Air in the Spine: A Rare Gas-Filled Cyst.

Gas-containing intraspinal synovial cysts are rare, and few surgical reports are available. This case highlights the importance of considering synovial cysts on the differential for presentations of radiculopathy and demonstrates successful surgical management in a rare case. A 63-year-old man with progressive low back pain and neurogenic claudication was found to have a gas-filled synovial cyst at L4-L5 causing severe central canal stenosis. Imaging revealed an 8 × 8 mm synovial cyst compressing the thecal sac and right L4 nerve root. He underwent L4 decompressive laminectomy with cyst resection. Postoperatively, the patient reported resolution of leg pain and improvement in mobility.