The Role of Neuromodulation in Complex Pain Conditions

North American Spine Society 34th Annual Meeting Highlight

Peer Reviewed

“Neuromodulation may be considered as part of the treatment pathways in complex acute as well as chronic pain,” said Alexander Bailey, MD, at the North American Spine Society 34th Annual Meeting in Chicago, IL. Outcome studies on spinal cord stimulation (SCS) are encouraging and suggest that neuromodulation is “a valid and appropriate tool in multiple clinical scenarios,” Dr. Bailey told attendees.
Man with back pain highlighted in red“Back pain and leg pain are often multifactorial and may exceed surgical options." Photo Source: 123RF.com.“Percutaneous and operative paddle lead implantation has decades of data and experience, and the technology continues to improve,” said Dr. Bailey, who is Medical Director and orthopaedic spine surgeon at Precision Spine and Orthopaedic Specialists in Leawood, KS. “It’s time for surgeons to reevaluate neuromodulation on a broader scale.”

Dr. Bailey discussed important studies on neuromodulation used in patients with chronic pain including spine conditions, and whether SCS has an impact on the opioid crisis.

Treatment of Chronic Pain Varies by Provider

While spine care physicians are well equipped at treating acute pain and typically follow the same treatment pathways, chronic pain conditions, including failed back surgery syndrome, are managed inconsistently.

“What we end up with is a hodgepodge of treatments for chronic pain,” Dr. Bailey said. These treatments often begin with injections, neuropsychiatric evaluation, tricyclic antidepressants, behavioral management, opioids, and surgery. Patients with failed back surgery then progress to revision surgery, neuroleptics, disability, opioids, and then the cycle continues with further revision surgery.

“We enter into a cycle of never-ending treatment with truly an unknown basis of outcome,” Dr. Bailey said.

“It’s not uncommon for a patient to come into my office who has been to several other physicians, and the last clinical note reads: ‘After latest fusion extension surgery, x-rays and MRIs look great, no complications or problem, hardware well placed, no central or neuroforaminal stenosis, sagittal balance is normal, adjacent discs look normal, pain 9/10–unchanged. Unfortunately, nothing further to offer and recommend follow-up with primary care physician.’”

“That patient leaves the spine surgery office and ends up in a primary care office, where primary care providers have few tools to treat these patients,” Dr. Bailey explained. “This has contributed to the opioid crisis.”

“Opioid use needs to balance the pros and cons,” Dr. Bailey continued. “Back pain and leg pain are often multifactorial and may exceed surgical options. Surgeons are doers, we want to do, and sometimes we shouldn’t.”

Efficacy Data on Neuromodulation Use for Pain

Dr. Bailey presented efficacy data from neuromodulation trials conducted over the past 20 years starting with a prospective randomized study from 2000 involving 54 patients with chronic regional pain syndrome. Pain intensity on the visual analog scale (VAS) was reduced by 3.6 cm in patients who received physical therapy plus SCS, compared with a slight increase among patients who received physical therapy alone (P<0.001).1

In a 2005 randomized crossover study involving 50 patients with failed back surgical syndrome, patients in the group who underwent SCS had a 47% success rate (ie, ≥50% pain relief) compared to an 8% success rate among patients who underwent reoperation (P<0.01).2 Crossover was less likely in the SCS group, with 5 out of 24 patients crossing over to surgery compared to 14 out of 26 patients crossing over into the SCS group (P=0.02).

A 2006 systematic review and meta-analysis showed a pooled mean reduction in VAS score of 4.7 among patients who received SCS for complex regional pain syndrome (CRPS).3 In a 2007 randomized controlled trial involving 100 patients with failed back surgery syndrome, the success rate (≥50% pain relief) was 48% in those in the SCS group versus 9% in the conventional medical management group (P<0.001).4

Next came a 2016 retrospective review of 141 patients with chronic intractable pain, nearly half of whom (45%) had failed back surgical syndrome. The patients showed a significant improvement in average VAS scores after SCS implantation (from 8 at baseline to 1.38 post implantation; P<0.0001).5 The implant was removed in 14 patients (10%), 9 of whom did not need the device because they no longer experienced substantial pain. The remaining 5 patients underwent laminectomy to control the pain.

“We know that SCS does not stop the disease process. Thus, degeneration continues, and a certain number of patients are ultimately going to have additional surgery,” Dr. Bailey said.

“The revision rate was 32.6% at 5 years, with the vast majority of revision surgeries being related to migration of percutaneous leads, infection, malfunction, or end of life of the battery,” Dr. Bailey said.5 The overall median revision-free survival rate was 75%, 65%, and 45% at 1, 3 and 5 years, respectively, he added.

“An insurance observational study from 2018 involving 5,476 patients found a 7.1% explant rate at 1 year,” Dr. Bailey said.6 “The primary determinant of system explant was preoperative opioid burden. After 1 year with continued SCS usage, opioid use decreased in 47% of patients.”

Furthermore, in a January 2019 trial involving 86 patients with chronic pain, 29 of the 53 patients (55%) who used opioids before SCS implantation were able to eliminate opioid use and 2 other patients were able to reduce their opioid dosage. The potential reasons for this marked decrease in opioid use include improved SCS technology, as well as improved education and knowledge among spine care physicians to decrease opioid use, Dr. Bailey said.

Key Findings from Clinical Trials of Neuromodulation

  • Pain relief ranges from 50% to ≥80% in a majority of patients
  • SCS revision and explantation rates are acceptable when compared to primary and revision spine surgery success rates
  • Long-term survivability and ongoing usage is improving with better technology development
  • Opioid use preoperatively impacts SCS success rates and should be managed appropriately
  • Opioid dose reduction or elimination can be expected after SCS in the majority of patients

Source: Bailey AS. Current data on spinal neuromodulation on decreasing opiate burden, spine surgeon’s outcomes and tips. Presented at: North American Spine Society 34th Annual Meeting, Chicago. Il. September 26, 2019.

Determinants of Spinal Cord Stimulator Success

“With chronic pain, we need to attempt to identify all multifactorial sources of pain, we need to manage with limited medications, and we need to limit pain management invasive procedures,” Dr. Bailey said. “We need to include neuropsychiatric tools, and we need to approach reconstructions carefully with predefined expectations. Patient selection, as always, is a key determinant.”

Dr. Bailey uses two primary predictors of SCS success in practice. The first is a >50 morphine equivalent dose (MED), which “exponentially begins the decrease in success of most surgical procedures, including SCS,” he said. “We need to start rehabbing our patients preoperatively.”

The second aspect is making an accurate assessment of SCS implant trial outcomes. “There is a lot of potential psychological manipulation of patients after trials to convince them that SCS worked, and we have to be honest during SCS trials,” Dr. Bailey said. “We need to look at aspects of addressing hope/patient expectations, the placebo effect, opioid use during and after the trial, and activity level during and after the trial,” Dr. Bailey said. “For example, if patients do well in the SCS implant trial, but they doubled their opioid use, of course they feel better.”

“Unexpectedly, the underlying diagnosis is not the primary determinant of SCS trial success,” Dr. Bailey told NASS attendees.

Conclusions

“In my opinion, SCS can be considered as a primary procedure and should not be ignored as a possible treatment modality in non-previous surgery conditions,” Dr. Bailey concluded. “Pain reduction may be equivalent or even exceed surgical outcomes. There are even greater potential outcomes in failed back surgical syndrome patients, as revisions carry low clinical success rates.”

“More spine surgeons need to consider neuromodulation as part of the treatment pathways,” Dr. Bailey added. “Referral to good pain management groups with active involvement in SCS will likely benefit our patients and may positively impact the opioid crisis. After all, a SCS trial is the one area that we can try first, before permanent SCS implant, primary surgical procedures, and certainly before reconstructive surgeries. Our goal is to reduce pain, lessen or eliminate narcotic burden, and achieve patient satisfaction, but not necessarily better-looking x-rays and MRIs.”

Disclosures
Dr. Bailey reports relationships with Medtronic, Life Spine, Stryker, and Boston Scientific.

Updated on: 10/24/19
Continue Reading
Integrating Spinal Cord Stimulation into Surgical Practice
Alexander S. Bailey, MD
Orthopaedic Spine Surgeon
Medical Director
Precision Spine and Orthopaedic Specialists
Leawood, KS
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