Peripheral field stimulation for Atypical face pain

Scenario

A 37-year-old woman who had been in severe pain for over 4 years after three dental procedures was referred to the clinic. Two other oral surgeons and a pain physician who specializes in facial pain had seen her over the past 2 years and concluded that the pain was likely from damage to parts of the left superior and also, secondarily, to the inferior alveolar nerves. She had tried several blocks and high doses of gabapentin, carbamezapine, duloxetine, and pregabalin without noticeable benefit or at least any possibility to drop her pain level below about 8/10. Her pain was burning and aching with intermittent sharper searing pains, all consistent with damage to these trigeminal nerve branches. On the skin surface, the pain appeared to be delineated fairly locally over the upper and lower regions of the maxilla and mouth, extending almost to the tragus laterally and about 3 cm from the midline medially. Touching the area on the skin or using her teeth or mouth for chewing on that side, or sometimes on either side, exacerbated the pain, but at baseline, it was virtually always at least a 7/10. She had no particular loss of sensation in the area, although it was difficult to be sure there was no loss at all as it was intolerable for her to test the area well enough.

She also had managed to reduce her opioid requirements over the last year as they were not particularly helpful for the pain, but she still was taking about 20 mg of oxycodone per day in 2–4 separate doses. She had been up to 80 mg per day at times in the past. She had more or less lost hope that there was anything that could be done for her pain and was reluctant to make the visit, but her pain physician had insisted that she go. She also saw a pain psychologist for the previous 3 years who encouraged her to make the visit as well. After getting through basics of the history and having her describe and show the regions where the pain was worse (superior over inferior), I explained that this was potentially treatable with stimulation and described how the electrodes could be placed within the face under these regions safely and so they were not visible. Importantly, I described as well how a trial for this could be accomplished noninvasively. She decided to go forward and arranged time to meet again in the clinic for the trial.

• Variation : The patient had prior trigeminal nerve decompression surgery -- In this scenario, the patient has been presumed to have had a typical version of trigeminal neuralgia and had a standard decompression and placement of Teflon cushioning to prevent pulsation to the nerve. If the history is truly consistent with this etiology, then facial trigeminal branch stimulation, as described in this case, will not be helpful. The surgeon must determine as best as they can whether the patient is more likely a failed case of typical trigeminal neuralgia or an atypical case with more distal nerve branch damage. Although it is possible that one could have both, it is quite rare. Often, the noninvasive trial in the clinic can provide more reliable information for a judgment on this.

• Variation : The patient has only brief episodic, lancinating types of pain occurring perhaps once or only a few times a day -- Often, patients with typical or atypical facial pain will describe it as a long history of very brief episodic pains—severe in nature, but brief nonetheless. They may occur several times each day or less frequently, numbering perhaps several per week. In either of these scenarios, such episodic pains are not as well treated with trigeminal branch stimulation as more persisting continuous pain. It is possible that the constant stimulation may prevent some pains from occurring or make the pain less severe, but it is very difficult to get trial information beforehand because of the infrequent nature of the pains. Most of the time when I have been presented with such cases, I have discouraged the patient from considering this type of therapy.

• Variation : The patient has no discernible trigeminal branch distribution of their pain -- Atypical face pains take on many variations. If the pain, however, cannot more or less be ascribed to one or more of the typical trigeminal braches in location or etiology, then placement of electrodes optimally becomes quite difficult. The noninvasive trial in the clinic can be helpful in this regard, but many locations of the electrodes may need to be tried before determining whether permanent placement is warranted.