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Pain Receptors in the Bone, Skull & Scalp Pain, and Botox

Headache specialist Christina Peterson‘s comments on the news that a patient’s skin sensitivity may help predict Botox’s effectiveness for migraine explains the exciting research behind the story. Dr. Peterson attended the lecture on the topic at the International Headache Society’s annual conference. She wrote:

This was far and away the coolest lecture, although it was also given at the American Headache Society Meeting. Dr. Rami Burstein, who is a basic science researcher at Harvard, has done some ground-breaking research.

It has been conventional wisdom that there are no pain receptors within bone; the only pain receptors are on the periosteum–the lining on the bone. Dr. Burstein took it into his head to wonder if this were actually true of the skull, and set out to trace the pain pathways in rats. He showed amazing slides of fluorescent lime green nerve fibers shooting right through holes in the bone of the skull (so, yes, your skull can hurt), and terminating at the hair follicle.

So–when people say they have headaches that feel as if their hair hurts, it can be literally true. These nerve fibers were most dense at the sutures in the skull, where the bony plates of the skull come together. And now we know why craniosacral therapy works!

Dr. Burstein has also determined that there are three major types of headache pain:

  • Explosive pain (like you feel as if your brain is too big and will explode out of your head)
  • Implosive pain (as if your head will cave in the pressure is so great)
  • Orbital/eye pain (your eye hurts, or it hurts behind your eye, or it hurts to move your eye)

Unfortunately, you are permitted to have more than one of these in a given headache. He has found that it is the implosive type of pain that is most likely to respond to Botox. [all emphasis mine]

Dr. Peterson’s latest e-mail newsletter, which arrived in my inbox today, explains more about the research. If you aren’t subscribed to the newsletter, you’re missing out on an excellent, up-to-date resource. Take a look at previous newsletters and sign up for future issues.

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A Headache Specialist’s Comments

Christina Peterson, a neurologist (and migraineur), is a blog reader who leaves terrific, educational comments. I always learn a lot from her. Some of her comments on recent posts are so informative that I want to be sure you all see them.

Warnings Proposed for OTC Painkillers

This is a really important post–it can’t be overstated.

In fact, the NYT article, if anything, understates the matter. The truth is that at this time, over 50% of all liver transplants are necessary because of the medical use of acetaminophen. It’s such a big problem that even the makers of Tylenol have run a commercial asking people not to exceed the recommended amount.

Gastritis and ulcers are no fun, and most people have been made aware of the cardiac and blood clot risks of anti-inflammatories like Vioxx and Celebrex, but a lot of people tend to think that ibuprofen and acetaminophen are benign.

They aren’t.

It’s also important to know that a lot of prescription analgesics, like Vicodin, Percocet, Fioricet, Amidrin (and all their generic names), also contain acetaminophen–so don’t double up.

If you are an intermittent migraine sufferer, and not a chronic headache sufferer, a double-blind randomized controlled trial has established that acetaminophen has no role in the treatment of acute migraine. There are better options available.

Men & Women Experience Pain Differently

This is vastly oversimplified. (Well, OK, it’s a newspaper…) But I trust this blog readership to be more sophisticated than the sixth grade level general readership a newspaper shoots for. So.

Most of the studies that have recently emerged have indeed shown a difference in pain processing between men and women. The major difference is that pain processing in women fluctuates with estrogen levels. (Estrogen–it’s our theme of the week, isn’t it? 🙂

Some of the studies available are simplistic and misleading–lab animals were injected with estrogen, and pain thresholds decreased, which led researchers to conclude that therefore, women were weak, and couldn’t tolerate pain as well as men. (Can anyone say, “Researcher bias”?)

But if you think this through, it is counter-intuitive. It makes no sense. Pregnant women have very high estrogen levels–estrogen levels climb throughout pregnancy, until they are very high by the time labor begins.

And menstrually-associated headaches occur when estrogen levels are at their lowest–the day before menstruation begins is the most common day for a menstrual migraine, and that is the day for a drop in estrogen.

Dr. Nancy E.J. Berman, who has done very important research on the effects of hormones on trigeminal neurons and the effects on orofacial pain, TMD, migraine and fibromyalgia, and who won the Wolff Award this year from the American Headache Society, also wrote the chapter on “Sex Hormones” in the book, The Headaches. She has noted that migraine improves both during pregnancy, when estrogen is high, and after menopause, when estrogen is low. She feels that this suggests that it is rapid changes in estrogen and progesterone that serve as a trigger for migraine attacks.

Some studies suggest that women tolerate pain better than men when estrogen levels are higher, and less well than men when estrogen levels drop–we are still discovering whether it is the rate of drop that is critical (likely), or whether it is also the estrogen:progesterone ratio that has an effect.

Other studies have shown that postmenopausal women process pain similarly to men.

I will say this, though: when I do Botox injections in the office, it’s generally not the women who get faint on me. 😉

Birth Control Pill News

This is all well and good…if you are young, and if you do not have migraine with aura.

Please refer to the following from the ACHE website: Will Using Oral Contraceptives Increase the Risk of Stroke?

It is the standard of care amongst headache experts to advise that women with migraine with aura either not use oral contraceptives at all, or use them very judiciously and with aspirin cardiac prophylaxis, and only if there are no significant cardiovascular risk factors. It is also recommended that women who have migraine without aura discontinue oral contraceptives after age 35. Smokers who have migraine should not use oral contraceptives at all.

I recall reading a recent article that surveyed migraine sufferers, and found that a significant proportion of primary care physicians were not aware of current recommendations regarding migraine and oral contraceptives. (I cannot, however, find the article in my giant stack-of-articles-to-be-filed. So, no citation for you–sorry. I think the author was Dr. Elizabeth Loder, but Google is not bringing it up.)

There is also newer data regarding the increased risk of heart disease in women with migraine, which was published in JAMA recently.

This study looked at women over 45, but estrogens, contained in the vast majority of contraceptives, are also a cardiac risk factor.

So–if you are going to proceed with this, be certain your physician knows you are a migraine sufferer (if you are), and research your family history and personal cardiovascular risk factors.

To learn more about and from Dr. Peterson, visit her websites, Migraine Survival and Headquarters Migraine Management.