gms | German Medical Science

Objective: Little is known about the influence of the stimulation frequency on outcome of dorsal root ganglion (DRG) stimulation. It is assumed that specific neural components of the DRG can be influenced in a targeted manner through the selection of different frequencies. Recent studies have favored the use of low-frequency stimulation. We have investigated mid to high frequencies recently. In this clinical trial we document treatment response to patterns including low stimulation frequencies as low as 4 Hz.

Methods: We report an on-going randomized double-blind clinical trial with a cross over design. Patients with a DRG stimulation system underwent phases of stimulation with 4 Hz, 20 Hz (mid frequency), 60 Hz (high frequency) and sham. For each setting, amplitude was individually adapted to subthreshold levels. Each phase lasted for 5 days and was followed by a wash-out period of 2 days. Pain intensity and quality of life were assessed with visual analogue scale, McGill Pain Questionnaire, EQ-5D and Beck Depression Inventory.

Results: This study is still ongoing, a total of 20 patients will be included till study termination in Q1/22. Updated data will be presented. Eight patients have completed the study so far. Those 8 patients were using a DRG stimulation system for a mean 32.4 months (6-94) and all were responders. CRPS was the most frequent pain etiology. Mean VAS was 4.4 at the baseline (with active stimulation, 1-8) and increased progressively to 4.6 under 4 Hz, 5.1 under 20 Hz, 5.4 under 60 Hz and 5.4 under sham stimulation. Similar trends were observed regarding QoL, MPQ and BDI data.

Conclusion: In a previous study, we already demonstrated that stimulation frequency clearly influences stimulation results. Lower stimulation frequencies seem to be most effective for neuropathic pain in our preliminary results. Longer trial periods should be considered to delineate the differences between stimulation setting more clearly, especially in CRPS patients.