Published February 6, 2018 By Adam Lowenstein

A common question we are asked as migraine surgeons is whether or not obtaining pain relief with a nerve block is necessary to be a candidate for migraine surgery. In other words, if your neurologist or pain doctor gives you a nerve block and it does not change your pain or symptoms at all, might migraine surgery still be an option?

The answer is YES! Let’s review some things:

How precise is a nerve block?

All non-invasive treatments, including nerve blocks, RFA (radio-frequency ablation), and even nerve stimulators may simply miss the target because none of these procedures actually visualizes the nerve directly. While in surgery a migraine surgeon actually finds the nerve and sees where it emerges and runs an ends up, these other treatments “indirectly” find the nerve in different ways.

These indirect techniques may be done by measuring where the nerve usually lies, using an ultrasound to try to find the nerve, or using electrical stimulation to find the nerve. None of these techniques actually see the nerve directly, though in many many cases these “indirect” ways of finding the nerve do work. Occasionally though the nerve block, RFA, or nerve simulation might miss the target. If the target is missed, the nerve block, RFA, or nerve stimulator will not work. But this is just because of an error in finding the nerve, not because the nerve would not respond to the treatment if the target was achieved.

To sum up, nerve blocks, RFA, and nerve stimulators are not as precise as surgical nerve decompression in migraine surgery, and just because one of these treatments don’t work, it doesn’t mean that migraine surgery needs to be ruled out as an option.

Who is doing your nerve block?

Thank goodness for neurologists and pain doctors. For years these teams have helped manage nerve and muscle pain in migraine patients and many others. Their knowledge of nerve medicine is fantastic and often their understanding of nerve anatomy is great too. Their expertise in their area usually surpasses that of a migraine surgeon who is often less knowledgeable about medications that are best to use and the medical treatments for many different diseases.

That said, one of the main areas of expertise of a surgeon is anatomy. No matter what type of surgeon we are talking about, she or he needs to know what to find where and how to get there through other structures of the body. And it is here that experience matters.
Surgeons are routinely looking at and working with different layers of the body, finding muscles, nerves, blood vessels, and

in the case of general surgeons, fining organs as well. For migraine surgeons, we are routinely looking at the nerves and working in the different muscle layers of the face and neck. There is nothing that substitutes for direct visualization.

And so, when performing a nerve block, migraine surgeons use their in-depth knowledge of anatomy and experience to do their nerve block injections in a very precise fashion. We are basically injecting the nerve block in the same place that we would be performing the surgery. If our nerve blocks don’t work, then it is likely that surgery is not a great option for you. But until you have had targeted injection mapping where the surgeon injects in the area of the anticipated surgery, you can’t know for sure if your previous treatments mean that you are or are not a candidate for migraine surgery.

What is in the nerve block?

Nerve blocks mean different things to different people, and there are several different things that can be injected to “block” a nerve. To a migraine surgeon, our nerve blocks are in fact exactly that- a local anesthetic that inactivates a nerve temporarily. The anesthetic actually “blocks” signals from traveling through the nerve tissue.

What are other types of nerve blocks? Many medical practitioners such as neurologists and pain doctors use steroids in their nerve blocks. The purpose of the steroids is to decrease inflammation and irritation, and that is why steroids are used in such varied conditions of poison ivy and allergies. When injected, the steroid is meant to relax irritated muscles and nerves. In the cases where inflammation of these structures is the cause of the problem, these steroid injections will work great. Their effect often lasts weeks and sometimes even months.

If, however, it is not inflammation of the tissue that is the problem, a steroid nerve block might not provide relief. In many cases, a blood vessel or band of connective tissue may be pushing on the nerve and causing irritation. Steroid injections will not be effective in these cases, and so a failed nerve block using steroid is not a clear indication of whether or not a migraine sufferer is a candidate for successful migraine surgery.

Sometimes, Botox is injected and called a “nerve block.” In fact, Botox works completely differently than the other injected medications. Botox does block nerves but does so in a manner that prevents the nerves that trigger muscles from activating the muscle to contract. This results in localized relaxation of the muscles around the Botox injection.

The nerves that are surgically decompressed during migraine surgery are actually sensory nerves, meaning that they provide feeling to a part of your scalp or forehead. While Botox also does seem to have a direct effect on these sensory nerves to some degree, the majority of the Botox effect seems to be related to the muscle associated nerves (motor nerves) rather than the sensation associated nerves (sensory nerves). This means that the primary “help” that Botox provides is to relax the tissues around the irritated sensory nerves and prevent the muscles from squeezing down on the nerves that run through them on their way to their sensory destination.

Here again, if the muscle is the main issue, as it often is, Botox will provide relief if injected properly near the problematic nerve. (See more about different ways Botox is injected here.) If the problematic nerve is compressed by bone or connective tissue or blood vessels, Botox injections may not provide significant pain relief even when properly injected. Here again, in these cases, a Botox injection that did not provide relief may not mean that migraine surgery would not work. If the migraine surgery decompressed the nerve from a blood vessel that was pushing on it, great postoperative relief could be achieved even in the case where Botox injections did not work previously.

What’s the take away here?

So, the failure of a nerve block does not necessarily mean that you should not consider having a word-up for migraine surgery. In many cases either because the nerve was missed or a different technique was used, or one or another injected medication didn’t work, migraine surgery may still provide long-term relief from migraine headaches and occipital neuralgia.

In order to see if a patient is a candidate for migraine surgery, a true nerve block provided by a migraine surgeon is really required to map out which nerves are involved. The “work up” of this targeted injection mapping is not excessive or involved, but needs to be done by the surgeon actually doing the migraine surgery to optimize the long-term success of a migraine patient’s treatment.

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