Although some in the medical field take issue with the word “failed” in Failed Back Surgery Syndrome, patients who continue to suffer with chronic pain after surgery really don’t care what you call it. They just want the pain to stop.
The name Failed Back Surgery Syndrome is kind of a misnomer. Often times the surgeon is successful in restoring structural stability, alignment, or nerve decompression through procedures like spinal fusion, laminectomy or discectomy. The problem arises, however, when the level of pain occurring after surgery exceeds the patient’s expectations and continues to minimize or restrict the patient’s lifestyle or ability to work.
Failed Back Surgery Syndrome (FBSS) refers to a subset of patients who have new or persistent pain after spinal surgery for back or leg pain. The pain can be reduced but still present, or may get worse within a few months after surgery. The term refers to a condition of continuing pain and is not meant to necessarily imply there was a problem during surgery. The likelihood of experiencing FBSS is considered greater with repeated surgery, and the condition will be more prevalent in regions where spinal surgery is more common.
There can be many reasons for continued chronic pain following surgery, such as scar tissue development, surgical hardware failure, wrong surgical site, transfer of pain to another level or pre-existing nerve damage that cannot be reversed even when successful structural fixes are accomplished with surgery.
Studies have shown up to 40% of patients experience chronic back pain after back surgery. That’s not acceptable. Proper surgical candidate selection can help to reduce this statistic. Nerve root compression and instability are the only two conditions demonstrated to be correctable at the present time. Proper expectations of surgical outcomes should be a conversation between the doctor and patient prior to surgery to alleviate many of the psychological effects of continued pain or new pain following surgery.
When a potential remediable lesion is found, these patients should undergo a reasonable attempt at physical rehabilitation and/or interventional pain management procedures to conservatively remedy their pain prior to surgery. Surgery should always be a last resort.
Consider these specific potential causes of FBSS:
- Fusion surgery considerations. Failure to fuse and/or implant failure, or a transfer lesion to another level after a spine fusion, when the next level degenerates and becomes a pain generator.
In general, it takes at least three months to get a solid fusion, and it can take up to a year after the spine surgery. For this reason, most surgeons will not consider further spine surgery if the healing time has been less than one year. Only in cases where breakage of the hardware is evident would a follow-up surgery be discussed.
Hardware is often used to support the spine during the 3-12 months times it takes for fusion to take place. The metal hardware has the capacity to fail before solid fusion takes place. Larger sized patients and multi-level fusion surgeries have higher likelihood of failure. A normal size patient who is only having one level fused will have very low incidence of hardware failure.
A patient may experience recurrent pain many years after a spine fusion surgery. This can happen because the level above or below a segment that has been successfully fused will bear increased biomechanical stress and have a higher propensity to degenerate and cause pain.
Lumbar fusions that include the L4/5 level have a higher incidence of causing a segmental transfer of degeneration and pain because this spinal level is responsible for the most segmental motion in the lumbar spine. Younger surgical fusion patients, ages 30-50, have a greater chance to develop transfer pain because they have a longer time for adjacent spinal segments to undergo breakdown.
- Lumbar decompression back surgery considerations. Recurrent spinal stenosis or disc herniation, inadequate decompression of a nerve root, preoperative nerve damage that does not heal after decompression surgery, or nerve damage that occurs during the surgery.
Years after decompression, lumbar stenosis can return from bone regrowth at the same level. New levels can also become stenotic and cause back or leg pain.
Pain that is relieved immediately following surgery and then returns abruptly is often due to a recurrent lumbar disc herniation. Recurrent lumbar disc herniation happens in about 5% to 10% of patients, and most likely during the first three months after back surgery.
Nerve root tissue can take a long time to heal following a lumbar decompression, such as a discectomy, microdiscectomy or laminectomy, making it difficult to immediately evaluate the outcome of the surgery.
In general, if a patient is getting better within three months of the surgery, improvement will generally continue. No pain improvement within the first three months after the decompression is considered a failure. This may indicate nerve damage that existed prior to surgery that was too severe for healing to take place regardless of successful decompression.
Decompression of the lumbar spine will usually relieve the patient’s leg pain directly after the back surgery. However, for 10-20% of patients, the nerve pain will continue, and in some instances worsen, until time allows for the nerve tissue to begin its slow healing process. Post-operative swelling around nerve tissue can make nerve pain worsen temporarily.
Three technical problems can cause the pain after decompression:
- Missed disc or bone fragment is still compressing nerve tissue
Decompressing a nerve root with back surgery is not always successful, and if a portion of the nerve root is still pinched after the back surgery there can be continued pain. If this is the case, there will usually be no initial pain relief following the back surgery, and subsequent postoperative imaging studies may show continued spinal stenosis in a portion of the lumbar spine.
- Surgery performed at the wrong level of the spine
One of the most common causes of FBSS is that surgery was performed at the wrong level. A work-up that inaccurately identifies the pain generating level or structure is frequent. This may not necessarily be the fault of the provider, but a result of the immense complexity and overlap of the musculoskeletal and nerve system.
- Trauma to nerve root during surgery
Nerve damage during a discectomy or a lumbar decompression is very uncommon, but has been reported in about 1 in 1,000 cases. When it does occur, a permanent neurological deficit with new weakness in a muscle group is possible. An EMG (electromyography) can be helpful to see if there has been nerve damage and if there is any reinnervation (nerve healing) after the back surgery.
- Scar tissue considerations. Epidural fibrosis, which refers to a formation of scar tissue around the nerve root.
Scar tissue formation is a normal reaction during the postoperative phase and it begins within 12 hours following the surgery. Scar tissue is often blamed for continued pain after surgery, however, in actuality it is less common. In patients that have similar pain postoperatively to what they had before surgery, it is unlikely that the formation of scar tissue has any clinical relevance.
The one time that scar tissue may be relevant is when a patient experiences initial pain improvement after a lumbar discectomy or a decompression, but recurrent pain develops slowly in the 6 to 12 weeks postsurgical time frame. 6-12 weeks post-surgery is the time frame when considerable scar tissue formation takes place and may cause new nerve entrapment, pressure or lack of movement.
Pain that starts years after surgery, or pain that continues after surgery and is never relieved, is not likely from scar tissue.
- Postoperative rehabilitation. Continued pain from a secondary pain generator.
Second only to an incorrect preoperative diagnosis, improper and/or inadequate postoperative rehabilitation is probably the second most common cause of continued back pain after surgery.
It often takes months to a year to fully heal after most back surgeries, and a postoperative rehabilitation program that includes stretching, strengthening and conditioning is an important part of any successful spine surgery.
Patients who undergo more comprehensive back surgeries as well as those who have experienced pain for longer periods of time prior to surgery, tend to have longer and harder postoperative rehabilitation.
Continued post-surgical rehabilitation and the care of an interventional pain specialist is generally preferable to further surgeries following FBSS. Of course, there are always exceptions.
- Facet Injection (medial branch block). For pain that originates in the moveable facet joints and injection of a corticosteroid mixed with an anesthetic around the median branch nerve, which innervates the often painful capsule surrounding the facet joint, can quickly reduce or eliminate pain. Facet Injection can act as a treatment as well as a diagnostic tool to help identify the origin of your pain.
- Radiofrequency Ablation (RFA). When the median branch nerve to the facet joints are identified as a source of your pain, then RFA can provide longer lasting relief than facet injection. The median branch nerve is heated to 90 degrees Celsius for about 90 seconds. This heat lesion created around the nerve prevents transmission of pain signals for 6-12 months on average.
- Pharmacological Intervention. NSAIDs, muscle relaxers, neuropathic pain medications and opioid pain medications may be utilized to control pain.
- SIJ Injection. The sacroiliac joint often mimic back pain. A sacroiliac joint injection bathes a mixture of anti-inflammatory and anesthetic medications into the painful joint and upon the nerves that transmit the pain from the joint to your spinal cord and eventually to your brain. This injection rapidly diminishes inflammation in the joint and around nerve tissue. When the pain cycle is broken, your body’s own healing mechanisms can now be more effective. Physical therapy or chiropractic care are often more valuable once the acute pain is managed.
- Epidural Injection. An injection of a corticosteroid into the epidural space may be utilized to rapidly diminish pain around painful nerve roots and discs. There are 3 ways to administer epidural medication. Your pain doctor will determine the most effective method based upon your symptoms, prior surgeries, scar tissue issues and prior treatment attempts. The three methods of administration are as follows: Interlaminar Epidural Injection, Transforaminal Epidural Injection and Caudal Epidural Injection.