Spinal Extradural Arachnoid Cyst
A 51-year-old female patient visited our clinic with left buttock pain and paresthesia for 3 years. Her pain was aggravated on coughing and she also complained of gait disturbance with both sole numbness on walking.\nMRI showed a large extradural cyst located posterior to the cord from T11 to L2 (). CT myelogram was performed to verify any communication between the subarachnoid space and the cyst (). The contrast dye diffused within the subarachnoid space reaching to T11-12 level, and then leaked into the cyst. It scantly spreaded above the level and we assumed that there might be communication between the cyst and the subarchcnoid cyst at T11-12 level.\nAt first, total laminectomy of T10 and T11 was planned to find a dural defect. The laminae overlying the cyst were thinned. The cyst wall was ruptured during laminectomy and CSF-like fluid was gushed out. Under microscopic exploration, transparent cyst wall was found at the margin of bony exposure (). There was a hole-like, 0.5 cm sized dural defect at the right posterolateral side of the dural sac at T11 level. A rootlet got caught in the dural defect and formed a loop around the hole (). The root was repositioned into the intradural space and the dural defect was repaired with black silk 6-0. The cyst wall was severely adherent to the dural sac and there was moderate bleeding on dissecting the cyst. We only fenestrated the cyst. Some portion of the cyst wall was removed and sent to pathologic department. Pathologic findings were compatible to arachnoid cyst ().\nHer symptoms relieved gradually and follow up MRI taken at 2months after the operation showed much decreased cyst and there was no evidence of cord compression due to residual cyst ().