High-frequency spinal cord stimulators provide more pain relief — Pain News Network

By Pat Anson, PNN Editor

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

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

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

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

The results of the study, published in the journal Bioelectronic medicine, also show that male patients benefit more than females from high-frequency neuromodulation.

“Our work was triggered by a growing literature that demonstrates that sex-specific immune pathways contribute differentially to chronic pain processes,” said lead author Imanuel Lerman, MD, associate professor of anesthesiology at UC San Diego Health. “The sex-based differences observed across parameters (high or low frequency) in the effectiveness of spinal cord stimulation and opioid use are definitely intriguing.”

It’s unclear why men benefit more than women, but researchers believe it may be because the male hormone testosterone has a modulating effect on pain signals. Gender differences may also be due to men and women dealing with chronic pain differently.

“It is clear that more work needs to be done to carefully characterize gender-specific pain regulatory pathways that may prove sensitive to specific types of neuromodulation and/or pharmaceutical therapies,” Lerman said.

Improved patient selection

Although most patients must undergo psychological testing and trial treatment before getting an SCS, device failure rates remain high, around 25-30%. With approximately 50,000 pacemakers implanted in the United States each year, this means that thousands of patients experience poor outcomes.

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

The researchers found two distinct groups of patients who differed significantly in age, duration of chronic pain, preoperative pain levels, and pain catastrophizing scores. They used computers to narrow down the results, identifying the 10 most influential features that contribute the most to the success of an SCS implant.

The results of the study, published in the journal Neurosurgery, demonstrate for the first time the ability of machine learning algorithms to predict patients’ long-term response to SCS placement. The next step is to validate the data in future patients to ensure 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 Schmidt College of Medicine. from Florida Atlantic University. “After validating this work, we hope this machine learning model can inform a clinical decision support tool to help physicians better choose the most appropriate patients.”

SCS is no longer limited to patients with incurable back and neck pain. Last year, the FDA expanded the use of SCS to include lower extremity pain due to diabetic neuropathy. Pacemakers are also used on patients with complex regional pain syndrome (CRPS).

The decision to get an SCS should not be taken lightly. A 2018 study by a team of investigative journalists found that pacemakers have some of the worst medical device safety records tracked by the FDA. A 2020 FDA review of adverse events involving SCS found nearly one-third were reports of unsatisfactory pain relief. The review also identified nearly 500 device-related deaths, as well as nearly 78,000 injuries and 30,000 device malfunctions.

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