Super-Sensitive Nerves Play Key Role in Migraine Pain

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April 27, 2000 -- Attention migraine sufferers: those weird pains aren't all in your head. A new study shows that when people say headaches makes their hair hurt, it's true.

In fact, the painful sensitivity to even the slightest touch -- experienced by many or perhaps most migraine sufferers -- has led researchers to the discovery of how migraines happen. It also offers clues to how they might be stopped. That's according to a study in the journal Annals of Neurology.

"The most interesting part of the study was when I asked patients 'Does your hair hurt? Do you feel pain from your earrings or glasses or water in the shower; can you shave without pain?'" lead investigator Rami Burstein, PhD, tells WebMD. "In general, they didn't want to admit it because they thought it had nothing to do with their migraines. After testing in the clinic showed it to be real, I was able to say, 'This doesn't mean you are crazy -- just tell me what you are feeling.' Then they went on and on and on about these symptoms that they were reluctant to tell about."

Burstein and colleagues at Harvard University found that almost 80% of 42 migraine patients they studied experienced painful sensitivity to touch and/or temperature in specific areas of their skin. This and earlier evidence from laboratory animals led them to the conclusion that migraine pain results from a chain reaction along the pain pathways leading to a region of the spine at the base of the neck.

Chemicals released by pain receptors, the part of the nervous system that senses pain, turn on nerve cells in the spinal cord. When these nerve cells get stuck in the "on" position, they turn even the slightest sensation into excruciating pain. This is why people with migraines say their head throbs -- the nerves connecting to their head become so sensitive that even the pulse of blood in the brain is a source of pain.

This new understanding of how migraines happen explains why, for many people, migraine medicine doesn't work once the headache has become severe.

"Not all patients experience increases in skin sensitivity -- and for them existing pain medications are almost 100% effective at any point of the migraine," notes Burstein, vice chair of the anesthesia department at Beth Israel Deaconess Medical Center in Boston. "However, 79% of the patients in our study exhibited this skin sensitivity. These patients will benefit from currently available drugs only if they take them in the first hour after the onset of an attack. If they take them later it is much, much less effective because these drugs do not address the sensitization that develops in the spinal cord."

However, drugs that can prevent or reverse the chemical changes in the spinal cord would benefit these patients. "There are hundreds of ways to do that, and this is the kind of medicine that will eventually do the job," Burstein says. He and his Harvard University research team currently are looking for drugs that can do this without too many unwanted side effects.

Stephen Silberstein, MD, director of the Jefferson Headache Center in Philadelphia, calls the research a major advance in understanding migraines. Silberstein, who was not involved in the study, tells WebMD that the findings confirm something physicians long suspected.

"This is a very important paper because for a long time we have been hypothesizing what happens in people during a migraine attack -- we've been saying maybe it is sensitization, but nobody ever demonstrated it is true," he says. "It tells us why migraine sufferers suffer pain everywhere, why their hair hurts. It may give us better approaches for treatment."

Burstein and his colleagues performed a battery of skin sensitivity tests on patients referred to a pain center for migraines. They then asked the patients to return to the center when they had a migraine so the tests could be repeated.

"The patients all got my pager number and they paged me whenever they got migraines," Burstein remembers. "They would call at three, four, five o'clock in the morning, on Sunday, around the clock. We met them in the clinic four hours into the attack, in which they took no medication. Then all we had to do was subtract the results of the pain testing in the presence of a migraine from the results we got in the absence of the headache. It became obvious that they had changes in their skin sensitivity."

This experience leads Burstein to recommend that people who get migraines should tell their doctor about anything unusual that happens to them, no matter how weird it seems. "Symptoms like the inability to form sentences, or a spreading sensation of numbness in the fingers, or hallucinations of different smells or tastes -- these are not part of what we studied, but ? they are related to migraines and not any other type of headache," he says.

And Burstein offers another important piece of advice. "Don't be stoic," he says. "If you are a patient who has skin sensitization, you have only one hour after the first symptoms of migraine for current drugs to be effective. Take the medication as soon as the pain starts."

Burstein and colleagues are now conducting studies to see whether the skin sensitivity seen in nearly 80% of their pain-clinic patients also happens in patients with less advanced migraine symptoms.

Vital Information:

  • Researchers report most migraine sufferers seem super-sensitive to even the slightest touch. Skin contact against their own hair or eyeglasses can be very painful.
  • The sensitivity may be a result of nerves getting stuck in the "on" position so that even gentle stimulation triggers extreme pain messages.
  • Nearly all of the 42 study subjects reported skin sensitivity, and the author notes today's drugs are most helpful if they are taken within the first hour of an attack in these patients. Researchers also need to determine which drugs can be used to reverse the changes in the spinal cord that cause patients to feel this pain.
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