Introduction: Lumbar facet joint synovial cysts are a recognized cause of back pain, radiculopathy, and neurogenic claudication. They are most frequent at the L4-5 level and are associated with osteoarthritis of the adjacent facet joint. Facet joint synovial cysts are usually detected by using computed tomography (CT) or magnetic resonance (MR) imaging. Surgical excision is effective in symptomatic facet joint synovial cysts. However, surgery can be avoided by distension and rupture of the cyst under image guidance, using a mixture of local anesthetic and corticosteroid.

Case report: A 61-year-old man was referred to our pain clinic due to low back pain with both lower leg radiating pain from 2 months ago. There was no tenderness on the lumbar facet joint. But, the pain worsened when he leaned back. Both toe walking & heel walking, the right side showed difficulty. L4 central canal spinal stenosis and right L4/5 facet cyst was observed in L-spine MRI image. We performed bilateral L4/5 facet joint injection under fluoroscopy. We have confirmed that contrast spreads out of the articular surface to the epidural space. 2 weeks later, there was significantly improvement in the symptom. After several repeated injections, almost resolution of the cyst was documented at follow-up imaging.

Conclusion: We have confirmed through MRI that we can relieve the symptomatic facet cyst by facet injection for lumbar facet cyst rupture. This will be an option to replace surgical treatment.