Why did the nerve block from my neurologist make things worse?

nerve block for migraines

A frequent question I get asked involves nerve injections that make things worse rather than better.  Many times nerves blocks work just as they are supposed to but when they don’t, patients are often left trying to figure out why???

So what happens when nerve blocks make the pain worse?

Remember that nerve blocks can be divided into diagnostic and therapeutic blocks, discussed in further here.  And remember that diagnostic blocks contain a small volume of local anesthesia, such as lidocaine or bupivacaine.  These are the blocks that I and my colleague migraine surgeons perform, and they shut down all signals traveling through the nerve.  Even if the needle were to hit the nerve which would cause worse pain, the anesthetic in these injections rapidly shuts the pain signal off and so these injections rarely worsen headache pain. 

These diagnostic blocks are different from the blocks performed by neurologists, that are supposed to be (and often are) “therapeutic.”  These therapeutic nerve blocks often also include steroids, and these steroids are diluted in a larger volume of liquid.  This is done because the neurologists are often not able to localize the nerve exactly, as opposed to the surgeon who sees these nerves and their location frequently.  The diluted steroid is meant to spread around the region, decreasing inflammation of anything that is inflamed in the area, as a kind of shotgun approach to migraine pain control.

This is similar to other steroid shots.  In an inflammatory situation, such as an inflamed joint, many of you might have had or know someone that had a steroid injection into that joint.  But the injections can hurt because you are adding volume to a closed space in the joint causing irritation and stretching.  Because steroids inhibit inflammation, the idea is that the injection of steroid into an inflamed joint reduces inflammation and therefore reduces joint pain.  This often works, because the inflammation of the cartilage in the joint reacts to the steroid injection by a reduction in swelling of that tissue and therefore the associated pain.

The same concept is supposed to work when injecting steroids around inflamed nerves.  The steroid is meant to calm the inflammation of the nerve and surrounding muscle, though it does not actually block the signals traveling through the nerve.  BUT, if the injection itself irritates the nerve, there is no mechanism in the injection to shut the nerve signals down that is causing the migraine pain.  And this is what often happens.

Because of the volume of the injection, if that injection does get right next to the nerve, the expansion of the tissue from the volume of the injection can actually cause a localized stress or stretching of the nerve, worsening the inflammation and pain rather than making it better.  Because the nerve is still conducting signals, the migraine pain worsens rather than improves.  This can also happen if the injection needle comes into contact with the nerve, again causing a worsening of the distressful nerve signals rather than an improvement.

Now to be fair, this can happen to anyone.  In fact, I have had a patient in whom I injected Botox to try to relax the muscle around the nerve, and her pain got worse for 5 days rather than better.  Why?  Because Botox takes about 5 days to start relaxing the muscles around the nerves, and it does not have a large direct effect on the conduction of pain signals.  The volume of the Botox irritated the nerve, and after 5 days, the muscle that was exposed to the Botox relaxed and the nerve’s compression from this muscle tissue was relieved.  And the migraine went away.

Nerve Blocks vs. Migraine Surgery

So here is the really interesting part.  If ANY of these circumstances happen to you, it is likely that you are a great candidate for migraine surgery.  The best patients to receive nerve decompression for the relief of migraine pain are those whose nerves are inflamed and are triggering the migraine pain.  So if your pain gets better with a nerve block, we know that it is the nerve traveling through that area that is the cause of your pain, and so decompression of that nerve will likely improve your migraine.  If your neurologist gave you an injection and your headache or occipital neuralgia pain got worse, it is again a very likely circumstance that it is that nerve in that area that is causing your pain.  Here again, surgical release of that nerve is the definitive manner in which to relieve the inflammation of the nerve.  Even these patients can have hope that there is likely a way to provide permanent improvement if not a complete relief to their migraine headaches or occipital neuralgia pain through an outpatient surgical procedure.

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