NeuroSpine Surgery Research Group (NSURG) Classification System for Grading Lumbar Synovial Cysts.

To classify facet joint cysts (FJC) which will assist in identification of patient groups to best fit with a particular intervention. Sagittal T2 -weighted magnetic resonance images (MRI) of these patients are used to measure cyst size, while axial T2 -weighted MRI are used to determine the percentage of the vertebral canal occupied by the cyst. The degree of spondylolisthesis is also measured through standing X-rays or sagittal MRI. The proposed grading system is as follows. Grade I includes cysts that occupy less than 25% of the canal diameter that usually present with unilateral radiculopathy. Grade II includes cysts that occupy less than 50% of the canal diameter and may present with radiculopathy, with or without claudicant symptoms. Grade III cysts may present with radiculopathy and claudication with bilateral leg symptoms, along with facetogenic pain symptoms. Grades IV and V include potential instability as defined by greater than 15% spondylolisthesis in addition to either less than or greater than 50% canal stenosis. With higher grade cysts, presentation may include: facetogenic back pain, radiculopathy and claudicant pain in variable degrees of severity. The optimal classification system grades FJC from I to V on the basis of canal compression and degree of spondylolisthesis. Prospective studies are required to confirm the validity of this grading scale for long-term use.