DR. DODICK: So, Dr. Aurora, I‘m going to assume that you, at least for some patients, use occipital nerve blocks as a treatment option. Can you tell us what you use and do you use it for acute therapy to terminate an attack? Do you use it for prophylaxis? Can you give us an idea of which patients you use it for and in what setting?
DR. AURORA: We mostly use this for trying to prevent further attacks, but I have used it for acute treatment as well. I find that cluster headache patients actually respond very well to it. In terms of what I use, for cluster headache patients, I use some kind of a steroid in conjunction; most commonly, I use bupivacaine (or Marcaine), but it‘s really quite arbitrary how I came to that choice.
Recently, when I worked at the pain center in Seattle, I used ultrasound guidance for some of these patients and found that some patients who didn‘t respond to the blind procedure seemed to respond better to ultrasound guidance. I find it very useful in pregnancy because, as you know, most of the medications are of category C, and patients cannot take preventive medications when they‘re pregnant. I find that using it as a prophylaxis during pregnancy works as well.
DR. DODICK: For both migraine and cluster?
DR. AURORA: For both migraine and cluster; just anecdotally, I‘ve seen that patients who have a lot of neck triggers, where they‘ve been categorized as having cervicogenic headache, although clearly, they have a history of migraine, which is triggered from the neck. Those patients seem to respond well to occipital nerve block.
DR. DODICK: A question for Dr. Goadsby: I, too, have had a clinical experience, whether there is a placebo or not, wherein for patients with cluster headache or migraine, you can terminate an attack rather abruptly with an occipital nerve block. Can you speculate the potential mechanism of action of that response?
DR. GOADSBY: Well, I think the acting mechanism of action in occipital nerve blocks is to modulate cervical neurons sufficient for the brain processes involved in migraine, cluster, or any of the primary headaches, to take their normal course of action, which is to terminate them. If you look at migraine, it‘s been defined as an episodic headache and cluster headache quintessentially. They are chronic versions, and typically, when the version is chronic, they have episodes over that as well, so there are clearly mechanisms in the brain that either exhaust or actively terminate acute migraine.
I think by stimulating these trigeminocervical neurons, either these mechanisms are exhausted or mechanisms normally turning the attack off are allowed to gain a foothold.
DR. SILBERSTEIN: If I can suggest an impossible-to-do trial, Dr. Dodick, it‘s penicillin for pneumococcal pneumonia. I don‘t think you can do it.
DR. DODICK: I hope that someone will find a way to do this trial because as we know, it‘s becoming increasingly difficult for clinicians to do this in practice because there is no reimbursement for it. So, clinicians are not able to implement what they see as a very useful tool in their therapeutic armamentarium, because in the absence of evidence, insurers are not willing to cover it. So, I‘m hopeful that we‘ll see a trial soon that will compel third-party payers to at least reimburse.
DR. SILBERSTEIN: Dr. Dodick, I believe the issue arose because people outside the headache field have patients come back on a weekly basis for blocks. That‘s what they do for a living, but I think that‘s the problem. I think all of us agree it works, but the problem and the way to maybe do a trial would be to compare once per week, once per month, and once every 3 months and look for outcomes. I think that might be the way to do it, because I think the issue, from the carrier‘s point of view, is cost. When it‘s done under fluoroscopic guidance, the cost can be astronomically high, and that‘s what they‘re reacting to.
I think one of the ways to do it is just take it to the carrier and say, this is what we‘d like to do, finance it or get the federal government to finance a study, and find out what their objections are.
My strongest objection is not the procedure, but the need for fluoroscopy and frequent repetitive blocks. The other issue that really bothers me is that you may want to see if the block is effective at all, or we could use a block instead of an ED transfer or admission. Permission should not be needed for diagnostic or emergency blocks.
DR. GOADSBY: If it‘s true that it has a modulating effect, it‘s likely that repeating it at short intervals will make it less useful, from a theoretical standpoint. I think in the headache world, we‘ve evolved to being judicious about the use of it from experience, and that actually makes a lot of sense because it‘s not like a pain procedure where there‘s an inflamed peripheral nerve and you can just anesthetize it. I think that because it works more centrally, and performing it too frequently is a very good way of stopping it from working.
DR. SILBERSTEIN: I think we now have a way of designing a multicenter clinical trial, making the assumption that it works. We could look at the response to different frequencies of injection. That might be the answer to the question.
DR. DODICK: Dr. Aurora, you said something very important about what you use in your pregnant patients, since we detest the use of any oral medication. How about botulinum toxin? Is there a role for the use of onabotulinum toxin A in patients who are pregnant?
DR. AURORA: Of course; it‘s of category C, but when I practiced in Seattle, there were a number of high-risk obstetrics practices just because of the nature of the hospital and its history. I have had some anecdotal experience with this and in fact, patients were referred to me from their obstetricians and gynecologists specifically for this reason. I worked with our perinatologist, who is quite an authority in his field, and he felt that given all the risks versus benefits of onabotulinum toxin A, because some of these patients had very refractory migraine with frequent vomiting and electrolyte imbalances that created more jeopardy to the mother‘s health, as well as the fetus, it was an appropriate choice for some patients.
DR. DODICK: Thank you. I think we‘ve covered the 3 topics that we wanted to cover today. Does anybody have anything to add or anything that they didn‘t get a chance to say on either the use of extracranial nerve blocks, peripheral nerve stimulation, or onabotulinum toxin?
DR. GOADSBY: On extracranial nerve blocks, we didn‘t discuss multiple extracranial nerve blocks as in supraorbital blocks. Although there is a general feeling in the headache community that occipital nerve blocks are useful, I‘m less convinced that using more injection is necessarily better. In fact, I‘m unconvinced, so that‘s an area that readers might be interested in.
DR. SILBERSTEIN: That makes sense to me. Here‘s what I do: I start with occipital nerve blocks. I keep the patient in the room, and I watch them until the block takes effect and see if they‘re entirely pain free. If they‘re not entirely pain free, I‘ll ask them what distribution they have pain in, and I‘ve often found that injecting in the inferior, anterior part of the temporalis muscle and hitting the branch nerve there will make a difference. But, I do that on an as-needed basis, not on a general basis. I‘ll start with occipital nerve block, but if there is residual pain in a different distribution, I have no problem just giving them some extra local anesthetic in that area in the absence of evidence.
DR. GOADSBY: When we looked systematically at occipital nerve blocks, we found an interesting phenomenon that slightly mirrors the effect of dihydroergotamine infusions: if you perform occipital nerve block—perioccipital nerve injection might be a better way to put it—you might well see effects that take 5 to 7 days to have their onset, and that will confuse the outcome of further blocks done on the day. I don‘t really think that the examination of multiple blocks has been done in a systematic fashion.
DR. SILBERSTEIN: When the patient is in my office, outside of a trial, I try to give them the best benefit that I can. But, I agree with you in the case of a systematic study. In fact, when we started the steroid study, we actually did what you suggested. We localized the blocks and only performed them in those certain areas so we could compare outcomes.
DR. DODICK: Since you‘re an advocate, Dr. Silberstein, of, let‘s say, supraorbital nerve blocks in some patients, if a patient came in with exclusively anterior pain, vertex or frontal, do you believe that an occipital nerve block can be effective for him/her, and would you preferentially perform a supraorbital nerve block in those patients? In other words, does the location of the pain guide you in terms of which nerve you block?
DR. SILBERSTEIN: If people have nummular headache, I‘ll go to the nummular area. But, often what we see are patients who have pain in a wider area of distribution in the front. I think as Dr. Goadsby says, we‘re modulating the central terminal. What I might do the first time I see the patient is to try the occipital nerve block therapeutically, diagnostically, and mechanistically. If it doesn‘t work, I will go anteriorly, and will then see how they do afterwards. I don‘t think I know the answers to those questions. My exception to the rule would be nummular headache, but I would only go to that area.
DR. GOADSBY: It is interesting when you look at the cluster headache data; for occipital nerve injection, the only place where randomized control trials have been done is cluster headache, and it is an anterior pain. I think it‘s probably the most sound systematic clinical trial evidence we have to show that the effect of the procedure is on a central basis. The reason I raise this multiple cranial nerve block matter is that if we‘re going to be asking payers of any form to approve these procedures, we have to be quite systematic in the procedures we describe and in the way we collect our evidence, because I can‘t imagine that payers are going to allow or want confused, randomly localized injections. That‘s part of the problem.
DR. DODICK: Well that‘s sage and wise advice.
DR. DODICK: I want to thank my colleagues for willing to share their expertise. I can‘t imagine 3 more authoritative voices in the field of headache to speak on these issues than the ones we‘ve had today, and I want to thank them.