Workup: Failed Back Surgery Syndrome
posted by : Dr. Barnetton: 20 March, 2019
Patients who have persistent or recurrent pain after lumbar spine surgery are often grouped under the nonspecific rubric of failed back surgery syndrome, or FBSS. With an incidence of FBSS of up to 40 percent after surgery, This is my most common complex patient.
A frequently missed cause of FBSS is discogenic pain. Discogenic lower back pain is worse with sitting. Often, MRI or CT scans will reveal degenerative discs, a loss of disc height, and bony changes and edema.
A discogram is used to evaluate the integrity of the disc as well as to evaluate for concordant pain with provocative pressure. Discographycan often confirm the diagnosis of discogenic back pain.
Other causes of lower back pain in FBSS include facet joint pain and sacroiliac joint pain. Facet pain and Sacroiliac pain can be detected on physical exam, both often worse with spinal extension, and both relieved with diagnostic blocks, and other treatments.
Sacroiliac joint pain presents as gluteal pain, and also is relieved by injection into the joint under radiographic guidance. It accounts for 30% or more of perceived back pain and is six times more common in women. Gait disturbance, fusion above, pelvic tilt, direct trauma all add to that risk. It often accounts for up to 28% of misdirected back surgery.
If the patient has ongoing leg or arm pain after spine surgery, then the most common cause is unresolved or new nerve compression secondary to foraminal or lateral recess spinal stenosis. The differential is muscle compression of the Sciatic or Brachial plexus.
Appropriate imagingis the first stage in diagnosis after a complete history and physical. Chronic ongoing foraminal stenosis, lateral recess stenosis and recurrent disc herniations are usually evident on an MRI or a CT myelogram. If nerve compression is suspected at a specific level, then a well-directed transforaminal epidural steroid injection can treat the patient’s pain. If it persists, surgical decompression or other modalities may be needed.
A recurrent disc herniation occurs in up to 10 percent of patients after a microdiscectomy and should always be suspected with a new onset of severe leg or arm pain.
The final cause of ongoing leg or arm pain after surgery is true neuropathic pain. Usually no obvious nerve compression is evident on imaging. The patient describes a burning ache with occasional numbness, and the pain is quite resistant to narcotics.
Neuropathic pain rarely resolves totally with injections. Advanced pain therapies such as a spinal cord stimulator trial and possibly permanent implantation can be performed if the pain relief is excellent