Spinal cord stimulation (SCS) for chronic pain involves delivering low levels of electricity directly into the spinal cord using an implanted device, which alters or blocks nerve activity to minimize the sensation of pain reaching the brain. The approach is most often used after non-surgical pain treatment options have failed to provide sufficient relief.
The mechanisms underlying how the SCS works are not fully understood, but in a new article published in the April 28, 2022 online issue of the journal
Bioelectronic medicinea research team led by scientists at the University of California San Diego School of Medicine reports that high-frequency SCS was found to be more effective in improving perceived pain reduction (PPR) than SCS at low frequency in the patients studied, and that there was some variation in PPR between male and female patients.
Low-frequency (50 Hz) SCS was originally approved by the U.S. Food and Drug Administration (FDA) as a treatment for incurable back and leg pain in 1989. In 2015, the FDA approved high-frequency SCS frequency (10,000 Hz), which delivers electrical stimulation pulses of shorter duration, lower amplitude and which do not induce paresthesia, the abnormal tingling or prickling sensation.
The recently published retrospective study looked at 237 patients who had received SCS treatment between 2004 and 2020: 94 patients (40 women, 54 men) who received HF-SCS and 143 patients (70 women and 73 men) who received LF -SCS. At three and six months after implantation, researchers found that all patients’ PPR improved from baseline, but HF-SCS produced higher PPR than LF-SCS. HF-SCS was also associated with less subsequent use of opioids for pain relief.
However, there were gender differences in results:
- Male PPR, for example, was significantly better for HF-SCS at three and six months compared to LF-SCS, while this was only true for females at 6 months.
- LF-SCS men used more opioids after implantation and at six months, while women used more opioids after implantation, at three, six and tended to use more opioids after 12 month.
“Our work was triggered by a growing literature that demonstrates that sex-specific immune pathways differentially contribute to chronic pain processes,” said lead author Imanuel Lerman, MD, associate professor of anesthesiology and specialist in the management of chronic pain. pain at UC San Diego Health. “The observed gender differences (high or low frequency) in the effectiveness of spinal cord stimulation and opioid use are truly intriguing.
“This is a first step in the right direction, but it is clear that more work needs to be done to carefully characterize sex-specific pain regulatory pathways that may prove sensitive to specific types of neuromodulation and/or or pharmaceutical therapies.
Co-authors include: Rosalynn RZ Conic, Zabrina Reyes, and Sopyda Yin, all at UC San Diego; Jacob Caylor, UC San Diego and Northwest Pain Care, Spokane, WA; Christina L. Cui, Duke University; and Eric Nelson, Pacific Western University of Health Sciences.
Funding for this research came, in part, from the Brain and Behavior Research Foundation and the Veterans Affairs Career Development Program.