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Symptomatic Lumbar Facet Synovial Cysts: Clinical Outcomes Following Percutaneous CT–Guided Cyst Rupture with Intra-articular Steroid Injection
CLINICAL STUDY
Symptomatic Lumbar Facet Synovial Cysts: Clinical Outcomes Following Percutaneous CT–Guided Cyst Rupture with Intraarticular Steroid Injection Steffen J. Haider, MD, MPH, Nu R. Na, BS, Clifford J. Eskey, MD, PhD, Jessica G. Fried, MD, Natalie Y. Ring, BS, Mike H. Bao, BS, and David A. Pastel, MD ABSTRACT Purpose: To evaluate clinical outcomes following percutaneous rupture of symptomatic lumbar facet synovial cysts (LFSCs) with intraarticular steroid injection. Materials and Methods: In this retrospective review, 44 consecutive patients with symptomatic LFSCs received primary treatment with CT–guided synovial cyst rupture with intraarticular steroid injection. Outcomes questionnaires were obtained before and 1, 4, 26, and 52 weeks after LFSC rupture. Assessment included pain medication use and numeric rating scale (NRS), Oswestry Disability Index (ODI), and 12-item short form health survey (SF-12) physical and mental composite scores (PCS and MCS). Clinical endpoint was 52-week survey response or surgery. Results: LFSC rupture was technically successful in 84% (37/44) of cases. Clinical endpoint was reached in 68% (30/44) of patients with 82% overall 1-year follow-up. Lumbar spine surgery was performed in 25% (11/44) of patients within 1 year after procedure. Mean NRS, ODI, and SF-12 PCS demonstrated significant improvement at all follow-up time points (P < .001). At 52-week follow-up, NRS decreased from 8.1 to 3.7 (P < .001), ODI improved from 35 to 24 (P ¼ .006), and SF-12 PCS improved from 31 to 42 (P < .001). Daily pain medication decreased from 71% (31/44) of patients before procedure to 29% (9/26) at 52-week follow-up (P ¼ .012). History of prior lumbar intervention was associated with poorer LFSC rupture success (P ¼ .025) and ODI (P ¼ .047). Conclusions: NRS, ODI, and SF-12 PCS indices improved and pain medication use decreased significantly at all time points over 1-year follow-up after percutaneous rupture of symptomatic LFSCs with intraarticular steroid injection.
ABBREVIATIONS LESI ¼ lumbar epidural spinal injection, LFSC ¼ lumbar facet synovial cyst, MCS ¼ mental composite score, NRS ¼ numeric rating scale, ODI ¼ Oswestry Disability Index, PCS ¼ physical composite score, SF-12 ¼ 12-item short form health survey
From the Department of Radiology (S.J.H.), Columbia University Medical Center, New York City, New York; Department of Radiology (N.R.N., C.J.E., N.Y.R, M.H.B., D.A.P.), Dartmouth-Hitchcock Medical Center, 1 Medical Center Drive, Lebanon, NH 03756; and Department of Radiology (J.G.F.), Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania. Received December 23, 2016; final revision received April 20, 2017; accepted April 22, 2017. Address correspondence to D.A.P.; E-mail: david.a.pastel@ hitchcock.org C.J.E. is a stockholder for Relievant Medsystems (Redwood City, California) and is a paid consultant for Intrinsic Therapeutics (Woburn, Massachusetts). None of the other authors have identified a conflict of interest. © SIR, 2017 J Vasc Interv Radiol 2017; ▪:1–7 http://dx.doi.org/10.1016/j.jvir.2017.04.021
Synovial cysts arising from the lumbar spine facet joints are most commonly seen in the setting of degenerative facet joint spondylosis (1–4). Lumbar facet synovial cysts (LFSCs) that project into the spinal canal may result in radiculopathy (87%), neurogenic claudication (44%), sensory loss (43%), and motor weakness (27%) (5). Percutaneous LFSC rupture (5–10), facet steroid injection (11,12), and surgical lumbar decompression (13–15) have been described as effective treatment modalities. Recent meta-analyses favor lumbar decompression over percutaneous interventions, citing only a lower cyst recurrence rate with surgery (16,17). The published literature on LFSC rupture is limited by narrow outcomes metrics or nonstandardized retrospective single-time-point follow-up (5–7,10). Demonstration of early pain relief and improved function would likely favor percutaneous
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approaches given the low morbidity associated with percutaneous LFSC rupture (16). The purpose of the present study was to provide a comprehensive assessment of clinical outcomes at multiple standardized time points after computed tomography (CT)–guided LFSC rupture to inform clinician and patient expectations. To this end, 4 different validated outcome scoring systems, progression to surgery, and use of pain medication over 1 year following CT-guided LFSC rupture are reported.
MATERIALS AND METHODS The study was approved by the institutional review board, which waived consent for the study. A retrospective review of the institutional synovial cyst database was performed. The institutional database includes all 44 consecutive patients who underwent a CT-guided percutaneous LFSC rupture procedure from October 1, 2013, to September 30, 2015. The decision to perform LFSC rupture was based on the presence of a synovial cyst on lumbar spine magnetic resonance (MR) imaging performed ideally within 2 months of the procedure and lower extremity radiculopathy corresponding to the location of the LFSC. Demographic and comorbid characteristics are presented in Table 1. Mean age of patients was 65 years (range, 43–94 y) with 30% (13 of 44) having a body mass index > 30. Of patients, 32% (14 of 44) had at least 1 prior spinal intervention, 78% of which were lumbar epidural spinal injection (LESI), prior lumbar surgery, or LFSC rupture (Table 1). In this study, 61% of LFSCs treated were located at the L4-L5 spinal level with a mean cyst diameter of 9 mm (Table 1). There were 9 faintly calcified synovial cysts; the rest of the LFSCs had no calcifications. There were no densely calcified cysts. Table 1. Baseline Characteristics of Patients Undergoing LFSC Rupture (N ¼ 44) Characteristic Male sex Age, y, mean ± SD (range) Mean BMI, mean ± SD
Value 19 (43%) 65 ± 12 (43–94) 28 ± 7
Obese (BMI > 30)
13 (30%)
Prior lumbar spine intervention
14 (32%)
Lumbar epidural spinal injection
11 (25%)
Lumbar surgery
3 (7%)
LFSC rupture
2 (5%)
Cyst level L2-L3 L3-L4
1 (2%) 8 (18%)
L4-L5
27 (61%)
L5-S1
7 (16%)
Multilevel Cyst diameter, mm, mean ± SD (range)
1 (2%) 9.2 ± 3.4 (2–18)
Note–Values are presented as number (%) unless otherwise noted. BMI ¼ body mass index; LFSC ¼ lumbar facet synovial cyst.
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All patients underwent MR imaging a mean 38 days (SD 27 d; range, 2–266 d) before the LFSC rupture. The MR examinations included T2-weighted axial and sagittal images with repetition time of 3,000–6,000 ms, echo time of 80–110 ms, section thickness of 4 mm with 5-mm spacing, and a matrix of 256 256 or 512 512 (Fig 1a, b). Follow-up imaging was performed only for symptomatic patients at the discretion of the primary providers. The LFSC rupture procedures were performed using a single treatment protocol by 6 different neuroradiologists with 3–31 years of experience. In this series, the 6 neuroradiologists each performed 1–13 LFSC rupture procedures. Procedural conscious sedation with fentanyl and midazolam was administered. For local anesthesia, 1% lidocaine buffered with 8.4% sodium bicarbonate was used. A 20-gauge spinal needle was advanced under intermittent CT fluoroscopy into the facet joint, and 1–2 mL of iohexol (Omnipaque 350; Nycomed Amersham, Princeton, New Jersey) diluted in normal saline at a ratio of 1:10 was injected to confirm continuity of the facet joint with the synovial cyst (Fig 1c). In patients with osteophytes covering the facet joint (14 patients), a 14-gauge coaxial system (Bonopty; AprioMed, Uppsala, Sweden) was used to access the facet joint. Once the cyst was opacified with contrast material, a 3-mL syringe made of polycarbonate to withstand highpressure hand injection was used to rapidly inject saline with dilute contrast agent. Technical success of cyst rupture was defined by demonstration of contrast material within the epidural space but outside the confines of the cyst wall on CT and by loss of resistance (Fig 1d). After cyst rupture, 80 mg of methylprednisolone (DepoMedrol; Pfizer Inc, New York, New York) was injected. Patients were observed for 1 hour after the procedure. The referring spine specialist then followed patients clinically as outpatients. Four outcome-scoring indices were used for each patient. The primary outcome measures were the numeric rating scale (NRS) (on a scale of 0–10, with 0 indicating no pain and 10 indicating “pain as bad as you can imagine”) and the Oswestry Disability Index (ODI) (scores 0–20 minimal, 21–40 moderate, 41–60 severe, 61–80 crippling, 81–100 bedbound) (18,19). The 12-item short form health survey (SF-12) physical composite score (PCS) and mental composite score (MCS) were the secondary outcomes (scale 0–100 with higher scores representing higher physical and mental well-being) (20). Outcomes scores and pain medication frequency and dose were recorded immediately before the LFSC rupture procedure and 1 week, 4 weeks, 26 weeks, and 52 weeks after the procedure. The initial questionnaire was completed in the holding room before the procedure. Subsequent surveys were completed by mail or telephone. Patient demographics were collected with chart review of the electronic medical record (EPIC Systems Corp, Verona, Wisconsin). Prior lumbar intervention was defined as a history of lumbar surgery, LESI, or prior LFSC rupture. Progression to subsequent lumbar spinal surgery or LESI within 1 year of LFSC rupture was also recorded. If a patient
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Figure 1. (a, b) T2-weighted axial and sagittal MR images demonstrate a 1.2-cm right-sided LFSC at the L4-L5 vertebral level, which impinges the right neural foramen and compresses the thecal sac. (c) Axial CT image obtained during the procedure demonstrates placement of needle into the facet joint. Opacification of the cyst confirms communication with the facet joint. (d) Axial CT image obtained during the procedure demonstrates contrast material outlining the epidural space indicating successful rupture of the cyst.
underwent lumbar decompression surgery during follow-up, the outcome scores were included up to, but not after, the time of surgery, scores after the surgery reflect the lumbar surgery rather than LFSC rupture. Clinical follow-up visits for lumbar evaluation were performed at the treatment hospital in 71% of patients (31 of 44) at a median of 13 months (range, 0.5–40 months). The rate of follow-up for enrolled patients was 82% at both 1 and 4 weeks (36 of 44) and 73% at 26 weeks (32 of 44). The study endpoint of progression to lumbar surgery or 52-week survey follow-up was attained in 68% (30 of 44) of patients. When combining survey response and surgery with clinical follow-up, follow-up within 1 year of LFSC rupture was 82% (36 of 44).
Regression of the repeated measurement of co-primary and secondary outcome scores between baseline through 1-year follow-up was modeled with general linear mixed models (21). The model used a random slope with random intercept and unstructured covariance. Analysis of covariance was used to compare outcomes between subgroups at 6-month follow-up. Significance was defined as P < .05. Statistical analysis was performed using IBM SPSS Statistics for Windows Version 23 (IBM Corp, Armonk, New York). Post hoc power analysis was performed at a ¼ .05 and accounted for the 32% questionnaire nonresponse rate at 1-year follow-up. There was 80% power to detect a 30% change in the co-primary outcome scores at 1-year followup in the overall cohort. In subgroup analysis, there was 50% power to detect 35% change in co-primary outcome scores at 6-month follow-up.
Statistics The difference in qualitative variables was analyzed by Fisher exact test. Differences in mean measurements between groups were assessed with Student t test. Change in pain medication use was analyzed by McNemar test.
RESULTS LFSC rupture was technically successful in 84% (37 of 44) of cases (Table 2). Figure 1a–d demonstrates
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Table 2. Cyst Rupture Outcomes Outcome Measure
Frequency or Mean
Technical success in LFSC rupture
84% (37/44)
Prior lumbar intervention* Technical failure in LFSC rupture Prior lumbar intervention*
24% (9/37)
rupture, 10% (4 of 44) underwent repeat rupture for symptomatic cyst recurrence at 3, 3, 4, and 5 months after the initial procedure with no further recurrence or progression to lumbar surgery during follow-up. LESI was performed in 25% (11 of 44) of patients within 1 year after LFSC rupture.
16% (7/44) 71% (5/7)
Repeat cyst rupture LESI within 1 y
10% (4/44) 25% (11/44)
Lumbar surgery within 1 y after rupture
25% (11/44)
Time to surgery if required, d, mean ± SD (range)
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128 ± 76 (52–300)
LESI ¼ lumbar epidural spinal injection; LFSC ¼ lumbar facet synovial cyst. *Technical failure associated with prior lumbar intervention (P ¼ .025). Prior lumbar intervention is history of prior LESI, LFSC rupture, or lumbar surgery.
technically successful LFSC rupture. Comparing unsuccessful and successful LFSC rupture, 71% of patients (5 of 7) with unsuccessful LFSC rupture had previous spinal intervention compared with 24% of patients with successful LFSC rupture (9 of 37) (P ¼ .025) (Table 2). Successful cyst rupture was achieved in 89% (8 of 9) of the faintly calcified LFSCs. There were no procedural complications related to percutaneous LFSC rupture in the present series. Of patients with initially successful LFSC
Primary and Secondary Outcome Scores The primary outcomes of NRS and ODI and the secondary outcomes of SF-12 PCS and MCS scores are reported in Figure 2a–d. Baseline pain and disability indices were severe in this patient cohort. Mean NRS, ODI, and SF-12 PCS scores improved significantly at 1-week follow-up, and this improvement was durable through 1 year (P < .001) (Fig 2a–c). Mean NRS decreased from 8.1 ± 2.6 at baseline to 3.0 ± 2.7 at 1-week follow-up (P < .001) and to 3.7 ± 2.3 at 52-week follow-up (P < .001) (Fig 2a). Mean ODI similarly decreased from 35 ± 17 at baseline to 13 ± 16 at 1-week follow-up (P < .001) and to 24 ± 17 at 52-week followup (P < .001) (Fig 2b). SF-12 PCS scores improved from 31 ± 10 at baseline to 45 ± 11 at 1-week follow-up (P < .001) and remained improved above baseline through 52 weeks of follow-up (P < .001) (Fig 2c). SF-12 MCS score improved from 51 ± 9 at baseline to 57 ± 11 at 1 week (P < .001) but worsened to the baseline by 1 month through the study endpoint at 1 year (P ¼ .9) (Fig 2d).
Figure 2. (a) NRS with LFSC rupture and steroid injection. (b) ODI with LFSC rupture and steroid injection. (c) SF-12 PCS with LFSC rupture and steroid injection. (d) SF-12 MCS with LFSC rupture and steroid injection.
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Table 3. Subgroup Analysis of Prior Lumbar Procedure with Primary Outcomes Outcome Subgroup
Time
Number of Patients
Mean (95% CI)
Prior intervention
Baseline
14
26 weeks
8
6.0 (4.2–7.9)
None
Baseline
30
7.9 (7.2–8.6)
26 weeks
15
3.3 (2–4.7)
Baseline 26 weeks
12 8
32 (23–41) 32 (21–43)
P
NRS 7.9 (6.8–8.9) .052
ODI Prior intervention None
Baseline
26
38 (32–44)
26 weeks
14
18 (10–26)
.047
P value refers to significance of the interaction of dichotomous subgroup and dichotomous time variables. CI ¼ confidence interval; NRS ¼ numeric rating scale; ODI ¼ Oswestry Disability Index.
Table 3 presents the effect of a prior lumbar intervention (surgery, LESI, or previous LFSC rupture) on NRS and ODI at baseline and 26-week follow-up. NRS improved from 7.9 (6.8–8.9) to 3.3 (2–4.7) without prior intervention compared with 7.9 (6.8–8.9) to 6.0 (4.2–7.9) with prior interventions (P ¼ .052). Mean ODI improved from 38 (95% confidence interval 32–44) to 18 (10–26) without prior intervention and was unchanged at 32 (21–43) with prior interventions (P ¼ .047).
Subsequent Lumbar Surgery Of patients, 25% (11 of 44) underwent decompressive lumbar surgery within 1 year of LFSC rupture (range, 52–300 d). Residual or recurrent synovial cyst was demonstrated in 4 of 5 patients who underwent repeat lumbar MR imaging. Technically successful cyst rupture was associated with a 24% (9 of 37) rate of surgery, whereas an unsuccessful cyst rupture was associated with a 29% (2 of 7) surgical rate (P ¼ 1). The subsequent surgical group had baseline NRS and ODI scores similar to the overall cohort (P > .6). At 4 weeks after attempted percutaneous cyst rupture, patients who later underwent subsequent lumbar surgery experienced a decrease in mean NRS by 2.8 ± 3.5 (P ¼ .04) and decrease in ODI by 12 ± 15 (P ¼ .048), which is similar to the pattern demonstrated in the overall cohort (Fig 1b, 2a).
Pain Medications Daily pain medication use was self-reported by 71% of patients (31 of 44) at the baseline interview. This included 16% (7 of 31) opiate and 55% (24 of 31) nonopiate regimens. At 1-week follow-up, self-reported daily pain medication use decreased to 36% of patients (13 of 36) (P ¼ .001). This response was durable through 52-week follow-up, at which time 35% of patients (9 of 26)
reported daily pain medication use (P ¼ .012 compared with before the procedure).
DISCUSSION This study reports the clinical outcomes of 44 consecutive patients who underwent CT-guided LFSC rupture with intraarticular steroid injection. Patients experienced marked improvements in pain and function at 1-week follow-up, which was durable through 1-year follow-up as measured by NRS, ODI, and SF-12 PCS. There was a concordant significant decrease in daily pain medication use after LFSC rupture. LFSC rupture was successful in 84% of cases as confirmed by leakage of contrast material into the epidural space, which is consistent with previous reports in the literature (5–8,10). Technical failure of LFSC rupture was associated with previous spinal procedures, most commonly LESI. Previous LESI may create scarring within the epidural space, making it more challenging to rupture a cyst that is adherent to the dura. Pain and function outcomes of the present study are in agreement with outcomes previously reported by Martha et al (6) with respect to NRS and ODI and Allen et al (7) with respect to NRS and several alternative outcome scores. However, the studies of Allen et al (7) and Martha et al (6) are notably limited by recall bias introduced with retrospective collection of the baseline outcome scores at the single follow-up interview. The single follow-up interview in these studies also creates a limited cross-sectional assessment of outcomes scores that may not reflect the pain and function at other time points. These limited studies allow the meta-analysis by Campbell et al (17) to favor surgical decompression citing only a lower cyst recurrence rate compared with LFSC percutaneous intervention without accounting for pain or morbidity at multiple time points during follow-up. The present study counters such an argument by demonstrating rapid and durable improvement in lumbar pain and function over multiple standardized follow-up assessments through 1-year follow-up. The rapid improvement in pain and function in the present study has not been demonstrated for surgical treatment of symptomatic LFSCs. There is an ongoing epidemic of narcotic dependence and abuse in the United States, and chronic low back pain has been implicated as a major contributor (21–23). Adoption of treatment modalities that reduce long-term opioid use is a necessary strategy (23). In this study, 71% of patients in this study reported pain relief sufficient to discontinue analgesics at 1 year after LFSC rupture. In the retrospective study by Martha et al (6), 55% of patients still reported pain medication use at a mean of 3.2 years after percutaneous rupture. No pain medication use before the procedure was reported in that study. The SF-12 MCS score improved 1 week after LFSC rupture and then returned to baseline despite improvement in pain and function. A similar result of unchanged MCS
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despite improved pain and function indices was observed in a study of revision lumbar surgery (24). This may speak to the broader physical, psychological, and social factors that influence mental well-being beyond the pain generator of a synovial cyst. The 25% rate of surgery within 1 year after LFSC rupture compares favorably with reported rates of 17%–54% in the literature (5–8,10,16,17). Similar to results reported by Martha et al (6), a successful cyst rupture did not prevent surgery in the present study. Given the known propensity of synovial cysts to recur, it is not surprising that a certain portion of the patients would ultimately progress to surgery (17). The reason for the relatively low use of surgery in patients without successful percutaneous treatment is less clear. It is possible that patients in this elderly population are not good surgical candidates. Other possible explanations include lack of consistent guidelines used in determining the need for surgery, differences in the clinical and pathologic characteristics of the cysts that could not be ruptured, and the small sample size for the group with unruptured cysts. All 4 patients with repeat LFSC rupture were managed successfully without surgery through the conclusion of the study. Amoretti et al (11) reported on steroid injection of LFSCs without rupture in a prospective study of 120 patients. Mean ODI in that cohort decreased from 72 ± 20 to 20 ± 6 at 6-month follow-up (11). This is a greater, but concordant, decrease in dysfunction compared with the present study with similar post-procedure ODI after the procedure. The study by Amoretti et al is comparable to the present study given that outcomes were collected prospectively and longitudinally over multiple time points. This suggests that steroid injection alone may be sufficient to improve symptoms of LFSC without the need for cyst rupture. Further randomized trials comparing LFSC rupture with steroid injection with steroid injection alone may clarify this question. This study has several limitations. Because this was a single-arm study without a control cohort that did not undergo LFSC rupture, the placebo effect cannot be excluded. However, pain and dysfunction were severe in this cohort at baseline with marked improvement by 1-week follow-up. This suggests that the effect was treatment based rather than by chance. Interpretation of the present results is limited by the small sample size with decreasing response rate over time. The patient endpoint manifested by survey response or surgery at 1-year follow-up was noted in 68% of patients but did not always include follow-up information from the referring provider. This improved to 82% if clinical follow-up at 1 year was included, which makes the outcome of progression to surgery more certain. Nevertheless, the response rate opens the study to nonresponse bias if nonresponders had worse or better outcomes compared with survey responders. This study demanded multiple extensive survey responses from an older rural patient population, which proved too demanding for some patients. Furthermore, the evaluations after the procedure consisted solely of
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mailed questionnaires without clinical examination of patients by the neuroradiologists. In conclusion, percutaneous treatment of LFSCs in this series had an 84% technical success rate with rapid improvement in pain, function, and analgesic medication use at multiple time points from 1 week through 1 year after the procedure. Progression to lumbar surgery occurred in 25% of patients within 1 year. Patient follow-up limits assessment of 1-year outcomes. The early treatment response and ability to avoid surgery in most patients is valuable information for clinicians and patients when considering treatment options for symptomatic LFSCs.
ACKNOWLEDGMENTS The authors acknowledge Todd A. MacKenzie, PhD, of the Dartmouth Clinical and Translational Science Institute (National Institutes of Health award number UL1TR001086) for his thoughtful review of the statistical methodology presented in this manuscript.
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17. Campbell RJ, Mobbs RJ, Rao PJ, Phan K. Interventions for lumbar synovial facet joint cysts: a comparison of percutaneous, surgical decompression and fusion approaches. World Neurosurg 2017; 98:492–502. 18. Childs JD, Piva SR, Fritz JM. Responsiveness of the numeric pain rating scale in patients with low back pain. Spine (Phila Pa 1976) 2005; 30:1331–1334. 19. Fairbank JC, Pynsent PB. The Oswestry Disability Index. Spine (Phila Pa 1976) 2000; 25:2940–2952; discussion 2952. 20. Ware J Jr, Kosinski M, Keller SD. A 12-item short-form health survey: construction of scales and preliminary tests of reliability and validity. Med Care 1996; 34:220–233.
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21. Califf RM, Woodcock J, Ostroff S. A proactive response to prescription opioid abuse. N Engl J Med 2016; 374:1480–1485. 22. Compton WM, Jones CM, Baldwin GT. Relationship between nonmedical prescription-opioid use and heroin use. N Engl J Med 2016; 374:154–163. 23. Volkow ND, McLellan AT. Opioid abuse in chronic pain—misconceptions and mitigation strategies. N Engl J Med 2016; 374:1253–1263. 24. Adogwa O, Carr RK, Kudyba K, et al. Revision lumbar surgery in elderly patients with symptomatic pseudarthrosis, adjacent-segment disease, or same-level recurrent stenosis. Part 1. Two-year outcomes and clinical efficacy: clinical article. J Neurosurg Spine 2013; 18:139–146.
Symptomatic Lumbar Facet Synovial Cysts: Clinical Outcomes Following Percutaneous CT–Guided Cyst Rupture with Intraarticular Steroid Injection Steffen J. Haider, MD, MPH, Nu R. Na, BS, Clifford J. Eskey, MD, PhD, Jessica G. Fried, MD, Natalie Y. Ring, BS, Mike H. Bao, BS, and David A. Pastel, MD ABSTRACT Purpose: To evaluate clinical outcomes following percutaneous rupture of symptomatic lumbar facet synovial cysts (LFSCs) with intraarticular steroid injection. Materials and Methods: In this retrospective review, 44 consecutive patients with symptomatic LFSCs received primary treatment with CT–guided synovial cyst rupture with intraarticular steroid injection. Outcomes questionnaires were obtained before and 1, 4, 26, and 52 weeks after LFSC rupture. Assessment included pain medication use and numeric rating scale (NRS), Oswestry Disability Index (ODI), and 12-item short form health survey (SF-12) physical and mental composite scores (PCS and MCS). Clinical endpoint was 52-week survey response or surgery. Results: LFSC rupture was technically successful in 84% (37/44) of cases. Clinical endpoint was reached in 68% (30/44) of patients with 82% overall 1-year follow-up. Lumbar spine surgery was performed in 25% (11/44) of patients within 1 year after procedure. Mean NRS, ODI, and SF-12 PCS demonstrated significant improvement at all follow-up time points (P < .001). At 52-week follow-up, NRS decreased from 8.1 to 3.7 (P < .001), ODI improved from 35 to 24 (P ¼ .006), and SF-12 PCS improved from 31 to 42 (P < .001). Daily pain medication decreased from 71% (31/44) of patients before procedure to 29% (9/26) at 52-week follow-up (P ¼ .012). History of prior lumbar intervention was associated with poorer LFSC rupture success (P ¼ .025) and ODI (P ¼ .047). Conclusions: NRS, ODI, and SF-12 PCS indices improved and pain medication use decreased significantly at all time points over 1-year follow-up after percutaneous rupture of symptomatic LFSCs with intraarticular steroid injection.
ABBREVIATIONS LESI ¼ lumbar epidural spinal injection, LFSC ¼ lumbar facet synovial cyst, MCS ¼ mental composite score, NRS ¼ numeric rating scale, ODI ¼ Oswestry Disability Index, PCS ¼ physical composite score, SF-12 ¼ 12-item short form health survey
From the Department of Radiology (S.J.H.), Columbia University Medical Center, New York City, New York; Department of Radiology (N.R.N., C.J.E., N.Y.R, M.H.B., D.A.P.), Dartmouth-Hitchcock Medical Center, 1 Medical Center Drive, Lebanon, NH 03756; and Department of Radiology (J.G.F.), Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania. Received December 23, 2016; final revision received April 20, 2017; accepted April 22, 2017. Address correspondence to D.A.P.; E-mail: david.a.pastel@ hitchcock.org C.J.E. is a stockholder for Relievant Medsystems (Redwood City, California) and is a paid consultant for Intrinsic Therapeutics (Woburn, Massachusetts). None of the other authors have identified a conflict of interest. © SIR, 2017 J Vasc Interv Radiol 2017; ▪:1–7 http://dx.doi.org/10.1016/j.jvir.2017.04.021
Synovial cysts arising from the lumbar spine facet joints are most commonly seen in the setting of degenerative facet joint spondylosis (1–4). Lumbar facet synovial cysts (LFSCs) that project into the spinal canal may result in radiculopathy (87%), neurogenic claudication (44%), sensory loss (43%), and motor weakness (27%) (5). Percutaneous LFSC rupture (5–10), facet steroid injection (11,12), and surgical lumbar decompression (13–15) have been described as effective treatment modalities. Recent meta-analyses favor lumbar decompression over percutaneous interventions, citing only a lower cyst recurrence rate with surgery (16,17). The published literature on LFSC rupture is limited by narrow outcomes metrics or nonstandardized retrospective single-time-point follow-up (5–7,10). Demonstration of early pain relief and improved function would likely favor percutaneous
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approaches given the low morbidity associated with percutaneous LFSC rupture (16). The purpose of the present study was to provide a comprehensive assessment of clinical outcomes at multiple standardized time points after computed tomography (CT)–guided LFSC rupture to inform clinician and patient expectations. To this end, 4 different validated outcome scoring systems, progression to surgery, and use of pain medication over 1 year following CT-guided LFSC rupture are reported.
MATERIALS AND METHODS The study was approved by the institutional review board, which waived consent for the study. A retrospective review of the institutional synovial cyst database was performed. The institutional database includes all 44 consecutive patients who underwent a CT-guided percutaneous LFSC rupture procedure from October 1, 2013, to September 30, 2015. The decision to perform LFSC rupture was based on the presence of a synovial cyst on lumbar spine magnetic resonance (MR) imaging performed ideally within 2 months of the procedure and lower extremity radiculopathy corresponding to the location of the LFSC. Demographic and comorbid characteristics are presented in Table 1. Mean age of patients was 65 years (range, 43–94 y) with 30% (13 of 44) having a body mass index > 30. Of patients, 32% (14 of 44) had at least 1 prior spinal intervention, 78% of which were lumbar epidural spinal injection (LESI), prior lumbar surgery, or LFSC rupture (Table 1). In this study, 61% of LFSCs treated were located at the L4-L5 spinal level with a mean cyst diameter of 9 mm (Table 1). There were 9 faintly calcified synovial cysts; the rest of the LFSCs had no calcifications. There were no densely calcified cysts. Table 1. Baseline Characteristics of Patients Undergoing LFSC Rupture (N ¼ 44) Characteristic Male sex Age, y, mean ± SD (range) Mean BMI, mean ± SD
Value 19 (43%) 65 ± 12 (43–94) 28 ± 7
Obese (BMI > 30)
13 (30%)
Prior lumbar spine intervention
14 (32%)
Lumbar epidural spinal injection
11 (25%)
Lumbar surgery
3 (7%)
LFSC rupture
2 (5%)
Cyst level L2-L3 L3-L4
1 (2%) 8 (18%)
L4-L5
27 (61%)
L5-S1
7 (16%)
Multilevel Cyst diameter, mm, mean ± SD (range)
1 (2%) 9.2 ± 3.4 (2–18)
Note–Values are presented as number (%) unless otherwise noted. BMI ¼ body mass index; LFSC ¼ lumbar facet synovial cyst.
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All patients underwent MR imaging a mean 38 days (SD 27 d; range, 2–266 d) before the LFSC rupture. The MR examinations included T2-weighted axial and sagittal images with repetition time of 3,000–6,000 ms, echo time of 80–110 ms, section thickness of 4 mm with 5-mm spacing, and a matrix of 256 256 or 512 512 (Fig 1a, b). Follow-up imaging was performed only for symptomatic patients at the discretion of the primary providers. The LFSC rupture procedures were performed using a single treatment protocol by 6 different neuroradiologists with 3–31 years of experience. In this series, the 6 neuroradiologists each performed 1–13 LFSC rupture procedures. Procedural conscious sedation with fentanyl and midazolam was administered. For local anesthesia, 1% lidocaine buffered with 8.4% sodium bicarbonate was used. A 20-gauge spinal needle was advanced under intermittent CT fluoroscopy into the facet joint, and 1–2 mL of iohexol (Omnipaque 350; Nycomed Amersham, Princeton, New Jersey) diluted in normal saline at a ratio of 1:10 was injected to confirm continuity of the facet joint with the synovial cyst (Fig 1c). In patients with osteophytes covering the facet joint (14 patients), a 14-gauge coaxial system (Bonopty; AprioMed, Uppsala, Sweden) was used to access the facet joint. Once the cyst was opacified with contrast material, a 3-mL syringe made of polycarbonate to withstand highpressure hand injection was used to rapidly inject saline with dilute contrast agent. Technical success of cyst rupture was defined by demonstration of contrast material within the epidural space but outside the confines of the cyst wall on CT and by loss of resistance (Fig 1d). After cyst rupture, 80 mg of methylprednisolone (DepoMedrol; Pfizer Inc, New York, New York) was injected. Patients were observed for 1 hour after the procedure. The referring spine specialist then followed patients clinically as outpatients. Four outcome-scoring indices were used for each patient. The primary outcome measures were the numeric rating scale (NRS) (on a scale of 0–10, with 0 indicating no pain and 10 indicating “pain as bad as you can imagine”) and the Oswestry Disability Index (ODI) (scores 0–20 minimal, 21–40 moderate, 41–60 severe, 61–80 crippling, 81–100 bedbound) (18,19). The 12-item short form health survey (SF-12) physical composite score (PCS) and mental composite score (MCS) were the secondary outcomes (scale 0–100 with higher scores representing higher physical and mental well-being) (20). Outcomes scores and pain medication frequency and dose were recorded immediately before the LFSC rupture procedure and 1 week, 4 weeks, 26 weeks, and 52 weeks after the procedure. The initial questionnaire was completed in the holding room before the procedure. Subsequent surveys were completed by mail or telephone. Patient demographics were collected with chart review of the electronic medical record (EPIC Systems Corp, Verona, Wisconsin). Prior lumbar intervention was defined as a history of lumbar surgery, LESI, or prior LFSC rupture. Progression to subsequent lumbar spinal surgery or LESI within 1 year of LFSC rupture was also recorded. If a patient
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Figure 1. (a, b) T2-weighted axial and sagittal MR images demonstrate a 1.2-cm right-sided LFSC at the L4-L5 vertebral level, which impinges the right neural foramen and compresses the thecal sac. (c) Axial CT image obtained during the procedure demonstrates placement of needle into the facet joint. Opacification of the cyst confirms communication with the facet joint. (d) Axial CT image obtained during the procedure demonstrates contrast material outlining the epidural space indicating successful rupture of the cyst.
underwent lumbar decompression surgery during follow-up, the outcome scores were included up to, but not after, the time of surgery, scores after the surgery reflect the lumbar surgery rather than LFSC rupture. Clinical follow-up visits for lumbar evaluation were performed at the treatment hospital in 71% of patients (31 of 44) at a median of 13 months (range, 0.5–40 months). The rate of follow-up for enrolled patients was 82% at both 1 and 4 weeks (36 of 44) and 73% at 26 weeks (32 of 44). The study endpoint of progression to lumbar surgery or 52-week survey follow-up was attained in 68% (30 of 44) of patients. When combining survey response and surgery with clinical follow-up, follow-up within 1 year of LFSC rupture was 82% (36 of 44).
Regression of the repeated measurement of co-primary and secondary outcome scores between baseline through 1-year follow-up was modeled with general linear mixed models (21). The model used a random slope with random intercept and unstructured covariance. Analysis of covariance was used to compare outcomes between subgroups at 6-month follow-up. Significance was defined as P < .05. Statistical analysis was performed using IBM SPSS Statistics for Windows Version 23 (IBM Corp, Armonk, New York). Post hoc power analysis was performed at a ¼ .05 and accounted for the 32% questionnaire nonresponse rate at 1-year follow-up. There was 80% power to detect a 30% change in the co-primary outcome scores at 1-year followup in the overall cohort. In subgroup analysis, there was 50% power to detect 35% change in co-primary outcome scores at 6-month follow-up.
Statistics The difference in qualitative variables was analyzed by Fisher exact test. Differences in mean measurements between groups were assessed with Student t test. Change in pain medication use was analyzed by McNemar test.
RESULTS LFSC rupture was technically successful in 84% (37 of 44) of cases (Table 2). Figure 1a–d demonstrates
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Table 2. Cyst Rupture Outcomes Outcome Measure
Frequency or Mean
Technical success in LFSC rupture
84% (37/44)
Prior lumbar intervention* Technical failure in LFSC rupture Prior lumbar intervention*
24% (9/37)
rupture, 10% (4 of 44) underwent repeat rupture for symptomatic cyst recurrence at 3, 3, 4, and 5 months after the initial procedure with no further recurrence or progression to lumbar surgery during follow-up. LESI was performed in 25% (11 of 44) of patients within 1 year after LFSC rupture.
16% (7/44) 71% (5/7)
Repeat cyst rupture LESI within 1 y
10% (4/44) 25% (11/44)
Lumbar surgery within 1 y after rupture
25% (11/44)
Time to surgery if required, d, mean ± SD (range)
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128 ± 76 (52–300)
LESI ¼ lumbar epidural spinal injection; LFSC ¼ lumbar facet synovial cyst. *Technical failure associated with prior lumbar intervention (P ¼ .025). Prior lumbar intervention is history of prior LESI, LFSC rupture, or lumbar surgery.
technically successful LFSC rupture. Comparing unsuccessful and successful LFSC rupture, 71% of patients (5 of 7) with unsuccessful LFSC rupture had previous spinal intervention compared with 24% of patients with successful LFSC rupture (9 of 37) (P ¼ .025) (Table 2). Successful cyst rupture was achieved in 89% (8 of 9) of the faintly calcified LFSCs. There were no procedural complications related to percutaneous LFSC rupture in the present series. Of patients with initially successful LFSC
Primary and Secondary Outcome Scores The primary outcomes of NRS and ODI and the secondary outcomes of SF-12 PCS and MCS scores are reported in Figure 2a–d. Baseline pain and disability indices were severe in this patient cohort. Mean NRS, ODI, and SF-12 PCS scores improved significantly at 1-week follow-up, and this improvement was durable through 1 year (P < .001) (Fig 2a–c). Mean NRS decreased from 8.1 ± 2.6 at baseline to 3.0 ± 2.7 at 1-week follow-up (P < .001) and to 3.7 ± 2.3 at 52-week follow-up (P < .001) (Fig 2a). Mean ODI similarly decreased from 35 ± 17 at baseline to 13 ± 16 at 1-week follow-up (P < .001) and to 24 ± 17 at 52-week followup (P < .001) (Fig 2b). SF-12 PCS scores improved from 31 ± 10 at baseline to 45 ± 11 at 1-week follow-up (P < .001) and remained improved above baseline through 52 weeks of follow-up (P < .001) (Fig 2c). SF-12 MCS score improved from 51 ± 9 at baseline to 57 ± 11 at 1 week (P < .001) but worsened to the baseline by 1 month through the study endpoint at 1 year (P ¼ .9) (Fig 2d).
Figure 2. (a) NRS with LFSC rupture and steroid injection. (b) ODI with LFSC rupture and steroid injection. (c) SF-12 PCS with LFSC rupture and steroid injection. (d) SF-12 MCS with LFSC rupture and steroid injection.
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Table 3. Subgroup Analysis of Prior Lumbar Procedure with Primary Outcomes Outcome Subgroup
Time
Number of Patients
Mean (95% CI)
Prior intervention
Baseline
14
26 weeks
8
6.0 (4.2–7.9)
None
Baseline
30
7.9 (7.2–8.6)
26 weeks
15
3.3 (2–4.7)
Baseline 26 weeks
12 8
32 (23–41) 32 (21–43)
P
NRS 7.9 (6.8–8.9) .052
ODI Prior intervention None
Baseline
26
38 (32–44)
26 weeks
14
18 (10–26)
.047
P value refers to significance of the interaction of dichotomous subgroup and dichotomous time variables. CI ¼ confidence interval; NRS ¼ numeric rating scale; ODI ¼ Oswestry Disability Index.
Table 3 presents the effect of a prior lumbar intervention (surgery, LESI, or previous LFSC rupture) on NRS and ODI at baseline and 26-week follow-up. NRS improved from 7.9 (6.8–8.9) to 3.3 (2–4.7) without prior intervention compared with 7.9 (6.8–8.9) to 6.0 (4.2–7.9) with prior interventions (P ¼ .052). Mean ODI improved from 38 (95% confidence interval 32–44) to 18 (10–26) without prior intervention and was unchanged at 32 (21–43) with prior interventions (P ¼ .047).
Subsequent Lumbar Surgery Of patients, 25% (11 of 44) underwent decompressive lumbar surgery within 1 year of LFSC rupture (range, 52–300 d). Residual or recurrent synovial cyst was demonstrated in 4 of 5 patients who underwent repeat lumbar MR imaging. Technically successful cyst rupture was associated with a 24% (9 of 37) rate of surgery, whereas an unsuccessful cyst rupture was associated with a 29% (2 of 7) surgical rate (P ¼ 1). The subsequent surgical group had baseline NRS and ODI scores similar to the overall cohort (P > .6). At 4 weeks after attempted percutaneous cyst rupture, patients who later underwent subsequent lumbar surgery experienced a decrease in mean NRS by 2.8 ± 3.5 (P ¼ .04) and decrease in ODI by 12 ± 15 (P ¼ .048), which is similar to the pattern demonstrated in the overall cohort (Fig 1b, 2a).
Pain Medications Daily pain medication use was self-reported by 71% of patients (31 of 44) at the baseline interview. This included 16% (7 of 31) opiate and 55% (24 of 31) nonopiate regimens. At 1-week follow-up, self-reported daily pain medication use decreased to 36% of patients (13 of 36) (P ¼ .001). This response was durable through 52-week follow-up, at which time 35% of patients (9 of 26)
reported daily pain medication use (P ¼ .012 compared with before the procedure).
DISCUSSION This study reports the clinical outcomes of 44 consecutive patients who underwent CT-guided LFSC rupture with intraarticular steroid injection. Patients experienced marked improvements in pain and function at 1-week follow-up, which was durable through 1-year follow-up as measured by NRS, ODI, and SF-12 PCS. There was a concordant significant decrease in daily pain medication use after LFSC rupture. LFSC rupture was successful in 84% of cases as confirmed by leakage of contrast material into the epidural space, which is consistent with previous reports in the literature (5–8,10). Technical failure of LFSC rupture was associated with previous spinal procedures, most commonly LESI. Previous LESI may create scarring within the epidural space, making it more challenging to rupture a cyst that is adherent to the dura. Pain and function outcomes of the present study are in agreement with outcomes previously reported by Martha et al (6) with respect to NRS and ODI and Allen et al (7) with respect to NRS and several alternative outcome scores. However, the studies of Allen et al (7) and Martha et al (6) are notably limited by recall bias introduced with retrospective collection of the baseline outcome scores at the single follow-up interview. The single follow-up interview in these studies also creates a limited cross-sectional assessment of outcomes scores that may not reflect the pain and function at other time points. These limited studies allow the meta-analysis by Campbell et al (17) to favor surgical decompression citing only a lower cyst recurrence rate compared with LFSC percutaneous intervention without accounting for pain or morbidity at multiple time points during follow-up. The present study counters such an argument by demonstrating rapid and durable improvement in lumbar pain and function over multiple standardized follow-up assessments through 1-year follow-up. The rapid improvement in pain and function in the present study has not been demonstrated for surgical treatment of symptomatic LFSCs. There is an ongoing epidemic of narcotic dependence and abuse in the United States, and chronic low back pain has been implicated as a major contributor (21–23). Adoption of treatment modalities that reduce long-term opioid use is a necessary strategy (23). In this study, 71% of patients in this study reported pain relief sufficient to discontinue analgesics at 1 year after LFSC rupture. In the retrospective study by Martha et al (6), 55% of patients still reported pain medication use at a mean of 3.2 years after percutaneous rupture. No pain medication use before the procedure was reported in that study. The SF-12 MCS score improved 1 week after LFSC rupture and then returned to baseline despite improvement in pain and function. A similar result of unchanged MCS
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despite improved pain and function indices was observed in a study of revision lumbar surgery (24). This may speak to the broader physical, psychological, and social factors that influence mental well-being beyond the pain generator of a synovial cyst. The 25% rate of surgery within 1 year after LFSC rupture compares favorably with reported rates of 17%–54% in the literature (5–8,10,16,17). Similar to results reported by Martha et al (6), a successful cyst rupture did not prevent surgery in the present study. Given the known propensity of synovial cysts to recur, it is not surprising that a certain portion of the patients would ultimately progress to surgery (17). The reason for the relatively low use of surgery in patients without successful percutaneous treatment is less clear. It is possible that patients in this elderly population are not good surgical candidates. Other possible explanations include lack of consistent guidelines used in determining the need for surgery, differences in the clinical and pathologic characteristics of the cysts that could not be ruptured, and the small sample size for the group with unruptured cysts. All 4 patients with repeat LFSC rupture were managed successfully without surgery through the conclusion of the study. Amoretti et al (11) reported on steroid injection of LFSCs without rupture in a prospective study of 120 patients. Mean ODI in that cohort decreased from 72 ± 20 to 20 ± 6 at 6-month follow-up (11). This is a greater, but concordant, decrease in dysfunction compared with the present study with similar post-procedure ODI after the procedure. The study by Amoretti et al is comparable to the present study given that outcomes were collected prospectively and longitudinally over multiple time points. This suggests that steroid injection alone may be sufficient to improve symptoms of LFSC without the need for cyst rupture. Further randomized trials comparing LFSC rupture with steroid injection with steroid injection alone may clarify this question. This study has several limitations. Because this was a single-arm study without a control cohort that did not undergo LFSC rupture, the placebo effect cannot be excluded. However, pain and dysfunction were severe in this cohort at baseline with marked improvement by 1-week follow-up. This suggests that the effect was treatment based rather than by chance. Interpretation of the present results is limited by the small sample size with decreasing response rate over time. The patient endpoint manifested by survey response or surgery at 1-year follow-up was noted in 68% of patients but did not always include follow-up information from the referring provider. This improved to 82% if clinical follow-up at 1 year was included, which makes the outcome of progression to surgery more certain. Nevertheless, the response rate opens the study to nonresponse bias if nonresponders had worse or better outcomes compared with survey responders. This study demanded multiple extensive survey responses from an older rural patient population, which proved too demanding for some patients. Furthermore, the evaluations after the procedure consisted solely of
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mailed questionnaires without clinical examination of patients by the neuroradiologists. In conclusion, percutaneous treatment of LFSCs in this series had an 84% technical success rate with rapid improvement in pain, function, and analgesic medication use at multiple time points from 1 week through 1 year after the procedure. Progression to lumbar surgery occurred in 25% of patients within 1 year. Patient follow-up limits assessment of 1-year outcomes. The early treatment response and ability to avoid surgery in most patients is valuable information for clinicians and patients when considering treatment options for symptomatic LFSCs.
ACKNOWLEDGMENTS The authors acknowledge Todd A. MacKenzie, PhD, of the Dartmouth Clinical and Translational Science Institute (National Institutes of Health award number UL1TR001086) for his thoughtful review of the statistical methodology presented in this manuscript.
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