is to illustrate our experience and review the literatures.

A 59-year-old man presented with both leg radiating pain and paresthesia for 4 years. Other physical findings were not remark-able. MRI showed a large, elongated posterior extradural cyst from T12 to L3 with surrounding bony erosion (Fig. 1A, B). Thinned overlying laminas were found on operative field and the cyst was ruptured during laminectomy. There was a hole-like dural defect near to right L1 root sleeve and we performed prima-ry closure of the defect. Some part of cyst wall was also removed. The patient’s symptoms were gradually subsided and follow up image taken 1 month after the operation showed complete disappearance of the cyst (Fig. 1C). Case 2 A 51-year-old female patient visited our clinic with left but-tock 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. MRI showed a large extradural cyst located posterior to th