Although magnetic resonance imaging (MRI) is frequently used to assess the lumbar spine, there are few reports in the medical literature that have evaluated using MRI immediately following spinal surgery. Furthermore, descriptions of the subdural changes after lumbar spine surgery are also infrequent. In this paper, we present two cases with subdural change seen on MRI immediately after lumbar surgery. Both the patients had mild symptoms that resolved spontaneously, and the follow-up MRI scans showed resolution of the subdural changes. Subdural changes should be considered as one of the possible causes of unexpected symptoms in patients following lumbar spinal surgery.