Classification of Lumbar Facet Joint Cysts Using the NeuroSpine Surgery Research Group (NSURG) Grading Score and Correlation with Recurrence and Clinical Outcomes

To assess the validity of the proposed NeuroSpine Surgery Research Group Classification System through a retrospective analysis of patients treated surgically for lumbar facet joint cysts at a single institution. In a cohort of 166 patients, sagittal T2-weighted magnetic resonance images were used to measure degree of spondylolisthesis, whereas axial T2-weighted magnetic resonance images were used to determine the percentage of vertebral canal occupied by the cyst. Grading was performed by 2 observers. Statistical analysis was conducted to correlate the given grades of each cyst with the treatment performed and the long-term outcomes of cyst and pain recurrence. In total, 158 were treated by decompression, whereas 8 underwent decompression with fusion; 25% of patients presented with a grade 1 cyst, 45% with a grade 2, 13% with a grade 3, 13% with a grade 4, and 4% with a grade 5 cyst. Of patients treated by decompression alone, a greater rate of recurrence was seen in grades 4 and 5 (29.4% and 33.3%) when compared with grades 1–3 (8.8%, 8.5%, and 0%, respectively, P < 0.05). There were no cases of a cyst recurrence after a fusion. The proposed NeuroSpine Surgery Research Group Classification System for lumbar facet joint cysts is effective in identifying patients most likely to endure a recurrent cyst after decompressive surgery. Patients with grades 4 and 5 cysts should be considered for decompressive surgery with concomitant stabilization of the involved segments on initial presentation.