Failed Back Surgery Syndrome
Following open spine surgery, whether it be fusion, discectomy, laminectomy, etc., a small percentage of patients will develop chronic pain in the back and or extremities.These syndromes are often due to identifiable causes but are termed by surgeons and the medical community to be failed back surgery syndrome (FBSS). It is difficult to estimate the incidence of FBSS because different measuring sticks are used by surgeons. For instance, spine surgeons often quote a 98% success rate for fusion surgery. This percentage however refers to the success of the fusion process, not the reduction of pain. In fact, pain reduction is far less than that amount. For single level fusions, the percentage obtaining significant pain relief are 40-80% while with three levels, this drops to approximately 15%. Microdiscectomy is widely quoted by the neurosurgeons as having a 95-98% success rate, however when success is defined is returning to their previous occupations without pain medications, the overall success rate drops to 74%. For workmans compensation patients, the success rate is 29% (Surg Neurol 1998 Mar;49(3):263-7; discussion 267-8).
The most common causes of FBSS based on a retrospective review of 183 consecutive patients with this diagnosis are shown below. This study was presented at the Annual Meeting, North American Spine Society, San Francisco, CA, October, 1998, and performed by Alexis Waguespack M.D., James Reynolds M.D., Jerome Schofferman, M.D. SpineCare Medical Group. Daly City,CA.5% of the causes were unknown.
29% Foraminal and Spinal Stenosis. Residual foraminal stenosis due to inadequate exploration of the nerve root during surgery or due to mechanical destabilization of the disc during enucleation with resultant foraminal disc bulge , residual spinal stenosis due to failure to appreciate the spinal anatomy during surgery. Diagnosis is usually via MRI or CT reconstructed images of the foramina. Therapy is usually re-operation.
16.9% Painful Disc Disease. This condition is due to residual pain emanating from the discs which still retain motion. It can be from the disc above, below, or at the fusion site. Discography will help determine the presence of painful degenerative disc disease at segments on which surgery is contemplated, thereby helping avoid this complication. Therapy may include IDET or re-operation.
14.8% Pseudoarthrosis. Inadequate fusion which leaves a the disc with excessive motion or bone-on-bone across the “fracture line” of the pseudoarthrosis. Inadequate fusion is due to smoking before and after fusion surgery, use of non-steroidal antiinflammatory agents before and after fusion surgery, inadequate surgical stabilization, and other factors. Diagnosis is made by CT or MRI. Functional correlation with the pain can be made by a provocative injection of the pseudoarthrosis. Treatment is by re-operation when absolutely necessary.
9.3% Neuropathic. This category includes peridural fibrosis. Diagnosis is by contrast MRI. In multiple revisions, the incidence of peridural fibrosis increases to above 60%. (Spine 1996 Mar 1;21(5):626-633). (Treatments are outlined under this subject elsewhere.)
6.0% Recurrent Herniated Nucleus Pulposis. This is much more uncommon than in the past due to some surgeons removing part of the central nucleus during microdiscectomy or laminectomy/discectomy in order to prevent the recurrent HNP from occurring. Unfortunately, this may destabilize the disc complex leading to spinal instability.Treatment of this condition is via re-operation.
4.9% Spinal instability. Removal of too much of the central disc, removal of too many supporting ligaments, facets, or operation on multiple segments without fusion may lead to a wobbly spinal segment and painful instability.Diagnosis is by flexion/extension films plus MRI.Treatment is via fusion surgery.
4.4% Painful discs plus foraminal or spinal stenosis
2.7% Painful discs within fusion
1.6% Recurrent HNP plus Stenosis
Other studies list wrong level of operation as a significant reason for FBSS. Some papers attribute up to 25% of the cause being peridural fibrosis (Neurol Neurochir Pol 2000 Sep;34(5):983-993) while others list arachnoiditis as the cause of up to 16% of FBSS.
Acta Med Port 1998 Jan;11(1):59-65 Lumbar arachnoiditis].Ribeiro C, Reis FC) Other significant causes in some studies list job dissatisfaction as a major motivation in returning to work and in continuing complaints about the low back.
Many with FBSS will gravitate from one physician to another and from one specialty to another for years seeking answers to their continuing pain. Some well meaning, but ignorant physicians will tell these patients that there is nothing wrong with their back or that it is all in their heads. As technology has progressed, we know there could be nothing further from the truth. The failure to make the diagnosis causing continued back pain is due to a knowledge deficit, technical advancement deficits, or both.