Allodynia is when you feel intense pain from things that don’t normally cause pain, like a soft breeze, change in temperature or pressure, or light touch. It’s a symptom of conditions like cluster migraines, Trigeminal Neuralgia, CRPS, and fibromyalgia.
Nociceptors are sensory nerve endings in our body that detect pain. They react to harmful triggers, like mechanical, thermal, or chemical stimuli, and send information about pain to the nervous system.
Why nociceptors are activated in response to non-painful stimuli, like in allodynia, is not fully understood yet (like most things related to CRPS). It could be because of changes in nociceptor sensitivity, altered pain signal processing in the nervous system, or changes due to long-term pain.
In addition to nociceptors, there are other types of sensory receptors in the body, including mechanoreceptors and thermal receptors. These also play a role in our perception of the environment and our sensations of touch, pressure, temperature, and other stimuli.
Three Types of Allodynia
Mechanical Allodynia
This type of allodynia is caused by light touch or pressure, such as the touch of clothing (like jeans) or a bedsheet. Here are some examples from daily life:
- Brushing your hair
- Hugging
- Massage
- brushing your teeth and exerting pressure on the gums can invoke pain.
- Putting on a shirt or tight jeans
- Laying down on a mattress or covering your body with a blanket can be painful.
The experience of mechanical allodynia is different for everyone and can even vary from day to day. Some people with CRPS can handle certain clothing or fabrics for a short time, but it can become uncomfortable or painful over time.
For example, you might be able to wear tight jeans for a short time, but as the pressure on your skin and tissues persists, the discomfort may become intense and even painful. Depending on your condition, some days you might not even be able to wear them at all.
This happens because the nerve receptors in your skin and tissues become super sensitive in CRPS. Even normal amounts of pressure can feel painful, causing discomfort and pain over time.
This type of allodynia is caused by changes in temperature, like exposure to cold or hot temperatures. For example, you may experience pain when taking a cold shower or when drinking a hot drink, or stepping on a cold floor.
Thermal Allodynia
Thermal allodynia is also associated with the activation of nociceptors, but in response to changes in temperature. Exposure to cold or hot temperatures activates these nociceptors, causing pain even though the stimuli would not normally cause pain.
This type of allodynia is often seen conditions such as neuropathic pain, migraines, or skin conditions such as burns or frostbite.
Here are a few examples of thermal allodynia in daily life:
- Showering or bathing: The sensation of warm or hot water on the skin can be painful or uncomfortable, even when the water is not hot enough to cause burns
- Drinking hot or cold beverages: The sensation of heat or cold in the mouth and throat can be painful or uncomfortable, even when the beverage is at a normal temperature.
- Going outside in hot or cold weather: The sensation of heat or cold on the skin can be painful or uncomfortable, even when the temperature is not extreme.
- Touching or holding objects that are too hot or too cold: The sensation of temperature on the skin can be painful or uncomfortable, even when the object is not hot enough to cause burns or cold enough to cause frostbite.
- Using hand sanitizer or other products with alcohol: The sensation of the alcohol on the skin can be painful or uncomfortable, even when the product is designed for sensitive skin.
Dynamic Allodynia
This type of allodynia is caused by movement, such as walking or moving a an arm or a leg. For example, you may experience pain when you walk or move your arm or feel it as a car rides by.
Dynamic allodynia is associated with the activation of nociceptors in response to movement, causing pain even though the stimuli would not normally cause pain.
External dynamic allodynia is a type of allodynia in which external stimuli, like sound or vibration, can cause pain or discomfort.
Here are a few examples of external dynamic allodynia in daily life:
- Loud noises: Sudden or loud noises, such as fireworks, construction noise, or car horns, can cause pain or discomfort.
- Vibrations: Vibrations from machinery, such as a lawn mower or power tool, can cause pain or discomfort in the hands and arms
- Wind or air movement: Strong wind or air movement, such as from a fan or open window, can cause pain or discomfort on the skin.
- Bright lights or flickering lights: Bright or flickering lights, such as from a strobe light or bright sunlight, can cause pain or discomfort in the eyes or head.
- Fast-moving objects: Fast-moving objects, such as a car rushing by or a bicycle passing close, can cause pain or discomfort on the skin.
Allodynia is pretty rare and difficult to explain. You may experience multiple types of allodynia at the same time. It may be at different sensitivity levels and even vary throughout the day.
It is important to be aware of the allodynia triggers that affect you!
Treating Allodynia
Work with an Occupational Therapist or Physical Therapist to develop a personalized treatment plan to your individual needs and symptoms. You might try wearing looser clothing, using padding or other protective measures, or practicing relaxation techniques such as deep breathing or meditation.
In future posts we will give more daily examples of Allodynia and how to challenge yourself to function despite it.
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