A 34-year-old male had occasionally experienced severe low back pain. Thoracic and lumbar plain X-rays and tomography showed enlarged interpedicular spaces and anteroposterior distances of the spinal canal at the thoracolumbar level. Myelography demonstrated epidural compression from the Th11 to the L2 vertebral levels. Amipaque computed tomography (CT) myelography showed a flattened spinal canal and a contrast-enhanced mass extending from the Th11 to the L2 vertebral levels. Magnetic resonance imaging revealed a mass situated in the same region, as well as compression of the spinal cord. A Th12 through L2 laminectomy was performed. When the dura and the adherent cyst wall (thickened arachnoid) were incised, liquid spurted out. The cyst cavity communicated with the subarachnoid space through a small pore. The pore was ligated and the cyst was subtotally excised. The redundant dura overlying the cyst wall was sutured to eliminate the dead space. The removed cyst wall was composed of thickened and partially hyalinized arachnoid. No inflammation was detected. Immediately after surgery, the patient's low back pain disappeared. Amipaque CT myelography performed 30 days postoperatively demonstrated restoration of the dural sac.
