Health Dictionary
Reliable, easy-to-read patient information on common medical conditions — written in plain language, free of jargon, and grounded in current evidence. Browse the most frequent diagnoses, understand what they mean for everyday life, and learn which steps and questions help you have a focused conversation with your doctor.
Allodynia
Introduction
Allodynia, meaning “other pain”, is an exaggerated response to otherwise non-noxious stimuli and can be either static or mechanical. Allodynia is not referred pain, but can occur in other areas than the one stimulated; it is also dysesthetic.
For example, a person with allodynia may perceive light pressure or the movement of clothes over the skin as painful, whereas a healthy individual will not feel pain.
Pathophysiology
Pathophysiology
One explanation of the mechanism for allodynia is that the associated nerve damage results in decreased firing thresholds of nociceptive fibres.
Alternatively, it has been postulated that peripheral nerve injury could induce collateral sprouting of non-nociceptive primary afferent neurones, such as A-beta low threshold mechanoreceptors, into the superficial (nociceptive) laminae in the dorsal horn of the spinal cord. These collateral branches could form functional contacts with nociceptive second order neurons, normally innervated by C-fibre nociceptive primary afferent neurones and transmit an innocous input as noxious.
Associated disturbances
Associated disturbances
Allodynia is a clinical feature of pain conditions such as migraine, postherpetic neuralgia, fibromyalgia, and neuropathies.
Types
Types
There are different kinds or types of allodynia:
- Mechanical allodynia (also known as tactile allodynia) – Pain from light touch/pressure applied to the skin in the area of the damaged nerve. Mechanical allodynia can be dynamic or static. Also it has been shown that lowering barometric pressure aggravates mechanical allodynia in a rat model of neuropathic pain
- Thermal (heat or cold) allodynia – Pain from normally mild skin temperatures in the affected area.