Occipital nerve stimulation: trial and permanent

Scenario

A 45-year-old woman presented in referral from a headache center with a long history of complex migraines and focal occipitoparietal head pain as well. The head pains seemed to be present all the time, or nearly so, while the more “typical” migraine, which was how she described it, came on every few days and lasted about a day or two. She had been prescribed numerous medications over the years, some of which may have helped at times but generally did not. Currently, she is taking a combination of tramadol and gabapentin. She had also had several injections to block the occipital nerve or trigger points in the back of her head. These had lasted for up to a few days at times. With further questioning about these injections, she did admit that they typically eliminated a significant amount of the pain for hours or a few days, but it always came back.

I asked her to show me where the primary area of pain was and whether she could outline it or delineate it well. She said it was always in the occipital area, spreading forward somewhat into the parietal margins. It began most often near what appeared to be the nuchal line. She did not believe she had had any history of trauma there, but could n’t rule it out either. After further discussion, it was more clear that this region of pain, more unrelenting, seemed nevertheless to bring about or have some role in initiating her migraine pains, which seemed also to originate on the same side of the head and extend in toward her eyes from that side.

I discussed how we could trial some stimulation in the area at the back of her head that might mitigate some of her pain, more likely having effect on the persistent occipitoparietal pain than the migrainous pain, which I was less sure about being related to or affected by stimulation. It seemed possible the migraine pains were a separate phenomenon and perhaps had been present in her life even before these other occipitoparietal pains. At this point, she said she would be likely to try almost anything and agreed to undergo a trial. I explained that noninvasive stimulation in the region was not really possible because hair would prevent the electrodes from adhering to the skin. We would need to place the electrodes in almost the same way as when they are placed permanently: shaving hair, general anesthesia, small incision, and so forth. The wires would exit the skin for over a week, perhaps even up to 2 weeks some times to be sure of the results. I also explained that they often migrate out or otherwise become displaced, and getting a perfect trial to go well the entire time was not always the case. If successful, we could place the permanent system with the implantable pulse generator (IPG) several weeks later. Either way, the leads would be removed in the office once the trial period had ended. She agreed, and we planned the initial trial lead placement surgery date.

• Variation : The patient only has a migraine -- Many people have migraines and migraine variants. If the patient had predominantly a well-documented migraine syndrome only, it would not rule out using stimulation in this same way, but I would be more reticent to endorse a positive outcome. On the other hand, frankly, it is hard to be sure of any of the outcomes with these head pain and migraine variants in any of the cases. And, because most of these patients are desperate and will try almost anything that sounds reasonably safe and not likely to end in their death, it is almost immaterial how much I try to give a truly straightforward assessment of the likelihood of success. The outcome data from occipital nerve stimulation (ONS) for migraine per se have been mixed but anecdotally successful. Ultimately, it may be worth considering a subthreshold trial in most of these cases.

• Variation : The patient has clear occipital neuralgia (secondary to a trauma) -- Clinically likely true occipital neuralgia is a very good candidate for ONS, with or without successful occipital nerve (ON) blocks, especially suprathreshold stimulation using two leads per side and just below the subthreshold locations. All the same attention to details in terms of trial length, anchoring techniques, tunneling techniques, and diligence about preventing infection applies in the same way. The only difference really is in lead location and the physiological basis for this is unclear presently.

• Variation : The patient has other more vague complaints of head, neck, or trunk fibromyalgia-type symptoms -- Just as migraine is a softer indication to consider ONS, even subthreshold ONS, these other types of atypical head or body pains are also a softer call. The presumption is that pain mitigation occurs somehow in the spinal trigeminal nucleus where head pain is also processed. In some anecdotal cases, my own included, there is some kind of ability for this region also to alter pain from other regions. It makes more sense to be conservative in endorsing the benefit from ONS for these types of cases, but then the morbidity from a trial is very minimal, and in a 2-week period of time, the information can be gleaned, pushing the recommendation into the trial category most of the time. If the pain is entirely in the trunk and migrating fibromyalgia-like pains, it is quite hard to predict any benefit.