at a later time. Even the most complete surgical excision of the disc still leaves 30–40% of the disc, which cannot be safely removed. This retained disc can re-herniate sometime after surgery. Virtually every major structure in the abdomen and the posterior retroperitoneal space has been injured, at some point, by removing discs using posterior laminectomy/discectomy surgical procedures. The most prominent of these is a laceration of the left internal iliac vein, which lies in close proximity to the anterior portion of the disc. In some studies, recurrent pain in the same radicular pattern or a different pattern can be as high as 50% after disc surgery. Many observers have noted that the most common cause of a failed back syndrome is caused from recurrent disc herniation at the same level originally operated. A rapid removal in a second surgery can be curative. The clinical picture of a recurrent disc herniation usually involves a significant pain-free interval. However, physical findings may be lacking, and a good history is necessary. The time period for the emergence of new symptoms can be short or long. Diagnostic signs such as the straight leg raise test may be negative even if real pathology is present. The presence of a positive myelogram may represent a new disc herniation, but can also be indicative of a post operative scarring situation simply mimicking a new disc. Newer MRI imaging techniques have clarified this dilemma somewhat. Conversely, a recurrent disc can be difficult to detect in the presence of post op scarring. Myelography is inadequate to completely evaluate the patient for recurrent disc disease, and CT or MRI scanning is necessary. Measurement of tissue density can be helpful. Even though the complications of laminectomy for disc herniation can be significant, a recent series of studies involving thousands of patients published under auspices of Dartmouth Medical School concluded at four-year follow-up that those who underwent surgery for a lumbar disc herniation achieved greater improvement than nonoperatively treated patients in all primary and secondary outcomes except work status. Spinal stenosis Spinal stenosis can be a late complication after laminectomy for disc herniation or when surgery was performed for the primary pathologic condition of spinal stenosis. In the Maine Study, among patients with lumbar spinal stenosis completing 8- to 10-year follow-up, low back pain relief, predominant symptom improvement, and satisfaction with the current state were similar in patients initially treated surgically