Study Finds Why Some Patients Do Poorly with Spinal Cord Stimulators

By Pat Anson, PNN Editor

Spinal cord stimulators (SCSs) are often considered the treatment of last resort for people with severe back or leg pain, who don’t respond well to more conventional ways of treating pain.

The neuromodulation devices are surgically placed near the spine and send out mild electrical impulses to mask pain signals. Because stimulators are invasive and have poor success rates, it’s customary for patients to go through a short trial period before having the devices surgically implanted.

A new study has documented why some patients do well with stimulators and others don’t.

In a retrospective analysis, researchers at the University of Kansas Medical Center looked at 237 patients who received SCSs, about a third of them considered “nonresponders.” They found that people with severe pain and disability who fear physical activity because of the pain it might cause – a condition known as kinesiophobia – are significantly less likely to respond to the devices.

The study is being presented this month at the annual meeting of the American Society of Regional Anesthesia and Pain Medicine (ASRA).

Researchers analyzed several patient characteristics, such as their age, gender, body mass index, history of spinal surgery, diabetes, alcohol and tobacco use, psychiatric illness, and use of opioids. None appeared to have an association with how a patient responds to SCS.

But researchers found that three out of four (76%) nonresponders had clinically high levels of kinesiophobia, compared to about half (56%) of those who did respond to SCS treatment. Nonresponders were also more likely to have severe pain, disability, and to complain or worry about their pain – a condition known as “catastrophizing.”

“Collectively, our findings indicate a clinically relevant association of high levels of kinesiophobia, greater disability, severe pain intensity and pain catastrophizing, as subtle indicators, and possible predictive factors to nonresponders,” researchers said.

“As such, it may be appropriate to utilize preoperative screening tools for these factors to help optimize patient selection and predict a patient’s response to neuromodulation. Furthermore, if risk factors are present, it might be prudent to consider a pre-rehabilitation program with pain neuroscience patient education prior to SCS therapy to address these modifiable risk factors and potentially enhance outcomes in neuromodulation.”

About 50,000 spinal cord stimulators are implanted annually in the U.S. The devices are often touted as a safer alternative to opioid pain medication, although a growing number of studies have questioned their safety and efficacy.

A recent Cochrane review of SCSs concluded the devices work no better than a placebo for treating chronic low back pain, and provide little to no benefit in improving quality of life. That negative review led some doctors who perform the surgeries to demand a retraction from Cochrane because of “striking errors in the methodology, execution and conclusions” of the study.

Meanwhile, a 2018 investigation found that SCSs have some of the worst safety records of medical devices and called for better FDA oversight of their growing use in pain management. A subsequent FDA review of complaints involving stimulators found that nearly a third were reports of unsatisfactory pain relief.

Yet another recent study found that many patients given stimulators did not reduce their use of opioids, and continued getting procedures such as epidurals, corticosteroid injections and radiofrequency ablation to relieve their pain.

Study Finds Spinal Cord Stimulation Has No Benefit for Back Pain

By Pat Anson, PNN Editor

A scathing new Cochrane review is raising more questions about the safety, efficacy and long-term benefits of spinal cord stimulators, medical devices that are increasingly used to treat chronic back pain.  

Cochrane reviews are considered the gold standard in medical research because they use robust methodology to gather good quality evidence and reduce the impact of biased, poor-quality studies.

The review by Australian researchers concluded that spinal cord stimulation (SCS) works no better than a placebo for treating chronic low back pain, and provides little to no benefit in improving quality of life.

The devices are surgically placed near the spine and connected to batteries implanted under the skin, which send electrical impulses into the spine to mask pain.

“Spinal cord stimulation is invasive and has a great financial cost to people who choose surgery as a last resort to alleviate their pain. Our review found that the long-term benefits and harms are essentially unknown,” said lead author Adrian Traeger, PhD, a Research Fellow at the Institute for Musculoskeletal Health at the University of Sydney. “Our review of the clinical data suggests no sustained benefits to the surgery outweigh the costs and risks.”

Treager and his colleagues analyzed the results of 13 clinical trials of SCS devices, looking at data from almost 700 patients with low back pain. They found little to no clinical data on the long-term effectiveness of SCS because most of the studies lasted less than a month, were poorly blinded, or had selective reporting bias.

The researchers also found that side effects from SCS surgery were poorly documented, preventing them from assessing the level of risk involved. Serious adverse events include nerve damage, infection, and the devices’ electrical leads moving, all of which may lead to more surgeries.

“Data in this review do not support the use of SCS to manage low back pain outside a clinical trial. Current evidence suggests SCS probably does not have sustained clinical benefits that would outweigh the costs and risks of this surgical intervention,” they concluded. 

Findings from the Cochrane review have been submitted to Australia’s Department of Health and Aged Care, which is reviewing the effectiveness of spinal cord stimulators. The devices' long-term safety and performance are also being re-assessed by Australia's Therapeutic Goods Administration (TGA).

“Our review found that the clinical benefit of adding spinal cord stimulation to treat low back pain remains unknown. When coupled with the reality that these devices are very expensive and often break down there is clearly a problem here that should be of concern to regulators,” said Chris Maher, PhD, Co-Director of Sydney Musculoskeletal Health.

Increasing Use of Stimulators

About 50,000 spinal cord stimulators are implanted annually in the U.S. and their use is growing. The devices are no longer limited to patients with back, neck and leg pain. In 2021, the FDA expanded the use of SCS to treat chronic pain from diabetic neuropathy. Stimulators are also being used on patients with Complex Regional Pain Syndrome (CRPS).

A 2018 study by investigative journalists found that SCSs have some of the worst safety records of medical devices tracked by the FDA. A 2020 FDA review of adverse events involving stimulators found that nearly a third were reports of unsatisfactory pain relief. A more recent study found that patients with the devices did not reduce their use of opioids, and continued getting procedures such as epidurals, corticosteroid injections and radiofrequency ablation.

Although evidence is growing that questions the safety and effectiveness of SCS, medical device companies continue to roll out new stimulators with more advanced technology. This week Nevro said it would release the first SCS system in the U.S. that uses artificial intelligence to optimize pain relief for each patient. The HFX iQ SCS system is designed for patients with diabetic neuropathy or chronic back and leg pain.

"This is an exciting time in spinal cord stimulation -- better waveforms, more conditions we can treat, and a massive treasure trove of patient data," said Usman Latif, MD, an interventional pain specialist and consultant to Nevro.

“What if we could take all the programming experience and clinical outcomes of tens of thousands of patients across the country, including what programs worked and what didn't, and bring the power of all that knowledge into the palm of our patient's hand -- with them 24/7, monitoring them, and offering them the best program for their exact situation with a tap on the screen. HFX iQ is the future of medicine, where expanded data holds the promise of new capabilities and improved care."

In addition to the U.S. release of HFX iQ, Nevro has asked for approval from regulators in Europe and Australia.

FDA Approves Smallest Rechargeable Spinal Cord Stimulator

By Pat Anson, PNN Editor

The Food and Drug Administration has approved a new spinal cord stimulator that’s being touted as the smallest implantable neuromodulation device of its kind on the market. Abbott’s Eterna stimulator can also be recharged wirelessly as few as five times a year, unlike other stimulators that need recharging daily or weekly.

Spinal cord stimulators (SCSs) are an invasive treatment of last resort for people with chronic back or leg pain. The devices are surgically implanted near the spine and connected to batteries placed under the skin. The implants send low-level electrical impulses into the spine to block pain signals.

Abbott says it developed Eterna after extensive studies with pain patients and healthcare providers, who wanted a smaller implant with less need for recharging.

Eterna utilizes the company’s BurstDR stimulation, which mimics the natural firing patterns of nerves to provide pain relief without the tingling sensation of other simulators.

"Abbott's low-dose BurstDR stimulation is clinically proven to reduce pain, improve people's ability to perform everyday activities, and reduce emotional suffering associated with pain," Timothy Deer, MD, president and CEO of the Spine and Nerve Centers of the Virginias, said in a statement provided by Abbott.

ABBOTT IMAGE

"Until now, it wasn't available on a rechargeable device that was this small, and that only needs to be charged a few times a year. This makes a big difference in comfort for many patients who now can have access to the best of both worlds – a small, best-in-class rechargeable device with superior stimulation therapy."

Another advantage of the Eterna SCS system is that patients with the device can still have full-body MRI scans – a critical need for those who need access advanced imaging and diagnostics. The devices can also been monitored and programmed with a mobile app.

About 50,000 SCSs are implanted annually in the U.S. and their use is growing – in part because of the belief they’ll reduce the need for opioids and other pain therapies.

A recent study found that premise to be untrue. Researchers at the University of California San Francisco School of Medicine found that pain patients with stimulators did not reduce their use of opioids, epidurals, corticosteroid injections or radiofrequency ablation compared to a control group. About a fifth of the patients experienced complications so severe the devices had to be removed or revised.

A 2018 study found that SCSs have some of the worst safety records of medical devices tracked by the FDA. An FDA review of adverse events involving stimulators found that nearly a third were reports of poor pain relief. The review also identified nearly 500 deaths linked to the devices, along with nearly 78,000 injuries and 30,000 malfunctions.

SCS’s are no longer limited to patients with intractable back and neck pain. Last year the FDA expanded the use of stimulators to include lower limb pain from diabetic neuropathy.  Stimulators are also being used on patients with Complex Regional Pain Syndrome (CRPS).

Spinal Cord Stimulators Fail to Reduce Opioid Use

By Pat Anson, PNN Editor

A large new study is raising questions about the long-term effectiveness of spinal cord stimulators and whether they really help patients reduce their use of opioids and other pain treatments.

Researchers at the University of California San Francisco (UCSF) School of Medicine analyzed health data for 1,260 patients who received permanent stimulators and found that — when compared to a control group — the devices did not reduce their use of opioids, epidurals, corticosteroid injections or radiofrequency ablation after two years. About a fifth of the patients experienced complications so severe the devices had to be removed or revised.

Spinal cord stimulators (SCSs) are considered an invasive treatment of last resort for people with chronic back or leg pain, because the devices have to be surgically implanted near the spine and connected to batteries placed under the skin. The implants send electrical impulses into the spine to mask pain.

About 50,000 SCSs are implanted annually in the U.S. and their use is growing – in part because of the belief they’ll reduce the need for opioids and other pain therapies.

But UCSF researchers found that SCS patients actually filled more opioid prescriptions after one year than a control group of pain patients (CMM) who did not get the devices. The use of other medications and procedures by SCS patients declined slightly after one year, but there were no significant differences between the two groups after two years.

“The lack of reduction in pharmacotherapy, epidural and facet corticosteroid injections, and radiofrequency ablations at 2 years among patients receiving SCS compared with those receiving CMM suggests that SCS was providing insufficient pain relief to forego other therapies or improve rates of depression or anxiety, as prescriptions for these drug classes did not decline,” lead author Sanket Dhruva, MD, an Assistant Professor of Medicine at UCSF, wrote in JAMA Neurology.

“Because most patients still had their permanent SCS in place at 2 years, some may receive prolonged benefit from this modality, although we were not able to identify this through reductions in opioid use or nonpharmacologic pain interventions.”

Researchers also found that the total cost of care was about $39,000 higher for SCS patients in the first year, while health costs were similar for the two groups in the second year.

‘Sobering Insights’

"The findings appear to belie the popular belief that SCS may result in reduced opioid medication usage or overall fewer physician visits in the years immediately following device implant," wrote Prasad Shirvalkar, MD, and Lawrence Poree, MD, both from the UCSF Division of Pain Medicine, in an accompanying editorial.

“Using robust propensity matching, the present study provides sobering insights that SCS does not appear to reduce chronic opioid use or the utilization of health care resources compared with CMM in the first 2 years after implant. We believe this will help mitigate excessive enthusiasm of SCS as a panacea for chronic pain syndromes and illuminate biases of SCS hype cycle that can possibly be fueled by industry-related conflicts of interest.”

Stimulators are no longer limited to patients with chronic back, neck and leg pain. Last year the FDA expanded the use of SCSs to include pain from diabetic neuropathy. Stimulators are also now being used on patients with Complex Regional Pain Syndrome (CRPS).

A 2018 study by a team of investigative journalists found that SCSs have some of the worst safety records of medical devices tracked by the FDA. A 2020 FDA review of adverse events involving stimulators found that nearly a third were reports of unsatisfactory pain relief. The review also identified nearly 500 deaths linked to the devices, along with nearly 78,000 injuries and 30,000 device malfunctions.

FDA Approves Device That Uses Artificial Intelligence to Treat Chronic Pain

By Pat Anson, PNN Editor

The Nevro Corporation says it has won approval from the Food and Drug Administration for an advanced spinal cord stimulator (SCS) that uses artificial intelligence to individualize treatment for each patient.

Nevro says its Senza HFX iQ stimulator “learns from patients” as they use the device and develops customized algorithms for treating chronic back pain, leg pain and pain from diabetic neuropathy.

"HFX iQ is designed to improve the consistency of pain relief and is the only SCS system that truly personalizes care," D. Keith Grossman, Chair and CEO of Nevro, said in news release.

"Pain is variable from patient to patient and over time. Using the big data from our HFX Cloud patient database, our unique HFX Algorithm was developed to identify those programs where patients have been more likely to get relief in the real world.  HFX iQ takes direct input from each patient on their pain and quality of life measures to get smarter over time and recommend program changes.”

Nevro says patients will start with a program most likely to provide pain relief, and then adjusts it over time based on patient input and medical data, such as pain scores, activity levels and changes in use of pain medication. Patients can also adjust their pain relief programs through an app on their smartphones.

Spinal cord stimulators are usually considered the treatment of last resort for people with intractable or severe chronic pain that doesn’t respond to other therapies. The surgically implanted devices emit low levels of electricity that reduce the intensity of pain signals.

Unlike older stimulators, Senza stimulators use electric pulses of 10 kHz, a high frequency that doesn’t create an uncomfortable tingling sensation and delivers more pain relief. Last year the FDA approved Senza stimulators for the treatment of painful diabetic neuropathy, making it the first spinal cord stimulation system approved for that condition. Until then, most SCS devices were only approved for patients with severe back pain.

About 50,000 stimulators are implanted in the U.S. every year, with failure rates for the devices estimated at 25 to 30 percent. Most patients are required to undergo psychological testing and a trial treatment before getting a SCS.

The FDA has come under scrutiny for its regulation of stimulators and other medical devices.  A 2020 report by Public Citizen accused the FDA of “dangerously lax” oversight of stimulators, which were linked to 156,000 injuries and 931 deaths.  The agency responded to the report by sending a letter to healthcare providers reminding them to only implant stimulators after a trial period that demonstrates the device are effective. An FDA review of adverse events involving stimulators found that nearly a third were reports of unsatisfactory pain relief.

Nevro says it will begin a limited release of Senza HFX iQ later this year, with a full market launch in the U.S. in early 2023. Nevro is also seeking approval of HFX iQ in Europe.  

High-Frequency Spinal Cord Stimulators Provide More Pain Relief

By Pat Anson, PNN Editor

Spinal cord stimulators are often considered the treatment of last resort for patients with intractable or severe chronic pain. The surgically implanted devices emit low levels of electricity that reduce pain signals, but have high failure rates and often have to be removed because they’re ineffective, cause infections or need new batteries.

Two new studies suggest there are ways to improve the success rate of spinal cord stimulators (SCS) through improved patient selection and the use of high-frequency devices.

Low-frequency SCS (50 Hz) was first approved by the Food and Drug Administration for intractable back and leg pain in 1989. Six years later, the FDA approved high-frequency devices (10,000 Hz), that deliver pulses of electrical stimulation that are shorter in duration, lower in amplitude and do not cause paresthesia, an irritating sensation of tingling or prickling.

In a retrospective study of 237 patients who received stimulators between 2004 and 2020, researchers at the University of California San Diego School of Medicine reported that high-frequency devices were more effective at reducing pain and opioid use than low-frequency ones.

The study findings, published in the journal Bioelectronic Medicine, also show that male patients benefit more than women from high-frequency neuromodulation.

"Our work was sparked by a growing literature that demonstrate sex specific immune pathways differentially contribute to chronic pain processes," said senior author Imanuel Lerman, MD, an associate professor of anesthesiology at UC San Diego Health. "The observed parameter-specific (high versus low frequency) sex-based differences in spinal cord stimulation efficacy and opiate use are definitely intriguing.”

It’s not clear why men benefit more than women, but researchers believe it may be due to the male hormone testosterone having a modulating effect on pain signals. The sex differences may also be due to males and females processing chronic pain differently.

"Clearly more work needs to be done to carefully characterize sex specific pain regulatory pathways that may prove responsive to specific types of neuromodulation and or pharmaceutical therapies," said Lerman.

Improved Patient Selection  

Although most patients are required to undergo psychological testing and a trial treatment before getting a SCS, failure rates for the devices remain high at around 25 to 30 percent. With about 50,000 stimulators implanted in the U.S. every year, that means thousands of patients are getting poor results.

To improve patient outcomes, researchers at Florida Atlantic University developed machine-learning algorithms to help predict which patients may benefit from SCS. Working with a cohort of 151 SCS patients, they evaluated 31 features or characteristics in each patient.  

Researchers found two distinct clusters of patients which differ significantly in age, duration of chronic pain, preoperative pain levels and pain catastrophizing scores. They used computers to fine-tune the results, identifying the 10 most influential features that contribute the most to a successful SCS implant.

Results of the study, published in the journal Neurosurgery, demonstrate for the first time the ability of machine-learning algorithms to predict long-term patient response to SCS placement. The next step is to validate the data in future patients to ensure that the algorithm is useful in real-world situations, not just computer models.

"Our study resulted in the development of a model to predict which patients would benefit from spinal cord stimulation," said lead author Julie Pilitsis, MD, dean and vice president of medical affairs at Florida Atlantic University's Schmidt College of Medicine.  "After we validate this work, our hope is that this machine-learning model can inform a clinical decision support tool to help physicians better choose which patients may be most appropriate."

SCS is no longer limited to patients with intractable back and neck pain. Last year the FDA expanded the use of SCS to include lower limb pain from diabetic neuropathy.  Stimulators are also being used on patients with Complex Regional Pain Syndrome (CRPS).

A decision to get a SCS shouldn’t be taken lightly. A 2018 study by a team of investigative journalists found that stimulators have some of the worst safety records of medical devices tracked by the FDA. A 2020 FDA review of adverse events involving SCS found that nearly a third were reports of unsatisfactory pain relief. The review also identified nearly 500 deaths linked to the devices, along with nearly 78,000 injuries and 30,000 device malfunctions.

FDA Approves Advanced Spinal Cord Stimulator

By Pat Anson, Editor

The U.S. Food and Drug Administration has approved a new spinal cord stimulator developed by Medtronic that can be managed, tracked and updated remotely on a Samsung Galaxy tablet.

The Intellis stimulator is designed for patients with chronic, intractable pain of the trunk and/or limbs.

The Intellis platform can track patient activity 24/7 on the Samsung Galaxy Tab S2 tablet, enabling physicians to personalize the settings for individual patients and monitor their progress using Medtronic’s Evolve software system. 

"The launch of the Intellis platform isn't just about a new device, but about combining cutting edge hardware with optimal therapy through the Evolve workflow to enable personalized, long-term pain relief," said Marshall Stanton, MD, president of Medtronic's Pain Therapies division.

“The Intellis platform was designed based on what is most important to patients and physicians. We considered the entire patient journey - starting with the primary goal of optimal pain relief and access to important diagnostic tools, like MRI, to ease of use with simplified programming, faster recharge and a smaller implant."

MEDTRONIC PHOTO

Spinal cord stimulators (SCS) are often considered the treatment of last resort for chronic back and leg pain, because the devices have to be surgically implanted near the spine and connected to batteries placed under the skin. The implants send electrical impulses into the spine to mask pain.

Some patients find the stimulators ineffective and have them removed. According to one study, only about half of patients who received a traditional SCS device have a 50 percent reduction in their back and leg pain. New technologies are being developed to make the devices smaller, more effective and easier to recharge.

Medtronic says Intellis is the world's smallest fully implantable SCS neurostimulator. Its battery can be fully recharged from empty to full in about one hour and physicians can estimate recharge intervals based on therapy settings. Software upgrades are also easier to get through Samsung Galaxy tablets.

"We are excited to partner with Medtronic in their aim to simplify programming, and streamline therapy management with the Intellis platform," said Dr. Dave Rhew, chief medical officer and head of Healthcare and Fitness for Samsung Electronics America. "Samsung's Galaxy tablets-secured by the HIPAA-ready Samsung Knox mobile security platform-will support future Medtronic therapies and over the air (OTA) software upgrades to ensure clinicians using Intellis have access to the most up-to-date solutions."

One of the first implantation procedures using the Intellis platform was performed at Duke University Medical Center.

"Chronic pain is challenging to manage. Having real-time data can provide more information about patients' quality-of-life changes. This platform represents a welcome new option for managing some kinds of chronic pain," said Lance Roy, MD, a pain medicine specialist at Duke University Medical Center.

New Stimulator Delivers Back Pain Relief

By Pat Anson, Editor

A new type of spinal cord stimulator (SCS) provides significantly more relief from chronic back and leg pain than traditional SCS therapy, according to the results of a new study published in the journal Anesthesiology.

The Senza spinal cord stimulator, which recently won approval from the U.S. Food and Drug Administration, uses high frequency pulses of 10,000 Hz to mask a patient’s perception of pain. Traditional SCS therapies use frequencies of 40 to 60 Hz.

"This is the first long-term study to compare the safety and effectiveness of high frequency and traditional SCS therapy for back and leg pain," said lead author Leonardo Kapural, MD, professor of anesthesiology at Wake Forest University School of Medicine and clinical director at the Carolinas Pain Institute.

"Chronic back and leg pain have long been considered difficult to treat and current pain relief options such as opioids have limited effectiveness and commonly known side effects. Given the prevalence of chronic pain, high frequency SCS is an exciting advance for our patients."

image courtesy of nevro

In a study of 171 patients with implanted SCS devices, 85 percent of those with back pain and 83 percent with leg pain using the Senza HF10 stimulator had a 50% reduction in pain or greater after three months.

Only about half the patients implanted with a traditional SCS device (44% with back pain and 56% with leg pain) experienced that kind of pain relief.

None of the patients in the HF10 therapy group experienced paresthesia – a tingling or buzzing sensation often felt with lower frequency stimulators. They were also more likely to be “very satisfied” with their pain relief (55% versus 32%).

Lower back pain affects about a quarter of the world’s adult population and is the leading cause of disability. Back pain is usually treated with physical therapy or pain relievers.

For chronic back pain, spinal cord stimulators are often the treatment of last resort because the devices have to be surgically placed near the spine and connected to batteries implanted under the skin. The devices send electrical impulses into the spine to mask pain.

The Senza SCS system is made by Nevro (NYSE: NVRO), a medical device company based in Menlo Park, California. Senza has been available in Europe and Australia for the last five years. In May, Senza won approval from the FDA for use in the United States.

MarketsandMarkets, a market research firm based in Dallas, estimates the global market for spinal cord stimulators and other neuromodulation devices could reach $6.8 billion by 2017.