Allodynia

A Distinct Pain Type

Definition:

Allodynia is pain, generally on the skin, caused by something that wouldn't normally cause pain.

This pain type is associated with fibromyalgia, and some people with chronic fatigue syndrome have it as well. Other conditions associated with allodynia include neuropathy, postherpetic neuralgia and migraines. Outside of these conditions, allodynia is a rare symptom.

Knowing this term may help you communicate better with your doctors and other health-care providers as well as with understanding research about your illness.

Kinds of Allodynia

Allodynia comes in three forms. You can have one, two or all three. They are:

  1. Tactile allodynia, which is pain caused by touch. This can include clothing laying against the skin (especially the tighter parts of clothing, such as waistbands, bra straps or the elastic part of socks.)
  2. Mechanical allodynia, which is caused by movement across the skin. This can be a towel as you dry yourself off, bed sheets brush against you, or even the air from a fan blowing moving over your skin.
  3. Thermal (temperature-related) allodynia, which is caused by heat or cold that is not extreme enough to cause damage to your tissues. (If your hands and feet turn blue when they're cold, talk to your doctor. This may be a symptom of a different condition called Raynaud's Syndrome.)

It's often hard for other people, or even us, to understand how these harmless things can cause so much pain. However, it is a real pain and doesn't mean that you're crazy or making too big a deal out of "normal" aches and pains.

Allodynia is different from hyperalgesia, which is the mechanism that "turns up the volume" on pain in these conditions. Hyperalgesia takes normal pain and makes it worse, while allodynia is an actual type of pain.

What Causes Allodynia?

Allodynia is believed to be a hypersensitive reaction that may result from something called central sensitization, which is associated with fibromyalgia and chronic fatigue syndrome.

"Central" means the central nervous system and "sensitization" means that it's become extra sensitive.

The pain signals of allodynia originate with specialized nerves called nociceptors. The job of nociceptors is to sense information about things like temperature and painful stimuli right from the skin. Nociceptors are special because they don't need to send signals to the brain, then get instructions back before they can react. That's what allows you to pull your hand away from something hot before you get burned.

When these nerves become sensitized, they start interpreting all kinds of sensation as pain.

Managing Allodynia

Allodynia can make things like wearing clothing uncomfortable, painful, or even agonizing. Many people with these conditions find that they need to tailor their wardrobes to reduce the impact of allodynia. For help with this, see:

Thermal allodynia can play a role in another one of our symptoms: temperature sensitivity.

To manage it, you may need to do things like moving work stations away from vents that blast you with hot or cold air. To learn more ways to keep this symptom at bay, see:

Most of the common drug treatments for these illnesses can help alleviate allodynia along with other types of pain. These include:

A lot of us also get some relief with topical painkillers such as lidocaine, BioFreeze, Tiger Balm and Aspercreme.

It's possible for massage therapy to make allodynia worse, so it's important to find a massage therapist who understands your condition and knows how not to aggravate this symptom.

Also see:

Pronunciation: AL-uh-DIN-ee-uh

Also Known As: Cutaneous allodynia

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