Mitempfindung, or referred itch, is the phenomenon in which a stimulus applied in one region of the body is felt as an itch or irritation in a different part of the body. The syndrome is relatively harmless, though it can be irritating, and healthy individuals can express symptoms. Stimuli range from a firm pressure applied to the skin – a scratch – to irritation or pulling on a hair follicle on the skin. The referred sensation itself should not be painful; it is more of an irritating prickle leading to the compulsion to scratch the area. The stimulus and referred itch are ipsilateral (the stimulus and the referred itch occur on the same side of the body). Also, because scratching or putting pressure on the referred itch does not cause the stimulus area to itch, the relationship between the stimulus and the referred itch is unidirectional. The itching sensation is spontaneous and can cease with continued stimulation.
There are two types of referred itch: normal and acquired (pathological). Normal mitempfindung is usually detected in early childhood and persists for the majority, if not the rest, of the individual’s life. Acquired or pathological mitempfindung is the effect of damage to the central nervous system and only lasts for a short period of time.