Commentary on: "Lumbar Percutaneous Intradiscal Injection of Radiopaque Gelified Ethanol ("Discogel") in Patients with Low Back and Radicular Pain"

I would like address my congratulations to the authors of the article titled: “Lumbar Percutaneous Intradiscal Injection of Radiopaque Gelified Ethanol (“Discogel”) in Patients with Low Back and Radicular Pain” [1]. I believe, it is the first randomized study assessing the efficacy of Discogel. The positive results reported in this study are not really astonishing for the usual users of Discogel. Indeed, several points could be enlightened about this study. First, the present results are better than in uncontrolled previous study [2]. This fact is really scarce and in my opinion, is due to that in the previous prospective study the pain duration before treatment is longer. In this previous study it had been proposed to wait the inefficacy of one or two epidural administrations of cortico-steroid, before proposing percutenous treatments. The problem with this procedure is that she can induce a too long time before nerve root decompression and thus decreases the rate of relief. From this point of view, this last study suggest that it could be interesting to propose the percutaneous treatments as soon as the usual medical care failed to relief the patient, ie in the same time of corticoid administrations. A second point is that the rate of nerve irritation reported in this study, is more important than the one reported when we use a 18 gauge needle and we perform a gaseous discography to verify the continence of the disc just before the intradiscal injection of the Discogel [2]. A third surprising point is that, in despite of the fact that Dicogel is usually indicated in radicular pain, 20% of the injected patients had only low back pain without radicular pain. Nevertheless, in previous studies, patients reported a similar decreasing of both low back and leg pain intensities. So it could be interesting to know if the patients with low back pain had better, equal or worse relief than those with radicular pain, in order to know if we can consider low back pain as a new unexpected indication of Discogel. A last interesting point to enlighten about this study is the long duration of the follow up. We can see that the initial relief is better in the Discogel group than in the steroid group; and moreover that the rates of relieved patients decrease with time in the steroid group but not in the Discogel group. This last point has been said like a key point to assess of the interest of the percutaneous treatment [3].

We are now looking for studies aiming to determine the best responders to this treatment, in order to increase again the rate of relief.