Migraine, Allodynia, and Central Sensitization
During your Migraine attack your hair literally hurts. Your child reaches out to caress you in empathy and it makes you cry. The air from the ceiling fan hurts you. The feel of your bedsheets is more than you can stand and you cry out in pain.
No, you’re not a hypochondriac or going crazy. You probably have Allodynia, a symptom of Migraine related Central Sensitization in the brain.
Pain actually occurs in the brain, not the area you feel it. When you touch a hot stove, specialized nerves in your hand send signals to your spinal cord, then on to your brain. They tell the brain that you have touched something hot. The brain recognizes the stimulus as pain and triggers the sensation we recognize as pain so you will pull away from the object that is burning you. Pain is your brain’s way to protect your body from harm. This is basically how things work when they are functioning correctly.
Sometimes our brains don’t work like they should though:
Allodynia is a medical term used to describe a patient who is experiencing pain from something that normally shouldn’t cause pain — like bedsheets, or air movement. It can occur anywhere there are pain receptors in the body, but in Migraineurs is most frequently seen as cutaneous (related to the skin) allodynia. Some of the most common places to see cutaneous allodynia in Migraineurs are the scalp, face and neck. Allodynia is a neurological phenomenon that is frequently very confusing to Migraineurs and their loved ones alike, and it is a result of the neurological processes of our Migraine Disease.
Central Sensitization is a medical term used to describe the brain’s neurons becoming hyperexcitable. The central nervous system has become unnaturally sensitized due to ongoing stimulation. An easy way to describe it is that the neurons develop a “memory” of the pain signals that are present during a Migraine attack and it changes accordingly to make the pain signals travel more easily. Some of these changes are related to neurotransmitters that relay messages between cells, especially glutamate and GABA. When these changes have been occurring for a while, allodynia can result.
The fact is, the better the pain memory, the easier it is for those pain signals to travel from neuron to neuron to the brain. Think of it like the evolution of a highway:
200 years ago a cattle path had a few cows coming and going. One day the farmer decided to use the cattle path as a road to get his family to town. He used it as a road for some time, it developed characteristic wagon ruts and soon the neighbors were using the new road too because it was easier than their less used route. Eventually the wagon ruts became a dirt road and lot of people were using it. The more people that used it, the easier it became to drive on it. The road is paved so even more could use it to go back and forth, and it eventually becomes a highway. If no one stops it, things get busy enough and it will turn into a freeway with thousands of cars each day traveling at high speeds.
In the case of our brains and central sensitization, a freeway is a bad thing because it represents changes within the brain that have lowered our ability to abort the Migraine attack. We want lightly-used cattle paths instead.
Migraine is being recognized now as a potentially progressive condition. Central Sensitization is one reason it is vital for Migraineurs to properly manage their Migraine disease (find and eliminate triggers, consider taking a preventive) and take their abortive as soon as they know an attack is happening. The abortive is one lonely cowboy. He can chase the cows away if there are only a few, but he is no match for the freeway full of speeding cars (pain signals). The longer (or more frequently) the Migraine attack occurs, the more difficult it is to stop the traffic traveling along the neuronal highway.
Once allodynia has set in, it is notoriously difficult to treat with any type of medication including NSAIDs and narcotics. Avoiding allodynia then is vitally important to us if we are to avoid the progression of our Migraine Disease and live productive lives.
Understanding central sensitization and allodynia is important because it can help us find better ways of managing our Migraine attacks.
For example, if you recognize your symptoms as that of central sensitization and allodynia and triptans are no longer as effective for you, this is important for your headache specialist to be aware of. Having this information may encourage him or her to look at a change of medications or other treatment strategies before the condition progresses and worsens. Knowing this information also gives you the power to begin a thoughtful conversation with your physician and the knowledge to ask the right questions.
Triptans are now considered first line treatment drugs for Migraine attacks, but typically have a relatively short window to work effectively against Migraine attacks. Triptan effectiveness generally occurs if it is less than two hours into the attack, especially in those susceptible to allodynia — sometimes less or more depending upon the individual patient. Once that mark is passed and allodynia has set in, triptan therapy may no longer be sufficient to stop the pain of the attack and other more aggressive approaches may be necessary.
This is one reason there are different kinds of triptans available to Migraineurs to abort their attacks. Some hit hard and fast. Others take longer to work, but hang in there for a much longer time period. Others are coupled with NSAIDs to further fight central sensitization. Each triptan is a little different and may or may not work for different people… or even for different Migraine attacks!
Do you suffer allodynia? What does your allodynia feel like? How do you treat your allodynia? Consider telling us about your Migraine story in the Share Your Story portion of the Migraine.com community!
Sharing our experiences with other Migraineurs is vital so we can all understand our disease better.
Understanding = empowerment.
Empowerment = better lives for patients and their families.
Have you shared your migraine story with us yet?