Lumbar synovial cysts: a review of diagnosis, surgical management, and outcome assessment.

Synovial cysts of the lumbar spine contribute significantly to narrowing of the spinal canal and lateral thecal sac and nerve root compression. Cysts form as a result of arthrotic disruption of the facet joint, leading to degenerative spondylolisthesis in up to 40% of patients. Clinical findings and neurodiagnostic confirmation prompt surgical intervention consisting of varying decompressions with or without primary fusion. Most patients present in their mid-60s, with a male-to-female ratio varying from 2:1 to 1:1. Preoperative symptoms include low back pain, radiculopathy, and neurogenic claudication. Motor and sensory signs usually reflect the anatomic location of the synovial cyst and the level of resultant maximal lumbar stenosis. In descending order of frequency, they are typically found at the L4-L5, L5-S1, L3-L4, and L2-L3 levels. Lumbar synovial cyst surgery includes unilateral or bilateral laminotomies, hemilaminectomies, or laminectomies alone or in combination with in situ or instrumented fusion. Those patients undergoing decompression alone may postoperatively develop progression or the new appearance of olisthy, while those primarily fused rarely show further increase or a new onset of slip. Outcome measures spanning 1- to 2-year postoperative intervals frequently included surgeon-based rather than the current patient-based analysis, the lat-ter including the Medical Outcomes Trust Short Form-36.