Spinal Cord Stimulation Beats Medication for Pain

Pauline Anderson

May 02, 2018

VANCOUVER – Spinal cord stimulation is associated with greater pain reduction than pharmacotherapy in patients with intractable spine or limb pain, results of a new systematic review and meta-analysis show.

The meta-analysis also suggests that new stimulation technologies, such as those that deliver high-frequency currents, are likely better at reducing pain than is conventional stimulation.

Previous research has demonstrated the effectiveness of stimulation over medical therapy, but these trials were relatively small.

"This analysis reinforces results of individual trials that found that for many of the most common refractory neuropathic pain problems, spinal cord stimulation is more effective than medical therapy," author Tim J. Lamer, MD, professor of anesthesiology, Mayo Clinic College of Medicine and Science, Rochester, Minnesota, and president-elect, American Academy of Pain Medicine, told Medscape Medical News.

The study was presented here at the American Academy of Pain Medicine (AAPM) 2018 Annual Meeting.

Robust Findings

After a comprehensive literature search, researchers selected 12 key randomized controlled trials that included 1080 patients for analysis

By far the most common condition in study patients was back and/or leg pain "in the setting of previous spine surgery," said Lamer. The second most common condition was complex regional pain syndrome. Two trials looked exclusively at patients with painful diabetic neuropathy.

In most trials, medical therapy involved medications typically used for neuropathic pain, including gabapentin, tricyclic antidepressants, and opioids.

The studies used a variety of spinal cord stimulation types. Such stimulation involves three parameters: frequency (the speed with which electrical pulse is delivered), pulse-width (the width of the electrical impulse), and amplitude (the intensity of the stimulation).

Conventional stimulation uses relatively low frequencies and relatively low pulse-wave stimulation. With these stimulations, patients may experience paresthesia or a tingling or prickling sensation.

Newer modes of neuromodulation include high-frequency stimulation, dorsal root ganglion stimulation, and burst stimulation that delivers closely spaced, high-frequency currents.

The trials used varying methods to assess pain relief, which made the analysis complex and challenging, said Lamer.

Some trials looked at the number of patients who achieved a certain amount of pain relief in the stimulation vs the medical therapy group.  Other trials reported the average pain score.

"In an ideal world, we would take all the trials and use the exact same comparators, but the problem is, the trials aren't done that way," said Lamer. "So you can't make a head-to-head comparison when you look at the data."

The researchers used a random-effect meta-analysis and frequentist indirect comparison methods to compare the interventions.

The analysis showed that in three trials, spinal stimulation significantly increased the odds of reducing pain by 50% or more compared with medical therapy (odds ratio [OR], 13.1; 95% confidence interval [CI], 4.96 - 34.17).

In three other trials, stimulation compared with medical therapy significantly reduced pain as measured by visual analogue scale scores (weighted mean difference, 1.43 scale points; 95% CI, 0.16 - 2.71).

Newer technology stimulation had increased odds of pain relief compared with conventional stimulation (OR, 2.07; 95% CI, 1.35 - 3.19).

"The value of a meta-analysis like this is that it allows you to put the studies together in a statistically meaningful way to increase the power or the impact of the results. By combining these studies, instead of having one study with 36 patents, or one study with 60 patients, now you have a much more robust patient number," said Lamer.

Attractive Alternative

Because opioid use is being discouraged in the pain management field, spinal cord stimulation for intractable pain is an attractive therapeutic alternative, although it's "probably underutilized," said Lamer.

"Opioids don't work very well for patients with nerve-related pain and yet many patients are treated with these drugs. On the other hand, spinal cord stimulation has been shown to work quite well for many types of neuropathic pain."

Patients with musculoskeletal pain, for example, fibromyalgia, and those with knee or hip arthritis typically don't benefit from spinal stimulation.

Although surgically implanted electrical stimulating devices are expensive, several studies have shown them to be cost-effective compared with medical therapy.

"Ten years of medical therapy is extraordinarily expensive," noted Lamer.

The researchers also compared newer spinal cord stimulation with medical therapy but have not yet reported these results.

Commenting on the study for Medscape Medical News, pain specialist James C. Watson, MD, associate professor, and vice chair, Department of Neurology, Mayo Clinic, said it shows a "consistency" with data from individual trials.

The comparison of trials of newer modes of spinal cord stimulation with those of traditional stimulation using pooled data — and benchmarked against traditional medical therapy — was particularly useful, said Watson.

"This showed that the newer modes of neuromodulation appear to have greater degrees of pain relief than traditional spinal cord stimulation," he said. 

"Head-to-head efficacy trials are lacking, and this is an important clinical decision; should we use newer techniques of neuromodulation or use traditional spinal cord stimulation." 

He noted that one of the trials compared high-frequency spinal cord stimulation with traditional spinal cord stimulation. It appeared to be more effective, but this trial was designed as a noninferiority and not as an efficacy study.  

The study was supported by a grant from Medtronic. Dr Lamer has disclosed no relevant financial relationships. Watson reports having consulted for Nevro, a company with a high-frequency spinal cord stimulator, but has not done so in the past year.

American Academy of Pain Medicine (AAPM) 2018 Annual Meeting. Abstract LB002. Presented April 27, 2018.

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