Paddle lead placement in the cervical spine region

Scenario

A 52-year-old man is referred for placement of a cervical spine paddle lead after a successful trial by a pain physician in the community. He has had two anterior cervical discectomies with fusion in the past, at two separate levels (C45 and C56) at two separate times (3 years apart – first C56 and then C45). Although there had been improvement in his C6 distribution arm pain following the first surgery, he continued to have uncomfortable mechanical neck pain and then developed extension into his opposite shoulder over the subsequent year, eventually leading to the second surgery when the adjacent level C45 disk protrusion was noted. However, after this surgery, he had unrelenting neck pain despite what appeared to be a solid fusion construct and radicular-type pain on both sides in various distributions consistent with C5 and C6 and even C7 at times. After reviewing his films and noting no significant disk protrusion at previous levels or new levels, stable flexion-extension views showing a solid fusion, lack of notable benefit from gabapentin at 1800 mg/day and inability to tolerate pregabalin, and lack of success with epidural steroids and facet blocks and that he reported benefit from the trial stimulation of over 65%, a decision was made to proceed with paddle lead and implantable pulse generator (IPG) placement in the operating room on the elective schedule. Of note, he had also tried a round of chiropractic care as well as acupuncture treatments and had become accustomed to taking 5–10 mg of oxycodone every 6–8 hours, although he admitted this only improved his visual analog scale by perhaps one to two points from a typical 8/10 to 6/10 or 7/10 on most days.

The plan was to place the paddle lead, from a company primarily relying on traditional paresthesia-based stimulation, at levels spanning C3-4-5. The goal of the stimulation was suggested to be for his arm pains, but in the trial, some benefit seemed to occur for the neck and trapezial axial pains as well. The patient was brought to the operating room and intubated. Using a total intravenous anesthetic technique approach for anesthesia, he was turned into the prone position using a chest and bilateral hip cushions, and his head was able to be positioned neutral to slightly flexed, resting on a horseshoe head holder attached to the Mayfield bed attachment. The back of his neck and base of the skull region was shaved adequately to allow for the midline incision and so the dressing afterward would adhere well. A midline incision was planned from approximately the C2 spinous process down to just superior to the C6 or C7 spinous process. An IPG site was planned in the flank region, marking it in the preoperative holding area with the patient in the upright sitting position – posteriorly located, to avoid having to perform two procedures in different positions (if the IPG was instead to be placed in the anterior subclavicular area) but not as far inferior as the upper buttock to minimize long wire pulling and extension wires. Both the subclavicular and upper buttock areas are viable alternatives, however. Also, this patient had enough excess tissue in his flank region to allow for this without likely discomfort once healed.

• Variation : Pain was primarily in neck and trapezial area -- Axial pain symptoms are rarely managed as well as extremity pain symptoms, and without doubt, neuropathic better than nociceptive. Axial pain is often more difficult to ascribe to the neuropathic category. That said, patients can have benefit from spinal cord stimulation (SCS) in treating axial symptoms, and it is worth a trial. The trial tends not to be a perfect discriminator in the long term but does provide justification to proceed with permanent placement if successful. In this case, if the patient were to have no extremity symptoms and pain was localized entirely to axial neck and maybe some trapezial elements and a trial was successful (i.e., >50% improvement for several days, perhaps better sleep or function, and worsening again once removed), then a paddle placement is likely the best option. In terms of location, such pain is more likely relatable to higher segmental levels than C4-7, which is represented in this case. In such a scenario, it would be more successful to place the lead from C1-3 if possible. Some have advocated placing a retrograde lead down from above C1. This is also reasonable but provides no significant advantage in my opinion to placing the lead from a lower level and sliding it superiorly; it can migrate or move from either position and needs to be anchored well in either place. In some cases, if a lower level cannot be accessed, the superior levels above C3 may yield lower segment pain benefit, even including low back or leg, but this is quite unreliable and rare in my experience. Even covering the hand is not reliable at all above C4.

• Variation : Pain is primarily in the hand -- As mentioned previously, pain predominantly in the hand, in failed back surgery syndrome (FBSS) or complex regional pain syndrome or other etiologies, is not reliably covered by paresthesia-based stimulators above the C4 level and ideally the lead needs to be at C5 or below. Placing it at C7-T1 may be too low and also unreliable. One might also consider peripheral nerve stimulation (PNS) over the distal median or ulnar nerves if SCS is unsuccessful.

• Variation : Pain is in the hand and neck -- If pain is in hand and neck, in other words, the most extremes – axial superior and distal extremity – then it is unlikely the patient will benefit with a single lead. In my view, the trial can be used in many cases to separate out the appropriate levels and may need to be considered as the permanent solution for therapy. If the patient can distinguish one as being more important than the other, that target should be treated first, but with the caveat that an inferior lead (e.g., C5-7) to treat hand will almost never treat neck pain, whereas a superior lead (e.g., C1-3) might treat hand.

• Variation : A nonparesthesia system is being used -- High-frequency (i.e., 10 kHz) and so-called Burst systems or subthreshold ∼1 kHz systems might be planned from the outset, instead of a “traditional” stimulation system used in this case. All of them can achieve successful pain benefit. However, it should be appreciated that it is less clear where the lead needs to be placed. My own personal view currently is that the lead position should be planned as if it were going to be paresthesia-based and tested as such in the operating room (OR) as noted in the case here. Should the other waveform fail, at least the lead is positioned to try paresthesia-based therapy anyway.