SPINAL EXTRADURAL ARACHNOID CYST IN THE THORACIC

Abstract

Spinal extradural arachnoid cysts are relatively rare, and the pathogenesis is still unclear. Here, we report a case with a Type I-A lesion by Nabors' classification (extradural arachnoid cyst without spinal nerve root fiber involvements) treated surgically. A 38-year-old female patient presented with a complaint of low back pain and bilateral hypesthesia of the legs. Physical examination showed no abnormality. Magnetic resonance imaging (MRI) showed an extradural cerebrospinal fluid (CSF)-containing lesion without involvement of the posterior epidural fat at Thll-Ll. CT with bone algorithms revealed bone erosion with widening of the canal, foraminal enlargement and scalloping of the vertebral body. Resection of the cyst wall and closure of the ostium were easily performed. This procedure resulted in the relief of her symptoms. Postoperative MRI demonstrated that both the cystic lesion and nerve root compression had disappeared. Histological examination showed clusters of meningothelial cells, which are a typical feature of arachnoid cysts. Radical cyst removal and dura defect closure are the surgical intervention of choice in patients with symptomatic extradural arachnoid cyst.