Effectiveness of a transforaminal surgical procedure for spinal extradural arachnoid cyst in the upper lumbar spine.

Spinal extradural arachnoid cysts are relatively rare, and the pathogenesis is still unclear. Here, we report a 24-year-old woman with a Type I lesion by Nabors' classification (extradural arachnoid cyst without spinal nerve root fiber involvements), who complained of low back pain and right thigh pain, treated surgically using a transforaminal approach. Magnetic resonance imaging (MRI) and myelography showed a large extradural cystic lesion close to the L1 nerve root sleeve, accompanied by moderate L1 nerve root compression and a communication between the extradural cyst and the subarachnoid space. Resection of the cyst wall and closure of the ostium were easily performed by this approach. This procedure resulted in the relief of both low back pain and right thigh pain. Histological examination showed clusters of meningothelial cells, which was a typical feature of arachnoid cysts. Postoperative MRI demonstrated that both the cystic lesion and nerve root compression had disappeared. This transforaminal procedure proved useful for the treatment of a lesion located around a lumbar spinal nerve root. Copyright 2002 Elsevier Science Ltd.