David Pastel, MD, Steffen Haider, MD, Nu NA, BSc, Mohsin Ghadiali, md Symptomatic lumbar facet synovial cysts: Clinical outcomes following percutaneous CT-guided cyst rupture with intra-articular steroid injection Poster # 195 David Pastel, MD, Steffen Haider, MD, Nu NA, BSc, Mohsin Ghadiali, md

Disclosures None

Purpose Prospectively evaluate clinical outcomes following percutaneous rupture of symptomatic lumbar face synovial cysts (LFSC) with intra- articular steroid injection.

Background Synovial cysts arising from the lumbar spine facet joints are most commonly seen in the setting of degenerative spondylosis of the facet joints (1-6). The incidence of lumbar facet synovial cysts (LFSC) detected by imaging ranges from 0.8% to 2.0% (7). LFSCs most frequently involve the L4-L5 level, the site of maximum spinal instability (Assam, Gorey, Onofrio, Sabo).

Background Clinical diagnosis is best achieved by MRI because of its superior contrast resolution (Davis, Imai, Hemminghytt, Jackson, Liu, Yuh, Marichal, Tillich, Mahallati). Typically LFSC are T2 hyperintense, but the signal intensity is variable and can affect outcomes. Cambron et al reported improved outcomes with T2 hyperintense cysts relative to intermediate and low signal intensity cysts. (Cambron et al AJNR 2013).

Background LFSC that project into the spinal canal can cause radiculopathy (87%), neurogenic claudication (44%), sensory loss (43%) and motor weakness (27%) (8). Surgical resection, with or without concomitant fusion, and percutaneous rupture have been described as treatment modalities for this disease. Percutaneous rupture of LFSCs are most commonly performed indirectly via the facet joint using fluoroscopic or CT-guidance.

Methods 44 patients with symptomatic lumbar facet synovial cysts (LFSCs) receiving attempted CT-guided synovial cyst rupture with intra- articular steroid injection as primary treatment were prospectively reviewed. Inclusion criteria consisted of lower extremity radiculopathy corresponding to the location of a LFSC on a lumbar spine MRI performed at least 2 months prior to percutaneous rupture.

Methods Numeric pain scores, pain medication use, and Oswestry Disability Index (ODI) and SF-12 questionnaires were collected pre-procedure and after 1 week, 1 month, 6 months, and 1 year following the procedure. Previous surgical history, technical success of cyst rupture and need for subsequent surgery or lumbar epidural steroid injection were recorded.

Baseline Patient Characteristics Total Patients undergoing cyst rupture 44 Male 43% (n=19) Mean Age 65 years (SD 12, range 43 to 94) BMI Obese (BMI > 30) 28 (SD 7) 30% (n=13) Any Prior lumbar procedure Lumbar epidural spinal injection Lumbar Surgery LFSC rupture 32% (n= 14) 25% (n=11) 7% (n=3) 5% (n=2) Self-reported Daily Pain medication (Pre-procedure) Opiate Non-opiate pain medication No daily pain medication 70% (n=31)   16% (n=7) 54% (n=24) 31% (n=13) Cyst Level L2/3 L3/4 L4/5 L5/S1 Multi-level 2%, (n=1) 18%, (n=8) 61%, (n=27) 16%, (n=7) Cyst diameter 9.2mm (SD 3.4, N=24)

Table 2 Cyst rupture Outcomes Technically Successful Cyst Ruptures 84% ( 37 / 44) Repeat cyst rupture 7% (3 / 44) Lumbar epidural spinal injection within 1 year 25% (11 / 44) Lumbar Surgery within 1 year after rupture Mean time to surgery if required 128 days (SD 76)

Procedure Methodology Moderate sedation was administered and 1% lidocaine buffered with sodium bicarbonate was used for local anesthesia. A 20-ga spinal needle was then advanced under intermittent CT fluoroscopy into the facet joint and 1–2mL of Omnipaque 350) diluted in normal saline at a ratio of 1:10 was injected to confirm continuity of the facet joint with the synovial cyst. In patients with osteophytes covering the facet joint, a 14-ga coaxial system was used to access the facet joint.

Procedure Methodology Once the cyst was opacified with contrast, a high-pressure syringe was used to rupture the cyst into the epidural space by use of dilute contrast. A technically successful cyst rupture was determined by the loss of resistance method and by extravasation of contrast outside the confines of the cyst wall on CT. After cyst rupture, 80 mg of methylprednisolone was injected into the facet joint. Patients were observed for 1 hour after the procedure.

Results Percutaneous LFSC rupture was technically successful in 84% of cases, with failure associated with previous lumbar procedures and surgery. 25% required surgery within 1 year which did not correlate with technical success of cyst rupture (p=1.0). Three LFSCs that recurred after an initial successful rupture were successfully managed with repeat rupture.

Table 3: Outcomes over time series by General Linear Mixed Model Worst Numeric Pain ODI SF 12 PCS SF 12 MCS Time Mean (95% CI) P p Pre 8.5 (7.7 , 9.4) .000 34 (28 , 40) .011 30 (27 , 34) 52 (47 , 56) .643 One week 3.6 (2.6 , 4.5) .259 12 (6 , 18) .045 45 (41 , 49) .111 58 (56 , 60) .010 One month 4.7 (3.6 , 5.9) .738 18 (12 , 24) .443 40 (36 , 45) .800 51 (47 , 55) .455 Six month 4.5 (3.3 , 5.7) .962 21 (15 , 28) .974 38 (33 , 42) .188 53 (48 , 57) .908 One year 4.5 (3 , 6) ref 21 (12 , 31) 41 (36 , 46) 53 (49 , 57) **p-values correspond to differences in scores compared to the reference 1 score, i.e., significant differences in pain or function compared to the study end-point. Models include covariate effect modifiers listed in Table 4 Scores obtained after a patient progressed to surgery were excluded.

Results Numeric pain scores, ODI, and SF12 physical composite scores all demonstrated significant improvement all time points. At 1 year follow-up, numeric pain scores decreased from 8.5 to 4.5 (p<0.001), ODI improved from 34 to 21 (p=0.011) and SF12 PCS improved from 30 to 41 (p<0.001). SF12 mental composite score significantly improved at 1 week (52 to 58, p=0.010), but was not significant at any other time point.

Results A history of previous lumbar spine intervention was associated with a higher combined post-procedure numeric pain score (+2) and a higher combined post-procedure ODI score (+17) compared to those without prior lumbar procedures (p=.014 and <.001 respectively). There was a trend towards worse SF12 PCS scores (p=.085) in this subgroup, but no difference in MCS scores (p=..244).

Results Obesity was associated with a higher combined post-procedure pain score (+2.2) when accounting for baseline differences (p=0.01), but no difference in ODI and SF12 PCS MCS scores p= .722, .258, .373). Rupture success had no impact upon any outcome scores (p=.24 to .59) when accounting for baseline differences, although this was the smallest sub-group with only 7 patients.

Results LESIs were performed upon 25% of patients within the year after LFSC rupture and was not associated with any measured patient characteristics, including progression to lumbar surgery (p=0.406) or prior lumbar procedures (p=0.722). Patients undergoing LESI within one year after LFSC rupture had similar pre-procedure pain and function to those that did not (p=0.52 and 0.97), but reported worse combined post-procedure pain scores(+2.9, p=.001), ODI (+11, p=.014), and SF12 MCS (-7, p=.034) (Table 4). SF12 PCS scores were unchanged (Table 4).

Table 4: Modification of the Effect of LFSC Rupture by Co-Morbidities and Rupture Success Direction of difference indicated by +/-. Value indicates the difference in score between presence and absence of covariate accounting for baseline differences. Prior Lumbar Procedure Obesity (BMI>30) Rupture Success Subsequent LESI Subsequent Surgery Effect Modifiers ∆ Score (95% CI) p ∆ Score (95% CI) p Numeric Pain Score +2.0 (0.4 , 3.6) .014 +2.2 (0.5 , 3.9) .010 +0.6 (-1.6 , 2.7) .593 2.9 (1.3 , 4.5) .001 -1.5 (-3.2 , 0.2) .089 ODI +17 (8 , 26) .000 +2 (-8 , 11) .722 -8 (-20 , 5) .240 +11 (2 , 20) -5 (-15 , 4) .262 SF 12 PCS -6 (-13 , 1) .085 -4 (-10 , 3) .258 -2 (-12 , 8) .585 -5 (-12 , 2) .148 +6 (0 , 13) .050 SF 12 MCS .244 -3 (-9 , 4) .373 -3 (-11 , 5) .481 -7 (-13 , -1) .034 **General linear mixed model with interaction terms. p-values correspond to the significance of differences in score changes pre to combined post-procedure by covariates **Scores obtained after a patient progressed to surgery were excluded.

Results 72% of patients self-reported regular pain medication use at the time of procedure, including 16% opiate and 54% non-opiate regimens. 39% were able to wean entirely off pain medication by 1 week post- procedure (McNemar p=0.001). Excluding patients who progressed to back surgery, this response was durable through 1 year with 34% remaining weaned off pain medication (McNemar p=.039).

Conclusion Our results confirm along multiple outcome measures that percutaneous rupture of symptomatic LFSCs rupture is a durable and effective treatment. 44 patients with lumbar facet synovial cysts showed significantly improved functional health and well-being, decreased low back pain disability, and decreased use of pain medication.

Conclusion Obese patients and those with a history of previous lumbar spinal surgery or percutaneous spinal procedures scored lower on several post-procedure patient-reported outcome measures. Unsuccessful cyst rupture did not predict need for subsequent surgery.

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