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The Anatomy of a Headache

New Horizons No. 2003
By Brian Cislak
Washington

January 8, 1998

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New Horizons!!!!

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The Voice of America presents -- New Horizons -- a weekly program on developments in science, technology and medicine. Today -- Anatomy of a Headache -- a new view regarding the cause of at least some headaches, and possible new approaches to their treatment.

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Tape Cut one - Hack: (:17)
"Our intent was not to find a connection to headache. Our intent initially was just to look at muscles that move the jaw. And purely by accident we stumbled on this tissue and now we're postulating what role it may play."

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Gary Hack, assistant professor in the department of restorative dentistry at the University of Maryland dental school. What does dentistry have to do with headaches, and what brings dentists into the field of headache research? The answer has a lot to do with a newly-discovered common interest among dentists and neurosurgeons regarding the structures that make up the lower part of the head. It also relates to some new interpretations about the origins of headaches.

The standard, conventional view is that headaches emerge from blood vessel changes inside the head. Seymour Diamond is executive director of the world-renowned Diamond Headache Clinic in Chicago:

Tape Cut two - Diamond: (:32)
"Basically, there's a great deal of argument where certain headaches come from. But there is a basic mechanism, a standard mechanism that occurs. The blood vessels surrounding the head and the tissues of the brain swell, or enlarge, and the muscles of the scalp and neck contract. And these things cause the basic pain of the headache."

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Doctor Diamond says the same blood vessel dilation mechanism applies whether the headache is of the migraine type -- a one-sided throbbing in the head; a cluster type that focuses around one eye; or the garden-variety tension headache:

Tape Cut three - Diamond: (:17)
"It's the degree of the swelling that makes the difference. There's only a minimal amount of swelling with what we call a 'tension' headache. That is the simple headache that may be caused by stress, frustration, anxiety, things like that."

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Obviously there are headaches that have more serious origins such as brain tumors or aneurysms, with accompanying dire consequences. But Doctor Diamond was referring to the more standard types of headaches that plague humanity, and which, in their own way, can make life difficult.

In recent years, a new model has been put forward to explain the origins of at least some headaches. Walker Robinson is a practicing neurosurgeon, and associate professor of neurosurgery at the University of Maryland School of Medicine:

Tape Cut four - Robinson: (1:04)
"There is a group of physicians who feel that one of the mechanisms -- not the mechanism -- but one of the mechanisms of headache is what's called cervicogenic headaches. This simply means that some headaches originate outside of the cranium, that problems in the musculature at the base of the neck and/or base of the skull can cause headaches. This is to be distinguished from migraine headaches or vascular-type headaches, or distinguished from headaches that originate inside the brain from blood clots, tumors or whatever.

"The idea of an extracranial cause for headaches is somewhat controversial. In the past, 'tension headache' has been used as the term; 'muscle contraction' headaches has been used as the term. Cervicogenic headache is simply the linear descendant, if you will, from those ideas."

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University of Maryland researchers Walker Robinson, Richard Koritzer and Gary Hack have reported what they consider a new anatomical mechanism for tension headaches and others that fit in the cervicogenic category. They presented their findings at a recent international headache symposium in Toronto, Canada, and at meetings of the American Association of Neurological Surgeons and the Congress of Neurological Surgeons in Orlando, Florida and Phoenix, Arizona.

What they found in cadaver heads is a previously-undiscovered connective tissue link between muscles surrounding the first cervical vertebra in the neck and the dura -- the thin but tough membranous sack that encloses the brain and the spinal cord. Professor Hack of the University of Maryland Dental School:

Tape Cut five - Hack: (:43)
"We're calling it a connective tissue bridge, and I would say it is approximately an inch (2.5cm) in length and about a half an inch (1.3cm) in width. The muscle that is associated with it is a bilateral muscle. one part was going to the bone where the first cervical vertebra at the top of the neck, and another part almost coming out as a y was passing through the skull below the skull and above the first cervical vertebra to the dura. so when we initially saw it, it looked like a two-headed muscle. And the tissue in many specimens ... has a muscular appearance to it. Whether it is muscle or not is something that we're looking at now."

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So what the researchers think happens is that when lower neck muscles tighten, they pull on this two-and-a-half centimeter-long piece of connective tissue, which, in turn, yanks at the dura, causing headache pain. Professor Hack says this should not be surprising, given the dura's nature:

Tape Cut six - Hack: (:52)
"The dura...is a sack that covers and protects the brain and spinal cord. The interesting thing is that this tissue is extremely sensitive. When neurosurgeons go in and operate on the brain, they can cut brain tissue all day. Surprisingly the brain itself is not sensitive. You can cut on brain tissue and there is no pain. But to get through the dura, any pressure, any tugging, any pushing on the dura elicits pain, and this pain is interpreted as headache. This dural membrane has nerves that subserve pain. That is, when these nerves are stimulated it will produce pain, and many times this pain that it produces is interpreted as headache."

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Professor Hack says the discovery of a connective tissue link between neck muscles and dura helps explain what neurosurgeons like walker Robinson have been seeing for years among many of their patients who underwent neck surgery:

Tape Cut seven - Hack: (:56)
"Interestingly, when we first saw this connection, doctor Robinson pointed out to us that when he operates on individuals who have broken their neck, in essence -- have broken the first cervical vertebra -- in order to get to that bony tissue to repair it, he has to cut through this area. Now, not realizing before, looking back, that it was there, but realizing now that it exists, he realizes in his mind that that tissue was cut, or severed, in his surgery.

"When he then sees these patients later on and says 'How are you feeling? How are you able to move your head?' 'I'm doing very well, doctor. I can move my head very well. And you know what, doctor? I used to get very bad headaches. And since the surgery that you did to repair this broken bone, my headaches have gone away!'"

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Doctor Robinson had this to say:

Tape Cut eight - Robinson: (:56)
"It is a known fact, and known for years, that tension in this area can cause pain in the head. What we have been able to show is that there actually is a physical connection between the dura and the musculature of the neck. So what we did was to change a postulate into fact.

"One of the questions that has come up is 'is this the cause' (of headaches)? No, not the cause. We're saying it is a cause. There are other things obviously that do it. everybody who has headaches will not have a problem at the skull base. so this is not a single theory for it. We feel that with the things we've discovered, we can intercede in different ways than you would for typical migraine. And using some less invasive techniques, perhaps give patients some relief."

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Doctor Robinson says this might open up a whole host of new therapies for headaches, including such things as muscle-relaxing drugs, biofeedback, and even relaxation techniques and simple massage:

Tape Cut nine - Robinson: (:53)
"Non-invasive things to start with. Massage, heat, cold. We have had people describe all sorts of other interventions and there's anecdotal evidence that it helps. There are a number of operative procedures done in this area, and the proponents of those procedures also say that they help. This includes releasing the muscle band, blocking various nerves, either with injections or with radiofrequency lesions or severing the nerves.

"All we are saying at this point is that we start with the easy stuff first. If you can give a patient relief with heat-cold massage, or with mild analgesics, then perhaps surgery won't be necessary."

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Perhaps the most interesting thing about the discovery of the link between the "brain bag," or dura, and the neck muscle was how it was made. dentistry professor Gary Hack says it grew out of a collaboration between dental and medical researchers at the University of Maryland:

Tape Cut ten - Hack: (:37)
"We had formed a team to look at the muscles of mastication -- those muscles that move the jaw. That was our initial intent. We obviously as dentists -- my colleague, Doctor Richard Koritzer and I -- were interested in the muscles of mastication, because dentists must understand how the jaw moves. Doctor Robinson, on the other hand, as a neurosurgeon, was interested in those muscles because he has to reflect, or lay back, those muscles in order to get to the brain. so we've had a common interest and we formed a team to approach it."

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One day, Professor Hack and his team were studying a head specimen from a cadaver that had been dissected in an unusual way. It was sliced in half along a line beginning at the scalp and extending down the forehead, past the nose and down to the chin. It was cut this way to get a bisected profile view of the jaw muscles. Professor Hack says this was an unusual way to look at the human head, and it explains why he and his team were able to see the headache-inducing connective tissue structure that others had missed:

Tape Cut eleven - Hack: (:37)
"Why others have missed it, I think for two reasons: number one, when surgeons go into that area, they're not looking for anything new. They're trying to get the structures that they know exist and they have to get to. And when you view it from a posterior view, or a view that normally would be approached by a neurosurgeon, it is very difficult to see these tissues because they are basically moved away as you advance into or toward the brain. But if you were to view it in cross-section, which is not a normal surgical approach, then it becomes readily visible."

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Upon noticing the unusual tissue, the dental researchers literally carried the bisected head -- in a box -- to their neurosurgeon colleague, Doctor Robinson. He concluded right away that the tissue they were looking at was, indeed, something new:

Tape Cut twelve -- Robinson: (:57)
"I looked at my textbooks -- my major interest in medical school was anatomy so I had a fairly large collection. And none of my texts had this listed. It's not mentioned in any surgical anatomy books, and in fact I couldn't remember from the thousands of operations that I had done coming across this, and recognizing it ... so we thought this was something new. When we went back to the cadaver lab at the dental school, it proved not to be an isolated finding. All the dissections showed it to a greater or lesser degree. The question that was raised by doctors Hack and Koritzer was, now that we know where it is, the question became, what is it and what does it mean? And can it have any possible relevance?"

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The University of Maryland researchers are now studying the newly-found connective tissue link in primates, as well as in living human patients through the use of advanced imaging techniques. Professor Hack:

Tape Cut thirteen - Hack: (:22)
"We are now beginning to see the tissues in MRI-scans, a type of X-ray(-like image), and now that the community at large knows that it exists, my colleague Doctor Robinson, who is a neurosurgeon, is getting calls from neurosurgeons all over the world who are saying: 'Yes, we're seeing it when we're doing our surgeries.'"

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Professor Hack adds that, while much about the origin of headaches remains shrouded in mystery, the possibility that at least some of them might be caused by a muscular link outside the brain seems to fit in with everyday experience:

Tape Cut fourteen - Hack: (:43)
"Our postulation is that if one were to be under either psychological tension or physical tension... hunched over, working at a computer all day, that these muscles in the back of the neck may go into a sustained contraction. And people that talk about headache will many times point to this area and say it just feels tight and knotted in this area. Our postulation is that if these muscles contract, could the sensitive covering of the brain and spinal cord be pulled on or irritated by this connective tissue bridge?"

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Professor Hack reiterates what Doctor Robinson said earlier -- that if the neck muscle-dura connection does prove out, it will be a cause, but not the only cause, of headaches:

Tape Cut fifteen - Hack: (:53)
"There are various types of headaches. There are vascular headaches, there are cluster headaches, there are so-called 'tension' headaches. It appears that there is a relationship between muscle contraction and headache. Whether the muscle contraction initiates the headache or the headache initiates muscle contraction is not known. But if headache pain were to be initiated by certain neurochemical changes in the brain, this pain may cause contraction of the muscles about the head and neck. And it may be that this secondary contraction of the musculature, although not a primary cause of the headache, may prolong or exacerbate the headache."

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In the meantime, neurosurgeon walker Robinson has been going back over the list of patients on whom he has operated over the past several years -- focusing on those who have had neck surgery involving severance of the dura-neck muscle connective tissue.

Tape Cut sixteen - Robinson: (1:13)
"I looked at it from the surgical and neurosurgical standpoints, and started looking at my patient population in a way to see if it made a difference. ... We found that in some patients, you can find that disruption of this area has changed headache patterns. Because we have not done a double-blinded, randomized study -- which is the gold standard for medical research -- we are unwilling to say that this is the cause or treatment in this area that would bring relief. But anecdotally we are accumulating patients who have told us that their headache pattern changed after surgery for other things. Because of that we have a list of all patients done recently with surgery in that area. And we are doing a retrospective study with questionnaires followed up with phone calls to see if we can discern a pattern.

"If this holds true -- and we believe that for a certain percentage of the population that it will -- then we will be in a much stronger position to talk about direct causation and the possibility of treatment options."

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Whether or not the newly-discovered connective tissue in the neck is found to be a major cause of headaches, dentistry professor Gary Hack is pleased with how things have worked out so far. He says the discovery may lead to a newfound respect, not only for dentistry, but for the study of anatomy -- long considered a rather dull subject by many aspiring dentists and physicians:

Tape Cut seventeen - Hack: (:46)
"The response from my students at the dental school has been overwhelming. They are very excited about this, that a dentist was involved in this type of discovery. They come up to the anatomy lab. I think it's generated a lot of excitement and interest among the dental students at the dental school.

"My hope, and I think all of my colleagues' hope, is that this does pan out to have a relationship to headaches, because as I've gotten involved in this work I realize that there are a great many people all over the world who suffer terribly with head pain. And if this can in any way relieve the terrible pain that they experience, it really affects the quality of their lives, and I think we will all be very satisfied and pleased."

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You've been listening to -- New Horizons -- a weekly Voice of America program on developments in science, technology and medicine. Today you heard -- Anatomy of a Headache -- a new view regarding the cause of at least some headaches, and possible new approaches to their treatment. This program was written and produced by Brian Cislak.

8-Jan-1998 10:16 a.m. EST (1516 UTC) nnnn Report 7-17836
Source - Voice of America