Background: Spinal cord stimulation (SCS) has been successfully used to treat chronic intractable
pain for over 40 years. Successful clinical application of SCS is presumed to be generally dependent
on maximizing paresthesia-pain overlap; critical to achieving this is positioning of the stimulation
field at the physiologic midline. Recently, the necessity of paresthesia for achieving effective relief
in SCS has been challenged by the introduction of 10 kHz paresthesia-free stimulation. In a large,
prospective, randomized controlled pivotal trial, HF10 therapy was demonstrated to be statistically
and clinically superior to paresthesia-based SCS in the treatment of severe chronic low back and
leg pain. HF10 therapy, unlike traditional paresthesia-based SCS, requires no paresthesia to be
experienced by the patient, nor does it require paresthesia mapping at any point during lead
implant or post-operative programming.
Objectives: To determine if pain relief was related to technical factors of paresthesia, we measured
and analyzed the paresthesia responses of patients successfully using HF10 therapy.
Study Design: Prospective, multicenter, non-randomized, non-controlled interventional study.
Setting: Outpatient pain clinic at 10 centers across the US and Italy.
Methods: Patients with both back and leg pain already implanted with an HF10 therapy device
for up to 24 months were included in this multicenter study. Patients provided pain scores prior to
and after using HF10 therapy. Each patient’s most efficacious HF10 therapy stimulation program
was temporarily modified to a low frequency (LF; 60 Hz), wide pulse width (~470 μs), paresthesiagenerating program. On a human body diagram, patients drew the locations of their chronic
intractable pain and, with the modified program activated, all regions where they experienced LF
paresthesia. Paresthesia and pain drawings were then analyzed to estimate the correlation of pain
relief outcomes to overlap of pain by paresthesia, and the mediolateral distribution of paresthesia
(as a surrogate of physiologic midline lead positioning).
Results: A total of 61 patients participated across 11 centers. Twenty-eight men and 33 women
with a mean age of 56 ± 12 years of age participated in the study. The average duration of
implantable pulse generator (IPG) implant was 19 ± 9 months. The average predominant pain
score, as measured on a 0 – 10 visual analog scale (VAS), prior to HF10 therapy was 7.8 ± 1.3 and
at time of testing was 2.5 ± 2.1, yielding an average pain relief of 70 ± 24%. For all patients, the
mean paresthesia coverage of pain was 21 ± 28%, with 43% of patients having zero paresthesia
coverage of pain. Analysis revealed no correlation between percentage of LF paresthesia overlap
of predominant pain and HF10 therapy efficacy (P = 0.56). Exact mediolateral positioning of
the stimulation electrodes was not found to be a statistically significant predictor of pain relief
outcomes.
Limitations: Non-randomized/non-controlled study design; short-term evaluation; certain
technical factors not investigated.Conclusion: Both paresthesia concordance with pain and precise midline positioning of the stimulation contacts appear to be
inconsequential technical factors for successful HF10 therapy application. These results suggest that HF10 therapy is not only
paresthesia-free, but may be paresthesia-independent.
Key words: Spinal cord stimulation, paresthesia, high frequency, 10kHz, pain relief, physiologic midline, paresthesia-free
High-Frequency Spinal Cord Stimulation for the Treatment of Chronic Low Back and Leg Pain: Implantation Technique of Percutaneous Leads and Implantable Pulse Generator