Reply

Dear Sir Stovner, Kolstad and Helde should be conscious that studies do not occur in scientific isolation. They occur also in a social context. For studies of pain treatment, that social context can be very unforgiving. In many countries, insurers are intent on not reimbursing practitioners for radiofrequency neurotomy, especially when it is performed for post-traumatic headache or whiplash in patients with compensation claims. In that context, a falsely negative study plays into the hands of insurers. They obtain a citable reference that justifies their resistance to reimbursement. Such studies are also captured in systematic reviews. Those reviews may not dissect studies in detail, and will accept the authors’ conclusions at face value. The results of such reviews reinforce opposition to the treatment in question.

My apparent hostility to the publication of the study by Stovner et al. (1) is not a personal attack. My concern is clearly directed to their study being misrepresented and misused, and is based on this having already occurred in the context of lumbar radiofrequency neurotomy, where negative, but technically flawed, studies have been used to disabuse proponents of this treatment for back pain.

In their letter, Stovner et al. emphasize their caution and dissatisfaction about the use of clinical features to diagnose cervicogenic headache; but this is not how their paper was cast. They render the treatment, not the selection, of their patients the object of the study. They conclude: ‘Since results are so dubious, we would recommend that RF-treatment for CeH is not performed on a routine basis, but is restricted to research protocols’. Unambiguously, this conclusion impugns the treatment, not the selection criteria. Yet, the data invite a reciprocal conclusion: that clinical diagnostic criteria do not predict outcome from RF neurotomy. The clinical criteria, not the treatment are what should be impugned.

Methodologically, the study of Stovner et al. (1) is not a valid test of RF neurotomy. A correct study for that purpose would recruit patients with unequivocal evidence not only of a cervical source of headache but also that source was in the zygapophysial joints. In this regard, Stovner et al. (1) misrepresent the criteria prescribed by the International Headache Society (IHS) (2). They state that response to blocks is not an obligatory criterion; yet it is. The criteria require either that the headache is abolished by controlled diagnostic blocks, or that the patient has signs with demonstrated reliability and validity for the diagnosis of cervical source of pain. Since there are no such signs, controlled blocks are the only criterion that can be satisfied. Furthermore, the diagnostic criteria used by Stovner et al. (1) are explicitly excluded by the IHS criteria.

The virtue of the study by Stovner et al. (1) is that they have honestly disclosed all of their outcome data. That allows the data and their interpretation to be discussed. Letters to the editor provide a forum for that discussion; and perhaps others might care to join in that discussion. My own motivation, in expressing my misgivings about the study, is not to chastise Stovner et al. (1) but to pre-empt misrepresentation of the results, and to vaccinate the literature against unjustified conclusions that would be detrimental to the responsible use of RF neurotomy in the treatment of cervicogenic headache.