFLS and LFRS may have mutually complementary effects in recovery from depression. S11-5 rTMS application in epilepsy Y. Wang1 1 Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China Transcranial magnetic stimulation (TMS) was developed in 1985 by Anthony Barker at the University of Sheffield. With regard to epilepsy, TMS is used for probing cortical excitability, for detecting the effects of antiepileptic drugs on excitatory and inhibitory brain mechanisms, for the preoperative localization of the epileptogenic zone and for mapping functionally important areas of the cortex. Recently, several studies have investigated the therapeutic potential of repetitive TMS (rTMS) in treating drug-resistant epilepsies. rTMS can produce outlasting effects that can be used to modulate neuronal activity in a targeted area of dysfunctional cortex to functional benefit. TMS-induced effects depends on the frequency, intensity and length of time for which the stimulation is applied. In general, low-frequency rTMS (less than 1 Hz) reduces cortical excitability. In contrast, higher frequencies (more than 5 Hz) enhance cortical excitability. These effects are reminiscent of longterm depression (LTD) and long term potentiation (LTP). Accordingly, low-frequency rTMS may exert antiepileptic effects by inducing LTD. The antiepileptic effects of TMS were investigated in open-label studies, single case studies, small scale series, and randomized controlled studies. The factors related with the therapeutic effects include frequency, intensity, coil shape, stimulation location and patient characteristics. S11-6 Potentiation and depotentiation of the motor cortex induced by quadripulse stimulation (QPS) H. Enomoto1 Department of Neurology, Fukushima Medical University, Fukushima, Japan
1
Purpose: The bidirectional excitability modulation is requisite for normal central nervous system function. The depotentiation of some already potentiated function may play some roles in getting rid of unnecessary, old knowledge in human brain. The aim of this study is to show QPS induced depotentiation of the potentiation already induced by QPS.
Oral Presentations: Symposia
and safety of conventional TMS protocols, undesired effects and risks of emerging TMS interventions, the applications of TMS in patients with implanted electrodes in the central nervous system, safety aspects of TMS in neuroimaging environments, and emerging safety issues related to the use of deep coils for stimulation. S11-2 Combined TMS and fMRI for studying network effects of TMS 1
S. Bestmann Sobell Department, Institute of Neurology, University College London, United Kingdom
1
A detailed understanding of the distributed consequences elicited by TMS is critical in light of rise in studies attempting to use TMS to promote plasticity in basic neuroscience and therapeutic settings. In combination with neuroimaging, TMS can now be used to study the consequences of functional interactions between the stimulated region and other parts of the network. Two main issues are of relevance for studying representational plasticity as promoted by TMS: (a) Measures of targeted brain networks that identify the brain regions remote to the stimulation site on which TMS impacts, (b) higlighting degenerate brain systems that may explain the frequent lack of functional consequences to rTMS, despite their established physiological impact. We will illustrate this using combined TMS-fMRI as one approach to highlight state-dependent interregional interactions during TMS in the healthy brain and after stroke. Importantly, we illustrate how model-based approaches such as dynamic causal modelling (DCM) express testable hypotheses in terms of neural connectivity, and how rTMS exerts its local and remote influences that ultimately must occur to promote plasticity. Such approaches have lead to a reappraisal of strictly modular views of TMS research of brain function, that emphasize functional properties of single (directly stimulated) brain regions, towards new perspectives on how TMS can change functional interactions between remote but interconnected brain regions. Critically, combined TMS & neuroimaging provides a handle on how TMS-evoked changes trigger the network changes that may support and promote therapeutic effects. For understanding TMS-evoked plastic changes at a functional and systems level, the combination with neuroimaging is not an optional, but a necessary condition. S11-3 Repetitive transcranial magnetic stimulation (rTMS) for neuropathic pain Y. Saitoh1 , K. Hosomi1 , H. Kishima1 , T. Goto1 , T. Yoshimine1 1 Osaka University Graduate School of Medicine, Japan The precentral gyrus (M1) is a representative target for electrical stimulation therapy of intractable neuropathic pain (NP). According to recent reports, rTMS can provide an effect similar to that of electrical stimulation. We have already performed rTMS on M1 for 120 patients with NP. Therefore, we would like to report the results and discuss about the mechanism of pain reduction with M1 stimulation. The parameters of rTMS were 5 Hz (total 500 or 1500 pulses) and 90% resting motor threshold. Averaged rates of pain reduction with rTMS were 23.2% (VAS) and 34.6% (SF-MPQ), and effective rates (30% pain reduction) were 31% (VAS) and 49% (SF-MPQ). In comparison between real and sham stimulations, averaged rates of pain reduction in VAS were 28.6% (real) and 13.8% (sham), and effective rates were 43% (real) and 13% (sham). There were significant differences between real and sham stimulations. In PET study, significant rCBF increases were identified in the posterior thalamus, insula, anterior cingulate cortex and orbitofrontal cortex after the electrical stimulation of M1 (J Neurosurg, 2007). In the tractography study of post-stroke pain, the rTMS effective group had higher delineation ratio of the cortico-spinal tract (p = 0.02) and thalamo-cortical tract (p = 0.005) than the rTMS-ineffective group (Pain, 2008). NP is significantly reduced by 5 Hz rTMS in comparison with sham stimulation. rTMS is suggested to modulate the pathways from the insula and orbitpfrontal cortex to posterior thalamus to upregulate the pain threshold and pathways from the posterior insula to the anterior cingulate cortex to control emotional perception. Thalamo-cortical tract may play a role in pain reduction by rTMS of M1. rTMS of M1 may modulate pain threshold through thalamocortical tract and at the same time, control the emotional perception related with NP.
S11-4 Neuroanatomical correlates of therapeutic efficacy of transcranial magnetic stimulation in the treatment of depression S. Kito1 1 Department of Neuropsychiatry, Kyorin University School of Medicine, Tokyo, Japan Transcranial magnetic stimulation (TMS) is a potential tool for the treatment of neurological and psychiatric disorders, and there is growing evidence that TMS of the dorsolateral prefrontal cortex is effective in the treatment of depression. Most studies of TMS for depression have used high-frequency left prefrontal stimulation (HFLS) and a number of double-blind, randomized, sham-controlled trials support antidepressant effects of HFLS in depression. Several studies have indicated that low-frequency right prefrontal stimulation (LFRS) is also effective in depression. Brain imaging studies in depression have revealed that several brain regions, especially the prefrontal cortex, anterior cingulate, subgenual cingulate, and orbitofrontal cortex are involved in the pathophysiology of depression. According to earlier studies, patients with depression generally show decreased cerebral blood flow (CBF) in the prefrontal cortex and anterior cingulate, and increased CBF in the subgenual cingulate and orbitofrontal cortex. In addition, the abnormal perfusion is known to be changed with recovery from depression. Recent brain imaging studies using TMS have shown that HFLS increases CBF in the prefrontal cortex, and the therapeutic efficacy is correlated with increases in CBF in the prefrontal cortex and subcortical regions, whereas, LFRS decreases CBF in several brain regions with improvement of depression, and the therapeutic efficacy is correlated with decreases in the subgenual cingualte and orbitofrontal cortex. Therefore, it seems that HFLS normalize hypoperfusion in the prefrontal cortex, and LFRS alleviates hyperperfusion in the subgenual cingulate and orbitofrontal cortex. Recent studies suggest that these brain regions play a critical role in the treatment of depression using TMS and raise the possibility that both HFLS and LFRS may have mutually complementary effects in recovery from depression. S11-5 rTMS application in epilepsy Y. Wang1 1 Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China Transcranial magnetic stimulation (TMS) was developed in 1985 by Anthony Barker at the University of Sheffield. With regard to epilepsy, TMS is used for probing cortical excitability, for detecting the effects of antiepileptic drugs on excitatory and inhibitory brain mechanisms, for the preoperative localization of the epileptogenic zone and for mapping functionally important areas of the cortex. Recently, several studies have investigated the therapeutic potential of repetitive TMS (rTMS) in treating drug-resistant epilepsies. rTMS can produce outlasting effects that can be used to modulate neuronal activity in a targeted area of dysfunctional cortex to functional benefit. TMS-induced effects depends on the frequency, intensity and length of time for which the stimulation is applied. In general, low-frequency rTMS (less than 1 Hz) reduces cortical excitability. In contrast, higher frequencies (more than 5 Hz) enhance cortical excitability. These effects are reminiscent of longterm depression (LTD) and long term potentiation (LTP). Accordingly, low-frequency rTMS may exert antiepileptic effects by inducing LTD. The antiepileptic effects of TMS were investigated in open-label studies, single case studies, small scale series, and randomized controlled studies. The factors related with the therapeutic effects include frequency, intensity, coil shape, stimulation location and patient characteristics. S11-6 Potentiation and depotentiation of the motor cortex induced by quadripulse stimulation (QPS) H. Enomoto1 Department of Neurology, Fukushima Medical University, Fukushima, Japan
1
Purpose: The bidirectional excitability modulation is requisite for normal central nervous system function. The depotentiation of some already potentiated function may play some roles in getting rid of unnecessary, old knowledge in human brain. The aim of this study is to show QPS induced depotentiation of the potentiation already induced by QPS.