Spinal Cord Stimulation (SCS) - Wiley Online Library

Neuromodulation: Technology at the Neural Interface Received: October 9, 2012

Revised: March 24, 2012

Accepted: May 31, 2012

(onlinelibrary.wiley.com) DOI: 10.1111/j.1525-1403.2012.00497.x

Spinal Cord Stimulation (SCS) in Conjunction With Peripheral Nerve Field Stimulation (PNfS) for the Treatment of Complex Pain in Failed Back Surgery Syndrome (FBSS) Claudio Reverberi, MD*, Alessandro Dario, MD†, Giancarlo Barolat, MD‡ Background: Failed back surgery syndrome (FBSS) is a well-defined pathologic condition observed over many years. Design: We have investigated the effect of spinal cord stimulation (SCS) with peripheral nerve field stimulation (PNfS) in eight patients with FBSS Outcome Measure: The following parameters were collected and analyzed: The pain intensity score on a 0–10 numbering rating scale (NRS), the psychologic profile with Beck Depression Inventory (BDI), the pain quality with McGill Pain Questionnaire—short form (MGPQ-sf ), the back pain with Oswestry scale score (OS), and the health general quality pattern with QualityMetric’s SF-36v2® Health Survey. Patients: Eight patients with low back and radicular pain in FBSS are reported. The mean duration of pain was 6.7 months, and the mean NRS score was 9.5, BDI 28.8, MGPQ-sf 16.8, OS 44.5, and SF-36 score was 72.8. The average drug intake of opioids was 250 mg/day. Intervention: In six patients, two octopolar leads were placed in epidural space at D7-D8 and D8-D9, in conjunction with two octopolar leads placed in lumbar-sacral subcutaneous space (Precision System, Boston Scientific, Valencia, CA, USA), and in two patients, a two tetrapolar leads was placed in epidural space at D8-D9 with two tetrapolar leads (Pisces Quad, Plus, Medtronic Inc., Minneapolis, MN, USA) placed in lumbar-sacral subcutaneous space (Restore Ultra, Medtronic Inc., Minneapolis, MN, USA). Results: After one year mean of follow-up, the mean NRS score was 4, BDI 8, MGPQ-sf 5, OS 21, and the SF-36 score was increased at 108.5. The mean drug intake of opioids was decreased at 20 mg/day. Conclusion: The combination of SCS and PNfS, using the latest rechargeable systems, may be a valid therapeutic strategy in FBSS. Keywords: Chronic pain, low back pain, neuropathic pain, percutaneous nerve stimulation, spinal cord stimulation Conflict of Interest: The authors reported no conflicts of interest.

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INTRODUCTION

MATERIALS AND METHODS

Failed back surgery syndrome (FBSS) is a well-known condition that affects about 20–40% of patients undergoing spinal surgery (1). These patients, most commonly ranging 30–50 years of age, have undergone one or more surgical interventions on their lumbar spine, and their postoperative progress is hindered by a number of complications (hematoma, infections, microinstability, to name a few) leading to the need for further surgery and often resulting in FBSS. In almost all patients affected by FBSS, spinal cord stimulation (SCS) with leads placed at T8-T10 offers a valid therapeutic alternative for the treatment of the direct Ab and d neuropathic pain in the lower extremities but is much less effective on low back pain. The complexity of the involved mechanisms explains why the combined utilization of SCS (effective in neuropathic pain in the limbs) and peripheral nerve field stimulation (PNfS) (also effective in mixed or nociceptive pain) may be the treatment of choice for patients with complex pain following repeated lumbar interventions.

Over the last three years, eight patients with complex FBSS pain have been treated with thoracic SCS implant combined with PNfS with leads placed in the lumbar-sacral region. Average follow-up is one year. In four patients, PNfS was added subsequently for persistent low back and sacral pain, which had not been controlled with SCS alone.

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Address correspondence to: Claudio Reverberi, MD, FIPP, Pain Therapy Department, Oglio-Po Hospital, via Staffolo n. 51, Casalmaggiore 26400, Italy. Email: [email protected] * Pain Therapy Department, Oglio-Po Hospital, Casalmaggiore, Italy; † Department of Neurosurgery, Macchi Foundation Hospital, Varese, Italy; and ‡ Department of Surgery, Barolat Neuroscience, Denver, CO, USA For more information on author guidelines, an explanation of our peer review process, and conflict of interest informed consent policies, please go to http:// www.wiley.com/bw/submit.asp?ref=1094-7159&site=1

© 2012 International Neuromodulation Society

Neuromodulation 2013; 16: 78–83

SCS + PNfS IN THE FBSS TREATMENTS

Figure 2. SCS and PNfS for lumbar pain (Precision System, Boston Scientific, Valencia, CA, USA). PNfS, peripheral nerve field stimulation; SCS, spinal cord stimulation.

Figure 1. Patient with eight-polar paddle D7-D8.


RESULTS The results were analyzed using the NRS score evaluation before the implant and at 3, 6, and 12 months follow-up. The following questionnaires were utilized: the Beck Depression Inventory (BDI)-II for psychologic assessment, the McGill Pain Questionnaire-short form for the assessment of the neuropathic pain, and the Oswestry scale for the assessment of the low back pain, as well as the SF-36 for assessing the patients’ general state of health. All the data were collected by a dedicated nursing staff during the follow-up visits and subsequently analyzed. We considered significant a 50% reduction on the NRS, the BDI-II, the McGill Pain Questionnaire—short form (MGPQ-sf ), and the Oswestry Score over the preimplant baseline and an increase of 20% on the SF-36. The first four patients tested were implanted with only SCS system, and the NRS index, MGPQ-sf, and Oswestry scale score were



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These patients were implanted with an Artisan paddle lead (Boston Scientific, Valencia, CA, USA) placed epidurally at T7-T8 (Fig. 1) (2). With the multisource current fractionalization and stimulationindependent system, we observed a discrete recruitment of the sacral fibers, although this was not always sufficient to achieve a significant and stable pain relief, particularly when moving and standing (nociceptive pain from load or segmental microinstability). Stimulation in the lumbo-sacral segments could be achieved, but excessive postural changes precluded therapeutic efficacy of the stimulation on the lumbo-sacral pain (possibly also because of the nociceptive nature of the pain). Based on this experience, the next four patients were directly implanted with combined SCS + PNfS systems; this consisted of quadric- or octo-polar epidural percutaneous electrodes at T9-T10 to recruit the lower extremities and two (quadri or octopolar) cylindrical electrodes placed subcutaneously in the painful lumbar areas (Fig. 2). Seven of the patients were female and one male, with an average age of 45 ⫾ 8; all had undergone at least two surgical interventions on the lumbar spine, and five were subjected to lumbar arthrodesis with posterior instrumentation. At the time of the implants, the pain had been present for over six months with an average numbering rating scale (NRS) of 9.5 and had not responded to any other conservative treatment. Given the relatively young age of the patients, 16-polar rechargeable systems were chosen. In the last two patients, a Precision Boston Scientific system was implanted with two parallel octopolar epidural leads in the epidural space, about 5 mm from midline at T9-T10, connected to two octopolar subcutaneous electrodes

placed in the painful lumbar-sacral area; the subcutaneous placement in one case was unilateral and in the other case was bilateral (Fig 2). The system was connected to the rechargeable implanted pulse generator with two “splitter” extensions to convert each octopolar lead to a quadripolar. The epidural leads had adjacent poles connected, whereas the subcutaneous ones had alternating poles connected. In the other two patients, the Restore Ultra, Sensor, Medtronic system was chosen, with four Pisces Quad Plus (Medtronic Inc., Minneapolis, MN, USA) leads; two were placed epidurally parallel to and 5 mm from the midline at T9-T10, and two were placed subcutaneously in the painful lumbo-sacral area (Fig. 3). Both systems provided complete coverage of the neuropathic pain in the lower limbs via the epidural electrodes and of the nociceptive lumbar-sacral pain via the subcutaneous electrodes.

REVERBERI ET AL.

Figure 4. SCS (two eight-polar paddles) + lumbar PNfS (Precision System, Boston Scientific, Valencia, CA, USA). PNfS, peripheral nerve field stimulation; SCS, spinal cord stimulation.

Figure 3. SCS and PNfS for lumbar pain (Restore Ultra, Medtronic, Minneapolis, MN, USA). PNfS, peripheral nerve field stimulation; SCS, spinal cord stimulation.

Table 1. 4 Patients Treated With Only SCS (Trial) for 45 Days.

NSR MGPQ-sf Oswestry scale

Preimplant

To 45 days

9.5 16.8 44.5

5.6 6 35.5

Table 2. 4 Patients Treated With SCS + PNfS (Trial) for 45 Days.

NSR MGPQ-sf Oswestry scale

Preimplant

To 45 days

9.5 16.8 44.5

3.6 3 16

MGPQ-sf, McGill Pain Questionnaire—short form; NSR, ••; PNfS, peripheral nerve field stimulation; SCS, spinal cord stimulation.

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evaluated during the test trial phase (average duration: 45 days). Using various programming parameters, we were able to obtain reductions in the NRS from 9.5 to 5.6, in the MGPQ-sf from 16.8 to 6, and in the OSWESTRY from 44.5 to 35.5. (Tables 1 and 2). Subjectively, the patient reported fair pain relief in the lower limbs but persistent low back pain when being physically active. www.neuromodulationjournal.com

Figure 5. Follow-up at one year on eight patients with complex pain treated wit a combination of SCS and PNfS. BDI, Beck Depression Inventory; NSR, Numerical Score Rating; SF-36; McGill Scale; OSWESTRY.

MGPQ-sf, McGill Pain Questionnaire—short form; NSR, ••.

With the addition of PNfS leads, further reductions in the NRS SCORE to 3.6, MGPQ-sf to 3, and Oswestry scale to 16 were observed, with subjective reduction in low back pain at rest and after slight to moderate physical activity (Table 2). There was a significant increase in the SF-36 score in all patients, especially for activity, pain, work, and health. Parameters utilized included contacts polarities -0 + 0 + 0-, Pw 300ms, freq. 50 Hz. Given these encouraging results, the four patients already implanted with SCS were implanted with PNfS, due to their persistent low back pain, and they were included in the follow-up (Fig. 4). With an average follow-up of one year, the data show extremely significant results as shown in Fig. 5. The use of opiate drugs and adjuvants (gabapentin) was dramatically reduced, with the average dose of opiates decreased from 250 mg/day (oxycodone) to 20 mg/day. Four of the eight patients are no longer taking neither opiates nor adjuvants.



SCS + PNfS IN THE FBSS TREATMENTS No patient resumed work that would require medium to hard physical duties, but sedentary or slight–moderate physical work was resumed and quality of life (measured using SF-36) was drastically improved in all subjects. Up to the one year follow-up, no complications have occurred associated with the PNfS.

DISCUSSION




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Optimal treatment for FBSS does not exist. It may reasonably to assume that “the most effective treatment for FBSS is to avoid or prevent FBSS itself”, since, once triggered, the psychologic, physical, and mechanical effects experienced by the patients contribute to a multifactorial, complex, painful syndrome. As shown in the literature (3), the outcome of patients who have been subjected to multiple surgical procedures on the spine is worse than those who underwent SCS. An analysis of data from the Evidence Based Medicine literature has also shown that repeated interventions often worsen the clinical picture, by causing additional epidural fibrosis and segmental microinstability (4,5). Four patients were implanted with dual octopolar paddle leads (Boston Scientific) at T7-T8. With a suitable high pulse width setting, we were able to obtain stimulation of the sacral fibers and to obtain a fair amount of pain relief at this level. However, even with such a system, the upper lumbar region is always difficult to recruit, and these patients continue to complain of low back pain. Medtronic recently launched a rechargeable system with a selfregulating current, depending on the patient’s postural position; even with that, we found recruitment of the lumbar fibers still to be problematic. PNfS, as suggested some years ago by Barolat, is an effective, simple way to recruit lumbar and sacral fibers directly from the painful region, by placing electrodes in the superficial subcutaneous layer to stimulate the nerve endings and dermal receptors (6). This type of stimulation travels through the dorsal roots reaching the spinal cord and providing a similar effect to that of SCS (7). PNfS can therefore be useful when one wants to stimulate areas that are difficult to reach with SCS, such as the lumbar and sacral regions. A second important feature of PNfS is that it is effective not just in the case of neuropathic pain but also in treating nociceptive pain, which may be due to the changes in the receptor membranes caused by the current in the dermal mechanoreceptors (8,9),. The release of local anti-inflammatories (cytokines) and the action on the dismutase nitric oxide system may complete the range of action of the PNfS (10,11). Several studies have shown the superior efficacy and flexibility of the combined SCS and PNfS approach. Bernstein et al. studied 20 patients with chronic low back and leg pain syndromes who had failed conventional therapies and who underwent implantation of a combination of traditional SCS and PNfS. Leads were placed in the epidural space, as well as superficially in the subcutaneous tissues of the lower back, directly in the region of maximum pain. In some patients, a combination was used at the time of the initial trial. In other cases, the decision to proceed with the combination was made later, either at the time of permanent implant, or later on, after SCS alone failed to adequately control pain. Although not all of these patients ultimately proceeded with the combination of SCS and PNfS to control their pain, the majority of patients found the combination better in controlling

their overall pain than either modality alone. In addition, using a combined approach at the time of trial provided a noninvasive and effective method of comparing the efficacy of each method, allowing patients to identify the best form of neuromodulation for their particular pain. The authors concluded that the availability of this combined approach for a trial of stimulation prior to implant allows patients to compare SCS with PNfS and to indicate a preference for one over the other or for the combination. They also concluded that PNfS may be used in combination with SCS as a safe and effective alternative treatment for patients with chronic low back and leg pain, and further suggest that the combined approach should be considered as a treatment option for this population (12). Mironer et al. performed a prospective two-part study including patients with low back pain because of FBSS and/or spinal stenosis. In the first part, 20 patients were implanted with SCS and PNfS. They selected the best program out of three: SCS alone, PNfS alone, or both together. In the second part, another 20 patients with the same implanted leads were selecting between three programs: SCS and PNfS separately, SCS as anode, and PNfS as cathode, or in reverse. In the first part, 79% of the patients selected simultaneous use of SCS and PNfS. The overall success of the trials was 85%. In the second part, communication between SCS and PNfS provided wider coverage of axial pain. The overall success of the trials was 90%. The authors concluded that simultaneous use of SCS and PNfS increase efficacy of both methods for axial back pain (13). Navarro et al. reported a retrospective data collection study aims to evaluate the responses of patients who have been implanted with a neuromodulation system using a combination of SCS and peripheral subcutaneous field stimulation (PSFS) leads for chronic intractable pain. The study included 40 patients with chronic, intractable pain implanted with both SCS and PSFS leads. One lead was placed epidurally at T8-9, and the other two leads were placed in the subcutaneous layer in the lumbar area bilaterally. The three leads created a triangle and were connected with their synchronized programs to produce a paresthesia in the targeted painful area. The majority of the patients experienced immediate and short-term pain relief and reduction in oral pain medications as a result of combination SCS/PSFS therapy. The improvements were maintained for some but not all patients by six months. Patients utilized multiple programs over follow-up; the use of triangular stimulation was consistent over time, and by six months, patients preferred this program over others (14). Hamm-Faber et al. reported 11 FBSS patients with chronic limb and/or low back pain whose conventional therapies had failed and who received a combination of SCS (eight-contact Octad lead) and/or subcutaneous stimulation (four-contact Quad Plus lead[s]). Eleven FBSS patients, five men and six women (age: 51 ⫾ 8 years; mean ⫾ standard deviation), in whom SCS alone was insufficient in treating lower back pain, were included. In nine cases, subcutaneous stimulation (SubQ) was used in combination with SCS to treat chronic lower back and lower extremity pain. In two cases, only SubQ was used to treat lower back pain. SCS significantly reduced limb pain after 12 months (visual analog scale [VAS]bl: 62 ⫾ 14 vs. VAS12m: 20 ⫾ 11; p = 0.001, N = 8). SubQ stimulation significantly reduced low back pain after 12 months (VASbl: 62 ⫾ 13.0 vs. VAS12m: 32 ⫾ 16; p = 0.0002, N = 10). Overall pain medication was reduced by more than 70%. The Quebec Back Pain Disability Scale improved from 61 ⫾ 15 to 49 ⫾ 12 (p = 0.046, N = 10). Two patients returned to work. The authors concluded that subcutaneous stimulation may be an effective additional treatment for chronic low back pain in patients with FBSS for whom SCS alone is insufficient in controlling their pain (15).

REVERBERI ET AL. In the patients we treated with the combined SCS + PNfS system, there has been a drastic reduction in the lumbar nociceptive pain compared with those treated with SCS only; this has led to a significant improvement in the quality of life, especially in the social activities (work, physical activity, and health), and to a reduction in drugs intake. The stimulation did not allow patients to resume medium to heavy duty work activities, mainly due to the fact that heavy physical activity triggered substantial low back pain that was unresponsive to stimulation PNfS also showed a higher long-term habituation and tolerance than SCS. Our patients were assessed every one to two months on average, and it was often necessary to vary the polarity configurations and the strength of stimulation to achieve a good therapeutic effect. Cycling modes were invariably utilized. During acute pain exacerbations, often we had to recommend periods of rest or the use of Non-steroidal anti-inflammatory drugs (NSAIDS) and/or opiate medications for brief periods of time. In patients who develop tolerance to the stimulation, intrathecal drug infusion implant may eventually become a further option. In that instance, ziconitide, a drug now often indicated for the treatment of complex regional pain syndrome, might become a viable alternative (16). Finally, a recent Italian study of pharmaceutical economics (17) confirmed earlier studies (18) that patients treated with the latest generation of rechargeable systems enjoy an economic benefit over time, in terms of their healthcare costs, compared with patients treated with drugs only or those undergoing multiple operations.

CONCLUSIONS FBSS is still a serious problem in terms of its social, physical, and psychologic effects on the affected individuals. The combination of SCS and PNfS, using rechargeable stimulation systems, may be a valid therapeutic strategy because the combined systems work on both the neuropathic (SCS) and the nociceptivemixed lumbar-sacral component of the pain (PNfS). Besides, the ability to connect four leads (two intraspinal and two peripheral) adds a tremendous amount of flexibility and programmability to the stimulation. As was shown a number of years ago (3), the prognosis for patients implanted with SCS is better than patients undergoing multiple spinal operations. This should make SCS combined with PNfS the treatment of choice for intractable low back pain as well as for complex neuropathic pain originating from the lumbo-sacral nerve roots that have not responded to other conservative management. Over a longer span, the cost for patients implanted with rechargeable systems should be lower than the one for patients treated with drugs or with multiple spinal surgeries, particularly because they experience better results and may be able to reduce their narcotic medications (17). This, however, will have to be demonstrated in a large prospective study.

Authorship Statements

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Dr. C. Reverberi and A. Dario designed and conducted the study, including patient recruitment, data collection, and data analysis. Dr. C. Reverberi prepared the manuscript draft with important intellectual input from Dr. A. Dario. www.neuromodulationjournal.com

Dr G. Barolat translated the manuscript in correct English language and reviewed the same and including some important reference data in the discussion. All the authors had complete access to the study data. All the authors approved the final manuscript and provided funding for editorial support.

How to Cite this Article: Reverberi C., Dario A., Barolat G. 2012. Spinal Cord Stimulation (SCS) in Conjunction With Peripheral Nerve Field Stimulation (PNfS) for the Treatment of Complex Pain in Failed Back Surgery Syndrome (FBSS). Neuromodulation 2013; 16: 78–83

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SCS + PNfS IN THE FBSS TREATMENTS

COMMENT This study is another confirmatory report of the efficacy of SCS and PNFS used in combination that follows quite a few other publications and presentations on the same topic. Unfortunately, the number of the patients in the current study is rather small. On the other hand, one significant advantage of this article is its very well documented outcome measurements. The next step for future researchers should be a large, well designed, blinded study rather than a continuous string of retrospective and prospective reports. Eugene Mironer, MD Greenville, SC, USA Comments not included in the Early View version of this paper.

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