Lumbar Synovial Cysts: Microsurgical Treatment and Outcome in 40 Cases: Review and Critical Analysis of the Literature

Background: Intraspinal synovial cysts (SCs) are uncommon benign growths that occur adjacent to the spinal facet joints. Surgical resection is the treatment of choice for symptomatic patients, but, much debate continues regarding the indication of concomitant fusion to prevent delayed instability. In this study, we report a retrospective review of 40 patients treated for lumbar SCs with microsurgical technique, and analyse the related literature in order to better understand and manage this pathology. Methods: All patients were evaluated with CT-scan and MR imaging. Follow-up review was available in 38 (95%) patients with a mean period of 22.8 months. Postoperative outcomes, cyst recurrence, delayed instability or worsening of previous instability was noted. Results: Over 80% of patients presented degenerative spinal disease. Ten patients (25%) presented spondylolisthesis; 36 patients underwent resection of the cyst by flavectomy and partial facetectomy; 3 patients required subtotal facetectomy; 1 patient underwent concomitant arthrodesis. Thirty-three patients (86.7%) reported excellent/good results, while 5 patients (13.3%) scored in the range of fair/poor. Four patients developed subsequent instability and were submitted to arthrodesis and posterior fixation. Overall, 5 patients underwent fusion: 1 at the first surgery and 4 (10.3%) due to delayed symptomatic spondylolisthesis. One experienced residual mechanical pain. The remaining patients did not developed new instability or worsening of their listhesis. Conclusions: Most patients undergoing excision of lumbar SC will experience excellent or good results. Microsurgical approach is the treatment of choice. The indication of fusion as a first-line procedure remains under debate. The data of literature are contrasting and does not allow for predictive factors for delayed instability.