What is allodynia?
Allodynia refers to the state in which an innocuous (e.g., normally nonpainful) stimulus is perceived as painful. It is not normal! It is common in many neuropathic pain conditions, such as postherpetic neuralgia, diabetic neuropathy complex regional pain syndrome, and other peripheral neuropathies. In thermal allodynia, the innocuous warm or cold sensation may be perceived as painful. With mechanical allodynia, a very light touch, such as the clothes rubbing against the skin or bed sheets placed on the lower extremities, may be extremely painful, while firmer pressure is not.
When allodynia occurs in a person experiencing a neuropathic painful disorder, the skin surface may appear normal. Allodynia is also present in skin sensitized by a burn or inflammation (ankle sprain), but in these situations the affected skin is visibly abnormal.