A new method for the measurement of itch and the response to treatment.

Two new methods are described for the quantitative measurement of itch: the principle is to measure scratch which is the major objective correlate of itch. The first method is to record whole body movement at night by a vibration transducer on a bed leg; this gives qualitative and quantitative information. The second method is to measure limb movement with movement-sensitive meters; this give only quantitative data but is quicker and more easily carried out. The subjective sensation of itch was found to correlate well with nocturnal scratch, confirming the basic assumption of the method. Itching as measured by scratch occurs throughout the night and increased severity of itch is accompanied by an increase in the number of bouts of itch and not in their duration. Nocturnal restlessness is associated with an increase in leg movement and so can be dissociated from itch-provoked scratch, which is mostly done by the hands. The response of pruritus to treatment was demonstrated by both methods.