Thoracolumbar Extradural Arachnoid Cyst

Three cases of symptomatic extradural arachnoid cyst were treated by surgery. Total excision of the cyst followed by tight closure of the fistula by suture was achieved in all 3 cases. Surgery improved the neurological deficits but urinary incontinence persisted in all three patients. Obliteration of the fistula is considered to be important at surgery from the etiological perspective of the cyst. There are many surgical options, but surgical removal of the cyst and obliteration of the communication usually leads to prompt improvement in neurological deficits. Instability, malalignment, and worsening scoliosis are well-recognized postoperative complications of excessive laminotomy, but the exposure should be wide enough to cover the cyst completely at the operation. Wide exposure of the entire cyst is preferable to avoid missing the fistula and to identify any adhesions or fistula between the cyst and the dura. Identification of the fistula location based on preoperative imaging studies is also important.