Wednesday, September 26, 2018 1:00 PM – 2:00 PM Interventional Pain Management: 35. Rate of conversion to surgery and risk factors analysis following fluoroscopically guided facet cyst rupture

BACKGROUND CONTEXT Facet cysts are a common finding on magnetic resonance imaging (MRI) when evaluating a patient with back pain and radicular symptoms. Several different clinical and radiographic findings have been associated with this diagnosis. It is thought that these differences may relate to the difference in efficacy of fluoroscopically guided cyst rupture. PURPOSE The purpose of this study was to evaluate the rate of conversion to surgery following cyst rupture, and to assess for clinical, radiographic and procedural variables that were associated with that conversion. If specific clinical and radiographic risk factors can be elucidated which are associated with conversion to surgery, it may be possible to more effectively and efficiently counsel and treat patients. STUDY DESIGN/SETTING A retrospective review at an academic medical center. PATIENT SAMPLE All patients who underwent fluoroscopically guided facet cyst rupture from 2010 to 2016. OUTCOME MEASURES The primary outcome was conversion to surgery. For those who converted to surgery, the rate of decompression and fusion compared to fusion alone was recorded. Secondary outcomes included clinical, radiographic and procedural variable analysis to determine if there were risk factors associated with conversion to surgery. The clinical variables included sex, age, number of comorbidities, location (unilateral or bilateral), type of symptoms (pain, motor deficit, sensory deficit), and whether the pain was predominantly leg, back or combined. The radiographic variables included cyst size, shape, cyst signal, rim signal, level involved, laterality, presence of spondylolisthesis, whether there was canal or lateral recess stenosis, presence of facet joint fluid, bilateral fluid, facet bone edema and bone erosion. The procedural variables included cyst opacification, successful rupture and difference in pre and post procedure pain. METHODS Basic statistics, as well as single and multivariate analysis was performed. RESULTS Forty-nine patients met the inclusion criteria. Four were excluded because they had either no clinical notes or no MRI available for review. Twenty-nine percent of patients eventually underwent a surgical procedure to address their facet cyst. The average interval to surgery was 95 days after cyst rupture. Of those who had a surgical intervention, 38% had a decompression and fusion. Of the clinical, radiographic and procedural variables evaluated, only the number of comorbidities and the MRI signal of the facet rim were associated with conversion to surgery, p=.03 and p=.05, respectively. CONCLUSIONS Facet cysts have been recognized as a cause of spinal stenosis, but their optimal treatment is unknown. Typically, all nonoperative interventions are attempted prior to conversion to surgery, which often includes fluoroscopically guided facet cyst rupture. However, there is a significant percentage of patients in whom this treatment fails to provide durable relief, and eventually, patients undergo a surgical intervention. Despite the two associated risk factors, at this time, we would recommend continuing to attempt fluoroscopic guided facet cyst rupture with postprocedural clinical monitoring for all patients. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.