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Radiofrequency Neurotomy Efficacy in the Treatment of Cervical Zygapophysial (Facet) Pain: 18 gauge versus 16 gauge Cannulae
Session: MP-03b
Thurs, Nov. 16, 1:30-3:30 pm
Saybrook Room

Please note, medically challenging cases are removed three months after the meeting and scientific abstracts after three years.

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Radiofrequency neurotomy of the third occipital nerve (TON) and cervical medial branches of the dorsal rami is the only validated treatment for neck pain of zygapophysial (facet) origin. In the literature, there are inconsistent results on the effectiveness of radiofrequency neurotomy (RFN)1 seemingly related to selection criteria and questionable technique. Although, size of the cannulae used is thought to be an additional factor.

The primary objective of this study was to ascertain whether there is a significant difference in the efficacy of cervical RFN when 18ga vs 16ga cannulae is used.

Materials and Methods

  • Retrospective study involved a medical record audit (2006-2017) of the consecutive cervical RFN procedures of a single physician in a private practice setting
  • IRB approval was obtained
  • Approximately 30 minutes following the diagnostic injections each patient was evaluated 
  • Pain intensity was assessed by querying the patient as to the percentage of index pain reduction
  • Patients stating less than 80% relief from either the first or second diagnostic block were excluded from undergoing RFN
  • Cervical RFNs were all performed using an 18ga radiofrequency cannula with 10mm curved active tip prior to the introduction of the 16ga cannulae by Bayliss (Kimberly Clark/Halyard) after which all were performed using the larger instrument
  • Patients returned for evaluation 4-5 weeks following the RFN to assess effectiveness of the treatment and were asked the current pain intensity by numeric rating scale and percentage of pain relief from the initial pain index level


Of the 213 patients, 51.6% (110) had undergone RFN with a 16ga cannula and 48.4% (103) an 18ga. No significant difference in pre- or post-operative pain was noted between the two cannula gauges. No significant side effects or complications to the RFN were reported by any patient. At 4-5 weeks, the mean percentage of pain relief with a 16ga cannula 68.1%, versus 64.3% for an 18ga evidencing no significant difference by independent t-test, (t(1)=0.77, p=0.581).

Analysis of the mean percent of pain relief with diagnostic blocks 1 and 2 (80-90% vs 91-100%) versus the percent of pain relief post-RFN evidenced no significant difference. (r(198)=-.130, p=0.067).   

Using Chi-square tests, no association between pain relief of ≥90% and cannula gauge was found, χ2(1, N=200) 2.86, p=0.091.


Using SIS Guidelines2,3 where the cannula is parallel and abutting targeted nerves, there is no significant difference between 18 and 16ga cannulae with curved 10mm active tips. Using an anatomically-based best practice technique, one can expect: 72% of patients having >50% relief; 57% having >75% relief; and 34% seeing >90% relief, over 4-5 weeks.

Given that larger cannulae form significantly larger lesions, a greater leeway in regard to “perfect” cannula placement is afforded using the larger cannula. This may benefit those physicians who are less meticulous with cannula placement or perform single lesions. 16ga RF cannulae cause no more procedural pain than smaller ones when adequate local anesthetic is used, evidence no increase in complications, create significantly larger neural lesions increasing the probability of good pain relief of long duration, and these larger gauge cannulae were used in the validating literature3. Therefore, use of smaller gauges should be seriously questioned.


  1. Niemisto L, Kalso EA, Malmivaara A, Seitsalo S, Hurri H. Radiofrequency denervation for neck and back pain. Cochrane Database of Systematic Reviews 2003, Issue 1
  2. International Spine Intervention Society. Principles of thermal radiofrequency neurotomy. In: Bogduk N (ed). Practice Guidelines for Spinal Diagnostic and Treatment Procedures, 2nd edn. International Spine Intervention Society, San Francisco, 2013
  3. International Spine Intervention Society. Cervical Medial Branch Radiofrequency Neurotomy. In: Bogduk N (ed). Practice Guidelines for Spinal Diagnostic and Treatment Procedures, 2nd edn. International Spine Intervention Society, San Francisco, 2013.
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