Radiofrequency denervation for neck and back pain: a
systematic review
(Letter to the Editor)
Michele Curatolo, M.D., Ph.D.a
Sebastian Reiz, M.D., Ph.D.b
a
Department of Anesthesiology, Division of Pain Therapy,
University Hospital of Bern, Inselspital, Switzerland.
b
Centre Anti-Douleur, Clinique de Montchoisi, Lausanne, Switzerland.
Corresponding author:
Michele Curatolo, M.D., Ph.D.
Department of Anesthesiology
Division of Pain Therapy
Inselspital, 3010 Bern
Switzerland
Phone:
Fax:
Email:
+41-31-632 30 27
+41-31-632 30 28
michele.curatolo@insel.ch
Radiofrequency neurotomy for spinal pain
We read with serious concerns the systematic review by Niemistö et al on radiofrequency
(RF) denervation for neck and back pain.1 Unfortunately, the authors have failed to detect
serious flaws in the studies they have included in their systematic review, thereby rendering
their conclusions largely invalid.
When RF neurotomy is used in pain management, the question is if destruction of a nerve
that transmits information from a nociceptive focus to the central nervous system will stop or
decrease the patient’s pain. Niemistö and al have examined several different more or less well
defined spinal pain pathologies. However, the only application that might be appropriate for
RF neurotomy is zygapophysial joint pain. This is because pain from the zygapophysial joints
can be diagnosed and these joints have a well defined nerve supply that can be interrupted. In
comparison, pain from the intervertebral disc can mainly be attributed to stimulation of
mechanoreceptors in the periphery of the disc due to circumferential fissures in the annulus
fibrosus, so called internal disc disruption.2 Placement of a RF electrode in the nucleus
pulposus, which is devoid of nerve supply, produces a thermal lesion that is too small to reach
the outer part of the annulus where the disc nerves are mostly concentrated.3 Thus, RF
denervation can be discarded already on anatomical grounds as a potentially effective
treatment for discogenic pain. The same arguments can be used to eliminate RF neurotomy
applied to the dorsal root ganglion for treatment of a poorly defined pain pathology. In our
comments, we will therefore only discuss whether or not there is evidence for efficacy of RF
neurotomy when used to treat zygapophysial joint pain.
Like for all surgical techniques, it is important to recognize that RF neurotomy can only
be effective if used on patients in whom a correct diagnosis has been made and if applied in
an anatomically correct manner. These two criteria are fulfilled in only one of the four studies
included in the review.
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Radiofrequency neurotomy for spinal pain
The first serious limitation of the three studies on lumbar zygapophysial joint
denervation4-6 included in the review concerns patient selection. All these three studies used
single local anesthetic blocks to identify the source of pain. Single blocks for zygapophysial
joint pain are associated with a false positive rate of 38% and a positive predictive value of
only 31%,7 which is unacceptably low. Therefore, a considerable proportion of patients
recruited for RF denervation in these studies did not suffer from the condition for which they
were treated. In the study by Gallagher et al,4 the diagnostic local anesthetic injection was not
performed selectively on the nerves that supply the joints that were subsequently subjected to
RF, but "into and around the appropriate painful joints".
One of these three studies yielded negative results.6 In this trial, patients were selected on
the basis of the outcome (evaluated by the patients’ family physicians) of mixed local
anesthetic-steroid injections performed around a potentially symptomatic zygapophysial joint.
No other criteria than the feeling that this “treatment” had provided some pain relief for at
least 24 hours during the week following the steroid injection were used before offering
patients RF neurotomy or sham operation. With the knowledge of the prevalence of
zygapophysial joint pain in the age group investigated,8 it is unlikely that more than 10% of
the study population had pain from the zygapophysial joints. In addition, patient with pain
relief shorter than 24 hours were denied entrance to the study! Previous RCTs published
during the period 1991-1994 had provided evidence that steroids are ineffective for treating
zygapophysial joint pain caused by either trauma9 or degenerative disease.10 It is therefore
surprising, in the first instance, that this study was ever accepted for publication by a peer
review journal in 2001 and, secondly, could be considered a high-quality RCT by Niemistö et
al.
An additional major flaw of all the three studies on lumbar zygapophysial joint
denervation4-6 is the surgical technique. In these studies, the RF electrode was placed
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Radiofrequency neurotomy for spinal pain
perpendicular to the nerve according to the old Shealey technique. The currently available
evidence tells us, however, that the electrode does not produce a lesion distal to its tip, but
circumferentially around the shaft of the active tip.11 Therefore, the appropriate method to
maximize the chance of coagulating the nerve is to place the electrode parallel to the nerve.
Based on the above facts, it is impossible to agree with the conclusion of this review on
lumbar zygapophysial joint denervation. A more appropriate conclusion might be: because
patients were inappropriately selected and a deficient surgical technique was employed, a high
proportion of the patients recruited to these three RTCs could not respond to the treatment.
Therefore we are, at present, left with conflicting data.
The only study that applied selection criteria and a surgical technique based on the best
evidence available (Lord et al12) obtained the best results: complete pain relief in the majority
of patients for almost one year. After an open diagnostic screening block series with 0.5%
bupivacaine, patients who responded with complete pain relief were subsequently included in
a double blind placebo-controlled protocol with 0.5% bupivacaine as the active substance.
Thus, only patients positive after the screening block and after the active block in the double
blind series, but negative after placebo, were offered RF neurotomy. Furthermore, an
anatomically appropriate operative technique was used, placing a RF electrode parallel to the
target nerves in an attempt to obtain the longest and most complete nerve destruction. In
addition, two different electrode passes (oblique and para-sagittal) were used to coagulate the
nerves along their entire available length from the nerve root to the joint. Multiple parallel
lesions were performed because of the relatively large anatomical variation in the positions of
the target nerves in the cervical spine. Operating times of this approach range from 2 to 5
hours, unlike the 20 min usually needed for the single lesion RF neurotomy that was
employed in the three other studies included in the systematic review.4-6
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Radiofrequency neurotomy for spinal pain
The study by Lord et al12 is small in size but has the necessary power to show what the
authors set out to prove, i.e. that RF neurotomy is not a placebo when used to treat cervical
zygapophysial joint pain after whiplash. Once that had been shown, no further extension of
the study was granted by the independent study review committee because it was found
unethical that sham-operated patients should be deprived of effective therapy for longer than
one year. It is worthy to repeat that the majority of patients were completely pain free after the
procedure. In this respect, RF neurotomy is the first palliative technique used in the treatment
of chronic pain that has shown such high degree of efficacy and success rate.
It is unclear why the authors of this review conclude that RF denervation of the cervical
zygapophysial joints produces a short-term effect. In the study by Lord et al,12 the median
time to return to > 50% of the preoperative pain level was 263 days. The same authors have
later performed a long-term follow-up study and have shown that the therapy can be
successfully repeated over years, with absence of pain for up to 900 days (i.e. the longest
follow-up time in individual patients) after RF neurotomy.13 We are not aware of treatments
that provide longer pain free periods in neck and low back pain and have been subjected to a
long-term randomized controlled trial.
Niemistö et al state that there is a need for further high quality studies with larger sample
sizes and longer follow-ups. However, performing a randomized controlled trial on a surgical
method is not equal to performing such a study on e.g. acetaminophen or a physiotherapy
regimen. Patients allocated to the sham group undergo the whole intervention (up to 5 hours
at the cervical level!) for no benefit. Even if an ethics committee is willing to approve such an
investigation, how to convince a "large" number of patients to participate? How to perform a
"longer follow-up" in unresponsive patients, if they know that they may have received a sham
treatment? There is already definite proof that RF neurotomy is a highly effective technique to
treat cervical zygapophysial joint pain after whiplash, if patients with such pain are correctly
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Radiofrequency neurotomy for spinal pain
identified and treated with an appropriate operative technique. There is published proof that
pain relief is long lasting in a majority of patients and the procedure can be successfully
repeated if pain comes back. There is no reason to believe that the anatomical localization
(lumbar or cervical) or the underlying cause of zygapophysial joint pain (trauma or
degenerative disease) would alter the efficacy of a defined operative technique, provided that
the diagnostic selection principles are the same. Few, if any ethics committees would
therefore be willing to grant permission for further sham controlled surgical studies once it
has been shown that RF neurotomy is clearly superior to placebo.
It is less clear whether the bench-mark results in the study by Lord et al12 can be achieved
by the average pain physician who is unwilling to subject himself to the same rigorousness in
his clinical routine. We do need confirmatory studies that analyze if a similar success level
can be achieved by other authors. Such data, although not obtained in RCTs, are available
both for cervical zygapophysial joint pathology causing chronic headache14 and lumbar
zygapophysial joint pain due to degenerative disease.15 These studies employed much the
same diagnostic and therapeutic protocols as the study by Lord et al.12 In addition, the latter
study15 also shows a close correlation between pain relief and neurophysiological evidence of
medial branch neurotomy.
Investigators publishing systematic reviews have an important responsibility: their
articles are often used to establish national or global treatment policies that might determine if
a given treatment method should be used and granted reimbursement. While we acknowledge
the important contribution of the authors of this review in several different areas of pain
medicine, we regret that they failed in their present report. The results of their review clearly
demonstrate that applying the "standard" criteria to evaluate RCTs for inclusion in a
systematic review is not a guarantee for appropriate conclusions on the effectiveness of a
surgical technique: authors of systematic reviews must also be aware of the background
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Radiofrequency neurotomy for spinal pain
literature on patient selection and surgical technique, and need to possess in-depth knowledge
of an operative technique that they set out to review.
The result in our country is that the National Board of Health and Welfare has decided
that RF neurotomy is an ineffective therapy and therefore should no longer be reimbursed as
of January 1st 2004. The consequences of that decision for patients are far reaching. To those
belong cervical trauma victims. Each year, traffic accidents in Switzerland generate
approximately 5500 new patients with neck pain. Two years later, about 1000 of these
individuals are still in pain and disabled.16 Half of them have pain from the cervical
zygapophysial joints17 and are now deprived of a highly efficacious pain therapy unless they
have means to pay out of their own pocket. Likewise, the large number of patients who suffer
lumbar zygapophysial joint pain due to degenerative disease and do not respond to
conservative treatment are let with no other option that further suffering.
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Radiofrequency neurotomy for spinal pain
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