Allodynia between attacks may contribute to your next migraine
A study published in this month’s edition of Cephalalgia confirms the results of a 2011 study. Migraineurs have a lower threshold for painful heat perception, even between attacks. This newer study also indicated a positive correlation between pain threshold and timing of the next attack. This suggests that the increase in sensitivity can predict the next attack and may directly contribute to the development of the next attack.
This study used 80 volunteers: 20 healthy controls, 20 episodic migraineurs, and 20 chronic migraineurs. Each subject was exposed to heat stimuli and asked to confirm when they first felt pain (perception) and also when the pain became intolerable (tolerance). Healthy controls were tested after being headache-free (tension headache) for 48 hours. Both groups of migraineurs were tested after being migraine-free for 48 hours. There was decreased pain perception and tolerance in both episodic and chronic migraineurs even though they were not experiencing an attack at the time of testing. There was no measurable difference between episodic and chronic migraineurs. There was also an increased correlation between higher levels of pain perception and the timing of the next attack. This finding supports earlier studies that suggest an increase in allodynia 24 hours prior to the onset of an attack.
Researchers also concluded that the presence of decreased pain perception and tolerance between attacks confirm that central sensitization is part of the migraine process and not caused by the migraine attack itself. They suggest this symptom could be a target for future preventive treatments. They also confirmed that migraineur reports of allodynia were physiological, not psychological in origin.
This study used a larger sample size: 112 migraineurs and 75 healthy controls. They tested for correlation between pain thresholds and attack frequency, allodynia severity, and time between pain exposure and the next attack. Each participant was exposed to a heat stimuli and asked to note when the sensation went from “hot” to “painful” to test pain threshold. All migraineurs were asked to complete a headache diary for one week after each test. Every subject was free of migraine as well as any pain medication or abortive for at least 48 hours prior to each test.
Researchers found a positive correlation between the time between the test and subjects’ next migraine. There was no correlation between pain threshold and attack frequency or allodynia severity. However, they did find that both episodic and chronic migraineurs had a lower pain threshold than healthy volunteers, even between attacks.
Researchers concluded that these results may indicate that lower pain thresholds between attacks predispose migraineurs to their next attack. They recognized that it was possible that between-attack hypersensitivity might be an early warning sign of the next attack
What this means for migraine research
The 2011 study proposed that future studies involve long term data collection from larger groups to determine if there is a statistical difference between the pain perception of episodic and chronic migraineurs. Future studies might also examine whether or not pain perception increases over time in migraineurs and determine whether this symptom is a result of cumulative migraine attacks or whether its presence increases the likelihood of future attacks.
What this means for future treatments
Both studies confirm that the presence of increased sensitivity even between attacks is involved in the migraine process. If that is the case, then future preventive treatments may be targeted to directly reduce this hypersensitivity, not just the frequency of attacks. These studies support the current view that migraine is a systemic neurological condition that happens to involve periodic attacks. We always have migraine disease and sometimes get painful attacks.
I was relieved to read that researchers are thinking about how to treat all the symptoms of migraine, not just the headache. It’s good to know that at least someone recognizes that migraine impacts our lives all the time, not just when our heads hurt.
What this means for you
Increased pain sensitivity is part of the prodrome, giving us one more early warning that an attack is on its way. We may not have treatments that abort an attack that early, but there are things we can do when we recognize the signs.
- Adjust expectations of ourselves
- Warn loved ones to be prepared
- Make sure our toolkit is stocked and easy to access
- Ensure our acute and rescue medications are available
By understanding when the next attack is coming, we gain a sense of control over our lives. We are no longer the unsuspecting victim of unpredictable attacks. Increasing awareness of prodrome symptoms is like recognizing the signs of an incoming thunderstorm. You can’t stop it from coming, but you can minimize its damage by being better prepared to weather the storm.
Both studies confirm that our experience with allodynia has a physical origin. So the next time someone tells you that this symptom is “all in your head”, please point them to the research that proves otherwise.
Researchers are hard at work to find the cause of migraine and develop treatments to prevent all of our symptoms. Someday we will have migraine-specific treatments that do more than just relieve our pain. Scientists and doctors are not giving up, so neither should we.1,2
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