Failed Back Surgery Syndrome: Historical Perspective

What Is Failed Back Surgery Syndrome?

FBSS is the name given to a spectrum of patient complaints and symptoms that can occur in those who have undergone spinal surgery, decompressions, deformity surgery, and fusions. FBSS is most often diagnosed when the outcome of the procedure does not meet or exceed the expectations of the surgeon and patient and the patient is left with residual back and/or leg pain or neck and/or arm symptoms. This syndrome has been described by many names in the past, most recently “postlaminectomy syndrome.” There has been confusion on the issue of what can be properly described as FBSS. In the strictest sense, only residual symptoms following a properly diagnosed and properly performed surgery are considered FBSS. Many authors have used the term “anatomically correct” to describe this proper execution of the correct treatment. When this fails to deliver relief, it is an FBSS. To the patient, however, surgical treatment that does not alleviate the problem is a failure. Therefore, the incidence of misdiagnosis and failed surgical treatment are included in the FBSS discussion. In fact, in recent years, there has been an increase in the number of cases of FBSS diagnosed as the number of surgeries on the spine have increased. The worldwide literature suggests that the incidence of FBSS is somewhere between 10% to 40% of surgical patients. Those numbers are even more daunting since it has recently been estimated (from controlled randomized trials) that 5% to 50% of patients who have surgery will fail with regard to patient outcome and satisfaction following spine surgery. Additionally, in 1997, there were over 317,000 lumbar surgeries performed in the United States ; by the year 2002, the number increased to over 1 million surgeries. Fusion operations, as a subgroup, increased by over 220%. Multiple surgical procedures in the same area have been reported to have decreasing clinical success. The initial positive outcome was decreased to around 30% after the second surgery, 15% after the third, and to around 5% after the fourth surgery. FBSS has a tremendous impact not only on the patients and families involved but also on the cost of health care delivery and society. There are many potential causes that land patients with the diagnosis of FBSS. These include, but are not limited to, poor patient selection, misdiagnosis and subsequent mistreatment, poor surgical technique or iatrogenic causes, permanent nerve damage, failure of fusion, failure or misplacement of instrumentation, and recurrence or progression of pathology. The treatment of this diverse group of patients must be individually tailored depending on the underlying etiology. It is also important to identify those patients who potentially have a secondary agenda. These include worker’s compensation patients or patients with litigation pending. The outcomes in these groups have been reported to be significantly worse when compared to controls.

Economic Impact of Failed Back Surgery Syndrome

FBSS affects the ability of the patient to function and participate in family and societal settings. It prolongs the normal recovery phase by weeks to months to years. Its socioeconomic impact has been studied exhaustively relative to low back pain, but studies are lacking for determining the true cost of FBSS. It has been reported that the true impact of FBSS on an individual's quality of life and its economic cost to society are considerable. It is more disabling when compared to other chronic pain syndromes and chronic medical conditions such as heart failure and motor neuron diseases. This inherently makes sense when one factors in the costs of multiple medical visits, the cost of the primary surgical procedure, and subsequent postoperative care. Added to those costs postoperatively are visits to the caregivers, physical therapy and inpatient rehabilitation, further postoperative diagnostic studies, continuing medications, pain management clinics, subsequent procedures, and the failure of the patient to return to the workplace.

Symptoms of Failed Back Surgery Syndrome

What then, are the primary complaints of patients in the postoperative period that would lead one to explore the possibility of FBSS? Patients who undergo surgery of the spine with or without fusions can have a variety of postoperative complaints; not all of them require further diagnostic workup. These patients sometimes require time after an operation to heal and for the symptoms that necessitated the initial procedure to subside. Attempts to resolve the symptoms during this period should be conservative and supportive without exposing the patient to invasive treatments. Guyer and colleagues suggested a classification system based on the length of time between surgery and the onset of pain. Patients were placed into three groups: early (immediately after surgery to 3 weeks), intermediate (pain recurrence or new symptoms 1–6 months after surgery), and late (after 6 months of acceptable pain relief). The early group included wrong-level surgeries and failure to adequately address the pathology. The intermediate group was separated into gradual recurrence of pain versus after a specific, sometimes traumatic, event. The late group was more attributed to recurrent pathology at the level of surgery or the level above. It would be prudent to include the formation of scar tissue in this group as epidural fibrosis has usually reached its maximum around this time. This system seems as good as any proposed to date, as it allows for the clinician to focus the examination and diagnostic studies on the most likely issues causing the pain. It is, however, of the utmost importance to diagnose the cause of postoperative symptoms.

The diagnosis of FBSS crosses into many different specialties in medicine. First and foremost, it is the responsibility of the treating surgeon to confirm that he or she has, indeed, correctly performed the operation that was outlined to the patient in the period of conservative care and during the presurgical consultation. This involves not only reviewing the preoperative radiographic and diagnostic findings but also meeting with and listening to the patient and performing a complete and thorough physical examination. Sir William Osler's famous words “Listen to your patient, he is telling you the diagnosis,” rings clearly here. The patient will frequently guide you to the appropriate area of concern if you take the time to get a complete history of the symptoms. This should be followed by a comprehensive examination of not only the affected area, to eliminate it as a possible source of the pain or symptoms, but a complete orthopaedic exam including the hips and knees. The presence or absence of associated medical conditions—such as heart disease, neuromuscular disease, and metabolic diseases—should also be ascertained. The use of other treatments for other diseases, such as chemotherapy or radiation therapy for cancer patients, is also critical information for the surgeon. A history of psychiatric disorders or depression and the patient's worker's compensation status should also be recorded. Diagnostic injections and electromyograms (EMGs) are sometimes also useful in determining the cause of postoperative pain.

Once the history and physical are complete, it is up to the surgeon to determine the appropriate diagnostic tests to be ordered. For example, when determining the cause of radicular symptoms after a decompressive procedure, diagnostic tests that allow visualization of the surgical site and the surrounding area should be ordered. Frequently, this will include magnetic resonance imaging (MRI) with or without gadolinium. Computed tomography (CT)/myelography can determine if there is any residual or recurrent compressive pathology centrally, laterally or extraforaminally or any additional pathology in the surrounding areas that was previously missed or not present. This can be very difficult to do, considering how hard it can sometimes be to identify an anatomic source of pain in patients without previous back surgery.

If the history and physical examination are complete, the appropriate imaging studies and injections are performed, and the psychiatric evaluation is completed, it has been reported that a diagnosis can be reached in over 90% of the patients. There is widespread agreement that the correct diagnosis is crucial to successful treatment of FBSS.

The most common diagnosis in patients diagnosed with FBSS is foraminal stenosis, which is found in 25% to 29% of the patients. This was followed by a painful disc in 20% to 22%, and pseudarthrosis in 14%. Other causes include recurrent disc herniation in 7% to 12%, neuropathic pain in 10%, facet joint pain in 3%, and sacroiliac pain in 2%. Sagittal plane imbalance has also been implicated in recent studies of correctable causes of FBSS. However, subsequent studies have shown an increase in the number of patients with residual pain due to sacroiliac joint dysfunction. The leading psychiatric factors identified were depression, substance abuse, and anxiety.

When dealing with patients with FBSS, it is perhaps even more critical that the treating physician and patient have their plans and goals regarding outcomes of treatment aligned. A goal of improving the visual analog scale by 1.8 units (or approximately 50%) is an excellent starting point and has been shown to provide good results.

Causes, Diagnosis, and Treatments of Components of Failed Back Surgery Syndrome

Foraminal or Lateral Recess Stenosis

There are many potential causes for residual back and leg pain in patients diagnosed with FBSS. Some are postsurgical complications and some are not. The primary cause of persistent radiculopathy after spine surgery is, for instance, inadequate decompression of the spine. This can occur centrally, in the lateral recess, or in the far lateral or foraminal areas of the spine. The incidence of this is reported to be between 25% and 29%. When patients present with symptoms of persistent or new radiculopathy, the radiographic study of choice is MRI with and without gadolinium if there has not been a fusion with instrumentation ( Fig. 102.1 ). If the patient has had a fusion with instrumentation, then a myelogram and postmyelogram CT is indicated. Attention should be paid to not only the central canal but to the lateral recesses, especially the areas around the facet joints and the foraminal and extraforaminal areas. Lateral and far lateral stenosis can occur from hypertrophic facet joints, disc degeneration with loss of vertical height and subsequent foraminal collapse superior to inferior. Lateral and far lateral disc protrusions or herniations cause anterior to posterior narrowing. Far lateral discs can be easily missed if attention is not specifically paid to this area when reviewing diagnostic studies. EMGs are also useful to help delineate or define the involved levels. They are particularly useful when multiple levels are affected with degeneration or disc space collapse and when there may be residual stenosis at a single location on a single side or at multiple levels in multiple locations. The presence of ongoing denervation with radiographically proven stenosis is a strong indication for revision surgery. Therapeutic and diagnostic injections can also aid in both treating and diagnosing the level of causative pathology. When the diagnosis of residual stenosis is made, the patient once again has treatment options. The first line of treatment can again be conservative care with physical therapy, nonsteroidal antiinflammatory drugs (NSAIDs), and antispasmodics and pain medication. This route is similar to the path they likely took when deciding on the initial procedure. If this does not relieve symptoms, then transforaminal, caudal, and epidural blocks can be used both therapeutically and diagnostically. Patients who respond to a single-level transforaminal block have an excellent chance of improvement or recovery with a revision decompression. If the injections fail, then the use of neurostimulation is an option. Finally, if the more conservative modalities fail to relieve symptoms, the surgical correction of the compressive pathology can be performed. Psychiatric evaluation prior to surgery is critical in this group, as chronic pain can lead to psychiatric pathology that can adversely affect the outcome. When performing revision decompression, particularly in the lateral recesses and transforaminal areas, care must be taken to not destabilize the area around the compressive pathology. Removal of greater than 50% of the facet joint has been shown to cause instability and could potentially necessitate future surgery, placing the patient right back into the FBSS group.