Data from a prospective, multicentre trial examining high-frequency spinal cord stimulation (SCS) at 10kHz for the treatment of chronic pelvic pain supports the safety and effectiveness of the therapy. “A clinically meaningful improvement for pelvic pain was indicated through a responder rate of 77% and a remitter rate 69% at three to 12-months follow-up,” reported Jordan Tate, Alliance Spine and Pain Centers (Atlanta, USA), whilst presenting the results at the North American Neuromodulation Society’s annual meeting (NANS; 23–26 January, Las Vegas, USA).
Tate highlighted that the subjects felt no paraesthesia, “which is extremely important when treating chronic pelvic pain”, she said. The baseline visual analogue scale (VAS) score of 7.9 was reduced down to 2.3 at three months, which was sustained through to 12 months. “Overall, we are looking at a 70% pain relief,” Tate reported.
In terms of the Pain Disability Index (PDI), she noted that the patients exhibited significant functional improvements. Patients at baseline were reporting 45.2, which decreased, on average, to 16.2. According to Tate, this reduction was three times the minimally clinical important difference.
Discussing the rationale behind the research, Tate commented that current treatment options for the treatment of chronic pelvic pain are “limited or ineffective”. In addition to medications, such as antidepressants and opioids, Tate said that physicians will try interventional procedures, including pudendal nerve blocks and radiofrequency thermocoagulation, while many patients will have multiple surgeries. “They [physicians] might try some physical therapy. Specifically, pelvic floor training, which is actually a great treatment option. But, it is very expensive and has to be undertaken repetitively and for a long term.”
Furthermore, Tate mentioned that the evidence in the space of SCS has previously been lacking. “There have been several case reports and case series, [but] there has not been, to date, a consensus on optimal lead placement or frequency for this patient population.”
Nevertheless, she said that given the SENZA randomised controlled trial results, in addition to anecdotal experience in clinical practice, the study investigators felt that it would be a reasonable assumption that high-frequency 10kHz therapy would present as a good treatment option for chronic pelvic pain. The study included all-comers with chronic pelvic pain, with the most common diagnoses being complex regional pain syndrome. The patients had to have pain for over three months, and a visual analogue scale (VAS) score above five. Patients who had previous neuromodulation experience, significant spinal stenosis, or mechanical spine instability were excluded.
In relation to the lead span, Tate remarked: “At the beginning of the study, we did not know where the sweet spot would be for the stimulation of chronic pelvic pain. We had a span at the top of T8, and the second lead reached to T12. This was important to give us control.”
Patients had a mean baseline VAS score of 8, while 91% were female and 49 years of age, on average. In total, 13 patients were followed through to 12 months, with post-surgical complications predominating the field in terms of diagnoses.
In addition to VAS scores, the study investigators also looked at various components of pain interference, including continuous pain, intermittent pain, neuropathic pain and affective descriptors. “These were all decreased across the board in all patients carried out to 12 months”, Tate reported.
There were no sustained neurological deficits, added Tate, but 10 adverse events occurred, such as non-clinically significant lead migration and infection. However, all adverse events resolved without sequelae.
“Overall, we were very impressed with the results. These are difficult patients, and we thought it would be a challenge. I thought I would be very happy to see even a 40% reduction in even some of the patients. But, once again with 10kHz therapy, we saw similar results to other pathologies, and these patients really had profound outcomes.”
Lastly, Tate explained: “Ultimately, lead placement was predictable. The sweet spot is around the mid T10 vertebral body. We had very few patients who we needed to stimulate up into T8, [but] we did have some that needed stimulation at T12. So it is important to have the leads a little lower than your standard back protocol.
“The data indicate promising results using 10 kHz SCS in chronic pelvic pain, which is a difficult-to-treat aetiology of chronic pain. We are excited to see the next steps for chronic pelvic pain might be.”