Arachnoidal Diverticula of Sacral Extradural Meningeal Cyst: A Novel Definition and Case Series.

Abstract

Sacral cysts are classically divided into Tarlov cysts and meningeal diverticula. However, the pathogenesis of sacral cysts remains unclear. This study aimed to clarify a novel type of sacral extradural spinal meningeal cyst with a specific arachnoidal structure. Nine patients with prophylactic diverticula were included in the study. All patients underwent MRI preoperative reconstruction and traditional neck transfixation. All patients presented with more than one symptom. The major symptom was lower extremity pain, followed by lower extremity numbness (77.8%, 7/9), lower extremity weakness (55.6%, 5/9), bowel/bladder and sexual dysfunction (55.6%, 5/9), and tenesmus (22.2%, 2/9). After long-term follow-up, the outcome was classified as improved in 9 patients (100%). The clinical findings of this study illustrate a special subtype and may help explain the mechanism of sacral cyst formation.