Prospective, Randomized Blind Effect-on-Outcome Study of Conventional vs High-Frequency Spinal Cord Stimulation in Patients with Pain and Disability Due to Failed Back Surgery Syndrome.

Objectives: Spinal cord stimulation (SCS) for patients with failed back surgery syndrome (FBSS) show variable results and limited to moderate evidence. In the last years the stimulation of high frequency (HF) has been considered as a better alternative in this pathology for its supposed benefits compared to the stimulation with conventional frequency (CF). To compare in one year follow-up, the efficacy of high-frequency SCS (HF) versus conventional frequency SCS (CF) on the patients with FBSS.

Design: Prospective, Randomized blind trial.

Setting: Academic University Pain Medicine Center.

Subject: Seventy eight patients with FBSS diagnosis based on internationally recognized criteria, and refractory to conservative therapy for at least 6 months, have been initially recruited, and.

Methods: Sixty subjects met the eligibility criteria and were randomized and scheduled for the trial phase.The patients were randomly assigned in either, one of the two groups: CF SCS or HF SCS. Within the study methods, special attention was paid to standardizing patient programming, so that these parameters would not impact the results.The trial period was considered successful if there was ?50% reduction in the NRS from baseline.

Results: A total of 55 subjects successfully completed all assessments during one year follow-up. Change patterns in scores do not differ based on high versus conventional frequency, with significant global average reduction at 1 year similarly for both groups. Among all the items included in the Short Form-12 questionnaire (SF-12), only the variations in the social function score between the instants t1 and t2 are somewhat higher in the high frequency group.

Conclusion: The evolutionary pattern of the different parameters studied in our patients with FBSS does not differ according to their treatment by spinal stimulation, with conventional or high frequency, in one year follow-up.