What is failed back syndrome? What is the best way to evaluate affected patients?
After spinal surgery, 5% to 40% of patients have persistent back or leg pain, and this is referred to as failed back syndrome. Approximately 10% of these patients undergo another operation. Causes of failed back syndrome include: (1) residual or recurrent disc herniation, (2) residual spinal canal, neural foraminal, or lateral recess stenosis, (3) formation of scar tissue in the surgical bed, (4) instability, (5) arachnoiditis, (6) surgical error (operation at the wrong level), and (7) surgical complications, including infection, hematoma, and cerebrospinal fluid leak. The best imaging method for evaluating these patients is with MRI before and after intravenous contrast administration, which can help distinguish recurrent disc herniation (nonenhancing) from postoperative fibrosis and granulation tissue formation (avidly enhancing).