Clinical trial NCT03801356
Conditions: Back Pain Radiculopathy Lumbar Degenerative Lumbar Spinal Stenosis
Keywords: back pain lumbar spine pain nerve root block foraminotomy radiculopathy lumbar foraminal stenosis
Sponsor: The Cleveland Clinic
Start date: 2018-08-23; Completion date: 2020-12-15
Enrollment: 11 participants; Allocation: NA; Intervention model: SINGLE_GROUP

Brief summary:
SNRB, as measured by the change in pain and objective functional ability, can solicit crucial information regarding a patient's clinical picture and can predict a patient's outcome post-surgery. By using the walk test as an objective functional assessment, the aim is to better standardize the threshold for a positive response to SNRB.

In summary, SNRB, despite utilized frequently in the diagnostic work-up with patients with lumbar radiculopathy, vary widely in their sensitivity and specificity. The reasons, as outlined above, are multifactorial. The proposed study aims to minimize the known limitations of these injections and prospectively define their positive and negative predictive value in a homogenous group of patients undergoing surgery for lumbar foraminal stenosis and radiculopathy. The design will define a threshold of response utilizing both subjective and objective measures and more accurately predict excellent results following surgery.

Detailed description:
The proposed study will identify the threshold response level that quantifies the predictive value of diagnostic SNRBs in patients who present with lumbar foraminal stenosis and radiculopathy. Specifically, the proposed study will address the question of whether there is a degree or length of response to SNRB, which predicts an excellent surgical outcome. The hypothesis is that diagnostic SNRBs, when performed correctly, are useful in localizing the level of involvement in LSS and improve the accuracy and efficacy of surgical intervention. Use of diagnostic SNRBs will thus be used to clarify the clinical picture, giving the surgeon the information to make the right decision to operate or not, and, in the case of operation, predicting the optimal level(s) for surgical intervention. In addition, the investigators plan to identify and fully characterize a standard threshold level and time of nerve block response that will optimize the accuracy, specificity, and sensitivity of SNRB in predicting surgical outcomes.

Arms: arm 1: Patient will receive a Selective Nerve Root Block injection at the target level prior to surgical intervention.
Interventions: intervention 1: Selective Nerve Root Block
Intervention descriptions: intervention 1: Prior to single level foraminotomy for lumbar foraminal stenosis, patients will undergo SNRB of the suspected nerve root. Patients will undergo surgery despite the response to injection. Patients will complete an ambulation assessment immediately before and after the injection. Distance and time will be noted. Patients will be called within 48 hours of injection to determine response to injection, and recorded as Pre-and Post-injection VAS leg as well as duration of the response. Patients will be seen at 6 weeks, 3,6, and 12 months post-surgery and outcome measured by VAS-leg, ODI, PDQ and EQ-5D scores. Data will be used to determine the ideal improvement in leg pain and duration of improvement, predicting a statistical and meaningful improvement in leg pain following foramintomy.

Protocol documents:
Prot_SAP_001.pdf: 
Protocol Title: Threshold Response of Lumbar Selective Nerve Root Block in 
Predicting Good Outcome Following Lumbar Foraminotomy 
Protocol Version: 7/24/2018 
Principal Investigator: Michael Steinmetz, MD 
NCT03801356 


Steinmetz, Michael P.  
Threshold Response of Selective Nerve Root Block 
1
Problem 
Lower extremity radiculopathy due to lumbar degenerative disease is a common 
presenting complaint. The prevalence is reported to be 3-5% of the US 
population24 while the annual cost to care for patients with lumbar degenerative 
disease is estimated to be $50 billion1. Although lumbar radiculopathy patients 
often present with diffuse degenerative disease, the specific nerve and/or nerve 
foramen causing the presenting symptoms is often unclear. This diagnostic 
uncertainty can be addressed with a selective nerve root block (SNRB). Surgical 
decision-making is then based on the patient’s positive or negative response to 
the SNRB.  Despite the widespread use of SNRB to localize the source of lumbar 
radiculopathy, prior studies of the positive and negative predictive value of SNRB 
in this patient population found mixed results. Possible explanations for this 
heterogeneity include a lack of a standardized approach to performance of a 
SNRB and difficulty performing an accurate injection. Furthermore, there is no 
standardization for what constitutes a positive injection response and no 
objective measures exist to determine SNRB effectiveness.  
It is overly simplistic to rely on a dichotomous response to a SNRB, i.e., positive 
or negative.  There is likely a threshold of response based on the degree of pain 
improvement, duration of improvement and/or improvement on an objective test 
such as a walking test.  The proposed study will be the first to prospectively 
assess the threshold of patient response to SNRB when predicting 
objective outcomes. Our study seeks to assess what degree or length of 
improvement in subjective pain and objective walking predicts an optimal 
outcome following lumbar foraminotomy.  The results of this pilot study may be 
used to plan a larger multicenter prospective study.  As the US health care 
system continues to transition toward value-based care, quantifying the clinical 
efficacy of common interventions such as SNRB become increasingly important. 
The results of the proposed pilot study and the future multi-center trial will 
advance lumbar spine care in an environment of value-based care. 
Specific Aims and Hypothesis 
Diagnostic selective nerve root blocks (SNRBs) are often utilized in the 
management of lumbar degenerative disease.  It is estimated that 2 million spinal 
injections are performed annually in Medicare patients alone.  Each injection 
costs approximately $2000, resulting in an annual expenditure of $4 billion. The 
sensitivity and specificity of SNRB have been previously reported in several 
studies with the sensitivity ranging from 9-100% and specificity ranging from 24-
96% depending on the reference standard used6. The data regarding diagnostic 
accuracy are largely inconclusive with the reasons for the observed 
heterogeneity including inconsistencies in procedure and approach for 
administering the nerve block, lack of a standard evaluation of nerve block 
response, relative dearth of up-to-date studies (older studies may have out of 
date practices), small sample sizes, study design (mostly retrospective), and 
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operator variances.  Another important reason for variance in previously 
published results is the lack of a standard for a threshold level of nerve block that 
constitutes a positive diagnostic SNRB.  The proposed study will address all of 
these problems by quantifying the predictive value of diagnostic SNRBs in 
patients who present with lumbar foraminal stenosis and radiculopathy.  The 
proposed study will identify the threshold response level that optimizes this 
predictive power. Specifically, the proposed study will address the question of 
whether there is a degree or length of response to SNRB, which predicts an 
excellent surgical outcome.  We hypothesize that diagnostic SNRBs, when 
performed correctly, are useful in localizing the level of involvement in LSS 
and improve the accuracy and efficacy of surgical intervention. Use of 
diagnostic SNRBs will thus be used to clarify the clinical picture, giving the 
surgeon the information to make the right decision to operate or not, and, in the 
case of operation, predicting the optimal level (s) for surgical intervention. In 
addition, we plan to identify and fully characterize a standard threshold level 
and time of nerve block response that will optimize the accuracy, 
specificity, and sensitivity of SNRB in predicting surgical outcomes.  
Aim 1:  Prospectively determine the positive and negative predictive value 
of SNRB in the surgical treatment of lumbar foraminal stenosis.  Prior to a 
single level foraminotomy for lumbar foraminal stenosis patients will undergo 
SNRB of the suspected nerve root. All enrolled patients will proceed to surgery 
despite the response to injection. All injections will be performed in a standard 
format-utilizing anesthetic only and under fluoroscopic guidance.  All patients will 
complete an ambulation assessment immediately before and following the 
injection.  Distance and time will be recorded.  All injection patients will be called 
within 48 hours of the injection to determine response to the injection and 
recorded as Pre- and Post injection VAS leg as well as length of time of the 
response recorded in minutes.  Patients will be seen at 6 weeks, 3 months and 
12 months following surgery and outcome measured by VAS-leg, Oswestry 
Disability Index (ODI), Pain Disability Questionnaire (PDQ) and EQ-5D.   
Aim 2:  Determine the threshold of positive predictive response.  The 
relationship between degree of pain improvement following SNRB and outcomes 
following surgery is currently unknown. Each patient will therefore report their 
change in leg pain before and after injection as well as the length of time of 
improvement.  These data will be used to determine the optimal improvement in 
leg pain and duration of improvement, which predicts a statistical and meaningful 
improvement in leg pain following foramintomy.  
Background and significance 
Lumbar radiculopathy in the setting of degenerative disease is a common 
presenting symptom; its prevalence is estimated to be 2-5% of the US 
population.  Although patients typically present with pain associated with one or 
multiple nerve roots, their MRI may demonstrate multi-level foraminal and/or 
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canal stenosis.   Moreover, these degenerative findings seen on imaging are 
common in asymptomatic people.  Several studies have found no correlation 
between MRI findings and clinical symptoms4, 16, 17, 25. Others have shown that 
MRI evidence of stenosis increases with age despite absence of symptoms, 
noting that almost 20% of individuals >60 years of age and up to 80% of those 
>70 years of age have evidence of stenosis without clinical symptoms3, 20.
In many cases the combination of patient history, physical exam and MRI 
findings may localize the source of radicular pain.  In others, the findings are 
equivocal and a selective nerve block may be used as a diagnostic tool.  Studies 
on the ability of SNRB to predict outcomes of spinal surgeries have been largely 
inconclusive.  The diagnostic yield is reported to vary from 30-90%7, 10, 21.  This 
variability has been attributed to several factors including: 1) the retrospective 
nature and sample size of existing studies, 2) variability in SNRB methods, and 
3) a lack of standard for a positive response to the nerve block.
Prior studies have reported both the positive and negative predictive value of 
SNRBs5,6,11,19,28.  Despite numerous reports, deficiencies in the literature are 
noteworthy.  Most studies assessing the ability of SNRB to predict outcomes 
following decompression have been retrospective in nature, lack a comparison 
group, and report relatively small sample sizes, ranging from 39 to 105 patients.   
Sasso and colleagues retrospectively reviewed their experience with selective 
nerve blocks in predicting surgical outcome for lumbar and cervical 
radiculopathy.  The authors reviewed 101 patients all, which underwent cervical 
or lumbar decompression.   The injection technique was standardized for both 
the cervical and lumbar regions.  A positive injection was determined if there was 
an immediate >95% relief of pain and VAS score of 0-1.  The overall predictive 
value of SNRB was 91% while the negative predictive value was 40%21. Williams 
and Germon recently reported on their experience with SNRB in 100 consecutive 
patients. This retrospective review included patients who presented with 
diagnostic uncertainty based on history, physical exam and imaging as to 
whether nerve root compression was responsible for their symptoms.  All patients 
had imaging demonstration of either foraminal or lateral recess stenosis.  All 
patients underwent a standardized injection performed by the same operator.  A 
standardized approach to a positive or negative injection was utilized. 
Specifically, the injection to be effective result in 1) initial reproduction of the 
patient’s typical radicular pain, 2) an initial radiculogram, 3) an appropriate motor 
and sensory disturbance immediately after blockade and 4) and whether good 
pain relief during activity was present during presence of blockade.  In patients 
who’s symptoms did not improve 3 months after surgery, an MRI was ordered. 
Fifty-one patients underwent decompression surgery after a successful SNRB; 
41 patients had a good outcome after surgery, while 10 did not.  Nine patients 
who did not have relief of their pain still underwent decompression surgery; 6 of 
these patients had relief of their symptoms, 2 did not improve and one was lost to 
follow-up.  The positive predictive value was found to be 80.4%; while the 
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negative predictive value was 22.2%.  The resultant sensitivity was 85.4% and 
specificity 16.7%26.   
Both Sasso et al. and Williams and Germon studies are limited by their 
retrospective design.  Bias regarding patients chosen for surgery, type of surgery 
performed and ultimate outcome cannot be minimized or mitigated.  Patients 
included were not homogeneous, especially in Sasso et al, where cervical 
patients were included.  Validated patient reported outcome measures were not 
utilized, which negatively impacts the true definition of outcome following surgery 
and overall predictive value of SRNB.  Most importantly, the threshold for a 
positive response was determined and set a priori in both studies.  A 
dichotomous positive or negative response to injection was utilized and is likely 
overly simplistic. As stated by the authors, the threshold for a positive response 
may have been set too high and this could have explained the low negative 
predictive value of SNRB reported.  Lastly, the sample size in both studies was 
too small to make subgroup analysis and determine which aspects of the 
response to the SNRB predict a good surgical outcome.   
There is currently no agreed upon gold standard against which to make 
comparisons of accuracy of SNRB.  Some have defined accuracy based on 
demonstration of epidural spread of contrast along the nerve of interest27, 
anatomic studies15, changes in physiology22, or compared to EMG or 
myelography10.  Moreover, there is no agreed upon standardized needle 
placement for SNRB.  The needle may be placed classically at the superior 
anterior foramen, alternatively, the needle may be placed in Kambin’s triangle. 
Both target the nerve in the foramen, but at differing anatomic positions.  An 
injection in either place should block the desired nerve, but in differing anatomic 
locations and potentially resulting in a varying diagnostic response.  Many 
consider a transforaminal epidural steroid injection diagnostic, yet this injection 
involves epidural placement of drug and steroid and thus is not diagnostic. 
Lastly, there is no standard as to what medication or cocktail of medication and 
volume should be injected.  Differing volumes and concentration of anesthetic 
injected will obviously have a variable impact on diagnostic accuracy.  
SNRB are technically difficult and the ability to selectively anesthetize a single 
nerve root has been questioned. The more recent studies attempt to circumvent 
this issue artificially by application of contemporaneous imaging to confirm SNRB 
placement in the correct location26, 28.  Evidence suggests that compression of 
the dorsal root ganglion is more predictive of radicular symptoms as compared to 
a more central region of compression8, 18.  Ideally, the target of “block” should be 
the DRG.  There is known variation in the location of DRG in foramen, it may be 
located intraforaminally, extraforaminally, or intraspinally15. In order to account for 
this, some studies have used electrostimulation in addition to fluoroscopy27.  This 
variability has impact on the diagnostic yield of SNRB.   
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Another issue with SNRB is the lack of consensus on what constitutes a 
“positive” response.  Some use a dichotomous approach with any improvement 
in pain used as a positive response, while others document an a priori level of 
pain improvement as a determination of “positive”.  Some use an arbitrary cut-off 
in pain reduction; 50%, 80% or a two-point reduction in the visual analog pain 
scale22.  If the cut-off is not met, the nerve is determined to not be the pain 
generator.  This arbitrary approach may have a significant impact on 
determination of diagnostic accuracy.  Patient expectations and placebo may 
also have an impact on diagnostic results.  The impact is unknown but must be 
minimized or at least realized when utilizing SNRB.  “Blinding” the patient to the 
procedure and a standardized informed consent and pre- and intraprocedural 
flow should minimize impact. 
The view that a dichotomous response (positive vs. negative) to SNRB is overly 
simplistic.  It is likely that there is a threshold of response, which predicts 
improving outcomes.  It may be that as the degree of pain or functional 
improvement following injection will have a greater predictive value.  Moreover, 
improvement on some aspects of the injection but not all may still predict a good 
outcome (i.e., motor and sensory changes in the nerve of interest but no 
significant improvement in pain).  Knowledge of such a diagnostic threshold will 
help plan ultimate surgical or non-surgical treatment. 
The true positive and negative predictive value of SNRB can only be determined 
in a prospective randomized controlled trial.  A standardized approach to patient 
selection in a homogenous cohort utilizing a standard injection technique and 
outcome measure is required.  Moreover, it is likely that an objective functional 
assessment vs. simple pain assessment should be utilized in determining a 
“positive” response. Recent studies have shown that functional assessment by 
walk test can be a quick and cost efficient way to assess severity of disability in 
patients. Walk tests are an improvement on inherently biased questionnaires that 
are subject to a patient’s ability to recall. A variety of walk tests have been used 
in the past to assess functionality including a 10-meter walk test, 30-meter walk 
test, 6 minute walk test, and exercise treadmill test. The 10-meter walk test is 
less applicable in this setting since it is largely a test of speed. The 30-meter walk 
test, 6 minute walk test, and exercise treadmill tests are relatively similar. The 
most detailed studies have been done on the 30-meter walk test in assessing 
lower extremity functional status in cervical myelopathy and are applicable in this 
setting  2, 12.  With this test, patients are asked to walk 30 meters. Time and count 
of cadence to walk 30 meters are recorded.  The onset of pain, as well as 
distance and time until pain occurs are recorded.  Limitations due to pain is 
assessed by time taken to complete test as well as cadence count.   
Our belief is that SNRB, as measured by the change in pain and objective 
functional ability, can solicit crucial information regarding a patient’s clinical 
picture and can predict a patient’s outcome post-surgery. By using the walk test 
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as an objective functional assessment, we hope to better standardize the 
threshold for a positive response to SNRB.   
In summary, SNRB, despite utilized frequently in the diagnostic work-up with 
patients with lumbar radiculopathy, vary widely in their sensitivity and specificity. 
The reasons, as outlined above, are multifactorial.  The proposed study aims to 
minimize the known limitations of these injections and prospectively define their 
positive and negative predictive value in a homogenous group of patients 
undergoing surgery for lumbar foraminal stenosis and radiculopathy.  The design 
will define a threshold of response utilizing both subjective and objective 
measures and more accurately predict excellent results following surgery.   
Scientific Approach 
Patients, age 18-80, who present with unilateral lower extremity radiculopathy 
due to degenerative foraminal stenosis will be considered for this study.  Patients 
will be included if they present with radiculopathy and with imaging and/or clinical 
history or physical exam that does not demonstrate a clear neurogenic source of 
their pain.  Examples include MRI with multi-level foraminal stenosis or 
discordance between MRI and clinical radiculopathy.  All patients enrolled in the 
study will undergo a SNRB of the suspected symptomatic nerve root.  Patients 
will undergo lumbar foraminotomy regardless of the response to the injection.  
Patients will be excluded if there is a clear correlation between imaging and 
radiculopathy.  An example would be an L5 radiculopathy in the face of an acute 
L4/5 herniated disc.  Additional exclusion criteria include: radiculopathy 
associated with trauma, tumor or infection.  Non-radicular lower extremity pain 
will also be excluded. Patients who cannot tolerate the SNRB without IV sedation 
will not be enrolled.   
Subjects must be available for the entire study duration (12 months) and willing 
and able to comply with scheduled visits including completing pain diary and all 
patient reported outcome questionnaires.   
Patients will be contacted by phone during the study follow-up (48 hours post 
injection). 
Other exclusion criteria: 
Surgery requiring multi-level decompression and/or fusion 
Surgical indication for malignancy, injection or acute or emergency trauma 
History of major surgery within 3 months prior to enrollment 
Pregnant females 
Presence of severe acute, chronic medical or psychiatric condition  
Patients meeting inclusion criteria and following signing of the informed consent 
will undergo SNRB prior to surgery.  The surgeon will be blinded to the 
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response to the injection.  Patients will proceed to surgery regardless of their 
response to injection.   
Description of Procedures 
1. Pre-Injection Pain and Functional Assessment
Prior to the injection the patient will report pain and functional status via
tablet.  Outcome measures recorded include VAS leg pain, ODI, PDQ and
EQ-5D.
Patients will perform a 30-meter walk test.   For this test, the patient will
start from a sitting position.  When begun, the patient will rise and walk a
pre-measured and level 30 meters.  The time to conduct the test as well
as a count of cadence will be performed by the research coordinator.  A
post walk VAS leg pain will be recorded immediately following the walk
test.
2. Selective Nerve Root Block
A single interventionalist in an ambulatory surgical center will perform all
injections.  Injections will be performed utilizing biplanar fluoroscopy to
appropriately localize the foramen of interest and optimal needle
placement.  Patients will not be administered IV analgesic or anxiolytic
medications.  After prone positioning, the skin in the lumbar region of
interested will be prepped and draped per hospital protocol.  One milliliter
of 1% lidocaine will be injected as a wheel into the skin in the planed
incision.  The injection needle will then be inserted into the anterosuperior
aspect of the foramen via biplanar fluoroscopy.  After confirmation of
appropriate placement, 0.5 milliliters of nonionic contrast will be injected
and a “radiculogram” confirmed.  Epidural spread or vascular uptake of
contrast will require abortion of the injection.  The patient will be
rescheduled for one week later for a repeat injection attempt.  Inability to
perform an adequate injection (i.e., lack of epidural spread) will result in
exclusion of the patient from the study. To be confirmed accurate the
injection should replicate the patient’s presenting radicular pain.   0.3
milliliters of 0.5% bupivacaine will then be injected into the foramen.  The
patients response to injection will be recorded:  did the injection of contrast
replicate the patients pain; did the injection of bupivacaine result in both
motor and sensory changes associated with the nerve injected?
Adequacy of injections (i.e., needle location and contrast spread) will be
reviewed by a third party (saved fluoroscopic images).
3. Post Injection Pain and Functional Assessments
Following recovery of the injection, the patient will report a post-injection
VAS leg pain score.  The patient will then perform a post injection 30-
meter walk test.  Time and cadence count will be recorded as well as post
walk test VAS leg pain.  Patients will resume normal activities and given a
pain diary.
4. 48 Hour Post Injection Assessment
At 48 hours post injection, all patients will be called.  A 48-hour VAS leg
pain will be assessed and pain diary reviewed.  The duration of pain
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change will be recorded. The change will be based on the minutes 
elapsed since pain improved post injection and the number of hours it took 
to return back to baseline.  
5. Lumbar Foraminotomy
All operations will be performed at the main campus Cleveland Clinic by a
fellowship trained spine surgeon.  After induction of general anesthesia
and patient positioning, the lumbar skin will be prepped and draped per
hospital protocol.  A preoperative lateral radiograph will confirm the level
of incision.  The smallest incision possible will be made and subperiostial
exposure utilized to expose the level of foraminotomy.  The spinous
process is next resected and a laminotomy performed on the index
ipsilateral side.  Following medial facetectomy, Kerrison Rongures will be
utilized to remove overgrown bone and ligamentum flavum to decompress
the neural foramen.  Discectomy may be required to fully decompress the
existing nerve root.  The easy passage of a Woodson elevator through the
foramen will be utilized to confirm adequate opening of the foramen.
6. Following surgery all patients will be seen at 6 weeks, 3, 6 and 12 months.
During follow-up, patient reported outcomes will be recorded including
VAS leg, ODI, PDQ and EQ-5D.  Any adverse events will be recorded and
noted associated or not associated with the index operation.  Any patient
without improvement in symptoms 3 months post surgery will
undergo MRI to assess adequacy of foraminal decompression.
7. An excellent surgical outcome will be defined at as 15-point improvement
in ODI, 26 point improvement in PDQ, improvement in VAS leg pain to 0-
2, and improvement in quality of life per EQ5D.
Statistical Analysis 
To improve the diagnostic value of SNRB, a threshold between positive and 
negative responses will be set that is best able to predict whether a patient will 
have a good surgical outcome.  To measure the response to injection, post-
injection VAS pain scores and functional assessments will be compared to pre-
injection values for each patient. 
First, the functional and VAS pain measures of improvement will be analyzed 
individually.  A positive functional response to injection will be defined by setting 
thresholds in the timed 30-meter walk test that best differentiates patients who 
respond to surgery from those who do not.  The accuracy of the test will be 
defined by its sensitivity and specificity and by its negative and positive predictive 
values.  Separately, a threshold defining a positive response to injection will be 
set using VAS leg pain improvements over pre-injection values. 
Then, a logistic regression analysis will be performed, including pain 
assessments and walk test improvements as predictors. This model will assign a 
value between 0 and 1 that represents how likely it is that a patient who responds 
to SNRB with some amount of reduction in leg pain and improvement in 
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functional ability has a good surgical outcome.  A threshold in the model’s 
predictive values will be set to define a positive response to the injection.  This 
will again be done to maximize its diagnostic accuracy with respect to sensitivity 
and specificity and to positive and negative predictive values. 
Positive and negative predictive values and their 95% confidence intervals will be 
reported both for the individual analyses and for the combined logistic regression 
analysis.  Lastly, variable selection will be performed in an attempt to simplify the 
logistic regression model. 
Due to the fact that a threshold response to SNRB has not been studied, we are 
not able to perform an adequate power analysis.  We will use the data from this 
pilot study to perform a power analysis for a planned larger randomized trial.   To 
have an adequate sample yet complete the study in a 12 month time period we 
plan to enroll 50 patients.   
Plans for Dissemination of Results 
We plan to disseminate the results of this study in multiple venues.  First, we will 
plan to submit the results via abstract for presentation at the Lumbar Spine 
Research Society Annual Meeting.  The results of this study will also be 
submitted for publication.  All presentations and publications will acknowledge 
the Lumbar Spine Research Society.   
The results of this pilot study will be utilized as pilot data for the submission of a 
larger multicenter prospective trial.  When completed the results will also be 
submitted for presentation at the LSRS annual meeting and for publication.  We 
anticipate multiple publications originating from a larger study.  All presentations 
and publications will acknowledge the Lumbar Spine Research Society. 
Future Funding and Next Steps 
The preliminary results from this study will be utilized as data for a larger 
randomized multi-center study.  This pilot study data will help formulate a proper 
power analysis for the design of a larger study.  Moreover, the pilot data will 
permit insight into the threshold effect of SNRB, which can be used in the design 
phase of a larger study.  We plan to submit an NIH RO1 grant in collaboration 
with other major spine academic centers.  With the expenditures on therapeutic 
and diagnostic injections increasing each year and significant questions 
regarding their efficacy, we believe the NIH would be very interested in funding 
such a study.   
Following completion of this study, we will first use the data to design a multi-
center study.  We believe that the data from this study will help us understand the 
proper SNRB to be performed and define what it truly means to have a “positive” 
injection.  Moreover, we believe our study will define a threshold response for a 
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positive or negative injection. This data will then aid in the design of an 
appropriate much larger study.  Our plan is to collaborate with our peers at large 
interdisciplinary spine centers in conducting a multi-center prospective study.   
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