Anodal Transcranial Direct Current Stimulation of the Motor Cortex Ameliorates Chronic Pain and Reduces Short Intracortical Inhibition

Department of Clinical Neurophysiology, Georg-August University, 37075 Göttingen, Germany.
Journal of pain and symptom management (Impact Factor: 2.8). 05/2010; 39(5):890-903. DOI: 10.1016/j.jpainsymman.2009.09.023
Source: PubMed


Consecutive sessions of transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) may be a suitable therapy to treat chronic pain, as it can modulate neural activities in the stimulated and interconnected regions.
The present study investigated the analgesic effect of five consecutive days of anodal/sham tDCS using subjective (visual analog scale [VAS]) and objective (cortical excitability measured by transcranial magnetic stimulation [TMS]) measurements.
Patients with therapy-resistant chronic pain syndromes (trigeminal neuralgia, poststroke pain syndrome, back pain, fibromyalgia) participated. As this clinical trial was an exploratory study, statistical analyses implemented exploratory methods. Twelve patients, who underwent both anodal and sham tDCS, were analyzed using a crossover design. An additional nine patients had only anodal or sham stimulation. tDCS was applied over the hand area of the M1 for 20 minutes, at 1mA for five consecutive days, using a randomized, double-blind design. Pain was assessed daily using a VAS rating for one month before, during, and one month post-stimulation. M1 excitability was determined using paired-pulse TMS.
Anodal tDCS led to a greater improvement in VAS ratings than sham tDCS, evident even three to four weeks post-treatment. Decreased intracortical inhibition was demonstrated after anodal stimulation, indicating changes in cortico-cortical excitability. No patient experienced severe adverse effects; seven patients suffered from light headache after anodal and six after sham stimulation.
Results confirm that five daily sessions of tDCS over the hand area of the M1 can produce long-lasting pain relief in patients with chronic pain.

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    • "No significant difference between the group effects on tension (F[1] [46] 5 0.34, P 5 0.561, h 2 p , 0.01) and stress (F[1] [46] 5 0.36, P 5 0.543, h 2 p , 0.01) was found; however, tension changed during the observed participation period as an effect of Time (F[6] [276] 5 2.17, P 5 0.046, h 2 p 5 0.05), but this effect was not evident for stress (F[2] [276] 5 1.06, P 5 0.388, h 2 p 5 0.02). Furthermore, there was no interaction between the 2 treatment conditions and tension (F[6] [276] "
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    ABSTRACT: Previous studies suggest that transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) reduces chronic pain levels. In this randomized controlled trial, we investigated the effects of 5 consecutive 20-minute sessions of 2-mA anodal tDCS directed to the M1 in 48 patients (45 females) with fibromyalgia. Changes in pain, stress, daily functioning, psychiatric symptoms, and health-related quality of life were measured. Pain and stress were measured 30 days before treatment, at each treatment, and 30 days after treatment by using short message service on mobile phones. Patients were randomized to the active or sham tDCS group by receiving individual treatment codes associated either with the sham or active tDCS in the stimulator. Adverse effects were registered using a standardized form. A small but significant improvement in pain was observed under the active tDCS condition but not under the sham condition. Fibromyalgia-related daily functioning improved in the active tDCS group compared with the sham group. The stimulation was well tolerated by the patients, and no significant difference in the adverse effects between the groups was observed. The results suggest that tDCS has the potential to induce statistically significant pain relief in patients with fibromyalgia, with no serious adverse effects, but small effect sizes indicate that the results are unlikely to reflect clinically important changes.
    Pain 01/2015; 156(1):62-71. DOI:10.1016/j.pain.0000000000000006 · 5.21 Impact Factor
    • "Further studies with additional H-reflex-measurements after cathodal stimulation and larger sample sizes are needed to explore the relationship between clinical effects and neurophysiology more deeply and to corroborate our findings. Future studies should also explore whether the clinical effects of anodal tsDCS can be enhanced, for example, by repeated stimulation [28] [33] similar to repetitive anodal tDCS for the treatment of chronic pain [14] [16]. Furthermore, the pathophysiology of RLS might influence the response to spinal stimulation. "
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    ABSTRACT: Background Transcutaneous spinal direct current stimulation (tsDCS) is a new non-invasive technique to modulate spinal cord activity. The pathophysiological concept of primary RLS proposes increased spinal excitability. Objective This pilot study used tsDCS to reduce pathologically enhanced spinal excitability in RLS patients and to thereby ameliorate clinical symptoms. Methods 20 patients with idiopathic RLS and 14 healthy subjects participated in this double-blinded, placebo-controlled study. All participants received one session of cathodal, anodal and sham stimulation of the thoracic spinal cord for 15 min (2.5 mA) each, in randomized order during their symptomatic phase in the evening. The soleus Hoffmann-reflex with Hmax/Mmax-ratio and seven different H2/H1-ratios (of two H-reflex responses to double stimuli) were measured. The RLS symptoms were assessed by a visual analogue scale (VAS). All parameters were measured before and twice after tsDCS. Results RLS patients showed increased H2/H1-ratios during their symptomatic phase in the evening. Application of anodal stimulation led to a decreased H2/H1-ratio for 0.2 and 0.3 sec interstimulus intervals in patients. Furthermore, application of anodal and cathodal stimulation led to a reduction in restless legs symptoms on the VAS, whereas application of sham stimulation had no effects on either the VAS or on the H2/H1-ratio in patients. VAS changes did not correlate with changes of H2/H1-ratios. Conclusions This is the first tsDCS study in idiopathic RLS, which resulted in short-lasting clinical improvement. Furthermore, our results support the pathophysiological concept of spinal cord hyperexcitability in primary RLS and provide the basis for a new non-pharmacological treatment tool.
    Brain Stimulation 09/2014; 7(5). DOI:10.1016/j.brs.2014.06.008 · 4.40 Impact Factor
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    • "We also aimed to determine the beginning and duration of tDCS-induced alterations. Several studies demonstrated that the effects of tDCS were stronger in the first 5 min after stimulation and persisted for about 20 min (Antal et al., 2010; Keeser et al., 2011b). Therefore, we studied the effects of tDCS over EEG power spectral parameters, specifically in theta, alpha, beta, and gamma bands, through a statistical analysis of variance, to determine: "
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    ABSTRACT: Transcranial direct current stimulation (tDCS) delivers low electric currents to the brain through the scalp. Constant electric currents induce shifts in neuronal membrane excitability, resulting in secondary changes in cortical activity. Concomitant electroencephalography (EEG) monitoring during tDCS can provide valuable information on the tDCS mechanisms of action. This study examined the effects of anodal tDCS on spontaneous cortical activity in a resting brain to disclose possible modulation of spontaneous oscillatory brain activity. EEG activity was measured in ten healthy subjects during and after a session of anodal stimulation of the postero-parietal cortex to detect the tDCS-induced alterations. Changes in the theta, alpha, beta, and gamma power bands were investigated. Three main findings emerged: (1) an increase in theta band activity during the first minutes of stimulation; (2) an increase in alpha and beta power during and after stimulation; (3) a widespread activation in several brain regions.
    Frontiers in Human Neuroscience 08/2014; 8:601. DOI:10.3389/fnhum.2014.00601 · 3.63 Impact Factor
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