• Kei Nakagawa, Hideki Mochizuki, Soichiro Koyama, Satoshi Tanaka, Norihiro Sadato, and Ryusuke Kakigi.
• Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki, Japan.
• Clin Neurophysiol. 2016 Jan 1; 127 (1): 827-832.

ObjectiveItching can be suppressed by scratching. However, scratching may aggravate itch symptoms by damaging the skin. Therefore, identifying an alternative approach to suppress itching is of clinical importance. The aim of the present study was to determine whether a transcranial direct current stimulation (tDCS) was useful for itch relief.MethodsThe present study was performed on a double-blind, Sham-controlled, and cross-over experimental design. A histamine-induced itch was evoked on the left dorsal forearms of healthy participants, who were asked to report the subjective sensation of itching every 30s for 23 min. tDCS was applied over the sensorimotor cortex (SMC) according to a bi-hemispheric stimulation protocol during the itch stimuli; one electrode was placed over the right SMC, while the other was placed over the left SMC. The peak and lasting sensations of itching were compared between R-A/L-C (anodal electrode placed over the right and cathodal electrode over the left), L-A/R-C (anodal electrode placed over the left and cathodal electrode over the right), and Sham interventions.ResultsThe peak and lasting itch sensation were significantly suppressed during the R-A/L-C intervention than during the Sham intervention. On the other hand, the L-A/R-C intervention suppressed the peak itch sensation, but the effects did not last for more than a few minutes.ConclusionsThese results suggest that a bi-hemispheric tDCS intervention, especially when the anodal electrode was placed over the SMC of the contralateral side, was a potentially useful method for relieving lasting itch sensations.SignificanceThe present study demonstrated that a tDCS intervention may be an alternative approach for suppressing unpleasant itch sensations in healthy participants. Since tDCS has some advantages, namely, its easy application and safety in a clinical setting, it may become a useful method for the treatment of itching.Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

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