Intradiscal high-voltage, long-duration pulsed radiofrequency for discogenic pain: a preliminary report.

Intradiscal radiofrequency, with the electrode placed in the center of the nucleus pulposus, has been a controversial procedure in patients with discogenic pain. Possibly the effect has not been due to the production of heat, but to exposure to electric fields. We have investigated the effect of high-voltage, long-duration intradiscal pulsed radiofrequency in patients with one-level discogenic low back pain, as confirmed by discography. The pain intensity score on a 0-10 numeric rating scale (NRS) was taken as outcome measure. Eight patients were reported. The mean duration of pain was 6.3 years (range 0.5-16, median 4). The mean NRS score was 7.75 (range 5-9). Disc height was reduced 60% in one patient and up to 30% in the others. A 15-cm, 20-gauge needle with a 15-mm active tip was placed centrally in the disc. Pulsed radiofrequency was applied for 20 min at a setting of 2 x 20 ms/s and 60 V. There was a very significant fall in the NRS scores over the first 3 months (P < 0.0001). On an individual basis, all patients had a fall of the NRS score of at least 4 points at the 3-month follow-up. A follow-up of 12.8 months (range 6-25, median 9) was available for five patients. All these patients are now pain free, except for one patient with an NRS score of 2. Conclusion. It is concluded that this method merits a controlled, prospective study.