Brain Stimul
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Randomized Controlled Trial
Treatment of chronic neuropathic pain by motor cortex stimulation: results of a bicentric controlled crossover trial.
Chronic motor cortex stimulation (MCS) with surgically implanted epidural electrodes has been proposed as a treatment for neuropathic pain refractory compared with medical treatment. However, no prospective controlled trial has been published to provide convincing evidence of MCS analgesic efficacy. ⋯ These results were in favor of real analgesic effects produced by MCS with no loss of benefit over time. The differential changes in MPQ subscores suggested that MCS relieved pain by acting predominantly on its affective aspect. The decrease in pain intensity was associated with improved daily living activities and quality of life and reduced consumption of analgesic medication.
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Synaptic plasticity in the motor cortex is involved at least in some forms of motor learning. Recent evidence showed that the extent of practice-dependent plasticity in the motor cortex can be purposefully enhanced by experimental manipulation. One way of improving motor learning is to transiently increase the excitability of the motor cortex during motor learning. ⋯ This principle is being referred to as "gating." Another strategy to boost learning is to decrease the threshold for induction of synaptic plasticity by lowering neuronal activity in the motor cortex before practice. This approach invokes homeostatic metaplasticity. Here we highlight how transcranial brain stimulation can exploit gating and homeostatic metaplasticity to enhance motor learning in healthy subjects and in patients after stroke.
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Over the last two decades, deep brain stimulation (DBS) has become a recognized and effective clinical therapy for numerous neurological conditions. Since its inception, clinical DBS technology has progressed at a relatively slow rate; however, advances in neural engineering research have the potential to improve DBS systems. One such advance is the concept of current steering, or the use of multiple stimulation sources to direct current flow through targeted regions of brain tissue. The goals of this study were to develop a theoretical understanding of the effects of current steering in the context of DBS, and use that information to evaluate the potential utility of current steering during stimulation of the subthalamic nucleus. ⋯ These results provide motivation for the integration of current steering technology into clinical DBS systems, thereby expanding opportunities to customize DBS to individual patients, and potentially enhancing therapeutic efficacy.
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Repetitive transcranial magnetic stimulation (rTMS) is a novel, noninvasive method of stimulating selected regions of the brain that has both research applications and potential clinical utility, particularly for depression. To conduct high-quality clinical studies of rTMS, it is necessary to have a convincing placebo (or sham) treatment. Prefrontal rTMS causes cutaneous discomfort and muscle twitching; therefore, an optimal control condition, ie, sham condition, would mimic the cutaneous sensation and muscular discomfort of rTMS without stimulating the brain. Ideally, the quality and intensity of the sham condition would feel identical to the quality and intensity of the rTMS condition, except that the sham would have no effect on cortical activity. We designed and built a focal electrical stimulation system as a sham rTMS condition. Although this electrical sham system is superior to methods used in previous studies, little is known about how the new electrical sham system compares with active rTMS in terms of the level of discomfort and type of sensation it produces. ⋯ We conclude that it is possible to create a truly indistinguishable sham condition (with appropriate acoustic masking as well), but more work is needed beyond these initial attempts.
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Transcranial magnetic stimulation (TMS) is a relatively noninvasive brain stimulation technology that can focally stimulate the human cortex. One significant limitation of much of the TMS research to date concerns the nature of the placebo or sham conditions used. When TMS pulses are delivered repetitively (especially prefrontal TMS), it is often experienced as painful. Most sham TMS techniques produce identical sounds to active TMS, but they do not cause much, if any, scalp or facial sensation or discomfort. This is a serious problem when investigators are attempting to evaluate the effects of TMS by using traditional sham techniques because of unintended systematic differences between real and sham TMS groups (ie, confounds). As long as traditional approaches to sham TMS are used, the validity of the inferences regarding the efficacy of TMS will be limited. Although some other sophisticated systems have been developed to address these concerns, they tend to be expensive and lack portability. Portability will likely become more and more important as TMS applications expand into different clinical areas (eg, TMS in the postanesthesia care unit after surgery). ⋯ The eSham system may be a simple, affordable, and portable approach to providing convincing sham TMS for future clinical trials. This study provides preliminary evidence supporting the use of the eSham system. Future larger-scale studies are warranted.