Recently, a colleague of mine sent me an in-depth piece from wired.com that explores a pain condition known as erythromelalgia. Erythromelalgia, also known as Mitchell’s disease or “man on fire” syndrome as the article calls it, is a pain disorder in which the blood vessels in the extremities are periodically blocked throughout the day. When they open, the area can become hypermic and inflamed, and it is usually accompanied by a burning sensation in the area.
Erythromelalgia episodes can be triggered by a number of different things. Some people are set off by heat, others by pressure, while others experience an episode due to mild activity, insomnia or stress. Patients who suffer from the condition have probably found their own personal way of achieving some minor relief when an episode comes, but a true treatment has yet to be found. However, we may be hot on the trail of a solution.
Causes of Erythromelalgia
Medical researchers have discovered that erythromelalgia is caused by a mutation of the voltage-gated sodium channel α-subunit gene known as SCN9A. This discovery led to the condition being recognized as the first human disorder that associated an ion channel mutation with chronic neuropathic pain.
This is all probably somewhat confusing, so we’ll try to simplify it a bit. Imagine your arm as a road and your hand as a bunch of cars where the cars represent pain sensations. In a normal functioning adult, the cars remain parked in the parking lot until you suffer an injury (say you touch a hot stove). When this happens, the cars get the green light to travel up to your brain and pass along pain signals to tell your body that it is in pain.
In a person with a gene mutation on SCN9A, stimuli other than pain causes the stoplight to go from red to green, which allows the pain signals to travel up to your brain and be interpreted as pain. Not only are non-painful stimuli causing this pain gateway to open, but researchers are finding that the pathway is often open longer for people with this condition, so their pain is more extreme or longer in duration. Interestingly, a different type of mutation on the same gene effectively causes the traffic light to permanently stay red, meaning the person feels the opposite effect – no pain. This may sound awesome, but remember, pain is a way of our brain telling our body to change what it’s doing. If you put your hand on a hot stove and don’t feel pain, you’re still going to do a lot of damage to your body, even if you can’t physically feel pain. However, the absence of pain may be better than chronic or extreme pain.
Treating The Condition
Now that researchers have a better understanding of the condition, they are hard at work at developing a solution. They can’t change the gene, and thus they can’t stop the cars from trying to drive down the road to the brain, but they believe they can try to fix the stop light. In individuals whose light goes green at random intervals or because of non-pain stimuli, researchers are hoping that they can find a way to stop that light from changing from red to green. If they can shut down or at least keep the light from going green at the wrong time, than pain will only occur when a real pain stimulus exists.
They are getting closer to an answer, as not long ago they found that spider venom can affect the problematic stoplight in patients with this condition. Synthetic formulas are being developed, and hope is on the horizon. The science behind pain management is fascinating, and hopefully it can be the catalyst for more research and effective treatment options. The more research we do into pain care, the better we can treat the most widespread condition in the world – pain.
Thomas Cohn, MD
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