Some people taste musical sounds, others feel colours or see sounds 1. Of the many somatic sensations to which man is heir, synaesthesiae are among the most intriguing. Synaesthesia is an involuntary physical experience of a cross-modal sensory linkage; it affects about 1 in 1,150 females and 1 in 7,150 males 2. 'Itch' derives from 9th century Old English giccan, akin to Old High German jucchen, to itch. 'Referred itch' or Mitempfindung is analogous, though not strictly a cross-modal sensation. It affects approximately 1 in 5 healthy individuals. One patient reported, 'when I scratch a small area on the right cheek I feel a sharp pricking pain for a moment on the front of my chest near the right nipple. It repeats 3 or 4 times, immediately after each scratch but then fatigues and won't recur, till a later time.'
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