Patients who have decompressive surgery and spinal fusion for stenosis, pseudoarthrosis, or adjacent segment disease can end up with persistent back and leg pain. This outcome is distressing to both the patient and the surgeon when just the opposite was expected (pain relief and improved function). Research to find out why these patients don’t get better has pinpointed depression as a possible factor.
By finding preoperative predictive factors, researchers hope to help surgeons identify and preselect patients for surgery who will have a good result. Predictive factors can be almost anything: age, health, sex (male or female), menopausal status for women, tobacco and/or alcohol use, body mass index (BMI), and so on.
In this study from The Spinal Column Surgical Quality and Outcomes Research Laboratory at Vanderbuilt University Medical Center, psychologic factors were examined. They evaluated 150 patients who had a second (revision) surgery for recurrent or persistent pain. Only patients with the three problems or diagnoses mentioned (i.e., stenosis, pseudoarthrosis, or adjacent segment disease) were included.
Spinal stenosis is a narrowing of the space in the spinal column for the passage of the spinal cord and spinal nerves. Pseudoarthrosis is a “false joint” that forms in a vertebral segment after fusion at that level has been done. Spinal fusion is supposed to create a stable segment that does not move. Pseudoarthrosis is the term given when there is no bridge of bone across the two vertebrae and movement is detected. And adjacent segment disease (ASD) occurs when spinal fusion results in a faster degenerative (break down) process of the spinal segment above or below the fusion site.
Previous studies have revealed that psychologic problems such as anxiety or depression can have an affect on patient results after surgery for these problems. But which came first: the depression followed by back pain or the back problem and then the depression? What is the role of depression on results of surgical treatment such as decompression and fusion? And finally, is depression a predictor of results after a second (revision) surgery? It is this last question that the Vanderbilt researchers evaluated in this study.
To conduct this study, each patient filled out several surveys and questionnaires before and after revision surgery. The areas assessed included pain (separate forms for back and leg pain), Oswestry Disability Index (ODI) for function and limitations, and the Zung Self-Rating Depression Scale. They measured the effect of depression present before surgery on the results two years after surgery.
The revision procedures included 1) arthrodesis (fusion) with hardware (called instrumentation for pseudoarthrosis, 2) decompression and extension of fusion for adjacent segment disease, and 3)fusion with instrumentation for stenosis.
They found that the presence of depression (as measured by the Zung Depression Scale) present before the revision procedure was an independent predictor of worse results. Patients with high scores on the Zung Scale were less likely to experience improvement in pain and disability after revision surgery. This effect was still present two years after surgery. The same link between depression and other types of spinal ssurgery has been reported in other studies.
Knowing the role of depression guides further research efforts. Recognizing that nonspinal health problems (including mental health issues) can affect the results of surgery is a big eye-opener. The next step may be to see if depression has the same influence on other types of treatment. Defining the role of other potential factors (e.g., diabetes, smoking, obesity, duration of symptoms before surgery) will also be important.