Failed Back Surgery Syndrome

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Definition/description

Failed back surgery syndrome (FBSS) is a term embracing a constellation of conditions that describes "persistent or recurring low back pain, with or without sciatica following one or more spine surgeries.” A more functional definition is that FBSS results when the outcome of the lumbar spinal surgery does not meet the pre-surgical expectations of the patient and surgeon.

Etiology

“Failed back surgery syndrome (FBSS) is a misnomer, not every FBSS is caused by a surgery, there are a lot of other causes besides surgery” .

The most non-surgical causes include:	Surgically related causes include :
• Herniated nucleus propulsus (HNP) at a non-surgical site • Facet arthrosis • Spinal Stenosis • Spondylolysis with or without Spondylolisthesis • Referred pain. • Myofascial pain • Segment instability	• Epidural haematoma, • Recurrent HNP at the operative site, • Infection such as diskitis, • Osteomyelitis or Arachnoiditis, • Epidural scar • Meningocele or Cerebrospinal fluid (CSF) fistula.

A classification of the etiology of FBSS (surgically related causes) can be done, based on preoperative, intraoperative, and postoperative factors (Table 1). To contribute to the development of FBSS, these factors have to be influenced.

Table 1: Etiology of failed back surgery syndrome Preoperative factors • Patient • Psychological (which are very powerful): anxiety, depression, poor coping strategies, hypochondriasis • Social: litigation, worker compensation • Surgical • Repeated surgery (50% increase in risk in spinal instability ≥ 4 revision) • Inappropriate candidate selection • Inappropriate surgery selection Intraoperative factors • Poor technique (e.g., misplaced screw, inadequate decompression) • Incorrect level of surgery • Inability to achieve the aim of surgery (e.g., foraminal stenosis) Postoperative factors • Progressive disease (e.g., recent disc herniation ) • Epidural fibrosis (this is the cause of 20-36% of the FBSS-patients) • New spinal instability secondary to altered biomechanics (e.g., discectomy) • Surgical complications (e.g., nerve injury, infection, and hematoma) • Myofascial pain development (During surgery, dissection and prolonged retraction of the paraspinal musculature result in denervation and atrophy, this leads to postural changes)

Initial Approach to Failed Surgery Patient

History

• Allow extra time to evaluate initially.
• Essential to have prior records.
• Preoperative vs.Postoperative complaints.
• Did surgery help initially? A period of relief followed by recurrence may indicate: a) recurrence of herniated nucleus pulpous, b) development of lateral stenosis.
• Was there a new problem immediately after surgery?
• Current medication usage and issues of dependency.
• Careful assessment of the psychological status
• Vocational status and workers' compensation
• Post-operative systemic complaints (often subtle)
• Back vs Leg pain.
• Unusual pain pattern (reflex sympathetic dystrophy, complex regional pain)
• Postoperative rehabilitation (aerobic, flexibility, strengthening, body mechanics, physical therapy).
• Relieving and exacerbating positions and activities.

Physical Examination

• Observe closely for pain behaviour as a warning of associated problems.
• Careful neurologic exam for focal localizing findings.
• Evaluate for potential major joint problems as a referral source (hip, knee)
• Palpation at surgery site for hematoma, local fluid, abscess and pseudo meningocele.
• Examination of extremity for sympathetic or Reflex sympathetic dystrophy (RSD) -type changes.
• Screening for neural tension signs (SLR, Adson's test)
• Long tract signs (Babinski's sign, Clonus, Hoffman's sign)
• Vascular assessment (diabetics, elderly patients)
• Local soft tissues (psoas muscle, iliotibial band, gluteal muscles)

Prevention  

This condition has a high impact on the patient and the healthcare system. It is good to know that this condition has a higher prevalence with increasing rates of spine surgery. The impact of FBSS on an individual’s quality of life and individual’s functions are considerable and more disabling when compared with other chronic pain conditions. These findings emphasize the importance of identifying strategies to prevent the development of FBSS and effective management guidelines for the management of established FBSS.
Sometimes surgery doesn’t meet the pre-operative expectations of the patient and surgeon, good communication and education on probable success are necessary to lower the unrealistic expectations. 
Other prevention strategies are:
• Give psychological aid to patients with social and psychological stressors.
• Use a meticulous technique during intervention

Diagnostic Procedures

A detailed assessment is necessary as it provides information in a lot of areas.

History

The most important part of the diagnosis of FBSS is the history, especially :
• The status before the operation
• The type of surgery that was performed
• The pain characteristics: location, time course
• Assessment of red and yellow flags
• Comorbid treatments and history

It is also good to look if the pain is either predominantly in the back or in the leg. Because this gives a high probability of where the pain comes from.

Further the examination has 2 purposes:
1. Ruling out serious pathology
2. Identify the source of pain

Inspection and examination

This inspection includes an assessment of the posture and functions. The lumbar spine has to be well inspected and there have to be taken note of surgical scars and alignment of the vertebrae. Palpation can identify points that elicit pain. Next, the range of motion should be assessed. Muscle power is assessed by resistance testing of each muscle group with a comparison with the corresponding group on the contralateral side. When there is evidence of nerve tension, special tests can be done.

Radiological evaluation of failed back surgery

Radiological examination usually includes X-rays and either MRI or CT scans. Standard radiographs with standing flexion and extension lateral views are used to assess alignment, the extent of degeneration and instability. Plain radiographs can detect spondylolisthesis, but are unable to show spinal stenosis and give information on soft tissues.
Unless the issue is pseudarthrosis, MRI is the optimal exam for most patients with FBSS, in which case CT with multiplanar reformations (CT/multi-planar reconstructions [MPR]) is preferred.

Role of diagnostic injections

The definitive role in the diagnosis of facet (zygapophysial or z-joint) and SIJ pain is played by the anesthetic diagnostic injections. It may be valuable to establish if nerve root compression or inflammation is causing pain.

Discography

Because some discs that look abnormal on MRI are pain generators, but others are not, we can use discography to help determine if a particular disc is the pain generator. One cannot rely on the discography on its own, it must be interpreted in light of the history, examination, radiological testing and other diagnostic injections.

Management / Interventions

The management of patients with FBSS can be challenging for a number of reasons. First, the patient is usually aggrieved about having undergone significant invasive surgery without achieving any symptom reduction or resolution. Not only are they left with the persistent pain for which the surgery was initially offered, but it may seem that there are no other options left. Second, the diagnosis (either initial or subsequent) may not be clear and whereby further treatment may be difficult to plan .

The general management plan for this group of patients should not focus solely on medical therapy. The objectives of management should be directed to the restoration of functional ability, improvement of quality of life, coping strategies, and pain self-management. Optimal care is often difficult because the evaluation of FBSS depends on the subjective symptoms of the patient.

There was strong evidence that function improved with intensive interdisciplinary rehabilitation with functional restoration.

Conservative treatments

Sometimes drug therapy combined with physical reeducation had excellent results, but the success rate is variable and depends from patient to patient.

Pharmacological

Medication should not only be prescribed to reduce pain, it should also facilitate exercises, therapy and enable improvements. Used pharmacological are :
• Acetaminophen
• Nonsteroidal anti-inflammatory drugs (NSAID’s)
• Cyclooxygenase-2 (COX-2) inhibitors
• Tramadol
• Muscle relaxants
• Antidepressants
• Gabapentinoids
• Opioids

The problem with these medications is that their efficacy is often disputed and most of them have considerable side effects

Physiotherapy

It is common that patients with FBSS will become deconditioned. This leads to weakness of the musculature (e.g., transverses abdominis, paraspinal muscles) responsible for maintaining spinal stability. Though different approaches exist, the general aim of exercise therapy is:
• Decrease pain
• Improve posture
• Stabilize the hypermobile segments
• Improve fitness
• Reduce mechanical stress on spinal structures.

An additional benefit is that patients are taught active coping mechanisms with pain, which gives them a sense of control over their predicament . There is however little evidence of the added value of physiotherapy. The best exercise program consists of an individualized, stretching and strengthening program under supervision. Core strengthening can help to reduce pain and to improve stability. Other forms of physical therapy that can be used are spinal manipulation, massage, acupuncture and Tens.

Psychological Therapy: Cognitive behavioral therapy (CBT)

Considering the influence of psychological factors on chronic low back pain (CLBP), it is not surprising that psychological therapy is an accepted component of therapy.

The common components of CBT include the following:
• teaching and maintenance of relaxation skills
• behavioural activation such as goal setting and pacing strategies
• interventions to change perception such as visual imagery, desensitization, or hypnosis
• promotion of self-management perspective

The effectiveness of this therapy in CLBP and chronic pain, in general, has been supported by recent reviews , but no studies specifically addressed the patients with FBSS.

Non-conservative treatment

The non-conservative treatment options are:

• Medial Branch Blocks and Radiofrequency Neurolysis

• Epidural injections :
The evidence for caudal epidural steroid injections was strong for short-term relief and moderate for long-term relief in chronic lumbar radicular pain and radicular pain associated with FBSS.

• Percutaneous  epidural adhesiolysis aims to reduce epidural fibrotic tissue and improve the delivery of epidurally administered drugs to their target tissue. This treatment option has strong evidence for short- and long-term pain relief .Also the functional status improved.

• Surgical options :

1. Spinal cord stimulation (SCS): This technique consists of inserting electrodes into the posterior epidural space of the thoracic or cervical spine ipsilateral to the pain (if unilateral) and at an appropriate rostro-caudal level to evoke the topographically appropriate paresthesia which are a pre-requisite for (but not a guarantee of) success. For this form of treatment there is moderate evidence. When the patients are appropriately selected there is high evidence. They also noted that SCS not only reduces pain, but has several opportunities :
   - It improves functions
   - It improves quality of life
   - Allows to return faster at work
   - It reduces analgesic consumption
   - Minimally invasive
   - Fewer permanent complications
   - Completely reversible
   - Can be screened for responsiveness before placing the electrodes
   - Parameters adjustable after implantation
   - Improvement in gait and muscle strength after 7 days
2. Intrathecal analgesic delivery implant systems: This form of therapy is efficacy, but there is a lack of long-term evidence and some side effects can appear.
3. Revision surgery: The success-rate (22-40%) after reoperation is low and declines after each additional procedure.  Probably the most important aspect of the decision for reoperation is for consultation with an expert spine surgeon with experience with FBSS.

  

Resources

• Chan CW, Peng P. Failed back surgery syndrome. Pain medicine. 2011 Apr 1;12(4):577-606..
• Chou R, Huffman LH. Medications for acute and chronic low back pain: a review of the evidence for an American Pain Society/American College of Physicians clinical practice guideline. Annals of internal medicine. 2007 Oct 2;147(7):505-14.
• Hayek SM, Helm S, Benyamin RM, Singh V, Bryce DA, Smith HS. Effectiveness of spinal endoscopic adhesiolysis in post lumbar surgery syndrome: A systematic review. Pain Physician. 2009 Mar 1;12(2):419-35.
• Schofferman J, Reynolds J, Herzog R, Covington E, Dreyfuss P, O'Neill C. Failed back surgery: etiology and diagnostic evaluation. The Spine Journal. 2003 Sep 1;3(5):400-3.