Transient Changes in Brain Metabolites after Transcranial Direct Current Stimulation in Spastic Cerebral Palsy: A Pilot Study.

BACKGROUND: Muscle spasticity is a disability caused by damage to the pyramidal system. Standard treatments for spasticity include muscle stretching, antispastic medications, and tendon release surgeries, but treatment outcomes remain unsatisfactory. Anodal transcranial direct current stimulation (tDCS) in patients with muscle spasticity is known to result in significant improvement in spastic tone (p < 0.001). However, the mechanism of action by which tDCS treatment affects spasticity remains unclear. This pilot study aimed to investigate the effect of anodal tDCS upon brain metabolites in the left basal ganglia and ipsilateral primary motor cortex (M1) in children with spastic cerebral palsy (CP). MATERIALS AND METHODS: This study consisted of three steps: a baseline evaluation, a treatment period, and a follow-up period. During the treatment period, patients were given 20 min of 1 mA anodal tDCS over the left M1 for five consecutive days. Outcomes were compared between pre- and immediate posttreatment in terms of brain metabolites, Tardieu scales, and the quality of upper extremity skills test. RESULTS: Ten patients with spastic CP were enrolled. Following tDCS, there were significant increases in the ratio of N-acetylaspartate (NAA)/creatine (Cr) (p = 0.030), choline (Cho)/Cr (p = 0.043), and myoinositol (mI)/Cr (p = 0.035) in the basal ganglia. Moreover, increased glutamine-glutamate (Glx)/Cr ratio in the left M1 (p = 0.008) was found. In addition, we also observed improvements in the extent of spasticity and hand function (p = 0.028). CONCLUSION: Five consecutive days of anodal tDCS over the left M1 appeared statistically to reduce the degree of spasticity and increase NAA, Cho, mI, and Glx. Future research studies, involving a larger sample size of spastic CP patients undergoing tDCS is now warranted.

The effects of transcranial direct current stimulation in patients with neuropathic pain from spinal cord injury.

OBJECTIVE: Transcranial direct current stimulation (tDCS) has demonstrated efficacy for reducing neuropathic pain, but the respective mechanisms remain largely unknown. The current study tested the hypothesis that pain reduction with tDCS is associated with an increase in the peak frequency spectrum density in the theta-alpha range. METHODS: Twenty patients with spinal cord injury and bilateral neuropathic pain received single sessions of both sham and anodal tDCS (2 mA) over the left primary motor area (M1) for 20 min. Treatment order was randomly assigned. Pre- to post-procedure changes in pain intensity and peak frequency of electroencephalogram spectral analysis were compared between treatment conditions. RESULTS: The active treatment condition (anodal tDCS over M1) but not sham treatment resulted in significant decreases in pain intensity. In addition, consistent with the study hypothesis, peak theta-alpha frequency (PTAF) assessed from an electrode placed over the site of stimulation increased more from pre- to post-session among participants in the active tDCS condition, relative to those in the sham tDCS condition. Moreover, we found a significant association between a decrease in pain intensity and an increase in PTAF at the stimulation site. CONCLUSIONS: The findings are consistent with the possibility that anodal tDCS over the left M1 may be effective, at least in part, because it results in an increase in M1 cortical excitability, perhaps due to a pain inhibitory effect of motor cortex stimulation that may influence the descending pain modulation system. Future research is needed to determine if there is a causal association between increased left anterior activity and pain reduction. SIGNIFICANCE: The results provide new findings regarding the effects of tDCS on neuropathic pain and brain oscillation changes.

The short-term effects of transcranial direct current stimulation on electroencephalography in children with autism: a randomized crossover controlled trial.

Abnormal synaptic maturation and connectivity are possible etiologies of autism. Previous studies showed significantly less alpha activity in autism than normal children. Therefore, we studied the effects of anodal tDCS on peak alpha frequency (PAF) related to autism treatment evaluation checklist (ATEC). Twenty male children with autism were randomly assigned in a crossover design to receive a single session of both active and sham tDCS stimulation (11 mA) over F3 (left dorsolateral prefrontal cortex). Pre- to postsession changes in a measure of cortical activity impacted by tDCS (PAF) and ATEC were compared between groups. We also examined the associations between pre- and postsession changes in the PAF and ATEC. The results show significant pre- to postsession improvements in two domains of ATEC (social and health/behavior domains) following active tDCS, relative to sham treatment. PAF also significantly increased at the stimulation site, and an increase in PAF was significantly associated with improvements in the two domains of ATEC impacted by tDCS. The findings suggest that a single session of anodal tDCS over the F3 may have clinical benefits in children with autism and that those benefits may be related to an increase in PAF.

Effect of anodal transcranial direct current stimulation on autism: a randomized double-blind crossover trial.

The aim of this study was to evaluate the Childhood Autism Rating Scale (CARS), Autism Treatment Evaluation Checklist (ATEC), and Children's Global Assessment Scale (CGAS) after anodal transcranial direct current stimulation (tDCS) in individuals with autism. Twenty patients with autism received 5 consecutive days of both sham and active tDCS stimulation (1 mA) in a randomized double-blind crossover trial over the left dorsolateral prefrontal cortex (F3) for 20 minutes in different orders. Measures of CARS, ATEC, and CGAS were administered before treatment and at 7 days posttreatment. The result showed statistical decrease in CARS score (P < 0.001). ATEC total was decreased from 67.25 to 58 (P < 0.001). CGAS was increased at 7 days posttreatment (P = 0.042). Our study suggests that anodal tDCS over the F3 may be a useful clinical tool in autism.

Transcranial Direct Current Stimulation in Neuropathic Pain.

Neuropathic pain (NP) is one of the most common problems contributing to suffering and disability worldwide. Unfortunately, NP is also largely refractory to treatments, with a large number of patients continuing to report significant pain even when they are receiving recommended medications and physical therapy. Thus, there remains an urgent need for additional effective treatments. In recent years, nonpharmacologic brain stimulation techniques have emerged as potential therapeutic options. Many of these techniques and procedures - such as transcranial magnetic stimulation, spinal cord stimulation, deep brain stimulation, and motor cortical stimulation - have very limited availability, particularly in developing countries. Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation procedure that has shown promise for effectively treating NP, and also has the potential to be widely available. This review describes tDCS and the tDCS procedures and principles that may be helpful for treating NP. The findings indicate that the analgesic benefits of tDCS can occur both during stimulation and beyond the time of stimulation. The mechanisms of cortical modulation by tDCS may involve various activities in neuronal networks such as increasing glutamine and glutamate under the stimulating electrode, effects on the µ-opioid receptor, and restoration of the defective intracortical inhibition. Additional research is needed to determine (1) the factors that may moderate the efficacy of tDCS, (2) the dose (e.g. number and frequency of treatment sessions) that results in the largest benefits and (3) the long-term effects of tDCS treatment.