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Query: UMLS:C0030193 (pain)
 261,466 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Using voltage-time-dependent negative resistance characteristics of Voltage-Current curves of excitable cell membranes estimated without using artificial voltage clamp method, the author made a quantitative analysis of excitability of cell membranes and different conditions of transmembrane action potentials as a bias voltage to the negative resistance of the excitable cell membrane. The pacemaker cells were classified as "Astable Oscillators" and nonpacemaker excitable cells as "Monostable Oscillators," and application of a rapidly changing electromagnetic field to the cells was analyzed as a means of stimulating the cells. The understanding of the 10 essential electrical parameters is highly desirable for safe and effective electrical stimulation. Among these, emphasis was placed on the often neglected, important electrical parameters of "output impedance" of stimulation pulse wave complexes for + and - polarity components, as well as the importance of capacitive current (Ic = C.dV/dt) which depends on rise time as well as fall time of the stimulation pulse wave, and undesirable side effects of electrolysis phenomena due to excessive D.C. current. The difference and similarity between TENS (Transcutaneous Nerve Stimulation) and TES (Transcutaneous Electrical Stimulation), TENMS (Transcutaneous Electrical Nerve and Muscle Stimulation) or TMS (Transcutaneous Muscle Stimulation) was discussed. The author's clinical study indicated that effective TES (TENMS)--characterized by effective muscle contraction without creating pain with a pulse repetition rate approximately the same as the heart rate of the individual--can often give superior beneficial effects in improvement of micro-circulation and subsequent relief of pain and other symptoms compared with TENS that creates stimulation of large diameter sensory nerve fibers without creating significant muscle contraction. Such improvement is often accompanied by the abolishment of the pain with disappearance of local substance P and increase in local serotonin with disappearance of local L-tryptophan.
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PMID:Basic electrical parameters for safe and effective electro-therapeutics [electro-acupuncture, TES, TENMS (or TEMS), TENS and electro-magnetic field stimulation with or without drug field] for pain, neuromuscular skeletal problems, and circulatory disturbances. 289 68

Only about 50% of central pain patients respond to motor cortex stimulation in the long run. There is a need for prognostic factors. Here we show that propofol test and TMS both predict short-term effect in nine patients with central pain. This may help reduce the number of failures.
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PMID:Low-rate repetitive TMS allays central pain. 1263 13

Noninvasive electrical stimulation of the human brain first was attempted in the 1950s. In the early 1980s, the first clinical application method of transcranial electrical stimulation was developed. Investigators in the mid-1980s showed that it was possible to stimulate the nerve and the brain using external magnetic stimulation (transcranial magnetic stimulation [TMS]), with little or no pain. TMS now is used commonly in clinical neurology to study central motor conduction time. Depending on the stimulation techniques and parameters, TMS can excite or inhibit brain activity, allowing functional mapping of cortical regions and creation of transient functional lesions. It now is used widely as a research tool to study aspects of human brain physiology, including motor function and the pathophysiology of various brain disorders.
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PMID:Motor evoked potentials. 1502 2

There is some evidence that repetitive transcranial magnetic stimulation (rTMS) can alleviate the experience of chronic pain. The mechanisms by which rTMS may induce pain relief, however, are unknown. The present study examined whether a session of rTMS would produce sensory threshold changes in healthy individuals. Detection and pain thresholds for cold sensations were compared following low frequency (1 Hz) (Experiment 1) and high frequency (20 Hz) (Experiment 2) repetitive TMS. While cold detection threshold was significantly lowered by both rTMS rates, only high frequency rTMS produced a significant change in cold pain threshold. In contrast, sham rTMS did not alter thresholds for cold stimuli. These findings provide evidence that sensory thresholds can be influenced by repetitive transcranial magnetic stimulation.
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PMID:Changes to cold detection and pain thresholds following low and high frequency transcranial magnetic stimulation of the motor cortex. 1535 48

Drug-resistant, neurogenic pain can be treated by chronic motor cortex stimulation using surgically-implanted epidural electrodes. High-frequency, subthreshold repetitive transcranial magnetic stimulation (rTMS) of the motor cortex was shown to be able to produce antalgic effects, at least transiently, in patients with chronic pain. Nevertheless, other cortical targets than the primary motor cortex are tempting (parietal or prefrontal areas for instance) for the management of pain and need to be studied. Motor cortex TMS was also found to modulate non-nociceptive sensory perception as well as acutely provoked pain in healthy subjects by means of a single conditioning pulse or repeated trains. On the contrary, spontaneous or provoked pain was shown to modify motor cortex excitability, as assessed by TMS technique. Taking into account all these observations, it appears that motor cortex function and pain process are closely related and that TMS is a potent tool to explore and to understand this relationship. Beyond this physiological purpose, rTMS could be useful to control episodes of neurogenic pain of limited duration or to select patients for the surgical implantation of a cortical stimulator.
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PMID:Transcranial magnetic stimulation in the management of pain. 1610 77

The precentral gyrus (M1) is a representative target for electrical stimulation therapy of pain. To date, few researchers have investigated whether pain relief is possible by stimulation of cortical areas other than M1. According to recent reports, repetitive transcranial magnetic stimulation (rTMS) can provide an effect similar to that of electrical stimulation. With this in mind, we therefore examined several cortical areas as stimulation targets using a navigation-guided rTMS and compared the effects of the different targets on pain. Twenty patients with intractable deafferentation pain received rTMS of M1, the postcentral gyrus (S1), premotor area (preM), and supplementary motor area (SMA). Each target was stimulated with ten trains of 10-s 5-Hz TMS pulses, with 50-s intervals in between trains. Intensities were adjusted to 90% of resting motor thresholds. Thus, a total of 500 stimuli were applied. Sham stimulations were undertaken at random. The effect of rTMS on pain was rated by patients using a visual analogue scale (VAS) and the short form of the McGill Pain Questionnaire (SF-MPQ). Ten of the 20 patients (50%) indicated that stimulation of M1, but not other areas, provided significant and beneficial pain relief (p<0.01). Results indicated a statistically significant effect lasting for 3 hours after the stimulation of M1 (p<0.05). Stimulation of other targets was not effective. The M1 was the sole target for treating intractable pain with rTMS, in spite of the fact that M1, S1, preM, and SMA are located adjacently.
Pain 2006 May
PMID:Reduction of intractable deafferentation pain by navigation-guided repetitive transcranial magnetic stimulation of the primary motor cortex. 1656 23

Cortical excitability changes induced by tDCS and revealed by TMS, are increasingly being used as an index of neuronal plasticity in the human cortex. The aim of this paper is to summarize the partially adverse effects of 567 tDCS sessions over motor and non-motor cortical areas (occipital, temporal, parietal) from the last 2 years, on work performed in our laboratories. One-hundred and two of our subjects who participated in our tDCS studies completed a questionnaire. The questionnaire contained rating scales regarding the presence and severity of headache, difficulties in concentrating, acute mood changes, visual perceptual changes and any discomforting sensation like pain, tingling, itching or burning under the electrodes, during and after tDCS. Participants were healthy subjects (75.5%), migraine patients (8.8%), post-stroke patients (5.9%) and tinnitus patients (9.8%). During tDCS a mild tingling sensation was the most common reported adverse effect (70.6%), moderate fatigue was felt by 35.3% of the subjects, whereas a light itching sensation under the stimulation electrodes occurred in 30.4% of cases. After tDCS headache (11.8%), nausea (2.9%) and insomnia (0.98%) were reported, but fairly infrequently. In addition, the incidence of the itching sensation (p=0.02) and the intensity of tingling sensation (p=0.02) were significantly higher during tDCS in the group of the healthy subjects, in comparison to patients; whereas the occurrence of headache was significantly higher in the patient group (p=0.03) after the stimulation. Our results suggest that tDCS applied to motor and non-motor areas according to the present tDCS safety guidelines, is associated with relatively minor adverse effects in healthy humans and patients with varying neurological disorders.
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PMID:Safety aspects of transcranial direct current stimulation concerning healthy subjects and patients. 1745 83

Pharmacological relief of neuropathic pain is often insufficient. Electrical neurostimulation is efficacious in chronic neuropathic pain and other neurological diseases. European Federation of Neurological Societies (EFNS) launched a Task Force to evaluate the evidence for these techniques and to produce relevant recommendations. We searched the literature from 1968 to 2006, looking for neurostimulation in neuropathic pain conditions, and classified the trials according to the EFNS scheme of evidence for therapeutic interventions. Spinal cord stimulation (SCS) is efficacious in failed back surgery syndrome (FBSS) and complex regional pain syndrome (CRPS) type I (level B recommendation). High-frequency transcutaneous electrical nerve stimulation (TENS) may be better than placebo (level C) although worse than electro-acupuncture (level B). One kind of repetitive transcranial magnetic stimulation (rTMS) has transient efficacy in central and peripheral neuropathic pains (level B). Motor cortex stimulation (MCS) is efficacious in central post-stroke and facial pain (level C). Deep brain stimulation (DBS) should only be performed in experienced centres. Evidence for implanted peripheral stimulations is inadequate. TENS and r-TMS are non-invasive and suitable as preliminary or add-on therapies. Further controlled trials are warranted for SCS in conditions other than failed back surgery syndrome and CRPS and for MCS and DBS in general. These chronically implanted techniques provide satisfactory pain relief in many patients, including those resistant to medication or other means.
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PMID:EFNS guidelines on neurostimulation therapy for neuropathic pain. 1771 86

Previous studies have shown that low-frequency repetitive transcranial magnetic stimulation (rTMS) suppresses motor-evoked potentials (MEPs) evoked by single pulse TMS. The aim of the present paper was to investigate the central nervous system level at which rTMS produces a suppression of MEP amplitude. We recorded corticospinal volleys evoked by single pulse TMS of the motor cortex before and after 1 Hz rTMS in five conscious subjects who had an electrode implanted in the cervical epidural space for the control of pain. One of the patients had Parkinson's disease and was studied on medication. Repetitive TMS significantly suppressed the amplitude of later I-waves, and reduced the amplitude of concomitantly recorded MEPs. The earliest I-wave was not significantly modified by rTMS. The present results show that 1 Hz rTMS may decrease the amplitude of later descending waves, consistent with a cortical origin of the effect of 1 Hz rTMS on MEPs.
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PMID:Low-frequency repetitive transcranial magnetic stimulation suppresses specific excitatory circuits in the human motor cortex. 1865 55

Expectations and beliefs modulate the experience of pain, which is particularly evident in placebo analgesia. The dorsolateral prefrontal cortex (DLPFC) has been associated with pain regulation and with the generation, maintenance and manipulation of cognitive representations, consistent with its role in expectation. In a heat-pain paradigm, we employed non-invasive low-frequency repetitive transcranial magnetic stimulation (rTMS) to transiently disrupt left and right DLPFC function or used the TMS device itself as a placebo, before applying an expectation-induced placebo analgesia. The results demonstrated that placebo significantly increased pain threshold and pain tolerance. While rTMS did not affect pain experience, it completely blocked placebo analgesia. These findings suggest that expectation-induced placebo analgesia is mediated by symmetric prefrontal cortex function.
Pain 2010 Mar
PMID:Prefrontal cortex modulates placebo analgesia. 1987 33


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