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,
average pain reduction is usually about 33% after single level lumbar
fusion surgery. Multiple level fusion surgeries have an even more dismal
percentage of pain reduction. 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). Overall, for those who undergo
lumbar spine surgery, between 9-11% will have worse pain over the
next 5 years, and 18% will undergo further surgery (Estridge, Roulte,
Johnson, 1982). Postoperative assessment of patients 3-6 years after
decompressive lumbar laminectomy for spinal stenosis indicates a 57-
75% success rate, with a 17-29% rate of re-operation (Katz et al, 1990).
While lumbar stabilization procedures demonstrate a high rate of fusion
(96%), fully 76% continue to have back pain (20 month follow-up)
(Dickman et al, 1992). Ultimately, 25% of patients who undergo
lumbar spinal surgery will never return to work, and 10% will
become permanently disabled. All of these statistics contribute to
what we categorize as the FBSS.
The single most striking factor influencing the outcome of surgery is
poor patient selection prior to the initial operative procedure (Long,
1991). However, as we assess patients with established FBSS a
pattern of failure emerges (Burton, 1981) which includes: (1) Untreated
spinal stenosis,(2)persistent or recurrent disc herniation,(3)
arachnoiditis,(4)epidural scar, (5) neural injury, (6) pseudoarthrosis, and
(7) wrong side/level of the original surgery.
The majority (70%) of patients with recurrent pain after lumbar spinal
surgery show epidural scar on MRI (Ross et al, 1996). In fact, fully 43%
of post-operative patients show scar by MRI at 6 months, but 84% of
these patients are asymptomatic (Ross et al, 1996). Although it has
been long argued that epidural scar cannot play an etiologic role in
FBSS, since it is so common in asymptomatic patients, more recent data
has suggested a strong correlation between the occurrence of epidural
fibrosis and the outcome from lumbar surgery. Post-operative pain may
(DeTribolet et al, 1997) or may not (Zeidman and Long) be alleviated by
reducing epidural fibrosis. Suffice it to say that epidural scarring is a
common finding post-operatively, but has unclear significance. For an
excellent review, goto www.imsn.nl/invconf/html/body_burchiel.html
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. It is notable the authors downplayed
scar tissue in the epidural space as a cause of FBSS and also
discounted muscle necrosis in the spine due to large retactors being
used placing damaging pressure on the muscles of the spine.
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 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, or from the same disc in which a
discectomy was performed. 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, endoscopic annuloplasty, Dynesis, artificial
disc replacement.
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 (epidural
scar tissue) but may also include intraneural (inside the nerve) injury,
damage to the nerve root during retraction of the nerve during surgery,
etc.. 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 (HNP) 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
2.7% Psychological
1.6% Infection
1.6% Recurrent HNP plus Stenosis
1.1% Arachnoiditis
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.
Diagnosis is made by evaluation of continuing symptoms, highly
selective diagnostic blocks, and therapeutic responses. Therapies are
designed to treat the suspected pathology. Advanced therapies include
intrathecal infusion pump implantation and spinal cord stimulation.
