Allodynia

Allodynia refers to pain caused by what would normally be non-painful stimulation, for example brushing the skin. Temperature change, light touching, and clothing can trigger the pain response resulting in a burning sensation often occurring after an injury to a site.

Presentation
There are three types of allodynia. Tactile, where pain is caused by touches such as clothing touching the skin or someone lightly touching the arm; Mechanical, caused by movement across the skin when drying with a towel or sheets brushing against the skin; and Thermal, which is caused by heat or cold that is not extreme enough to cause damage to skin tissues.

Allodynia in ME/CFS and Fibromyalgia
Allodynia is not a diagnostic symptom of ME or CFS, and is not even referred to in the International Consensus Criteria Primer for ME although other forms of pain are.

Prevalence
A study of over 3,000 patients with fibromyalgia found that allodynia was "surprisingly common."

Notable studies

 * 2009, Models and Mechanisms of Hyperalgesia and Allodynia (Full text)
 * 2010, A cross-sectional survey of 3035 patients with fibromyalgia: subgroups of patients with typical comorbidities and sensory symptom profiles (Full text)

Possible causes
Central pain sensitization (increased response of neurons) has been proposed as a possible cause, but this term has conflicting definitions and scientific evidence is unclear.

Learn more

 * Pain terminology - International Association for the Study of Pain