1. Evaluation of Lesion Size for Water-Cooled Cervical Radiofrequency Ablation (RFA) and the Effects of Various Injectates and their Volume on the Lesion Size Eric W Stewart, MD; Joseph C Tu, MD; Kenneth X Nguyen, DO; Maged Ghattas, MB/BCH

2. Disclosures  Eric Stewart, MD has no relevant financial disclosures.  Joseph Tu, MD has no relevant financial disclosures.  Kenneth Nguyen, DO has no relevant financial disclosures.  Maged Ghattas, MB/BCH has no relevant financial disclosures. 2

3. Objectives  Purpose of the study  Background  Experiment Set Up  Results  Discussion/Conclusion  Limitations

4. Purpose of our study Objective: To test the hypothesis that lesion size using cervical water-cooled RFA is not affected by different injectates and different volumes of injectate. Design: Basic science - preclinical in vitro study Setting: Outpatient Interventional Spine Clinic Participants: Lesions were created in thawed chicken breasts using the water-cooled RFA probes and generator. Main Outcome Measures: Lesion size

5. Background Neck pain is a common recurrent complaint, ~15% prevalence in the general adult population Most commonly caused from cervical radiculitis, strains and sprains, and cervical facet syndrome Symptoms of facet-mediated pain – tenderness to palpation over facet joint or paraspinal muscles, pain with extension/rotation, absence of neurologic abnormalities Medial branch nerve blocks are used to diagnose and confirm the facets as the pain generator 5

6. Background RFA can be used as an effective therapeutic treatment option for cervical facet pain Traditional cervical RFA is done from a posterior- anterior approach due to the shape and size of traditional RFA technology. Limitations of this approach may be: Patient intolerance (positional, respiratory) Anatomical Barriers (dental, neck size, shoulders) Equipment (needle length) 6

7. Background  Water-cooled probes create a spherical lesion, distal to the tip of the needle, purported to be larger than traditional RFA lesions; thus allowing a lateral approach  Technically easier  Patient comfort  Time saving 7

8. 8 Experiment Set-Up 8

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11. Intervention:  Cervical water-cooled RFA probes and generator used to create lesions  Different injectates  None/dry  1% Lidocaine  0.25% Bupivicaine  0.5% Bupivicaine  Different volumes  0.5ml, 1ml, 2ml

12. Intervention:  The lesion was created for 150 seconds at 80 degrees Celsius (60 degrees at the tip of the probe with water-cooled technology).  Diameter of lesions measured (mm) 12

13. 13 Results – Water-Cooled RFA 13

14. 14 Results – Water-Cooled RFA

15. 15 Results – Traditional RFA 15

16. 16 Water-Cooled RFA Data 16 InjectateVolume (ml)Lesion Diameter (mm) Nothing/Dry07 Sterile Saline0.56.5 17 27 1% Lidocaine0.57 16.5 26 0.25% Bupivicaine0.56.5 16 26 0.5% Bupivicaine0.57 16 26

17. Results  The diameter of the lesions was consistently between 6 and 7mm  NOT affected by the injectate nor the injectate volumes

18. Discussion:  Water-cooled lesions were NOT significantly affected by different injectates nor their volumes.  Practitioners using water-cooled RFA can be confident that the lesion size will be consistent.  The spherical shape and the distal formation of the water-cooled lesions allows the procedures to be done in the lateral approach.  Water-cooled needles should be positioned perpendicular  Traditional needles should be positioned parallel

19. Limitations  Gross visualization only, no thermal imaging  Measuring tool  Precision of volume control (3cc syringe)  in vitro vs in vivo

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21. References:  1. Bezon H, Raja S, et al. 2011. Essentials of Pain Medicine, 3 rd Edition. Saunders, an imprint of Elsevier Inc.  2. Bogduk N. Cervicogenic headache: anatomic basis and pathophysiologic mechanisms. Curr Pain Headache Rep 2001, 5:382–386.  3. Dwyer A, Aprill C, Bogduk N. Cervical zygapophyseal joint pain patterns: a study in normal volunteers. Spine (Phila Pa 1976) 1990, 15:453–457.  4. Falco FJ, Manchikanti L, et al. Systematic review of the therapeutic effectiveness of cervical facet joint interventions: an update. Pain Physician. 2012 Nov-Dec; 15(6):E839-68.  5. Haldeman S, Dagenais S: Cervicogenic headaches: a critical review. Spine J 2001, 1:31–46.