Administration Of rTMS Research Articles

Low-Frequency Repetitive TMS Plus Anodal Transcranial DCS Prevents Transient Decline in Bimanual Movement Induced by Contralesional Inhibitory rTMS After Stroke

Background. Low-frequency repetitive transcranial magnetic stimulation (rTMS) over the unaffected motor cortex may improve motor function of the paretic hand after stroke. However, low-frequency rTMS might adversely affect bimanual movement by decreasing transcallosal function. Objective. The authors investigated whether combined administration of rTMS and transcranial direct current stimulation (tDCS) prevents deterioration of bimanual movement induced by low-frequency rTMS over the unaffected hemisphere. Methods. A total of 27 participants with chronic subcortical stroke were randomly assigned to receive either 1 Hz rTMS over the unaffected hemisphere, anodal tDCS over the affected hemisphere, or a combination of rTMS and tDCS. All patients performed a pinching motor-training task after stimulation. Bimanual movement and transcallosal inhibition (TCI) were evaluated after stimulation. Results. rTMS and rTMS-tDCS enhanced the motor training effect on the paretic hand. rTMS decreased bimanual coordination and reduced TCI from the unaffected to the affected hemisphere (TCIunaff-aff). rTMS-tDCS changed TCI balance of both hemispheres but did not affect bimanual coordination or TCIunaff-aff. The change in bimanual coordination was negatively correlated with TCIunaff-aff. Following stimulation, improvement in the pinch force in the paretic hand was negatively correlated with TCI balance. Conclusions. Inhibitory rTMS over the unaffected hemisphere transiently caused deterioration of bimanual movements for the current task in stroke patients. This short-term decline was prevented by combined administration of low-frequency rTMS over the unaffected hemisphere and anodal tDCS over the affected hemisphere. These responses to bihemispheric stimulation suggest possible caution and opportunities for the rehabilitation of hand function after stroke.

Neural Correlates of the Antinociceptive Effects of Repetitive Transcranial Magnetic Stimulation on Central Pain After Stroke

Background. Repetitive transcranial magnetic stimulation (rTMS) modulates central neuropathic pain in some patients after stroke, but the mechanisms of action are uncertain. Objective. The authors used diffusion tensor imaging (DTI) and functional MRI (fMRI) to evaluate the integrity of the thalamocortical tract (TCT) and the activation pattern of the pain network in 22 patients with poststroke central pain. Methods. Each patient underwent daily 10-Hz rTMS sessions for 1000 pulses on 5 consecutive days over the hotspot for the first dorsal interosseus muscle. Pain severity was monitored using the Visual Analogue Scale (VAS). Mood was assessed by the Hamilton Depression Rating Scale. Results. Clinical data from all participants along with the DTI and fMRI findings from 10 patients were analyzed. VAS scores decreased significantly, if modestly, following administration of rTMS in 14 responders, which lasted for 2 weeks after the intervention. Regression analysis showed a significant correlation between less initial depression and higher antalgic effect of rTMS. Integrity of the superior TCT in the ipsilesional hemisphere showed significant correlation with change of VAS score after rTMS. fMRI showed significantly decreased activity in the secondary somatosensory cortex, insula, prefrontal cortex, and putamen in rTMS responders, whereas no change was noted in nonresponders. Conclusion. Mood may affect the modest antinociceptive effects of rTMS that we found, which may be mediated by the superior TCT through modulation of a distributed pain network.

The Use of Topical Lidocaine to Reduce Pain During Repetitive Transcranial Magnetic Stimulation for the Treatment of Depression

Repetitive transcranial magnetic stimulation (rTMS) is a form of neurostimulation therapy that was recently approved by the Food and Drug Administration for the treatment of depression. Repetitive transcranial magnetic stimulation is considered noninvasive and relatively safe; however, there have been reports of scalp pain during and at the site of stimulation. This case report documents the use of topical lidocaine to reduce scalp pain during rTMS administration. All patients had a diagnosis of major depressive disorder according to research diagnostic criteria and were washed off antidepressant medications before treatment. Patients were given active rTMS treatment during a masked, open-label, or long-term follow-up treatment schedule. Treatment was delivered to the left dorsolateral prefrontal cortex at 120% of the patient's observed motor threshold. Ten patients received 3000 magnetic pulses per session with an on time of 4 seconds and an off time of 26 seconds. Patients who reported pain during stimulation were given topical lidocaine HCl 2%, which was applied 20 minutes before treatment. Patients reported mixed outcomes of using topical lidocaine to reduce scalp pain during stimulation. Half of the patients reported no significant reduction in pain, whereas the other half indicated a noticeable decrease during rTMS. As a case report, our study has limited results. Given the recent approval of rTMS for the treatment of depression, additional studies are warranted to determine optimal methods of reducing scalp pain.

Paroxetine pretreatment does not change the effects induced in the rat cortical β-adrenergic receptor system by repetitive transcranial magnetic stimulation and electroconvulsive shock

Repetitive transcranial magnetic stimulation (rTMS) has been proposed as a clinically effective antidepressant treatment, but meta-analysis suggests that its efficacy is marginal. We investigated whether the administration of rTMS together with paroxetine would enhance its effects on the beta-adrenergic system of the rat. We compared our results with the effects of electroconvulsive shock therapy (ECS). The experiment was performed for 12 d on male Wistar rats that received a physical treatment of either rTMS (B=1.4 T, f=10 Hz, 300 s) or ECS (I=130 mA, f=50 Hz, t=500 ms), preceded by sterile water or paroxetine (10 mg/kg i.p. 30 min earlier). All rats were decapitated 24 h after the final treatment. Cyclic AMP (cAMP) was measured in cortical slices prelabelled with [3H]adenine and stimulated with noradrenaline. beta-adrenoceptor parameters (Bmax and KD) were assessed in the P2 fraction of cortical homogenates using [3H]CGP 12177 as a ligand. ECS resulted in down-regulation of both the cAMP response and beta-adrenoceptor density, while rTMS depressed only the responsiveness of the cAMP-generating system. Paroxetine, which was only effective in dampening the cAMP response, did not change the effects of either physical treatment. The data suggest that any possible interaction between paroxetine and rTMS or ECS does not involve the beta-adrenergic mechanisms.

Transcranial Magnetic Stimulation to Understand the Pathophysiology and Treatment of Substance Use Disorders

Recent studies support an association between substance use disorders (SUDs) and cortical excitability. Transcranial magnetic stimulation (TMS) is a non-invasive tool that can be used to assess cortical physiological processes (e.g., inhibition, excitation) and has proven to be a useful diagnostic tool in brain disorders associated with alterations in cortical excitability. In this manuscript, we review studies that employ TMS to evaluate cortical excitability in patients with SUDs. Furthermore, we discuss preliminary studies that examine repetitive TMS (rTMS) as a potential treatment for patients with SUDs. Although the use of TMS to evaluate and to treat those individuals with SUDs is in its early stages, these studies reveal significant alterations in both cortical inhibition and excitation. Specifically, elevated cortical inhibition was reported in both cocaine and nicotine dependent individuals, while one study demonstrated an increase in cortical excitability in those who use 3, 4-methylenedioxymethamphetamine (MDMA). Furthermore, three studies examining rTMS as a potential treatment in cocaine and nicotine addiction report decreases in the level of cravings and in the number of cigarettes smoked following rTMS administration to the dorsal lateral prefrontal cortex. Thus, TMS has provided early interesting findings vis à vis cortical excitability in SUDs. Moreover, preliminary evidence suggests that rTMS is efficacious in the treatment of cocaine and nicotine addiction. Further work is needed to enhance our understanding of the altered neurophysiology in SUDs as well as the ways in which rTMS treatment can be directed to optimize treatment.

Repetitive transcranial magnetic stimulation as treatment for anxiety disorders

Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive and generally well-tolerated method of focally stimulating brain regions. It has been shown to be efficacious in the treatment for depression, but only to a limited degree. It has also been investigated for the treatment of some anxiety disorders, particularly obsessive–compulsive disorder, post-traumatic stress disorder and panic disorder. While anecdotal reports and open studies have suggested a therapeutic role for rTMS in anxiety disorders, controlled studies, which have varied greatly in terms of rTMS administration, have not shown it to be superior to placebo. Furthermore, reports in animal models of anxiety have not been consistent. Therefore, to date, there is no convincing evidence for the clinical role of rTMS in anxiety disorders. Further research is needed, drawing on advances in our understanding of pathological neurocircuitry in anxiety disorders and the mechanisms of action by which rTMS may alter that neurocircuitry. With advances in neuroimaging technology, this understanding is likely to be more accessible than it has been in the past.

Acute prefrontal rTMS increases striatal dopamine to a similar degree as d-amphetamine

Prefrontal repetitive transcranial magnetic stimulation (rTMS) has been shown to increase striatal dopaminergic activity. Here we investigated dopaminergic neurotransmission using single photon emission computed tomography (SPECT) and [ 123I]IBZM to indirectly assess the change in endogenous striatal dopamine concentration upon rTMS as compared with d-amphetamine challenge. SPECT imaging was performed twice each in five patients during rTMS, and in two patients who received 0.3 mg/kg d-amphetamine. Administration of rTMS led to a mean relative decrease in striatal IBZM binding by 9.6 ± 6.2%, and d-amphetamine challenge ( n = 4) induced a mean relative reduction by 8 ± 2.95% (difference not statistically significant). Acute rTMS challenge showed similar striatal dopaminergic effects to those associated with the administration of d-amphetamine, a substance known to increase synaptic dopamine.

Chapter 42 Topics in transcranial magnetic stimulation

This chapter reviews the important areas regarding transcranial magnetic stimulation (TMS), which is making a significant impact in neuroscience, neurology, clinical neurophysiology, and psychiatry. Using the method in different ways, it can be used to measure central motor conduction times, determine physiological processes in the brain, and potentially treat various disorders. TMS has extra ordinary potential as a tool to investigate the pathophysiology of psychiatric disorders and as a therapeutic intervention for psychiatric illness. Examples in the study of schizophrenia are illustrated in the chapter. By far, the greatest focus in the field has been on using repetitive TMS (rTMS) as a potential antidepressant treatment. Conventional rTMS is intended to be non-convulsive and it is believed that daily administration of rTMS may result in significant therapeutic effects in major depression. Recently, it has been established that at very high intensity, rTMS may reliably produce generalized seizures in primates. This development offers a different approach to the treatment of severe major depression—that is, the replacement of transcranial electrical stimulation to induce seizures (electroconvulsive therapy (ECT)) with magnetic induction.

Intranasal stimulation of long-lasting immunity against aerosol ricin challenge with ricin toxoid vaccine encapsulated in polymeric microspheres

Intranasal (i.n.) immunization with ricin toxoid (RT) vaccine encapsulated in poly(lactide-co-glycolide) microspheres (RT-PLG-Ms) and poly(L-lactide) microspheres (RT-PLA-Ms) stimulated systemic and mucosal immune responses and protected mice from aerosolized ricin intoxication. High titers of anti-ricin IgG2a were stimulated in the serum of mice with one or two doses of RT-Ms 6 weeks postimmunization. However, in the lungs, no IgG2a or total IgG was elicited either with RT-Ms or with aqueous RT. At 6 weeks postimmunization, a single dose of the RT-Ms stimulated secretory IgA (sIgA) in the lungs of four of six mice, but a second immunizing dose did not enhance the stimulation. A single dose of aqueous RT vaccine failed to stimulate sIgA in the lungs, while, a second dose induced sIgA in 50% of the mice. One or two i.n. doses of RT-Ms protected most of the mice against lethal aerosol-delivered ricin toxin 6 weeks post-immunization. In contrast, protection was absent or marginal after one or two doses of aqueous RT vaccine. In both studies, the protection against lethal aerosol challenge was significantly better with one dose of RT-Ms than with two doses of aqueous vaccine, which may be attributed to the induction of sIgA in the lungs and the serum. Duration of the IgG2a and IgA in the serum, particularly that of IgG2a was much longer after the administration of RT-Ms than after the aqueous vaccine. The geometric mean IgG2a titers stimulated with two doses of RT-Ms remained high during 40 weeks postimmunization and were up to 25 times higher than the titers induced with aqueous RT vaccine. After 6 weeks, the IgG2a induced by two doses of aqueous vaccine was no longer detectable. Persistence of antibody response was predictive of efficacy. At 1 year postimmunization with two doses of RT-Ms, 100% of mice were protected against lethal ricin challenge. However, at the same time no protection was afforded by two doses of aqueous RT. The results of the present study consistently demonstrated the advantages of microencapsulated RT vaccine to stimulate effective and long-lasting protection by i.n. administration.