Diagnosis and treatment of noncommunicating extradural spinal thoracolumbar arachnoid cyst

Background Noncommunicating extradural spinal arachnoid cysts are extremely rare. They are believed to arise from congenital defects in the dura mater and become enlarged as a consequence of increased cerebro-spinal fluid (CSF) pressure within the subarachnoid space. Most retain a communicating pedicle through which the extradural cyst maintains connection with the subarachnoid space, and only rarely does this communication become sealed. The optimal treatment consists of complete surgical removal of the cyst with ligation of the communicating pedicle. Case Description A 29-year-old male presented with a progressive spastic paraparesis of 6 months' duration. The MRI showed a circumscribed intradural extramedullary cystic lesion located from D11-L2. Notably, peroperatively, the cyst appeared to be entirely extradural, without a communicating intradural pedicle. Further, no CSF leak was observed even after Valsalva maneuvers. Following surgical extirpation of the cyst, the patient sustained an uneventful recovery within 1 postoperative month. Conclusion Noncommunicating extradural arachnoid cysts are extremely rare causes of spinal cord compression and should be fully excised.