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Hyperalgesia and Allodynia

By Mary Pettigrew

Let’s talk about pain and multiple sclerosis. I continue to be amazed at the comments I read from patients who are dealing with some sort of pain or discomfort, yet are sadly dismissed by their doctors who say, “MS doesn’t cause pain.” This is simply inexcusable. There is pain with MS, but it’s not the same for all patients. I hope those who are not being heard will speak up, find a physician who will listen, who cares enough to delve deeper into the problems concerning each patient, and do their best to offer support and help. 

I am pleased to see the topic of “pain” being studied and discussed in several trials and platforms these days. It’s truly important for us – the patients – to continue to research, pose questions, and advocate more for ourselves and others. No matter if you are a newly diagnosed patient or a “veteran” living with MS, there is always something new we can learn about this bizarre thing called MS. 

There are many different types of pain. There are many different causes for pain as well. The two types of pain I’d like to address are Allodynia and Hyperalgesia. Each of these terms can be reviewed in more detail by clicking on the hyperlinks with information provided though the Cleveland Clinic. 

Allodynia is defined as “pain due to a stimulus that does not normally provoke pain.” An example would be a light feather touch that should only produce a (normal) sensation yet causes some pain or discomfort. Many conditions and injuries can cause allodynia. I first came to find out about this kind of pain from reading a blog post written by Anna Laura Herndon about her experiences with it and her fibromyalgia. I had never heard this term, allodynia, but I could definitely relate to her descriptive story and how it affects her.

I never even knew there was an actual word for this hypersensitivity to stimuli condition. I always related it to a sort or nerve or sensory discombobulation – which it is, and more. This type of pain or discomfort stems from our nociceptors

Here are the three types of Allodynia. Each can affect people differently or not at all.

Tactile (Triggered by touch): For me, I can’t stand wearing tight or constricting clothes. If I must wear a bra, then it can’t have any wires or clips. The minute I get home, the bra and clothes come off and my soft, loose pajamas go on. The only jewelry I wear these days (if any at all) are loose earrings. Otherwise, no more jewelry, period.

Mechanical (triggered when something moves across the skin): Bedsheets, air, ceiling fans, clothes, reading glasses, loose hairs, etc. All these and more can drive me crazy. Even my hair hurts and I sometimes wonder about cutting it all off. I’m having a hard time figuring out what to do with all that.

Thermal (pain resulting from temperature related triggers, heat or cold): This discomfort or pain can vacillate minute-by-minute causing issues with pain, insomnia, and much more. 

Hyperalgesia and allodynia are somewhat similar in nature, but the key difference between the two is how you would normally respond to a pain stimulus. With hyperalgesia, you will feel more pain to things which are supposed to hurt (i.e., cuts, burns, injuries, etc.). This happens when your pain receptors are highly sensitive. With allodynia, you will feel pain or discomfort in response to things that should not hurt at all (as mentioned in the above text). There are many causes of hyperalgesia (burns, bites, stings, cancer, neuropathy, diabetes, lupus, MS, Ehlers-Danlos, fibromyalgia, migraines, CRPS, trauma, etc.).

The two main types of hyperalgesia are:
  • Primary hyperalgesia: When an injury changes how you feel the pain from actual injury.
  • Secondary hyperalgesia: When your nervous system is “confused” as to how to handle pain signals (If you feel pain in areas not directly affected by injury or condition). I tend to relate to this one. 

Also, it’s worth investigating these two different forms of hyperalgesia:
  • Referred hyperalgesia: The pain and nerve connections are more in sync with the original problem.
  • Visceral hyperalgesia: This pain is deeper, more internal, and possibly widespread.

Remember, we’re all different. For some people, these pain issues can be quite painful, frustrating, and chronic. For others, it might manifest as a weird, bothersome sensation, irritant, or discomfort. I found it quite interesting to discover these pain/sensory issues have clinical names and definitions I had never heard of until recently. I urge you all to look further at the links I’ve included in this article for more detailed information. Some of you may want to discuss further with your doctors. I know I will.

In closing, there is pain with MS, but it’s not the same for all patients. I truly hope those who are not being heard will speak up, find a physician who will listen, who cares enough to delve deeper into the problems concerning each patient, and do their best to offer support.