Inclusion Criteria:  Subjects satisfying the following criteria will be considered eligible for enrollment in this study:  Patient is ≥ 18 years and < 80 years of age; Patient who received thoracic decompression surgery via posterior approach Patient who diagnosed as symptomatic spinal epidural haematoma and received revision surgery.  Exclusion Criteria:  Thoracic spinal stenosis caused by trauma, tumor, infectious, deformity and other disease; Symptomatic spinal epidural haematoma happened at cervicothoracic and thoracolumbar junction; Initial surgeries were performed at other hospital; Incomplete clinical data.