A comprehensive physical examination and appropriate diagnostic imaging techniques can often pinpoint the responsible pathology - the underlying cause - of the patient's pain. For instance, a definitive diagnosis of recurrent disc herniation or other disorders may be made.
In a number of cases, however, an MRI scan reveals only the presence of scar tissue as a remarkable finding, suggesting to some clinicians and researchers that the scar tissue is the likely source of the continued back pain and/or leg pain after lower back surgery. As mentioned above, although almost all postoperative MRI scans show scar tissue, postoperative pain for most patients probably has little to do with the scar tissue.
Causes of Pain after Failed Back Surgery
At this point, the physician and patient will need to take a fresh look at the problem to exclude other causes of postoperative pain.
- Improper preoperative patient selection before back surgery. This is the most common cause of failed back surgery syndrome. Surgeons look for an anatomic lesion in the spine that they can correlate with a patients pain pattern. Some lesions are more reliable than others. For example, degenerative disc disease is less commonly correlated with patients back pain than leg pain from a disc herniation pinching a nerve root. There are other sources of pain that can mimic back pathology such as piriformis syndrome, sacroiliac joint dysfunction and hip pathology (such as hip osteoarthritis).
For more information, see Failed Back Surgery Syndrome (FBSS): What It Is and How to Avoid Pain after Surgery
- Recurrent disc herniation after spine surgery. This is another common cause of recurrent pain after a discectomy/microdiscectomy spine surgery. The typical clinical picture is one where the patient initially has substantial pain relief, followed by a sudden recurrence of leg pain. In contrast to symptomatic pain caused by scar tissue (epidural fibrosis), in which symptoms tend to appear gradually, the symptoms of recurrent disc herniation tend to occur acutely. In addition to clinical history and presentation, an MRI scan is also useful in distinguishing the two pathologies.
- Technical error during spine surgery. The spine surgeon must also consider technical error if there is continued pain after a discectomy or microdiscectomy or a laminectomy. For example, was a fragment of herniated disc material missed, or a piece of bone left adjacent to the nerve? In either case, the resulting compression of the nerve root could cause pain. Were the correct operative levels chosen during surgical planning? If not, an adjacent disc may be the true source of the pain. Again, postoperative imaging and clinical presentation will help answer these questions.