Kazuaki Morizane1, Shunsuke Fujibayashi2, Bungo Otsuki2, Takeshi Sakamoto3, Ryosuke Tsutsumi3, Seiichi Odate4, Akira Kusuba5, Shuichi Matsuda2. 1. Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, 54 Shogoin Kawahara, Sakyo, Kyoto, 606-8507, Japan. Electronic address: morizane@kuhp.kyoto-u.ac.jp. 2. Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, 54 Shogoin Kawahara, Sakyo, Kyoto, 606-8507, Japan. 3. Department of Orhopaedic Surgery, Osaka Red-cross Hospital, 5-30 Fudegasaki, Tennoji, Osaka, 543-8555, Japan. 4. Department of Orthopaedic Surgery, Spine Center, Gakkentoshi Hospital, 7-4-1 Seikadai, Seika, Kyoto, 619-0238, Japan. 5. Department of Orthopaedic Surgery, Kurashiki Central Hospital, 1-1-1 Miwa, Kurashiki, Okayama, 710-8602, Japan.
Abstract
BACKGROUND: Although a valve-like mechanism has been proposed for expansion of spinal extradural arachnoid cysts (SEACs), the detailed mechanism remains unclear. Moreover, closure of the communication site is essential during surgery, but the method to identify the communication site remains unclear. The aim of this study was to determine the detailed mechanism of expanding SEACs through retrospective analysis of SEAC cases undergoing surgery and to elucidate the characteristics of the communication sites. METHODS: The authors retrospectively evaluated 12 patients with SEACs who underwent surgery between 2000 and 2014 and analyzed their perioperative findings. RESULTS: Dural defects were detected in 11 out of 12 patients, and a valve-like mechanism was observed in 7 patients, wherein a nerve root fiber moved back and forth through the dural defect along with the flow of cerebrospinal fluid (CSF) between the intradural space and the extradural arachnoid cysts. The dural defect was located at the thoracolumbar junction in 7 patients, below the distal end of the bridging ossification in 2, at the level of vertebral wedge deformity in 2, and at the level of disc herniation in 1. CONCLUSIONS: A valve-like mechanism was observed in 7 of the 12 patients, which suggests that it could serve as a mechanism of SEAC formation. The communication sites were variously located at the end of ossification in patients with diffuse idiopathic skeletal hyperostosis (DISH), wedge deformity of the vertebral body, or disc herniation, indicating the contribution of mechanical stress to SEAC formation.
BACKGROUND: Although a valve-like mechanism has been proposed for expansion of spinal extradural arachnoid cysts (SEACs), the detailed mechanism remains unclear. Moreover, closure of the communication site is essential during surgery, but the method to identify the communication site remains unclear. The aim of this study was to determine the detailed mechanism of expanding SEACs through retrospective analysis of SEAC cases undergoing surgery and to elucidate the characteristics of the communication sites. METHODS: The authors retrospectively evaluated 12 patients with SEACs who underwent surgery between 2000 and 2014 and analyzed their perioperative findings. RESULTS:Dural defects were detected in 11 out of 12 patients, and a valve-like mechanism was observed in 7 patients, wherein a nerve root fiber moved back and forth through the dural defect along with the flow of cerebrospinal fluid (CSF) between the intradural space and the extradural arachnoid cysts. The dural defect was located at the thoracolumbar junction in 7 patients, below the distal end of the bridging ossification in 2, at the level of vertebral wedge deformity in 2, and at the level of disc herniation in 1. CONCLUSIONS: A valve-like mechanism was observed in 7 of the 12 patients, which suggests that it could serve as a mechanism of SEAC formation. The communication sites were variously located at the end of ossification in patients with diffuse idiopathic skeletal hyperostosis (DISH), wedge deformity of the vertebral body, or disc herniation, indicating the contribution of mechanical stress to SEAC formation.
Authors: Grégoire P Chatain; Keshari Shrestha; Michael W Kortz; Stephanie Serva; Patrick Hosokawa; Ryan C Ward; Akal Sethi; Michael Finn Journal: Neurospine Date: 2022-06-23