Surgical management of facet cysts in the thoracic spine: Radiological manifestations and results of fenestration

Background: Facet cysts in the thoracic spine are a rare cause of thoracic myelopathy. We aimed to investigate the clinical/radiological features and surgical results of these lesions. Methods: Nine thoracic facet cysts in eight patients (seven men, one woman) were diagnosed based on magnetic resonance imaging (MRI) and computed tomography (CT) with facet arthrography findings and surgically treated. The mean patient age was 71 (59-83) years. The cysts were distributed as follows: one each at T8-9 and T9-10, two each at T1-2 and T11-12, and three at T10-11. The mean follow-up period was 1.8 (1-5) years. Clinical and radiological features were retrospectively investigated, and surgical outcomes were evaluated according to modified Japanese Orthopaedic Association (JOA) scores for thoracic myelopathy (full score: 11). Results: Neurological examination revealed progressive thoracic transverse myelopathy in all patients with a mean disease duration of 1.2 months (2 weeks-2 months). MRI revealed a total of nine cysts across the eight patients: four in the median region and five in the paramedian portion of the spinal canal. CT revealed degeneration in all involved facet joints. All the cysts were in communication with the neighboring facet joint confirmed by CT facet arthrography. All patients underwent bilateral fenestration, and the cysts were resected with the ligamentum flavum. The mean preoperative and postoperative modified JOA scores were 4.5 and 8.8, respectively. The mean recovery rate was 67.5%. Differences in the degree of local kyphosis were 2 degrees or less between before and after surgery. On histopathology, synovial lining cells were not noted in any case. Conclusions: Decompression surgery is recommended for treating progressive myelopathy in patients with cystic lesions. Our study suggests that thoracic facet cyst resection with satisfactory surgical outcomes would be possible through fenestration. (C) 2021 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.