Radiofrequency Treatment for Sacroiliitis • 349Table 1. Presented Here are General Characteristics of 26 Patients Treated with Cooled Radiofrequency of TheirSacra Lateral Branches and Dorsal Ramus of L5 and Their Data on Pain Scores, Functional Capacity Change (PDI),Patient Satisfaction, and Opioid Use VAS (cm) PDI GPE Opioid MSO4 mgNo Age (Years) Sex Years of Pain Base After Base After Pain Function Satisfaction Before After 1 70 M 3 8 2 28 7 3 3 3 90 30 2 59 M 2 8 3 30 16 2 2 2 30 15 3 69 M 5 5 0 23 8 3 3 3 40 0 4 63 M 11 6 0 21 7 3 3 3 20 0 5 50 F 6 8 7 26 26 0 0 0 30 30 6 78 F 3 10 4 19 9 2 2 2 20 20 7 55 F 5 7 5 22 10 2 2 2 20 20 8 55 F 6 5 4 37 32 1 1 1 40 40 9 45 F 10 8 3 32 11 3 3 3 80 8010 78 F 1 8 7 23 16 0 0 0 10 1011 77 F 7 10 3 23 9 3 3 3 0 012 53 F 1 5 0 23 1 3 3 3 60 2013 92 F 20 7 5 34 19 2 2 2 30 3014 38 F 10 7 7 32 10 3 3 3 240 24015 51 F 3 8 7 30 13 3 2 3 20 2016 72 F 1 8 7 40 37 -2 -2 -2 0 017 44 F 1 10 3 31 17 3 3 3 30 1518 82 F 2 8 10 29 27 0 0 0 0 019 57 M 3 6 2 59 23 3 3 3 250 20020 56 F 17 8 8 46 46 0 0 0 10 1021 75 F 6 8 4 32 22 2 2 2 140 16522 53 F 11 5 2 46 23 3 3 3 120 4023 58 F 5 5 5 38 38 0 0 0 0 024 52 F 2 5 5 32 32 0 0 0 60 6025 44 F 10 5 5 43 42 2 2 2 40 4026 55 M 10 6 2 50 28 3 2 2 15 15Sex: M, male; F, female; VAS, visual analog scale; Base, baseline; PDI, pain disability index; GPE, global percieved effect; MSO4 mg, morphine opioid equivalent in mg.major contribution from the lateral branches of S1 and applications in pain management, cooled RF electrodesS2 and from the dorsal ramus (DR) of L5. Radiofre- rely on a closed loop ﬂuid circuit consisting of sterilequency (RF) denervation of the joint capsule or lateral water and a computerized peristaltic pump to regulatebranches has been performed using conventional RF cooling during RF delivery.cannula either individually or in a bipolar arrange- In this study, we conducted an initial evaluation ofment.4,7,10,11 Although preliminary results were largely the Pain Management SInergy System (Baylis Medicalpositive, no gold standard for treatment has emerged Inc., Montreal, Canada) to treat chronic SI joint pain.subsequently. Presented here are data on pain relief, functional capac- The inherent challenge when treating SI joint pain ity and patient satisfaction from a 27-patient case-series.with RF energy is the inconsistent location of targetedlateral branch nerves.7,12 The development of a novelcooled RF electrode to create larger lesions may provide METHODSa means of overcoming this difﬁculty. By treating a After Institutional Review Board approval wasgreater volume of the tissue lateral to the S1 through S3 obtained, chart review was conducted of 27 consecutivesacral foramina, it intuitively follows that there is a patients with chronic SI joint mediated pain who weregreater likelihood of disrupting sacral lateral branches. treated using cooled RF denervation of the SI joint. The use of electrode cooling to increase lesion size Patients were identiﬁed based on the computer-was previously described for tumor ablation by Gold- generated list from our database of patients who under-berg et al.13 and Lorentzen et al.15 Cooled electrodes went this procedure. To be included in the study, theare capable of creating larger lesions compared with patient record had to contain all of the data shown innoncooled ones because they remove heat from adjacent Table 1. Among the 27 charts reviewed, one had incom-tissue and allow power delivery to be increased without plete data. A database was generated for the remainingcausing high impedance and tissue charring.14,15 For 26 patients (Table 1).
350 • kapural et al. Figure 2. Anterior-posterior ﬂuoroscopic view of the sacral bone. Note a 27G spinal needles placed within S1, S2, and S3 foramina serving as orienteer for the placement of radio- frequency electrode introducer. Epsilon shaped ruler is used to limit the area of heating away from the foraminal opening. Visible is appropriately positioned radiofrequency electrode lateral and somewhat inferior to the S1 foramina similar to the position shown in schematic of the Figure 1.Figure 1. Schematic describing electrode position during cooledradiofrequency of S1 lateral branches. Epsilon ruler guidesappropriate distance of the electrode from the foramina. Three Because the posterior sacral foramina (PSFA) are difﬁ-lesions are suggested at the lateral aspect of S1. cult to identify with certainty on most patients, three 27-gauge 3.5-inch Quincke needles were placed into the Patients who received RF denervation had pre- S1, S2, and S3 PSFA under anterior-posterior imaging toviously failed to achieve adequate improvement with establish internal reference points. There were sevencomprehensive nonoperative treatments including reha- patients where such placement could not be achieved inbilitation and medical therapies. Diagnosis was based one or two out of three sacral foramina. We did not useon physical examination (axial pain below the L5 bowel enema/preparation before the procedure tovertebrae).16–18 Diagnosis was conﬁrmed by >50% improve sacral foramina visualization.improvement in visual analog scale (VAS) pain scores Beginning at the S1 level, an introducer with styletfollowing two ﬂuoroscopically guided SI joint injections was inserted onto the bone endpoint of the posteriorusing a 3 cc of local anesthetic bupivacaine 0.5% and sacrum. The distance between the introducer and the40 mg triamcinolone. aperture of PSFA of S1 was measured using a circular RF denervations were completed under minimal stainless steel ruler (Epsilon Ruler, Baylis Medical Inc,sedation, anxiolysis (midazolam 1–2 mg) and inﬁltra- Montreal, Canada). The ﬁnal position of the introducertion of local anesthetics. Patients communicated with was 8–10 mm from the lateral edge of PSFA (Figures 1the attending staff physician throughout the procedure. and 2). A depth marker was ﬁxed to the level of the skinAfter placing the patient in the prone position with and the stylet removed. When inserted, the styletsterile site preparation and drape, the skin was inﬁl- extends 6 mm beyond the tip of introducer. The RFtrated with 1% lidocaine over the desired target entry probe, which was subsequently inserted via same intro-point. C-arm ﬂuoroscopy was used to visualize the ducer, extends only 4 mm beyond the tip of introducersacrum by imaging through the L5/S1 disc space. (Figure 3a,b). Therefore, the ﬁnal position of the probe
Radiofrequency Treatment for Sacroiliitis • 351 (a) (b)Figure 3. Sequence photographs of the cooled radiofrequency introducers and electrode introduced through the skin within thesacroiliac area. (a) Three 27G spinal needles and two electrode introducers are shown piercing the skin over the sacral area. Havingtwo introducers facilitated procedure itself, as they can be re-positioned under different angles to denervate a speciﬁc points lateralto sacral foraminal openings while other electrode is in use. (b) Shown here (middle, black) is a cooled radiofrequency electrodeinserted via one of two introducers placed appropriately in the sacral area. The electrode is connected to the generator via electricalcable (shown black) and tubing used for the electrode cooling by water pump (shown transparent). Two introducers are needed tofacilitate the procedure eg, while the ablation is conducted using electrode positioned via one of the introducers, other is beingrepositioned under ﬂuoroscopy.tip should be approximately 2 mm from the surface of one or two procedures) 3–4 months after procedures.the sacrum. Lateral ﬂuoroscopy conﬁrmed that the RF Comparisons were made using unpaired and pairedprobe was not within sacral canal and impedance was t-tests and the graphs were generated using Sigma Plotveriﬁed to be in the range of 100–500 ohms. If higher (Systat Software Inc, Chicago, IL) computer program.impendence was observed, the electrode repositioningwas performed by ﬁrst re-introducing stylet and slightly RESULTSadjusting the location of the introducer. Once suitable A summary of absolute and relative VAS pain scores iselectrode location and impedance were achieved, the provided in Table 1. The mean VAS scores of theheating protocol was initiated, delivering RF energy for patients in this study decreased from 7.1 1 1.6 to2 minutes and 30 seconds. Target electrode temperature 4.2 1 2.5 (P < 0.001) at 3–4 months after procedures.was 60°C. Once energy delivery was complete, the RF Functional capacity also improved signiﬁcantly, with aprobe was removed, stylet replaced and introducer redi- change in PDI scores from 32.7 1 9.9 to 20.3 1 12.1rected to the next target. Either two or three lesions (P < 0.001). A summary of all baseline and outcomewere created at each sacral level. Typically, these lesions data is presented in Tables 1 and 2.were spaced about 1 cm apart from one another, creat- A benchmark for successful treatment of SI joint paining a strip of lesioned tissue lateral to each foramina has been reported in the literature as a 50% reduction(Figure 1). Only one skin entry point was made at each on VAS from baseline.7,10,19 For continuity among pub-level. Multiple electrode placements could be achieved lished outcomes, we present data using similar metricsat a given level by changing the angle of introducer from for successful response (Tables 2 and 3). At three to fourthe same location at the skin. Those who required bilat- months following treatment, 13 of 26 patients (50%)eral RF received contralateral RF within 1–2 weeks (10 had achieved the primary outcome of at least 50%out of 27 patients). reduction in VAS pain scores. Four of the responders Outcome tools included pain disability index (PDI), (15%) had over 75% pain relief and three patientsVAS pain scores, global perceived effect (GPE) for patient (12%) reported being completely pain free. The meansatisfaction, and morphine (MSO4) mg equivalent reduction in pain scores (VAS) among responders wasopioids used. Data were collected at baseline (before the 5.2 +/-1.2. 15 patients (58%) experienced at least a
352 • kapural et al.Table 2. Summarized Outcome Measures for All of the Patients Treated Using Cooled Radiofrequency All patients Responders NonrespondersOutcome measure Mean SD Mean SD Mean SD P valueVisual analog scale for pain severity (0–10) n (patients) 26 — 13 — 13 —Pretreatment 7.1 1.6 7.3 1.9 6.8 1.3 0.49 3–4 months 4.2 2.6 2.2 1.4 6.3 1.7 0.0000008 Change 2.8 2.6 5.2 1.2 0.5 1.1Pain Disability Index for physical functioning (0–70) n (patients) 26 — 13 — 13 —Pretreatment 32.7 9.9 32.1 12.3 33.2 7.4 0.77 3–4 months 20.3 12.1 13.9 8.2 26.8 12.3 0.004 Change 12.3 9.3 18.2 7.1 6.5 7.6Opioid use and subsequent post-treatment reduction (mg MSO4 equivalent) n (patients) 26 — 13 — 13 —Pretreatment (median) 30 — 40 — 20 — 0.25 3–4 months 20 — 20 — 20 — 0.76 Change 10 — 20 — 0 —Patient subjective rating (global perceived effect) n (patients) 26 — 13 — 13 — Pain 1.8 1.4 2.8 0.44 0.8 1.4 Function 1.7 1.4 2.7 0.48 0.8 1.5Satisfaction 1.8 1.4 2.7 0.48 0.8 1.4SD, standard deviation.Table 3. Demographic, Clinical and Treatment Characteristics of Treated Patients Using Cooled RF Based onOutcomesFeature Responders (n = 13) Nonresponders (n = 13) All patients (n = 26)Age 61 1 12 years 60 1 16 years 61 1 14 years (38–92)Gender 6 male, 7 female 0 male, 13 female 6 male, 20 femaleYears back pain 5.6 1 3.8 6.8 1 6.0 years 6.2 1 5.0 yearsOpioid use (median in mg 40 mg 20 mg 30 mg MSO4 equivalent)Bilateral RF 6 patients 4 patients 10 patientsRF, radiofrequency; MSO4 mg, morphine opioid equivalent in mg.2-point drop in VAS, which is considered clinically rel- formed (Table 3). The novel use of internally cooledevant (Table 2).20,21 electrodes to create lesions along the posterior sacrum Opioid use varied greatly among the patients, both did not result in any complications, and the procedureprior to and following procedure (Tables 1 and 2). was generally well tolerated.However, following treatment there was an observeddecrease from a median value of 30 mg morphine DISCUSSIONequivalent to 20 mg morphine equivalent. Among This case series of 47 procedures (uni- and bilateral)responders, median opioid use decreased by 50%; from completed on 27 patients is the ﬁrst to retrospectively40 to 20 mg MSO4 equivalent (Table 2). observe the effects of novel cooled RF denervation of Eighteen patients (67%) rated their improvement in sacral lateral branches and L5 DR on chronic SI jointpain scores using GPE as improved or much improved, pain. At 3–4 month follow-up signiﬁcant improvementswhile eight patients (30%) claimed minimal or no in patient’s pain scores and ability to perform everydayimprovement. Similar ratings were observed for GPE functions were observed (Tables 1 and 3). All of the 13related to daily activities and whether these patients responders (based on their pain scores) experiencedwould recommend the procedure to others (Tables 1 more than 10 points improvement in function by PDIand 2). We were not able to observe any difference in scores (Tables 1 and 2). Correspondingly, GPE amongprocedure success related to patient’s age, years of responders was rated high (Table 2). Among the 13chronic pain, or whether unilateral or bilateral RF per- nonresponders, only three patients experienced a >50%
Radiofrequency Treatment for Sacroiliitis • 353improvement in physical disability. Average GPE among originating from the SI joint complex.7 Additional efﬁ-nonresponders was predictably low (Table 2). As cacy study is required to support this conclusion, and toexpected, there is a good correlation between positive further justify the additional cost of the equipment.outcomes for pain severity on VAS and positive out- However, loss of functional capacity, long-term inactiv-comes both PDI and GPE, respectively. ity and dissatisfaction with daily chronic pain might be While many of the patient records demonstrated sig- associated with higher costs to both the individual suf-niﬁcant reduction in pain severity, there were an equal fering and the society.number of patients who improved their pain scores 50%or less. The observed inconsistency among outcomesmay be due to a number of factors including dener- REFERENCESvation of some but not all of the communicating 1. 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