Measurement of itch

Abstract

Itch is a major symptom of skin disease. Yet, until the last thirty years the investigation of itch has been ignored by researchers. One important reason has been the lack of reliable and sensitive measurement. We can only indirectly measure different aspects of itch perception which is performed on several levels of the nervous system. Physiological itch participates in the defence of the organism from harmful agents and involves multiple steps including the peripheral receptor, the afferent nerve transmitting the impulse to the spinal cord, the signal processing in the dorsal horn and finally transmission to higher cerebral centres in the thalamus and the cortex.1 The perceived itch induces scratching with the purpose of removing harmful agents from the skin. Scratching has for a long time been recognised as the most objective and reliable measurement of itch.2 This chapter provides a historical and critical review of the objective and subjective methods of itch measurement both in experimental and in clinical setting. © 2010 Springer-Verlag London.