Evaluation of scratch movements by a new scratch-monitor to analyze nocturnal itching in atopic dermatitis.

Itching is very important in atopic dermatitis, but the details of itching or scratch movements, especially during sleep at night, have not yet been fully comprehended. We designed a new, simple device, the Scratch-Monitor (SM), to evaluate scratch movements at night and assessed the usefulness of this device by a comparison involving 26 patients and 17 healthy controls. The SM, a box weighing only 25 g with a pressure sensor on the bottom, is attached to the back of each hand under a cotton glove and records the number as scratch movements per minute in the case of more than three successive changes of pressure. The SM indicated that patients with atopic dermatitis scratched more frequently and suffered more severe sleep disturbance than healthy controls. Although the SM had several problems related to specificity and sensitivity, we conclude that the SM is a useful tool for evaluating nocturnal itching.