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Requests for reprints should be addressed to Richard D. deShazo, MD, Department of Medicine, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216.
The 80,000 or so patients a year who continue to have chronic, disabling back pain after one or more spinal surgeries are said to have failed back surgery syndrome. There are no controlled studies to guide physicians in the management of these patients. Six anatomical abnormalities of the spine most commonly result in back surgery, and 7 undesirable outcomes lead to failed back surgery syndrome. On the basis of 5 large retrospective studies and our clinical experience, we suggest a systematic approach to these patients. This approach is focused on determination of the specific anatomical abnormality responsible for ongoing symptoms, an abnormality that may or may not be related to the initial abnormality for which surgery was performed. One or more of 5 nonsurgical treatment options may be useful to prevent the need for further surgery, as each subsequent surgery has a lower likelihood of success.
In a retrospective study of 24,882 patients who underwent spinal surgery in Washington State from 1990-1993, 19% required reoperation for pain or complications of surgery over the ensuing 11 years.
If these estimates are correct, there may be over 80,000 “failed” back surgeries per year. Success rates fall to around 30% after a second back surgery, 15% after the third, and to 5% after the fourth surgery.
Often, internists are asked for advice by these challenging patients but are unfamiliar with the conditions leading to back surgery, the types of back surgery, and the best approaches to diagnosis and management. We review these areas in this article.
Internists are generally unfamiliar with the conditions for which back surgery is performed or how to deal with patients with failed back surgery.
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Best estimates suggest that 40% of back surgery for low back pain is unsuccessful, and these patients often gravitate to internists.
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An understanding of the 6 spinal abnormalities most commonly associated with failed back surgery syndrome is required for adequate clinical management.
Anatomical Abnormalities of the Back for Which Initial Back Surgery is Performed
Spinal surgery is optimally performed only when the pain and symptoms correlate with a corresponding anatomic abnormality to yield the best outcomes (Figure 1). Six commonly encountered spinal abnormalities for which spinal surgery is performed are listed in Table 1.
Figure 1Anatomical abnormalities of the spine for which back surgery is frequently performed. The upper figure is a lateral representation of the spine with a normal intervertebral disc and a normal articulation of the inferior articular process of L3 and the superior articular process of L4 to form the L3-L4 facet joint. There is anterior displacement of L4, a condition called spondylolisthesis, and degeneration of the L4-L5 facet joint. Spondylolisthesis may cause no symptoms or entrapment of the spinal nerve, causing sciatica, while osteoarthritis of a facet joint can cause no symptoms or chronic low back pain, sometimes accompanied by spinal stenosis (lower figure). With weakening of the annulus fibrosus and herniation of an intervertebral disc (lower figure) sciatica, spinal stenosis and chronic low back may occur. Reproduced from Deyo RA. Back surgery—who needs it? N Engl J Med. 2007;356(22):2240.
A condition resulting from extrusion of the nucleus pulposus from the fibrous cover of the disc. This is associated with parethesias relieved by lying down.
A condition in which the vertebral canal is narrowed, causing pain that radiates down the back to the buttocks, thighs, and lower legs (sciatica). This is often accompanied by limping and leg pain and made worse with extension (standing) and better by flexion (sitting).
Instrumentation means the use of hardware such as screws, rods or plates. The function of the instrumentation is to provide temporary stability until fusion and bone healing is complete.
A condition where one of the vertebrae of the lower spine slips forward in relation to the other. This can cause no symptoms or chronic low back pain and sciatica.
Can occur from instability of an adjacent segment, deformity, spondylolisthesis, or trauma.
Fusion with instrumentation
A condition resulting from extrusion of the nucleus pulposus from the fibrous cover of the disc. This is associated with parethesias relieved by lying down.
† A condition in which the vertebral canal is narrowed, causing pain that radiates down the back to the buttocks, thighs, and lower legs (sciatica). This is often accompanied by limping and leg pain and made worse with extension (standing) and better by flexion (sitting).
‡ A condition where one of the vertebrae of the lower spine slips forward in relation to the other. This can cause no symptoms or chronic low back pain and sciatica.
§ Can occur from instability of an adjacent segment, deformity, spondylolisthesis, or trauma.
‖ Instrumentation means the use of hardware such as screws, rods or plates. The function of the instrumentation is to provide temporary stability until fusion and bone healing is complete.
Data on the causes of failed back surgery are limited. Among orthopedists, there is consensus that the timing of recurrent symptoms provides information helpful in diagnosis.
Immediately after surgery, failure to achieve relief of symptoms or a continuation of preoperative symptoms has been attributed to an initial wrong diagnosis, technical error, or poor patient selection because of psychosocial factors. Temporary relief after surgery followed by pain recurrence within a few weeks of surgery suggests infection. When pain occurs months after surgery, reherniation, battered root syndrome (inflammation of the nerve root as a result of surgical manipulation), epidural fibrosis, or arachnoiditis are suspected. Failures after several years may be caused by loss of spinal instability or spinal stenosis, either at the previous surgical site or at an adjacent level. Loss of stability can result from excessive bone removal during decompression surgery. For instance, resection of 50% or more of the facet joint affects the stability of the spine.
Spinal instability also can occur at an adjacent level after fusion surgery, due to increased motion as the adjacent segments compensating for the loss of motion at the fused segment. Spinal instability increased from 12% after one operation to 50% after 4 or more revision surgeries in one retrospective study.
Some authors have suggested that the cause of ongoing back pain in patients with failed back surgery syndrome may be possible to diagnose in as many as 90% of patients
Approach to a Patient with Failed Back Surgery Syndrome
After extensive review of the English literature, we found that there are no controlled studies to guide the physician in the management of failed back surgery syndrome, and retrospective data are limited as well (Table 3). Therefore, the recommendations to follow are based on experience and consensus and require further study. Chronic back pain after surgery mandates an in-depth investigation of the spine, and alarm symptoms suggest the need for immediate consultation with a spine surgeon (Table 4).
Table 3Studies of Salvage Surgery for Failed Back Surgery Syndrome
The approach to the patient starts with a history and physical examination, looking for clues to the origin of persistent back pain and evidence of neurological involvement such as muscle weakness, parasthesias, or radicular pain and numbness in the lower extremities. Tension on a nerve root produced by stretching the root over an offending structure such as a herniated disc results in tension signs. The femoral stretch test, straight leg-raising test, and Lasagne sign are used to elicit these findings. Sensory deficits are determined by comparing the patient’s perception of light touch and pin prick in both legs. Muscle weakness is detected by resistance testing of each muscle group individually as compared with the same muscle group in the contralateral leg. The lumbar spine is checked for range of motion, paravertebral muscle spasm, localized points of tenderness and step-offs, soft tissue indentation along the midline of the spine caused by high-grade spondylolisthesis. Other causes of back pain such as cancer in the retroperitoneum and pelvis, aortic aneurysm, hip arthritis, or myofascial syndromes can mimic chronic low back pain and should always be kept in the differential diagnosis.
Imaging
Magnetic resonance imaging (MRI), computed tomography (CT)/myelograms are required in the diagnosis of back pain with neurogenic symptoms. The CT scan is most effective in demonstrating the bony anatomy and, in combination with a myelogram, demonstrates the neural anatomy in relationship to the bony structures. Plain radiograph alone misses spinal stenosis and many soft tissue conditions. Spinal stenosis can best be quantified by MRI, as the condition of the disc and the degree of disc degeneration also can be determined. MRI also is superior to CT scan/myelogram in the detection of stenosis or other pathology in the spinal foramen or extraforaminal area, as the dye of the myelogram and the cerebrospinal fluid does not extend into the spinal foramen. The CT myelogram is useful when MRI cannot be obtained because of a pacemaker, previous brain surgery with clips, or the presence of hardware from previous lumbar spine surgery.
Invasive Diagnostic Procedures
Nerve root blocks with local anesthetics or epidural steroid injections can relieve pain and serve as diagnostic tests to determine whether surgery will be of benefit and to identify the levels in the spine that require surgery. Nerve root blocks have been among those found effective in pain relief and have been included in the evidence-based practice guidelines for the management of chronic spinal pain.
For example, if a patient has radicular leg pain and the MRI scan demonstrates entrapment of more than one nerve, nerve roots may be individually injected with a local anesthetic with or without steroid. The source of the pain and the level for any future surgery required can thus be determined. Posterior spinal joint (facet) blocks and blocks of the medial branch nerves (nerves supplying sensation to the facet capsules) also may relieve pain originating from an arthritic facet. Medial branch blocks provide pain relief by desensitizing the capsule of the respective facet joints.
Myofascial Pain Syndromes in Patients with Failed Back Surgery Syndrome
Myofascial pain syndromes are poorly understood chronic pain syndromes, variously termed nonarticular rheumatism, fibromyalgia, and soft tissue rheumatism, and are invariably associated with disorders of sleep. Diagnostic criteria for fibromyalgia are based on the presence of tender points at specific locations, including those in the back.
The prevalence of these syndromes in failed back surgery syndrome is unclear, although they are common in our experience. If present, symptoms seem best approached by evaluation and treatment of sleep disorders if present, warm-water-based exercise programs, and antidepressants. Other factors that can contribute to musculoskeletal back pain include poor posture, pes planus, leg length differences, reduced strength of the muscles in the lower torso, lack of oxygen in the back tissues caused by smoking, and psychosocial factors. Consultation with a rheumatologist can be helpful in the management of these patients.
Non-Surgical Treatment Modalities for Failed Back Surgery Syndrome
Oral Pain Medications
All patients with recurrent back pain should be offered a regimen of pain management for chronic and breakthrough pain plus physical therapy (Table 5). Non-steroidal anti-inflammatory drugs (NSAIDs) have been convincingly shown to be more effective than placebo. There also are no documented differences in pain control for back pain between NSAIDs, narcotic analgesics, or muscle relaxants. In one study, pain relief from the combination of a NSAID and a muscle relaxant was not different from a NSAID alone in the management of low back pain.
Muscle relaxants have a number of side effects, and their use in the treatment of chronic low back pain is limited. In a meta-analysis, antidepressant treatment was found to be more effective than placebo in reducing pain severity, but not functional status, in chronic back pain.
If oral regimens are not effective in pain management and surgery is not indicated, contraindicated, or delayed, consultation with a pain management specialist may be useful.
Table 5Typical Oral Pain Management Regimens for Low Back Pain
Drugs for Use Each 24-h Period Maintenance
Drugs for Use Every 4-6 h Breakthrough Pain
Naproxyn sodium 250-500 mg twice a day plus a proton pump inhibitor with or without nortriptyline 25-150 mg/day
Codeine SO4 (30-60 mg) or Hydrocodone (5 to 10 mg) or Oxycodone (5-10 mg)
Celecoxib 100-200 mg twice a day with or without nortriptyline 25-150 mg
Physical therapy has been shown to be effective at decreasing pain and improving function in adults with chronic low back pain in several meta-analyses or randomized controlled trials
(Table 6). The Philadelphia Panel Evidence-Based Clinical Practice Guidelines on Selected Rehabilitation for Low Back Pain found rehabilitation to be beneficial for chronic, subacute, and postsurgery low back pain.
On the other hand, one randomized clinical trial on low back pain that did not include patients with failed back surgery syndrome, found only limited benefit for either physical therapy or chiropractic manipulation, and showed no difference between those therapies and use of an educational booklet on low back pain management.
Table 6Typical Physical Therapy Prescription for Chronic Low Back Pain
Problem
Physical Therapy Program
Herniated nucleus pulposus
Core strengthening (trunk muscle strengthening, including isometric abdominal and paravertebral muscles and back extensors) with McKenzie isometric program
If patients still experience incapacitating symptoms after physical therapy, epidural steroid injections (see below) may be considered. After 6 months of pain management and physical therapy, other treatments should be considered.
Other Nonsurgical Treatments
Other options for treatment of failed back surgery syndrome include spinal cord stimulation, radiofrequency neurolysis, and rehabilitation programs. There are no controlled studies on the effectiveness of these treatments in failed back surgery syndrome.
Spinal cord stimulation has a role in the management of failed back surgery syndrome.
After implantation, the spinal cord stimulator generates an electric impulse near the dorsal surface of the spinal cord and induces a tingling sensation that alters the perception of pain by the patient.
In one retrospective study of patients with failed back surgery syndrome, spinal cord stimulation was more effective than re-operation at 3 years of follow-up.
However, 34% of patients who received a spinal cord stimulator had complications such as infections and lead wire or electrode dysfunction. In a systematic review of patients with failed back surgery syndrome, spinal cord stimulators reduced pain 50% or more in 37.5% of patients, compared with 11.5% of patients undergoing revision surgery.
Other studies have suggested that spinal cord stimulators provide sustained, long-term reduction in pain levels at 50% or more in over 60% of patients.
Radiofrequency neurolysis has been shown to reduce pain lasting as long as 3 years, however, there are no studies comparing this procedure to re-operation.
A systematic review suggested that an intensive, multidisciplinary rehabilitation program involving physical therapists also improved function and reduced pain.
The authors concluded that rehabilitation for patients with failed back surgery syndrome must be intensive, multidisciplinary, involve pain management, psychological support, exercise, and occupational therapy, and be focused on return to work. A meta-analysis found that exercise therapy is effective at decreasing pain and improving function in adults with chronic low back pain.
The average number of patients undergoing revision surgery ranged from 102 to 182, with an average follow-up of 1-28 years. The percentages of “good” or “successful” outcomes ranged from 22% to 80%. Outcomes varied greatly, depending on the length of follow-up. One study demonstrated a decrease in the successful outcome from 80% at 2 years to 22% at 28 years,
The decision to perform additional back surgery is based on the failure to relieve back pain with nonsurgical techniques, the development of new neurologic findings, an appropriate diagnosis of the cause of ongoing symptoms, the patient’s understanding of the risks and benefits of further surgery, and the surgeon’s willingness to perform further surgery on the patient (Table 7). If the decision to perform surgery is made, we feel the type of surgery should be decided upon jointly by the surgeon and the patient so that realistic expectations are completely understood.
Lumbar spinal fusion is usually the procedure performed (Figure 2). However, studies have shown that the incidence of reoperation after lumbar spine surgery is 19% within 11 years and that the incidence of reoperation was higher following fusion than decompression alone (21.5% vs 18.8%, respectively).
Figure 2Spinal fusion is performed to relieve pain and other neurologic symptoms of spondylolisthesis. When spondylolisthesis is present, the entrapped nerves are decompressed by laminectomy before the placement of bone-grafts between transverse processes of adjacent verterbrae and between the posterior elements of the vertebrae. If there is disc herniation, the protruding disc segment is removed at the same time. Various metal devices may also be used to stabilize the vertebrae. Reproduced from Deyo RA. Back surgery—who needs it? N Engl J Med. 2007;356(22):2242.
Patients who have undergone spinal fusion and require a second procedure have worse clinical and functional results than patients who did not undergo fusion.
In one study, the overall rate of failure of repair of pseudoarthrosis, defined by a need for another operation for continued functional disability, was 30% for fusion patients and 37.7% for nonfusion patients.
Repair also infrequently led to improvement in pain. Female sex, history of disability, compensation or pending litigation, multiple previous surgeries, perineural scarring, history of psychosocial problems, pseudoarthrosis, and lack of preoperative objective findings have been associated with a poor outcome.
There are no prospective controlled studies to guide the physician in the comprehensive management of patients with failed back surgery syndrome, although a few randomized controlled trials address modalities in the symptomatic treatment of failed back surgery syndrome.
We suggest a standardized approach based on a collaboration among a primary care physician, back surgeon, physical therapist, psychiatrist and, if required, a pain management specialist in the management of these patients (Figure 3).
Figure 3Algorithm for management of failed back surgery syndrome.
A condition resulting from extrusion of the nucleus pulposus from the fibrous cover of the disc. This is associated with parethesias relieved by lying down.
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