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Background: Despite the evident progress in treating vertebral column degenerative diseases, the rate
of a so-called “failed back surgery syndrome” associated with pain and disability remains relatively high.
However, this term has an imprecise definition and includes several different morbid conditions following
spinal surgery, not all of which directly illustrate the efficacy of the applied technology; furthermore,
some of them could even be irrelevant.
Objective: To evaluate and systematize the reasons for persistent pain syndromes following surgical
nerve root decompression.
Study Design: Prospective, nonrandomized, cohort study of 138 consecutive patients with radicular
pain syndromes, associated with nerve root compression caused by lumbar disc herniation, and resistant
to conservative therapy for at least one month. The minimal period of follow-up was 18 months.
Setting: Hospital outpatient department, Russian Federation
Methods: Pre-operatively, patients were examined clinically, applying the visual analog scale (VAS),
Oswestry Disability Index (ODI), magnetic resonance imaging (MRI), discography and computed
tomography (CT). According to the disc herniation morphology and applied type of surgery, all participants
were divided into the following groups: for those with disc extrusion or sequester, microdiscectomy was
applied (n = 65); for those with disc protrusion, nucleoplasty was applied (n = 46); for those with disc
extrusion, nucleoplasty was applied (n = 27). After surgery, participants were examined clinically and
the VAS and ODI were applied. All those with permanent or temporary pain syndromes were examined
applying MRI imaging, functional roentgenograms, and, to validate the cause of pain syndromes,
different types of blocks were applied (facet joint blocks, paravertebral muscular blocks, transforaminal
and caudal epidural blocks).
Results: Group 1 showed a considerable rate of pain syndromes related to tissue damage during the
intervention; the rates of radicular pain caused by epidural scar and myofascial pain were 12.3% and
26.1% respectively. Facet joint pain was found in 23.1% of the cases. Group 2 showed a significant rate
of facet joint pain (16.9%) despite the minimally invasive intervention. The specificity of Group 3 was the
very high rate of unresolved or recurred nerve root compression (63.0%); in other words, in the majority of
cases, the aim of the intervention was not achieved. The results of the applied intervention were considered
clinically significant if 50% pain relief on the VAS and a 40% decrease in the ODI were achieved.
Limitations: This study is limited because of the loss of participants to follow-up and because it is
nonrandomized; also it could be criticized because the dynamics of numeric scores were not provided.
Conclusion: The results of our study show that an analysis of the reasons for failures and partial effects
of applied interventions for nerve root decompression may help to understand better the efficacy of the
interventions and could be helpful in improving surgical strategies, otherwise the validity of the conclusion
could be limited because not all sources of residual pain illustrate the applied technology efficacy. In the
majority of cases, the cause of the residual or recurrent pain can be identified, and this may open new
possibilities to improve the condition of patients presenting with failed back surgery syndrome.
Key words: microdiscectomy, nucleoplasty, epidural scar, facet joint pain, recurrent herniation,
myofascial pain
Pain Physician 2011; 14:545-557
Prospective Study
An Analysis of Reasons for Failed Back
Surgery Syndrome and Partial Results after
Different Types of Surgical Lumbar Nerve Root
Decompression
From: 1Municipal Hospital 39
of Nizhniy Novorod, Russian
Federation; 2Municipal Hospital
13 of Nizhniy Novorod, Russian
Federation; and 3Scientific
Research Institute of Traumatology
and Orthopedics, Nizhny
Novgorod, Russian Federation.
Dr. Bokov is scientific officer
and neurosurgeon with
Scientific Research Institute of
Traumatology and Orthopedics,
Nizhniy Novgorod. Dr. Istrelov is
a neurosurgeon with Municipal
Hospital 13 of Nizhniy Novgorod.
Mr. Skorodumov is with
Municipal Hospital 39 of Nizhniy
Novgorod. Dr. Aleynik is scientific
officer and neurosurgeon with
Scientific Research Institute of
Traumatology and Orthopedics,
Nizhniy Novgorod. Dr. Simonov
is a neurosurgeon with Municipal
Hospital 39 of Nizhniy Novgorod.
Dr. Mlyavykh, is a neurosurgeon
with Scientific Research
Institute of Traumatology and
Orthopedics, Nizhniy Novgorod.
Address correspondence:
Dr. Andrey Bokov
Scientific Officer
Scientific Research Institute of
Traumatology and Orthopedics
2nd Neurosurgical Department
Moskovskoye Shosse-144
Nizhny Novgorod
Russian Federation
E-mail:
Andrei_Bokov@mail.ru
Disclaimer: There was no
external funding in the
preparation of this manuscript.
Conflict of interest: None.
Manuscript received: 06/19/2011
Revised manuscript received:
09/18/2011
Accepted for publication:
10/19/2011
Free full manuscript:
www.painphysicianjournal.com
Andrey Bokov, PhD1, Alexey Istrelov, PhD2 Alexander Skorodumov, PhD1, Alexander Aleynik,3
Alexander Simonov, PhD1, and Sergey Mlyavykh, PhD1
www.painphysicianjournal.com
Pain Physician 2011; 14:545-557 • ISSN 1533-3159
Pain Physician: November/December 2011; 14:545-557
546 www.painphysicianjournal.com
can be associated with the limitations or disadvantages
of the applied type of surgery. Some of them represent
mostly the naturally determined development of the
disease or even could be irrelevant to the assessment
of the technology efficacy. This analysis of the reasons
for failed back surgery syndrome may help to under-
stand better the clinical efficacy of different surgical
techniques and to elaborate rational surgical strategies
with clear guidelines for performing different surgi-
cal techniques. Therefore, theobjective of the present
study is to evaluate and to systematize the reasons for
persistent pain syndromes after different types of surgi-
cal nerve root decompression.
Methods
Study design
This is a prospective, nonrandomized cohort study
of patients presenting with radicular pain associated
with nerve root compression caused by disc herniation.
The participants underwent surgical interventions dur-
ing the period from March 2006 to October 2007; 88
patients were treated with nucleoplasty and 74 with
microdiscectomy. The results of microdiscectomy were
analyzed in 65 participants (88%) and the results of nu-
cleoplasty in 73 participants (83%). Potential benefits,
risks, advantages and disadvantages were explained,
and written informed consent was received from all
participants (concerning the applied type of surgery
and participation in the present study).
Inclusion criteria
Patients with pain syndromes caused by nerve root
compression associated with lumbar disc herniation re-
sistant to at least one month of conservative therapy
(including different types of blocks including selective
transforaminal nerve root blocks with corticosteroids)
were selected for this study. The inclusion criteria were
a pain intensity of no less than 40 on the 100-point Vi-
sual Analog Scale (VAS) and at least a 40% decrease
on the Oswestry Disability Index (ODI). Patients were
standardized by neurological deficit and only those
with a mild neurological deficit were selected. Written
informed consent was received from all participants.
Exclusion criteria
The exclusion criteria were litigation, uncontrolled
psychological disorders, severe or progressive neurolog-
ical deficit, and other serious pathological conditions
which might impact the results. Those with evidence of
Despite the evident progress in treating
vertebral column degenerative diseases, many
problems remain unresolved, and the rate
of failed back surgery syndrome after surgical nerve
root decompression remains considerable (1-9). The
term “failed back surgery syndrome” has an imprecise
definition and includes different morbid conditions
following spinal surgery that are associated with
persistent pain and disability (1-3). According to the
results of different studies, the rate of such cases varies
from 10% to 40% (10-16) and the following reasons are
likely to be the most frequent: nerve root compression
caused by recurrent disc herniation or retained disc
fragment; epidural fibrosis; lateral and foraminal
stenosis; segment instability; progressive facet joint
degeneration; and myofascial pain (1-3,17-26).
The rate of nerve root compression caused by re-
current disc herniation ranges from 5 to 26% of micro-
discectomies and the frequency is sometimes reported
to be as high as 38% (14,15,27-32).
Epidural fibrosis is a progressive disease, which is
associated with radicular pain and unfavorable out-
comes after surgery. It has been reported that the rate
of this source of pain accounts for up to 20-36% of
all cases with failed back surgery syndrome presenta-
tion (1-9,14,15,33,34). It has been determined that this
pathological process may develop as a response to tis-
sue damage during the intervention (33,34); it also has
been established that retained hematomas are likely to
develop into scar tissue (35). Additionally, some studies
have indicated that the material of the nucleus pulpo-
sus itself is capable of initiating aseptic inflammation in
the epidural space and thus contributing to a progres-
sive epidural fibrosis formation (36,37).
Some causes of persistent pain syndromes follow-
ing surgery are likely to be associated mostly with the
progression of degenerative changes; among them
are spinal stenosis, facet joint degeneration, and seg-
ment instability. According to the results of other stud-
ies, the degenerative processes in a disc leading to disc
height loss may provoke degeneration of other struc-
tures of the vertebral segment (17,42,47), finally result-
ing in different types of stenosis or segment instability
(17,44,48-50).
Given this history, it was felt that an analysis of the
reasons for failed back surgery syndrome as a supple-
ment to the earlier studies which have had the objec-
tive of evaluating the efficacy of different surgical tech-
nologies focused on nerve root decompression could be
helpful because not all of the reasons for this failure
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Reasons for Pain Syndrome After Lumbar Nerve Root Decompression
spinal stenosis, infection, tumors, or segment instability,
and those with spinal surgery in anamnesis (any type)
were excluded.
Participants’ examination.
Before the interventions, all participants were
given a neurological examination; initially all of them
presented with compressive radicular pain pattern
(prevalence of leg pain corresponding to the relevant
autonomous zone of innervation).
All participants were examined preoperatively ap-
plying the VAS (scale 0-100 was applied) and Oswestry
disability questionnaire V1 (51-53). All patients under-
went magnetic resonance imaging tomography (MRI
tomography). According to the results of MRI tomogra-
phy, disc herniations were classified as a disc protrusion if
the greatest distance between the edges of disc material
displaced from the disc space was less than the distance
between the edges of the base measured at the same
plane (contained disc herniation) and was classified as an
extrusion (uncontained disc herniation) when displaced
disc material beyond the outer annulus had the maximal
size at any plane greater then the distance between the
edges of the base at the same plane on MRI images (54).
Discography was utilized to certify if disc herniation was
contained or not.
Surgical interventions
Nucleoplasty was performed by several surgeons in
sterile conditions under the guidance of fluoroscopy; 6
channels were created within the disc using a radio-
frequency wand applying ablation and coagulation
mode. The surgical technique was standard without ac-
ceptance of any variances; the standard technique has
been described in several manuscripts (55-57).
All microdiscestomies were performed by the same
surgeon using a standard technique: transmuscular
translaminar approach was applied in order to diminish
tissue damage; there were no cases with damage of ve-
nous vessels during the intervention and no diathermy
was used in the epidural space. The reconstruction of
the lateral channel was performed in case of narrowing
by hypertrophied facet joints and osteophytes. Abso-
lute hemostasis was achieved in all cases.
Outcome measures
Participants were examined after one month, 3
months, 6 months, 12 months, and 18 months. No less
than 50% pain intensity relief on the VAS and at least
40% decrease on the ODI were considered to be clini-
cally significant; among them, cases with total pain re-
lief were registered (25). The results were considered
unsatisfactory in case of unresolved or recurred nerve
root compression on the same level after the interven-
tion. All cases with temporary, recurrent, or permanent
pain syndromes after surgical interventions were ana-
lyzed. In order to validate the source of pain in these
cases, MRI imaging, functional roentgenograms, com-
puted tomography (CT) myelograms, diagnostic facet
joint blocks, caudal epidural blocks, transforaminal se-
lective nerve root blocks, and blocks of the paraverte-
bral muscles were applied during the follow-up period
in order to evaluate the reasons for persistent pain syn-
dromes after the different types of surgery.
The recurrence of disc compression was confirmed
by the results of MR tomography. For validation of oth-
er sources of pain, different types of blocks were ap-
plied repeatedly and in cases of a combination of pain
sources, appropriate types of diagnostic blocks were
administered.
Diagnostic facet joint blocks were performed twice
in sterile conditions under the guidance of fluoroscopy
with 2 different anesthetics and different action times.
Needles were introduced using standard landmarks
for the medial branch location (junction of the upper
border of the transverse process base and the lateral
border of the upper articular process base). At least 2
of the adjacent medial branches – the nerve supply of
the supposed source of pain – were blocked on each
side. No more than 0.5 mL of anesthetic was injected
to block each medial branch. Different types of anes-
thetic were used repeatedly (novocaine, lidocaine, bu-
pivacaine). Repeated diagnostic facet joint blocks with
different types of anesthetics are known to be the only
valid diagnostic method to confirm the facet joint as
the origin of pain (21,58,59). At least 50% pain relief
on the VAS during the time of anesthetic action was
considered to be diagnostically significant for the vali-
dation of facet joint pain.
In cases when myofascial pain was suspected, para-
vertebral muscle blocks with anesthetic and corticoste-
roid were performed in order to block trigger zones,
terminate muscular spasm, diminish the inflammatory
process, and perform a hydraulic dissection of a post-
operative scar. No less than 50% pain relief on the VAS
after the procedure was the criteria for the myofascial
origin of pain.
In the case of radicular pain syndrome after sur-
gery, caudal epidural blocks, transforaminal blocks and
percutaneous adhesiolysis were administered; those
Pain Physician: November/December 2011; 14:545-557
548 www.painphysicianjournal.com
interventions are known to be positive in regards to
short-term and long-term pain relief in patients pre-
senting with failed back surgery syndrome (59,60).
The diagnosis of epidural adhesive process was mostly
based on the combination of radicular pain correspond-
ing to the relevant autonomous zone of nerve root in-
nervation and the results of the MRI imaging showing
epidural scar formation. In those cases, caudal epidural
and transforaminal nerve root blocks with corticoste-
roids and hydraulic dissection of epidural structures
with saline solution anesthetics provided partial pain
relief. No less than 50% pain relief on the VAS was con-
sidered clinically significant.
Statistical analysis
For datasets presented in dichotomized scale,
Fisher`s exact test was applied. If a statistically signifi-
cant difference was established, the logistic regression
analysis was applied (quasi-Newton algorithm). The
power analysis was performed twice: once when plan-
ning this study in order to calculate a sample size and a
posteriori by applying the Monte Carlo method.
Results
According to the disc herniation morphology and
the applied surgical intervention, all participants were
divided into the following subgroups:
For those with a nerve root compression caused by
disc extrusion or sequester: microdiscectomy was ap-
plied (n = 65) – Group 1.
For those with a nerve root compression caused
by contained disc herniation – disc protrusion. In these
cases no contrast medium leakage beyond the disc
space was evaluated during the discography, thereby
confirming the disc herniation continuity: Nucleoplasty
was applied in all cases (n = 46) – Group 2.
For those with a nerve root compression caused
by uncontained herniation - disc extrusion. These par-
ticipants insisted on having nucleoplasty instead of mi-
crodiscectomy. The morphological type was confirmed
by MRI images and discography (the contrast medium
leakage into the epidural space was evident) (n = 27) –
Group 3.
Demographic characteristics are represented in Ta-
ble 1. Table 2 shows the percentage of participants with
total pain relief without any temporary or permanent
pain syndromes presentation and those who presented
at least satisfactory results throughout all the period of
follow-up during 18 months.
Comparing Groups 2 and 3 it is possible to conclude
that in the case of a total annulus disruption, the rate
of clinically significant results and total pain relief after
nucleoplasty is lower (the statistical significance was P =
0.0049 and P = 0.0024 respectively).
Table 1. Demographic characteristics of patients’ groups.
Group 1 Group 2 Group 3
N 65 46 27
Females 33 (50.8%) 15 (32.6%) 15 (55.5%)
Males 32 (49.2%) 31 (67.4%) 12 (44.4%)
Smoking 48 (73.8%) 22 (47.8%) 18 (66.7%)
Age m=43.55±1.3001
SD=10.48
m=43.9783±1.7327
SD=11.7521
m=41.22±2.0481
SD=10.64
Table 2. The rate of stable clinically significant results (at least satisfactory) and total pain relief in different groups of patients.
Group 1 Group 2 Group 3
N 65 46 27
At least satisfactory results 61 – 93.8%
95% CI (85%-98.3%)
36 – 73.8%
95% CI (58.9%-85.7%)
12-44.4%
95% CI (25.5%-64.7%)
The rate of total pain relief 36 – 55.4%
95% CI (42.5%-67.5%)
24 - 52,2%
95% CI (37%-67.1%)
4 – 14.8%
95% CI (4.2%-33.7%)
The rate of cases with pain
syndromes presentation
44.7%
95% CI (32.3%-57.4%)
47.8%
95% CI (32.9%-63.0%)
85.2%
95% CI (66.3%-95.2%)S
Note: All cases with permamanent and temporary pain syndromes were registered.
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Reasons for Pain Syndrome After Lumbar Nerve Root Decompression
To test the observed differences logistic regres-
sion analysis was performed and statistically significant
models were estimated for the rates of total pain relief
and clinically significant results:
Parameters of the regression model for clinically
significant results rates, Group 2 versus Group 3: Β0=
–2.7850; 95% CI [–4.4065; –1.1635], P = 0.001. Odds ra-
tio = 4.50; 95% CI [1.5731; 12.8727]. Goodness-of-fit χ2
= 8.56212, P = 0.0034.
Parameters of the regression model for total pain
relief rates, Group 2 versus Group 3: Β0 = –3.6270; 95%
CI [–5.8627; –1.3932], P = 0,0018. Odds ratio = 6.2727;
95% CI [1.8328; 21.4677]. Goodness-of-fit χ2 = 10.8693,
P = 0.00098.
Statistically significant regression coefficients con-
firm the association of observed differences and disc
herniation morphology as explanatory factor.
Comparing Groups 1 and 3 it is possible to conclude
that nucleoplasty is less effective than microdiscectomy
in case of uncontained disc herniations (statistical sig-
nificance for differences of at least satisfactory results
and total pain relief rates presented in Table 2 was P <
0.0001). This conclusion is supported by the results of
logistic regression analysis.
Parameters of the regression model estimated for
the rates of clinically significant results, Group 1 versus
group 3: Β0 = –5.6723; 95% CI [–7.8636; –3.4810], P <
0.0001. Odds ratio = 19.0625; 95% CI [2.2870; 68.7301].
Goodness-of-fit χ2 = 26.564, P < 0.0001.
Parameters of the regression model for total pain
relief rates, Group 1 versus group 3: Β0= –2.1816; 95%
CI [–3.6452; –0.7181], P = 0.0039. Odds ratio = 7.1379;
95% CI [2.1820; 23.3507]. Goodness-of-fit χ2 = 13.963,
P = 0.00019. Statistically significant regression coeffi-
cients confirm that observed differences are associated
with the type of the applied surgery.
According to the datasets represented in Table 2,
the rate of patients presenting temporary, partially re-
solved, or unresolved pain syndromes throughout all the
period of follow-up achieved 44.6% in Group 1; formed
47.8% in Group 2; and came to 85.2% in Group 3.
In cases of nerve root compression caused by recur-
rent disc herniation or retained disc fragment and cases
of epidural fibrosis, pain syndromes were presented
by radicular pain in the lower limbs corresponding to
the relevant autonomous zone of innervation of the
affected nerve root. In other cases, the pain syndrome
changed to a noncompressive type profile with the
prevalence of low back pain with irradiation to the but-
tocks or lower limbs without correspondence to exact
autonomous zones of nerve root innervation.
The overall frequencies of different residual pain
causes after different types of surgery evaluated
throughout the 18 month period of follow-up are pre-
sented in Table 3. According to these results, it is possi-
ble to conclude that each group has distinctive features
in regards to the structure of residual pain syndrome
sources.
Group 1
This group can be distinguished by the significant
rate of epidural scar formation associated with radic-
ular pain (verified in 8 cases – 12.3%), the significant
rate of myofascial pain which was identified in 17 cases
(26.1%), and the high rate of facet joint pain (verified
in 15 cases – 23.1%). It should be mentioned that in 16
cases (24.6%) there was a combination of pain sources:
the combination of epidural fibrosis and segment in-
stability was verified in one case; the combination of
epidural fibrosis and myofascial pain in 7 cases; epidur-
al fibrosis and facet joint pain in one case; and a the
combination of myofascial pain and facet joint pain in
7 cases.
Group 2
In this group, the rate of myofascial pain was rela-
tively low (6.5% - 3 cases); however, the rate of facet
joint pain was significant despite the minimal surgical
aggression. This source of pain was verified in 11 cases
(16.9%).
Table 3. The rates of different causes of pain syndromes after surgical nerve root decompression directly or indirectly related to the
applied surgery.
Recurrent Disc Herniation or
Retained Fragment
Epidural Scar
Formation
Instability of
Vertebral Segment
Facet Joint
Pain
Myofascial
Pain
Group 1 n=65 3 (4.6%) 8 (12.3%) 2 (3.1%) 15 (23.1%) 17 (26.1%)
Group 2 n=46 4 (8.7%) 0 (0%) 3 (6.5%) 11 (16.9%) 3 (6.5%)
Group 3 n=27 17 (63.0%) 0 (0%) 0 (0%) 6 (22.2%) 2 (7.4%)
Note: Cases with the onset of pain syndromes irrelevant to the applied surgery were excluded from the analysis.
Pain Physician: November/December 2011; 14:545-557
550 www.painphysicianjournal.com
Group 3
The specificity of this group was the high rate of
unresolved nerve root compression or recurrent disc
herniation (verified in 17 cases – 63.0%), facet joint
pain was determined in 6 cases (22.2%), myofascial pain
in 2 cases (7.4%), the combination of facet joint pain
and myofascial pain was diagnosed in 2 cases.
Comparing these groups of patients, it is possible
to conclude that Group 1 differs from Group 2 by a sig-
nificant rate of epidural scar formation (P = 0.0199) and
by a significantly higher rate of myofascial pain presen-
tation (P = 0.0110), however no difference in the rate
of facet joint pain was found in these 2 groups (P =
0.9988).
Group 3 can be distinguished from Group 1 and
Group 2 by the high rate of recurrent or unresolved
nerve root compression (P < 0.0001 in both cases), the
prognostic value was confirmed by significant logistic
regression models.
Group 1 versus Group 3, parameters of the regres-
sion model: Β0 = –5.6723; 95% CI (–9.0678; –4.1076), P <
0.0001. Odds ratio = 35.1333; 95% CI (8.5159; 144.7458).
Goodness-of-fit χ2 = 36.432, P < 0.0001.
Group 2 versus Group 3, parameters of the regres-
sion model: Β0 = -5.2334; 95% CI (-7.46724; -2.999517),
P < 0.0001. Odds ratio = 17.85; 95% CI (4.806283;
66.2929). Goodness-of-fit χ2 = 24.833, P < 0.0001.
Analyzing the difference in the myofascial pain rate
observed in Groups 1 and 2, it is possible to conclude that
this cause of pain syndrome is associated with a more
aggressive intervention. Estimated parameters of logistic
regression model for myofascial pain difference:
Β0 = -4.287188; 95% CI (-6.719846; -1.85453), P =
0.0007. Odds ratio = 5.0764; 95% CI (1.3710; 18.8026).
Goodness-of-fit χ2 = 7.8241, P = 0.0052.
Different types of causes of the persistent pain syn-
dromes can be illustrated by the following cases.
Case 1
Before the intervention, this participant (Group 2)
presented a typical radicular pain pattern correspond-
ing to the L5 autonomous zone of innervation. MRI to-
mography diagnosed a protrusion on the level L4-5 and
also signs of spondyloarthrosis were evident (Fig.1). Af-
ter nerve nucleoplasty, there was more than a 50-point
decrease in VAS and ODI scores. The residual pain syn-
drome was mostly axial and there was no evidence of
unresolved nerve root compression. Control MRI tomo-
grams showed a decrease in disc protrusion size after
nucleoplasty (Fig. 2). Facet joint pain was confirmed by
diagnostic blocks and this residual pain syndrome in
this case does not illustrate the inability of nucleoplasty
to provide total pain relief because nerve root compres-
sion was resolved.
Fig. 1. Case 1 MRI before nucleoplasty. Fig. 2. Case 1 MRI after nucleoplasty.
www.painphysicianjournal.com 551
Reasons for Pain Syndrome After Lumbar Nerve Root Decompression
Case 2
This participant presented a typical compressive
radicular pain pattern at L5 and disc extrusion was di-
agnosed on the level L4-5. (Fig. 3 represents MR to-
mograms one month before the intervention). After
microdiscectomy, total pain relief was achieved. How-
ever, after 5 months passed, pain recommenced. Pain
was mostly axial with irradiation to the buttock and
posterior hip areas. Control MR tomograms showed
only a significant progression of the spondyloarthrosis
(Fig. 4 represents MR tomograms 6 months after the
intervention) and facet joint pain was confirmed by
the results of diagnostic facet joint blocks. In this case
disc extrusion formation and consequent microdiscec-
tomy resulted in a disc space narrowing, finally result-
ing in an apparent increase in load on the facet joints;
thereafter, the progression of the spondyloarthrosis is
expected.
Case 3
This participant (Group 1) presented a severe ra-
dicular pain and a large disc sequester was diagnosed
by the MR tomograms at the level L5-S1. Figs. 5 and 6
represent MR tomograms before the intervention. In
Fig. 3. Case 2 MRI before the microdiscectomy. Fig. 4. Case 2 MRI 6 months after the microdiscectomy.
Fig. 5. Case 3 MRI before the microdiscetomy. Fig. 6. Case 3 MRI before the microscectomy
Pain Physician: November/December 2011; 14:545-557
552 www.painphysicianjournal.com
this case, microdiscectomy was applied and the result
was unsatisfactory because of the epidural fibrosis for-
mation and progression of the degenerative changes
resulting in a retrospondylolisthesis. Figures. 7 and 8
represents MR tomograms 4 months after microdis-
cectomy. In this situation, microdiscectomy was insuf-
ficient to achieve total pain relief and segment fusion
was required. However, this case mostly illustrates the
biomechanical disadvantage of the intervention.
Case 4
As mentioned above, some cases with pain pre-
sentation after surgery were excluded from the analy-
sis. This case illustrates the type of pain syndrome not
related to the applied type of surgery and thereafter
excluded from the analysis. This participant presented
a typical radicular S1 pain pattern and disc extrusion
was confirmed by the results of MR tomography (Figs.
9, 10). In this case, microdiscectomy was applied. After
Fig. 7. Case 3 MRI after microdiscectomy. Fig. 8. Case 3 MRI after microdiscectomy.
Fig. 9. Case 4 MRI before microdiscectomy. Fig. 10. Case 4 MRI before microdiscectomy.
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Reasons for Pain Syndrome After Lumbar Nerve Root Decompression
12 months had passed, pain recommenced; however, it
was associated with disc degeneration on the adjacent
level (Fig. 11). In this case, the recurrent pain syndrome
was irrelevant in regards to the applied surgery. Those
types of cases were excluded from the presented analy-
sesin order to avoid bias.
disCussion
Nucleoplasty applying coblation technology has
been widely introduced into clinical practice since 2000;
the reported rate of clinically significant results were
scattered from 56% to 88%. In all cases the conclusions
concerning the efficacy of the applied technologies
were based on the analysis of pain-associated numeric
scores dynamics (VAS, ODI) and none of the manu-
scripts provided the explanation for the partial results
and failures. Finally, it is impossible to explain such a
wide range of reported clinically significant results (55-
57,60-62). Even if an analysis of total pain relief and
clinically significant results is performed, it is impossible
to figure out the reason for the observed differences; in
other words, whether it was a result of an unaccounted
for factor of the groups’ inequality or whether an unfa-
vorable prognostic factor was present in some studies.
In studying the efficacy of the applied technolo-
gies, first of all it is necessary to define if the applied
intervention is capable of providing stable nerve root
decompression in the particular cases studied. The
results of our study show that nucleoplasty, being ef-
fective in cases of contained disc herniation, failed to
provide stable nerve root decompression in the major-
ity of cases when nerve root compression was caused
by uncontained disc herniation (disc extrusion), while
the results of microdiscectomy in the same situation
were considerably better despite the higher invasive-
ness and biomechanical disadvantages. By analyzing
the rates of cases when unresolved or recurred nerve
root compression was present, it is possible to make a
valid conclusion that total annulus disruption is a limi-
tation for the nucleoplasty indication because of the in-
ability to provide stable nerve root decompression and
not because of any other factors. This type of analysis
is closely related to the analysis of the clinically signifi-
cant results rate and has the advantages of comparing
with analysis based on the pain related numeric scores
dynamics (ODI, VAS), especially in case when a consid-
erable number of different interventions were applied
during the follow-up period to manage the residual
pain. The analysis based on pain related scores dynam-
ics (VAS and ODI) represents the agglomerative analysis
Fig. 11. Case 4 MRI one year after microdiscectomy.
of specific and nonspecific factors influence thereafter
the statistical significance of observed effects could be
decreased. For example, when the ability of the applied
intervention to provide stable nerve root decompres-
sion was tested, the estimated regression models were
of a higher statistical significance than those estimated
analyzing the rates of clinically significant results based
on VAS and ODI scores dynamics.
The next category of reasons for pain syndromes
after surgical nerve root decompression is related to tis-
sue damage during the intervention. However, the fre-
quency of this kind of pain source illustrates mainly the
technical disadvantage of the applied type of surgery.
Despite tissue damage being minimized during micro-
discectomy and absolute hemostasis being achieved, a
considerable rate of radicular pain associated with fi-
brosis in the epidural space was detected after open
surgery. Myofascial pain is known to be caused by mul-
tiple factors 63,64) and the results of different studies
have supported the hypothesis that myofascial pain
may contribute to failed back surgery syndrome (65,66).
According to the results of our study, the higher rate of
myofascial pain was estimated in the group of patients
treated with microdiscectomy and the association with
a more aggressive type of surgery was proved by the re-
Pain Physician: November/December 2011; 14:545-557
554 www.painphysicianjournal.com
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should be clearly defined when despite the obvious dis-
advantages, open surgery procedures are more effec-
tive than minimally invasive ones, thereby justifying the
rational guidelines among the different technologies.
The third category of persistent pain syndromes is
related to the naturally determined disease develop-
ment; among them are facet joint pain, stenosis, and
segment instability. It was proved that those degen-
erative changes can develop regardless of the type of
surgery (20,39,44,46,48,49). Because of the minimal
number of cases with clinical presentation of stenosis
and segment instability after surgery, the rates of these
pain sources were not analyzed. In contrast, the rate of
facet joint pain was considerable; however, it has been
reported that the higher frequency of facet joint pain
has no association with previously applied lumbar sur-
gery: while the overall prevalence of facet joint pain
achieves 31% with a 95% CI of 28%-33%, the rate of
this source of pain after lumbar surgery was 16% with
a 95% CI of 9-23% (20,21,25,58). Also, it was reported
that there was no relation of the facet joint pain rate
and a number of previous surgeries (20). Even though
the higher frequency of facet joint pain was expected
in the group treated with microdiscectomy because
of more significant loss of disc height, no relationship
of this pain source rate to the applied type of surgery
was found. Despite evidence that this category of pain
sources has a limited specificity in regards to the ap-
plied surgery, detailed analysis could provide significant
information because rapid progression of degenerative
changes is highly associated with altered biomechanics
(67,68). Finally, this analysis may point out indirectly the
biomechanical disadvantages of surgical interventions
(69,73).
Studying the efficacy of different interventions,
it is necessary to analize the reasons for failures and
partial results in order to explain the observed effects
adn finally to understand better the efficacy of applied
technology. This information could be helpful to elabo-
rate the optimal surgical strategies, and this analysis
may help to discover biomechanical and technical limi-
tations. and Their disadvantages could disclose other
factors which could impact the results. Finally, the abil-
ity to identify the main and the secondary sources of
pain makes possible the application of different mini-
mally invasive interventions, supplementing those ap-
plied previously for nerve root decompression, which
may improve the condition of patients presenting with
failed back surgery syndrome.
This study is limited because of the groups’ dispro-
portionate, loss of patients to follow-up, and that it is
nonrandomized. Also, this study could be criticized be-
cause the dynamics of numeric scores were not provid-
ed; however, the main aim was to show different types
of analyses of technology efficacy and the significance
of the additional statistical analysis focused on the eval-
uation of causes of failures and partial results compar-
ing different types of surgical interventions.
ConClusion
The results of our study show that the analysis
of the reasons for failed back surgery syndrome and
partial effects of interventions applied for nerve root
decompression might help to better understand the
efficacy of the interventions and could be helpful for
improving surgical strategies. However, the conclusion
could be limited because not all sources of residual pain
illustrate the efficacy of the applied technology. In the
majority of cases, the cause of the residual or recurrent
pain can be identified, and this may open new possi-
bilities to improve the condition of patients presenting
with failed back surgery syndrome.
aCknowledgMents
The authors would like to thank the editors of Pain
Physician journal for their review and constructive criti-
cism in improving the manuscript.
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