Sciatica in degenerative spondylolisthesis of the lumbar spine.

Intraspinal synovial cysts are an uncommon but well recognised cause of backache and sciatica, and should be considered in patients, in particular with degenerative spondylolisthesis, who are symptomatic. MRI is the initial investigation of choice. If there is any doubt as to the diagnosis, CT with or without facet joint arthrography is helpful.