Clinical and Radiologic Outcomes Following Fenestration and Partial Wall Excision of Idiopathic Intradural Spinal Arachnoid Cysts Presenting with Myelopathy

Abstract Background Intradural spinal arachnoid cysts (ISACs) with associated neurologic deficits are infrequently encountered. Various management strategies have been proposed with minimal data on comparative outcomes. Objective We describe the clinical and radiologic presentation as well as the outcomes of 14 surgically managed patients who presented with an ISAC and associated myelopathy. Methods We retrospectively reviewed the clinical course of consecutive patients presenting with neurologic deficits associated with idiopathic ISACs at our institution. The diagnoses were based on pre-operative MRI studies followed by intraoperative and histopathological confirmation. Results 14 consecutive patients with ISACs (1 cervicothoracic, 12 thoracic, and 1 thoracolumbar) and associated myelopathy were identified. Syringomyelia was noted in 8 patients. All ISACs were treated with cyst fenestration and partial wall resection through a posterior approach. Pre-operative neurologic symptoms were noted to be stable or improved in all patients starting at 6-week post-operative follow-up. The median (interquartile range) pre-operative mJOA score was 13 (12.0 – 14.8) while the post-operative median score at a mean follow-up of 22 months (range 6-50 months) was 16 (14.0 – 17.0), which represents a median improvement (ΔmJOA) of 2.0 (1.3 – 3.0) (p < 0.001). Comparison of ΔmJOA scores between cases without and with associated syrinxes did not reveal a significant difference (p 0.23). Post-operative MRI scans revealed spinal cord re-expansion at the level of the ISAC in all cases and either complete or partial syrinx resolution in 7/8 cases. Conclusions Early treatment with fenestration and partial wall resection allows for cord decompression, syrinx resolution, and gradual resolution of myelopathic symptoms in most cases.