Spinal Pain and Fluoroscopy Guided
Facet Joint (Medial Branch) Nerve and Epidural Injection – A critical review of
the science and the evidence
Authors: Sota Omoigui MD
Affiliation: Division of Inflammation and Pain Research
L.A. Pain Clinic, Los Angeles, California
All
authors have read and approved the manuscript. Work was done at the L.A. Pain
Clinic. The study was not supported by any grant. There is no conflict of
interest.
ABSTRACT – We review and analyze the science and the evidence in several
opinions that are repeatedly found in pain and radiology literature. There is
no evidence for a single pain trigger in the spine where inflammation is
confined. Inflammation and the inflammatory process are characterized by recruitment
and spread. There is evidence to revise the current focus on searching for one
pain trigger at a time to acknowledging and targeting of multiple pain triggers
responsible for spinal pain. There is no evidence that a block utilizing
fluoroscopy for either facet joint or epidural blockade translates into a
greater therapeutic advantage than a block performed utilizing anatomical
landmarks. Fluoroscopy is required when anatomical landmarks are difficult to
discern and with procedures that bring the needle close to vital structures. As
a diagnostic tool, the facet intra-capsular injection is meaningless and this
procedure should be discontinued. There is no scientific foundation and no
evidence that fluoroscopic guidance can result in a limited, controlled or
diagnostic block of the medial branch innervation to the facet joint. A medial
branch block administered as a diagnostic test cannot localize the pain to the
facet joint. In the absence of systemic analgesia, the block confirms that the
source of pain is from any or several of the posterior spinal structures
innervated by the medial branch nerve (facet
joints, facet capsular ligaments, the interspinous and
supraspinous ligaments,
spinous process and paraspinal mutifidus muscles). EMG guidance during a
facet joint block - whether performed with fluoroscopic guidance or by
utilizing anatomical landmarks - is the only objective method of confirming
accuracy of the procedure. There are no studies that demonstrate increased
safety or efficacy of facet joint nerve blocks using fluoroscopy compared with
the use of anatomical landmarks. The constant questioning of “established”
truths is necessary for progress and improvement in outcome at optimum cost.
Keywords:
Fluoroscopy; anatomical landmark; guidance; diagnostic; blind; facet
intracapsular joint; facet joint (medial branch) nerve; dorsal ramus; epidural
INTRODUCTION
SPINAL PAIN AND MULTIPLE PAIN
GENERATORS
Spinal pain is the second most
common reason for a visit to a doctor's office and the leading cause of
disability in people younger than 45 years of age. Spinal pain may arise from
arthritis of the facet or sacro-iliac joints, degenerative disk disease,
herniated disks, nerve root compression, spinal stenosis, ligamentous or
muscular strain/sprain, osteoporotic or osteolytic fractures, misalignment of
the vertebra, tumors and infection. The common biochemical thread in these
structural lesions is the presence of inflammation and the inflammatory
response[1]. Non-spinal causes of back or
neck pain include genitourinary, gynecologic, gastrointestinal, or systemic
disease. In the majority of patients, the origin of back pain is not from a
single pathology but rather multifactorial with the pain arising
from a variety of structures (muscles,
ligaments, facet joints, nerves, disks and bone)[1].
Discogenic disease with disc space
narrowing progressively transfers more weight to the facet joints thereby
damaging the joints. Mechanical
stress that affects a joint will affect the surrounding tissue. Degenerative
spinal disorders that lead to facet osteoarthritis will also affect other
structures in the spinal segment. For example, chronic arthritis of the
posterior facet joints is usually associated with hypertrophy and degeneration
of fibers of the ligamentum flavum[2] or with degenerative disk disease[3]. In
females, the more frequent pathologies, in decreasing order, were: bulging
disc, synovial facet syndrome, disc herniation and vacuum phenomenon. In males
incidence and frequency of various pathologies were similar to that observed in
females[4].
In
one study, volumetric CT imaging of the lumbo-sacral column was performed in
2012 consecutive patients with back pain, and included 866 males and 1,146
females, aged 22 to 91 years. 172 males were affected by one pathologic lesion,
586 from 2 to 4, 102 more than 4 lesions; 6 subjects were without. On the
contrary, 196 females had a single lesion, 611 from 2 to 4, 331 more than 4 and
8 did not have any one. In
another study, magnetic resonance and computed tomography scans of L4/5 and
L5/S1 levels in 129 patients operated for herniated intervertebral disc were
assessed to establish the relationship of facet joint asymmetry, disc prolapse
and degenerative disease. Statistical analysis revealed significant correlation
between facet joint asymmetry and disc disease or degenerative stenosis within
lumbar spine[5]. Another
study determined the relationship between facet joint osteoarthritis and disc
degeneration in subjects in whom both MRI and CT scans had been obtained.
Sixty-eight sets of scans were included and 330 discs and 390 facet joints were
evaluated. There were 144 degenerated discs and 41 levels with facet
osteoarthritis. Disc degeneration without facet osteoarthritis was found at 108
levels, while all but one of 41 levels with facet degeneration also had disc
degeneration. That one exception occurred in a patient with advanced Paget's disease.
Disc degeneration and facet osteoarthritis both were found to increase with
increasing age. The authors concluded that disc degeneration occurs before facet
joint osteoarthritis, which may be secondary to mechanical changes in the
loading of the facet joints3.
TREATMENT OF SPINAL PAIN
Many
medical specialties treat this highly prevalent condition and the type of
intervention performed is highly variable and dependent on the specialty of the
treating physician. Back or neck pain that does not respond to medical
treatment by the primary care physician or surgical intervention by the
orthopedic or neurosurgeon is often referred to the interventional pain
specialist. Utilizing the history, clinical examination, imaging,
electro-diagnostic and laboratory studies, the pain physician establishes the
possible etiology of the spine pain. It should be noted that radiographic
abnormalities demonstrating osteoarthrosis of the
lumbar spine and facet joints and varying degrees of disk bulge and disk
degeneration are the rule in both asymptomatic and symptomatic patients[6].
A high rate of lumbar
disc alterations and spinal stenosis is also detected in asymptomatic
individuals by magnetic resonance imaging[7] [8]. Facet joint, medial
branch nerve blocks and epidural steroid injections are most commonly performed interventions
utilized frequently by the pain
specialist for the treatment of chronic spinal
pain. These
diagnostic and therapeutic interventions are based upon numerous opinions and
guidelines are stated in the pain and radiology literature. Implementation of
these opinions and guidelines are associated with a significant increase in
medical costs. The costs of interventional treatment for spinal pain were at a
minimum of $13 billion (U.S. dollars) in 1990, and the costs are growing at
least 7% per year. Medical treatment of chronic pain costs $9000 to $19,000 per
person per year[9]. There is a need for a critical evaluation of the
evidence behind these opinions and guidelines as most of these publications
have not documented any outcome studies or cost-benefit analysis of some of the
procedures that they advocate.
OPINIONS AND GUIDELINES IN THE
LITERATURE
Numerous opinions and assertions
are stated in the pain and radiology literature and repeated so often that they
get a life of their own and become “established” truths. One of these is the
statement that that diagnostic blocks of the facet joints or their nerve supply
are the only means available to confirm or deny these structures as pain
generators[10] [11] Other opinions hold that needle position is synonymous with
success of a nerve block and needle position can only be accurately verified
using fluoroscopy[12] [13]. Another opinion often repeated is
that imaging-guided techniques appear to provide better results and reduce
complication rates12.
This has led to other
opinions in the pain and radiology literature[14] [15] [16] 11,
which advocate that fluoroscopy, be required for performance of diagnostic and
therapeutic facet medial branch nerve and epidural injections. We now set out
to analyze the science and the evidence to justify the opinions and theories.
METHODOLOGY
We first analyze the anatomical
foundation for diagnostic and therapeutic facet joint nerve blocks and epidural
injections. We review the
recommendation of fluoroscopy for facet joint nerve blocks and epidural injections. We then
analyze the medical literature that has been used to support these
recommendations. The
literature review was conducted by a database search of Medline (PubMed, Ovid
and MDConsult) database published to December 2007. The keywords used in
various combinations were fluoroscopy, pain, injection, facet joint (medial
branch) nerve, block, articular, adverse effect, complication and epidural
injection. We identify and analyze the relevant literature that has been used
to support these opinions and recommendations. Our analysis includes a
selection of studies whose conclusions are based upon flawed study designs and
a lack of scientific foundation. Where appropriate we highlight opinions and
theories in the pain literature that have no scientific foundation and are not
supported by any studies including but not limited to randomized controlled
trials and controlled clinical trials.
RESULTS
FLUOROSCOPY
Fluoroscopy is a radiologic technique that uses x-ray to produce real-time video images. After the x-rays pass through the patient, instead of using film, they are captured by a device called an image intensifier and converted into light. The light is then captured by a TV camera and displayed on a video monitor.
Fluoroscopy provides excellent visualization of bone structures, but soft tissue resolution is poor. When using fluoroscopy for interventional procedures the operator must rely upon secondary anatomical landmarks when targeting soft tissue structures unless contrast is used. Contrast material is needed to visualize tubular structures with fluoroscopy. One disadvantage of fluoroscopy is the definitive radiation exposure to the operator and the patient. The radiation dose varies according to fluoroscopy time, which is dependent upon the procedure
Fluoroscopy
enables better structural accuracy of needle positioning over a bony landmark
in order to block the nerve branches in close proximity. It ensures immediate
discovery of a wrong needle position either away from the target or intravascular
(when contrast is injected), before a local anesthetic or other substance is
injected. Techniques for facet joint nerve blocks utilizing anatomical
landmarks have been described in numerous articles and textbooks [17] [18] [19]. There are currently no studies that
demonstrate increased safety, efficacy or outcome of facet joint nerve blocks
or epidural injections using fluoroscopy compared with the use of anatomical
landmarks. The
principal rational for the opinions advocating fluoroscopy for facet joint
nerve blocks is that needle position is synonymous with success of a nerve
block and needle position can only be accurately verified using fluoroscopy12 13.
However, the medial branch nerve innervates several structures including the
facet joints, facet capsular ligaments, the interspinous and
supraspinous ligaments,
spinous process and paraspinal mutifidus muscles. Thus relief of pain
subsequent to blockade of the medial branch can be due to blockade of
nociceptive afferent input from any combination of these spinal structures and/or
blockade of nociceptive efferent input to the paraspinal musculature.
Fluoroscopy cannot image or target the branches of the medial branch nerve that
are involved in the inflammatory process and cannot visualize or target the
inflammatory mediators generated by the posterior spinal structures. The medial
branch nerves being blocked using fluoroscopic guidance or anatomical landmarks
may or may not innervate the posterior spinal structures that are involved in
inflammation and pain. Fluoroscopy is required when anatomical landmarks are
difficult to discern and in the performance of procedures that bring the needle
close to vital structures such as a celiac plexus block or with nerve
destruction procedures such as radiofrequency lesioning. Fluoroscopy should
also be utilized to ensure reliability and consistency of needle position when
a facet joint nerve block is performed as a diagnostic block prior to
radiofrequency neurotomy. Fluoroscopic imaging is helpful with teaching and
demonstrating injection techniques, providing a record of the procedure,
advancing through a learning curve, providing a level of comfort of the
practitioner thereby enhancing performance and providing reassurance that the
block was performed adequately if a clinical failure arises. In his response to
a Letter to the Editor criticizing the use of anatomical landmarks for facet
joint nerve blocks, Waldman stated that the use of fluoroscopic guidance should
be based upon the clinician’s individual training or experience and a careful
weighing of the cost-benefit ratio and risk-benefit analysis for the use of
fluoroscopy14.
Fluoroscopy is associated with significantly higher medical costs as well as
exposure to radiation. In one study cost minimization analysis suggested that
epidural injections under fluoroscopy may not be justified by the current
literature9.
DECREASED COMPLICATION RATE WITH
USE OF FLUOROSCOPY
Opinions have also been expressed in the radiology literature stating that despite controversy regarding their effectiveness, imaging-guided techniques appear to provide better results and reduce complication rates12. We did not find a single study that measured and documented a decrease in complication rate with the use of fluoroscopy. There is no study in the literature that has measured safety, efficacy or outcome with the use of fluoroscopic guidance compared with the use of anatomical landmarks in the performance of facet joint nerve blocks and epidural injections. Complications and adverse effects may occur with either the use of fluoroscopy or the use of anatomical landmarks to perform these procedures, as neither technique can visualize the nerves or the spinal cord[20] [21]. The use of fluoroscopy has not provided any protection from liability suits over complications. In the last two decades in the United States, there has been increasing use of fluoroscopy in the performance of interventional pain procedures by anesthesiologists and radiologists including epidural injections. One study identified and described issues and trends in liability related to chronic pain management by anesthesiologists. Data from 5,475 claims in the American Society of Anesthesiologists Closed Claims Project database between 1970 and 1999 were reviewed to compare liability related to chronic pain management with that related to surgical and obstetric (surgical/obstetric) anesthesia. Acute pain management claims were excluded from analysis. Claims related to chronic pain management increased over time (P < 0.01) and accounted for 10% of all claims in the 1990s. Compensatory payment amounts were lower in chronic pain management claims than in surgical/obstetric anesthesia claims from 1970 to 1989 (P < 0.05), but during the 1990s, there was no difference in size of payments. Nerve injury and pneumothorax were the most common outcomes in invasive pain management claims. Epidural steroid injections accounted for 40% of all chronic pain management claims. The authors concluded that frequency and payments of claims associated with chronic pain management by anesthesiologists increased in the 1990s[22]. Updated data from the ASA Closed Claims Project database (n=7,328) was also used to compare chronic pain claims from 1985-94 to chronic pain claims from 1995-2004[23]. Just as previous trends have shown, chronic pain claims continued to increase from 7 percent (222 of 3,152 claims) in 1985-94 to 12 percent (224 of 1,839 claims) in 1995-2004 (p<0.01). Neuraxial blocks and injections were the most common chronic pain intervention in claims, accounting for nearly half (47 percent) of the most recent chronic pain claims. Cervical blocks and injections increased from 5 percent of chronic pain claims in 1985-94 to 14 percent in 1995-2004 [p<0.01]. Patterns of injury associated with chronic pain management malpractice claims have changed over time. The proportion of claims associated with nerve injury significantly increased between time periods and now accounts for the most common complication (38 percent) in chronic pain management claims. These nerve injuries (n=86) included both peripheral nerve injury (n=43) and spinal cord injury (n=48) (five claims had both peripheral nerve and spinal cord injury).
Due to the risk of serious neurological injury following
inadvertent intra-arterial injection of particulate corticosteroid - not
detected by aspiration or vascular uptake of contrast[24]-,
it is recommended to use only soluble corticosteroids such as Dexamethasone for
transforaminal epidurals or selective nerve root blocks. Careful monitoring of local
anesthetic dosing should be done to ensure that toxic levels are not attained
even with accidental intravenous or epidural injections.
USE OF FLUOROSCOPY FOR EPIDURAL
INJECTION
There is currently no consensus on the technical aspects of performing epidural injections with or without fluoroscopy. One study done at MGH set out to establish whether consensus exists on technical aspects of this procedure. The study found that there is a wide variation among individual practices in almost every technical aspect of epidural steroid injections. Private practices use significantly more fluoroscopy than academic centers. The authors concluded that there is no consensus on the use of fluoroscopy[25] A requirement for fluoroscopy for epidural injections makes no consideration of the mechanics, pathophysiology or inflammatory profile of spinal trauma or degenerative spinal disorders. A review of the numerous studies of the diffusion patterns of liquid local anesthetics will demonstrate that there is no linear correlation between needle position and success of a nerve block. One study demonstrated a lack of a linear relationship between injected volume of local anesthetic and spread of epidural anesthesia[26]. Another study examined the site of catheter tips and the spread of contrast material in the epidural space using computed tomographic (CT) imaging in patients receiving successful epidural analgesia. Catheter tips were most often found lateral to the dura in the intervertebral foramen. In these subjects with normally functioning epidural analgesia, there was remarkable inter-individual variability in patterns of spread, including various amounts of anterior passage, layering along the dura, and compression of the dura creating a posterior fold. The author concluded that non-uniform distribution of injectate is common and is compatible with uniform anesthesia[27].
DIAGNOSTIC USE OF NEURAL BLOCKADE
Intra-articular facet joint or
medial branch nerve block is currently
recommended for the diagnosis and treatment of painful conditions involving trauma, arthritis, or inflammation of
the spinal facet joints or in situations where the facet joint is thought
to be contributing to afferent nociceptive
traffic[28].
Diagnostic blocks have been used to obtain information about the source
of a patient's pain[29]
and facet joint nerve blocks are described as a diagnostic tool for facet joint
pain[30].
Some opinions in the pain and radiology literature14 15 16
and guidelines from societies such as the American Society for Interventional
Pain Physicians (ASIPP)11
have advocated the performance of diagnostic facet joint and facet joint nerve
injections. However, these guidelines have been recently challenged, and a
recent journal editorial of one of such societies stated: “A Shocking
Problem Unearthed: What if there is no such thing as a 'diagnostic'
medial branch block or for that matter, a
'diagnostic' nerve block?”[31]. Some of these
opinions state that diagnostic
blocks of the facet joints or their nerve supply are the only means available to
confirm or deny these structures as pain generators10
11.
However these opinions are based upon erroneous assumptions and severely flawed
anatomical studies of the spread of contrast medium after injection of the
medial branch nerves[32]. There has been no examination of the shared
medial branch and sinu-vertebral innervation of the facet joints with other
pain triggers in the posterior spinal structures. There has been no
consideration of the mechanics, pathophysiology or inflammatory profile of
spinal trauma or degenerative spinal disorders. They have not reviewed the numerous studies of
perineural
transport and spread
of injectate in peripheral nerve blocks[33] [34].
As stated in an article by
Hildebrandt[35],
these opinions on the
diagnostic use of neural blockade rests on three unsubstantiated premises.
First, pathology causing pain is located in an exact peripheral location, and
impulses from this site travel via a unique and consistent neural root. Second,
injection of local anesthetic totally abolishes sensory function of the intended
nerves and does not affect other nerves. Third, relief of pain after local
anesthetic block is attributable solely to block of the target afferent neural
pathway. Hildebrandt further stated that complexities of anatomy, physiology,
and the psychology of pain perception and the effect of local anesthetics on
impulse conduction limit the validity of these assumptions.
ANATOMY OF THE FACET JOINT
The facet joint is made up of an inferior articular process from the vertebra above and a superior articular process from the next vertebra below (Fig. 1). There is a ligamentous capsule surrounding the joint, and a synovial membrane lining the inner aspects of the articular processes- similar to the anatomy of other joints.
Facet capsular ligaments have been shown to contain free (nociceptive) nerve endings, and distending these ligaments by administering facet intracapsular joint injections has produced whiplash-like pain patterns in healthy individuals[36]. The facet capsule is richly innervated with C fibers and A-delta pain fibers[37][38]. Local pressure and capsular stretch can mechanically activate these nerves. These neurons can be sensitized or excited by inflammatory mediators including cytokines, substance P and phospholipase A that are produced from injury to the capsule[39] or from adjacent tissues[40] (vertebrae, intervertebral discs, spinal cord, nerve roots, sensory nerves, the sympathetic nervous system, spinous process, interspinous and supraspinous ligaments, or muscles). Input of noxious stimuli from spinal trauma may induce physiologic changes in the spinal cord, particularly the dorsal horn.
NERVE SUPPLY OF THE FACET JOINT AND ADJACENT STRUCTURES
At the level of the intervertebral
foramen is the dorsal root ganglion. The ganglion lies within the outer confines
of the foramen. Distal to the ganglion three distinct branches arise; the most
prominent and important is the ventral ramus, which supplies all structures
ventral to the neural canal. The second branch, the sinu-vertebral nerve of
Luschka, is a small filamentous nerve that originates from the ventral ramus.
The sinuvertebral nerve is formed just outside the intervertebral
foramen with contributions from the main segmental nerve and from the grey
ramus communicans, whose cell bodies are located in the sympathetic trunk84. The
sinuvertebral nerve progresses
medially over the posterior aspect of the disc and vertebral bodies,
innervating these structures as well as the posterior longitudinal ligament and
the facet joint. The third branch is the dorsal ramus. This
branch courses dorsally, piercing the intertransverse ligament near the pars
interarticularis. Three branches from the dorsal ramus innervate the structures dorsal to the neural canal. The
lateral and intermediate branches provide innervation to the posterior
musculature (longissimus
and iliocostalis muscles of the erector spinae apparatus)
and skin. The medial branch (facet joint nerve) separates into three branches
to innervate the facet joint at
that level and the adjacent levels above and below[41]
[42]. The medial branch continues across the lamina just deep to the
multifidus muscle and sends a branch to the interspinalis muscle, and
eventually enters the multifidus muscle. Terminal branches of the medial branch
supply the ligaments and periosteum of the vertebral arches and spines[43].
The discs, vertebrae,
intervertebral discs, muscles,
facet joints and facet capsular ligaments
and spinal ligaments at the same level are in close proximity to each other and
share the same dorsal ramus nerve supply and may also share the nerve supply of
an adjacent segment. The medial branches of the dorsal ramus do not constitute
the only nerve supply to the facet joints. The facet joints are also innervated
by the sinu-vertebral
nerve, branches from the ventral ramus[44] and sensory nerves passing through the sympathetic trunk. Studies have demonstrated that
the neuropeptide levels in the cell bodies located within the dorsal root
ganglion of these sensory nerves fluctuate according to the physiological state
of the zygapophyseal joint[45].
In
one study in a cat, electrical stimulation of a lumbar facet capsule evoked
lumbar multifidus muscle electromyographic activity. Injection of lidocaine
into the facet or into the multifidus muscle around the facet joint
significantly decreased the magnitude of the multifidus electromyography one to two
vertebral segments caudal to the stimulated facet. These findings indicate that
afferent pain impulses conveyed by the medial branch of the dorsal ramus
reflexly alter efferent activity to an adjacent lumbar muscle segment[46]
Another study determined
whether the lumbar multifidus muscle is polysegmentally innervated by the facet
joint nerve. A 49-year-old man with chronic mechanical low back pain underwent bilateral
percutaneous radiofrequency neurotomy of the medial branches of the L3 dorsal
rami. Electromyography (EMG) examination was performed in the L2-5 multifidi
both prior to and 3 weeks after the procedure. Positive sharp waves and
fibrillations appeared in the L3-L5 multifidi after the neurotomy. According to
the authors, this study provides electrophysiological evidence in the human
lumbar spine that the medial branch of the lumbar root innervates the
multifidus muscle on multiple levels[47].
In another study in a swine, electrical stimulation of the disc annulus
fibrosus induced reactions in the multifidus on multiple levels and on the
contralateral side, whereas stimulation of the facet joint capsule induced
reactions predominantly on the same side as and at the segmental level of the
stimulation. Introduction of lidocaine into the facet joint resulted in
significantly reduced electromyographic response to either stimulation, with
the most drastic reduction seen when stimulating the facet joint capsule. The
clinical implications observed by the authors are that there may be interactive
responses between injured or diseased structures, i.e., disc or facet joints,
and the paraspinal musculature[48].
Dreyfuss et al[49]
determined the effectiveness of lumbar medial branch neurotomy by performing electromyography of the
multifidus muscle before and after the procedure to ensure accuracy of the
neurotomy. Relief was associated with denervation of the multifidus in those
segments in which the medial branches had been coagulated.
The clinical implication of these studies is that EMG guidance during a facet
joint nerve block or neurotomy - whether performed with fluoroscopic guidance
or by utilizing anatomical landmarks - is the only objective method of
confirming accuracy of the procedure. In some patients,
the paraspinal muscles may be a major contributor to the pain57 [50]
[51]
[52].
In such situations, the medial branch innervation of the paraspinal muscles may
play an equal or more significant role than the medial branch innervation of
the facet joints85 86
PROCEDURE TECHNIQUES – WITH AND WITHOUT FLUOROSCOPY
We will now review techniques for three procedures performed
with and without fluoroscopic guidance namely: Intra-capsular facet joint injection,
Facet joint (medial branch) nerve injection and Epidural Interlaminar Injection
INTRA-CAPSULAR FACET JOINT INJECTION
WITH FLUOROSCOPY
The standard technique described for a fluoroscopic guided
intra-capsular facet joint injection is to puncture the skin directly over the
target, align the spinal needle along the axis of the X-ray beam and direct the
needle into the capsule of the facet joint. A trace amount of contrast is
injected to confirm needle placement and 1 mL of
local anesthetic with or without steroid
is injected into the joint17.
Due to the size of the facet joint fluoroscopic guidance is the only way to
inject into the joint.
WITHOUT FLUOROSCOPY
This procedure cannot be performed without fluoroscopy.
FACET JOINT (MEDIAL BRANCH) NERVE BLOCK
WITH FLUOROSCOPY
The standard technique described for a fluoroscopic guided
facet joint nerve block is the placement of a spinal needle on the superior and medial point at which the transverse process
joins the vertebra. The medial
branch is targeted at the point at which the nerve curves around the top of the transverse process. As described by
Waldman, after correct needle placement is confirmed by fluoroscopy, 1.5 mL
of local anesthetic with or without
steroid is injected through the spinal needle.
WITHOUT FLUOROSCOPY
Several techniques
for performing facet joint nerve blocks using anatomical landmarks have also
been described 17 [53].
As described by Raj[54],
the patient is placed in a prone position and then rotated obliquely with a 30° angle pillow placed under the iliac crest
of the side to be injected. For lumbar procedures, the needle is placed 6-8 cm
lateral to the midpoint of the spinous process. After sterile prep and drape, a
22G to 25G, 2 inch-3 ½ inch spinal needle is advanced until bone is contacted.
Gentle aspiration of the needle is
carried out. If the aspiration test is negative,
2-5 mL of local anesthetic and steroid solution is injected through the spinal needle.
As described by Hoerster
et al 44, a
larger volume of local anesthetic administered at the lamina of the vertebral
arch will spread along the muscles of the frontal plane, cranially, caudally
and laterally, blocking the deep areas supplied by the medial and lateral
branches of the dorsal rami of the spinal nerves, including the adjacent
component of the vertebral joints up to the region of the ventral rami of the
spinal nerves. For a lumbar procedure, the patient is placed in a prone
position. One and one-half centimeters lateral of the midline and at the level
of the upper spinous process, a 4-6 cm spinal needle is introduced through a
skin wheal, in a strictly sagital plane and at 90 degrees to the skin surface.
After bony contact, which may occur at a depth of 2-5 cm, depending on the
thickness of the muscle layer, and after negative aspiration in two planes, a
test dose of 2 mls of the local anesthetic is injected. If there is no
sensation of warmth and no segmental hypesthesia, an additional 3-5 mls of
local anesthetic solution is injected. Low concentrations of local anesthetic
should be used.
EPIDURAL INTERLAMINAR
INJECTION WITH FLUOROSCOPY
For a
dorsal interlaminar approach, the patient is placed in the prone
position. Under fluoroscopic guidance, a 22-gauge spinal needle is advanced to
the posterior margin of the spinal canal. Positioning in the epidural
space is detected with a loss-of-resistance technique. Gentle
intermittent pressure is applied on a syringe while advancing the
needle. A sudden loss of resistance occurs on entering the epidural
space. Absence of cerebrospinal fluid flow is verified with
aspiration. Epidurography is performed with 2–3 mL of nonionic
myelography-approved iodinated contrast material to document epidural position
and evaluate the distribution pattern. Local anesthetic with steroid is
then injected into the epidural space.
EPIDURAL INTERLAMINAR
INJECTION WITHOUT FLUOROSCOPY
Using a strict aseptic technique
local infiltration into the skin and interspinous ligament is performed with a
small volume of local anesthetic, such as 1% lidocaine. A 16, 17, or 18 gauge
Tuohy needle is then advanced into the interspinous ligament and a "loss
of resistance" technique is used to identify the epidural space. Air or
saline may be used for identifying the epidural space, depending on personal
preference. After placement of the tip of the Tuohy needle into the epidural space,
local anesthetic with steroid is injected into the epidural space. If desired,
a catheter is threaded through the needle. The needle is then removed.
Generally the catheter is then withdrawn slightly so that 4-6 cm remains in the
epidural space.
ANALYSIS
OF THE EVIDENCE
DIAGNOSTIC
BLOCK OF THE FACET JOINT CAPSULE
The intracapsular facet
joint block is achieved by injecting the local anesthetic strictly within the
facet joint capsule. Due to the small size of the facet joint capsule,
fluoroscopy is a requirement for this procedure. However we have not found any
anatomical, mechanical or patho-physiological evidence for the targeting of the
joint capsule. The joint capsule is but one component within a zone of
inflammation comprising any combination of the facet joint, facet capsular
ligament, spinous ligaments, spinous process, vertebral end plate,
intervertebral disc and paraspinal muscle. It is an anatomical rule that joints
are surrounded and stabilized by ligaments and muscles. Any trauma sufficient
to injure the facet capsule will result in injury to the surrounding ligaments.
The resultant inflammation will result in a nociceptive afferent and efferent
output of the nerves innervating the facet joint leading to pain and spasm of
the paraspinal muscles. One study compared fluoroscopically
guided intra-articular and peri-articular cervical facet joint injections.
There was no significant difference in response between patients receiving intra-articular
or peri-articular injections[55]
Other studies
including a randomized controlled trial of facet joint injections and medial
branch blocks in eighty-six patients with refractory chronic low back pain
found both procedures to be of equal value[56] [57].
In a series of 14 patients with cervicogenic headache, blockade of C2 cervical
nerves resulted in freedom from pain in 5 of 10 patients compared with two
patients out of 9 who reported freedom from pain following C2/C3 facet joint
injection. The study authors stated that when evaluating the C2/C3 facet joint
injection, the possible leakage of anesthetic agent from the joint needs to be
taken into consideration, since the third occipital nerve which runs close to
the facet joint may be anesthetized through the leakage[58].
Another
study questioned the specificity of the intraarticular facet block as a
diagnostic test for facet joint disease. The study found that facet capsular
rupture with epidural and periarticular diffusion is probably responsible for
many false positive findings. The authors found a comparatively low success
rate of the procedure in patients in whom maximal volumes were strictly
controlled to avoid extravasation[59]. The capacity of a lumbar facet joint is 1.0-1.5 mls
and a cervical facet joint is 0.5-1.0 ml. However, the anterior facet capsular
ligament is often fenestrated or partially degenerated. Anterior
rupture of the facet joint during injection can occur with as little as 0.2 ml
of injectate and can cause anesthetization of the medial branch nerve and its
peripheral branches, sinuvertebral nerves, spinal nerve, dorsal root ganglion
as well as spillage of local anesthetic into
the epidural space and complete loss of selectivity. One study determined the
prevalence of facet joint pain in patients with chronic spine pain using controlled comparative local
anesthetic blocks (1% lidocaine or 1% lidocaine followed by 0.25% bupivacaine).
False-positive rates after
the facet joint diagnostic
blocks were 63%, 55%, and 27% for cervical, thoracic, and lumbar facet
joint blocks, respectively.
The authors also acknowledged that their study of chronic spine pain may be
criticized because they failed to evaluate other potential sources of pain[60]. In addition to these significant
false-positive rates and study design flaws, a placebo-controlled, double-blind evaluation has shown that even the administration of sedation
with midazolam or fentanyl
could be a confounding factor in the
diagnosis of facet joint pain[61]. We have
found no evidence to support the concept that a diagnostic test can be
performed by an intracapsular
facet joint block. We
have also found no evidence to support the concept that
injecting a volume of local anesthetic over the facet joint (medial branch) nerve
can perform a diagnostic test and localize pain to the facet joint. The facet joint nerve innervates
several structures including the facet joints, facet capsular ligaments, the interspinous
and supraspinous ligaments,
spinous process and paraspinal muscles. Thus relief of pain subsequent to
blockade of the facet joint nerve can be due to blockade of nociceptive
afferent input from any combination of these spinal structures and/or blockade
of nociceptive efferent input to the paraspinal musculature.
DIAGNOSTIC
BLOCK OF THE FACET JOINT (MEDIAL BRANCH) NERVE
Dreyfus et
al performed a study to determine whether blocks of the medial branches
anesthetize these nerves exclusively or whether they anesthetize other
structures that are potential sources of pain. In the cadaveric study, the
branches of the dorsal rami were exposed, spinal needles were placed over the
nerves, and plain radiographs were taken to demonstrate the precise
radiographic locations of the nerves. In the second phase of the study, healthy
volunteers underwent injections of radiographic contrast over the nerves, and
plain radiographs and computed tomographic images were taken. Injections were
performed using different rates of injection and in two positions for each
nerve. Radiographic contrast incorporated the medial branches of the dorsal
rami in every injection. However with some needle placements, aberrant flow of
contrast medium was demonstrated with extension into the epidural space or
intervertebral foramina. On the basis of this anatomical study Dreyfus et al
concluded that if the appropriate technique is used, medial branch blocks are
target specific32.
There is no basis for this conclusion in the absence of any electro-diagnostic
quantification of medial branch neural blockade on the adjacent spinal
structures. Furthermore current techniques for fluoroscopic medial branch
blocks describe three times the volume of local anesthetic (1.5 mls) that was
used in the anatomical study by Dreyfus et al [62].
Another study by Barnsley and Bogduk determined the specificity of cervical
medial branch blocks for the diagnosis of cervical zygapophyseal joint pain by
ascertaining the disposition of the local anesthetic after injection of the
medial branches of the cervical dorsal rami. Sixteen consecutive patients with
chronic neck pain from motor vehicle accidents underwent cervical medial branch
blocks. A 22-gauge, 90-mm spinal needle was placed onto the target nerve under
image-intensifier guidance. Immediately after each target nerve had been
infiltrated with 0.5 ml of local anesthetic, 0.5 ml of contrast medium was
injected to map the spread of injectate. Radiographs were recorded to document
the pattern of spread. Twenty-five injections of local anesthetic and contrast
medium were performed. The authors observed that contrast medium dispersed in
characteristic patterns at all vertebral levels and always incorporated at
least 5 mm of the perceived course of the target nerve (sic). According to the
authors, there was never any spread to the ventral ramus, beyond the medial
fibers of semispinalis capitis or to the adjacent medial branches. No other
single structure was consistently within the field of the contrast. Eleven
patients obtained complete or definite relief of their pain, which according to
the authors could only be attributed to anesthetization of the zygapophyseal
joint innervated by the nerves blocked. The authors concluded that local
anesthetic blocks of the cervical medial branches are a specific test for the
diagnosis of cervical zygapophyseal joint pain. The authors further stated that
local anesthetic always reaches the target nerve and does not affect any other
diagnostically important structures[63].
There is no basis for such a conclusion to be derived from visual observations
of the dispersal of contrast medium to “at
least 5 mm of a perceived course of a target nerve”. The facet
joint (medial branch) nerve
cannot be visualized under fluoroscopy but the study came to a conclusion based
upon spread of contrast medium to a segment of its perceived course! An even
more serious omission is that the
study came to a conclusion that relief of their pain could only be attributed
to anesthetization of the zygapophyseal joint innervated by the nerves blocked
yet the authors did not conduct any electro diagnostic measurements of medial
branch neural blockade of any of the other posterior spinal structures.
INFLAMMATION
AND MULTIPLE PAIN GENERATORS
The idea
of localizing the pain generator to the facet joint is not sustained by any
knowledge of pathophysiology. Inflammation results from a physical, chemical or
biological trauma or irritation. A primary characteristic of inflammation and
the inflammatory process is recruitment and spread[64]. A single or cumulative traumatic or
degenerative event results in spread of inflammation and multiple pain
generators. In one study, a piece of gelatin sponge containing complete
adjuvant was inserted into the L5-L6 facet joint in rats (arthritis group).
Saline was used in the control group. Inflammatory cells infiltrating the
epidural space were counted, and changes in cartilage were assessed
histologically. Tumor necrosis factor (TNF)-alpha-immunoreactive cells in the
L5 dorsal root ganglion were counted. Mechanical allodynia was observed in the
arthritis group from day 3, gradually recovering during the observation period.
Significantly larger numbers of inflammatory cells had infiltrated the epidural
space by days 3 and 7 in the arthritis group than in controls. Numbers of
TNF-alpha-immunoreactive cells were significantly increased at days 1 and 3 in
the arthritis group compared with controls. Thus when inflammation was induced
in facet joint, inflammatory reactions spread to nerve roots, and leg symptoms
were induced by chemical factors40. In another study, lumbar
facet joint cartilage and synovial tissues in 40 cases of posterior lumbar
surgery were harvested to measure tumor necrotizing factor-alpha (TNFalpha),
interleukin-1beta (IL-1beta), and interleukin-6 (IL-6) during operation. Inflammatory
cytokines were detected in the joint tissues in the lumbar spinal canal
stenosis (LSCS) and lumbar disc herniation (LDH) groups. Intraspinal canal
tissues including lumbar nerve root were stained by injection of methylene blue
into the facet joints39. Inflammatory mediators and
cytokines produced by tissue injury, infection or inflammation of a spinal
structure will diffuse and inflame adjacent tissues. The other immune cells,
which include white blood cells such as T helper cells, lymphocytes,
neutrophils, eosinophils, and other cells such as fibroblasts and endothelial
cells invade an area of injury. These immune cells respond to the chemical
mediators, release destructive enzymes to kill any invading organism and
release more chemical mediators to attract more immune cells. A consequence of
this immune response is tissue damage, pain and muscle spasm. In a sense the
initial immune reaction ignites a cascade of immune reactions and generates an
inflammatory soup of chemical mediators. These chemical mediators produced by
the immune cells include prostaglandin, nitric oxide, tumor necrosis factor
alpha, interleukin 1-alpha, interleukin 1-beta, interleukin-4, Interleukin-6
and interleukin-8, histamine and serotonin. In the area of injury and
subsequently in the spinal cord, enzymes such as cyclooxygenase increase the
production of these inflammatory mediators[65] [66] [67]. There are multiple pain
generators involved in inflammation of a spinal segment and the objective should
be to block multiple sites of inflammation utilizing local anesthetics in
combination with anti-inflammatory medication including inflammatory mediator
blockers. The facet
joint nerve itself may be the pain generator. Repeated firing of
sensory nerves causes
release of the inflammatory neuropeptides at the peripheral endings of these
fibers[68] [69] [70].
These neuropeptides may induce vasodilation, increase vascular permeability,
attract other immune cells such as T helper cells and excite surrounding
sensory nerve fibers - the phenomenon referred to as neurogenic inflammation.
At the level of the central nervous system, the increased input from peripheral
pain receptors alters the central processing mechanisms and subsequently up regulates the expression of
genes associated with immune response and microglia activation
in the dorsal root ganglion or spinal cord (central sensitization)[71]
[72]
64. The false positive
results obtained with capsular rupture with epidural and periarticular
diffusion of local anesthetics59 are indicative of pain relief resulting
from blockade of medial branch innervation to adjacent sites of inflammation.
In one study, the duration
of pain relief was significantly superior with medial branch nerve blocks
utilizing local anesthetic and steroid (Depo-medrol) compared with blocks
utilizing local anesthetic only[73].
BENEFIT OF
EPIDUROGRAPHY
It has
been stated that the benefit of using fluoroscopy in epidural steroid
injections is to perform a pre-injection epidurogram to assess whether the volume
of injectate can cover the targeted nerve levels. Such statements make a
presumption of the anatomical location of the source of inflammation and make a
presumption that local anesthetics and steroid will exert their therapeutic
effect only if injected at an exact anatomical location. There is no evidence
to support these statements. One
study tested the postulate that the lack of positive effects of epidural
steroids in patients with radicular leg pain may in part be
incorrect placement of injectate. This was in response to studies that claimed
a therapeutic advantage for epiduroscopy compared with traditional
epidural steroid administration techniques due to a targeted
placement of corticosteroid around the affected nerve root when
epiduroscopy was utilized. The study investigated whether the site
of steroid placement within the epidural space made a difference in outcome.
The study randomized 60 patients with a 6–18 months history of
sciatica to either targeted epidural local anesthetic and steroid placement
with a spinal endoscope or caudal epidural local anesthetic and
steroid treatment. Pre-treatment and 6-week, 3-month, and 6-month
SF-MPQ and HAD scores were recorded. The authors concluded that the
targeted placement of epidural steroid onto the affected nerve root
causing sciatica does not significantly reduce pain intensity and
anxiety and depression compared with untargeted caudal epidural
steroid injection. When
analyzed individually, both techniques benefited patients[74].
Another study utilized epidurography to confirm epidural filling defects for contrast dye
in the patients with epidural fibrosis. Epidural adhesiolysis was performed by
insertion of an epidural catheter via the sacral hiatus. Injections of contrast
dye, local anesthetic, corticosteroid, and hypertonic NaCl 10% were carried out
daily for 3 days. Spread of the contrast dye in the epidural space was
evaluated after 10 and 20 ml injection volume. Statistical analysis (chi square
analysis) could not demonstrate that improvement of contrast spread was
correlated with better pain behavior[75].
INFLAMMATION
AND MULTIPLE PAIN GENERATORS
Inflammation
results from a physical, chemical or biological trauma or irritation. A single or
cumulative traumatic or degenerative event results in spread of inflammation
and multiple pain generators. In one study, lumbar facet
joint cartilage and synovial tissues in 40 cases of posterior lumbar surgery
were harvested to measure tumor necrotizing factor-alpha (TNFalpha),
interleukin-1beta (IL-1beta), and interleukin-6 (IL-6) during operation. Inflammatory
cytokines were detected in the joint tissues in the lumbar spinal canal
stenosis (LSCS) and lumbar disc herniation (LDH) groups. Intraspinal canal
tissues including lumbar nerve root were stained by injection of methylene blue
into the facet joints39. Inflammatory mediators and
cytokines produced by tissue injury, infection or inflammation of a spinal structure
will diffuse and inflame adjacent tissues. The other immune cells, which
include white blood cells such as T helper cells, lymphocytes, neutrophils,
eosinophils, and other cells such as fibroblasts and endothelial cells invade
an area of injury. These immune cells respond to the chemical mediators,
release destructive enzymes to kill any invading organism and release more
chemical mediators to attract more immune cells. A consequence of this immune
response is tissue damage, pain and muscle spasm. In a sense the initial immune
reaction ignites a cascade of immune reactions and generates an inflammatory
soup of chemical mediators. These chemical mediators produced by the immune
cells include prostaglandin, nitric oxide, tumor necrosis factor alpha, interleukin
1-alpha, interleukin 1-beta, interleukin-4, Interleukin-6 and interleukin-8, histamine and serotonin. In the area of injury and
subsequently in the spinal cord, enzymes such as cyclooxygenase increase the
production of these inflammatory mediators[76] [77] [78]. There are multiple pain
generators involved in inflammation of a spinal segment and the objective
should be to block multiple sites of inflammation utilizing local anesthetics
in combination with anti-inflammatory medication including inflammatory
mediator blockers. The facet
joint nerve itself may be the pain generator. Repeated firing of
sensory nerves causes
release of the inflammatory neuropeptides at the peripheral endings of these
fibers[79] [80] [81].
These neuropeptides may induce vasodilation, increase vascular permeability,
attract other immune cells such as T helper cells and excite surrounding
sensory nerve fibers - the phenomenon referred to as neurogenic inflammation.
At the level of the central nervous system, the increased input from peripheral
pain receptors alters the central processing mechanisms and subsequently up regulates the expression of
genes associated with immune response and microglia activation
in the dorsal root ganglion or spinal cord (central sensitization)[82]
[83]
64. The false
positive results obtained with capsular rupture with epidural and periarticular
diffusion of local anesthetics59 are indicative of pain relief
resulting from blockade of medial branch innervation to adjacent sites of
inflammation. In one study, the duration
of pain relief was significantly superior with medial branch nerve blocks
utilizing local anesthetic and steroid (Depo-medrol) compared with blocks
utilizing local anesthetic only[84].
BLOCK OF THE FACET JOINT (MEDIAL
BRANCH) NERVE UTILIZING ANATOMICAL LANDMARKS
Several
techniques for performing
therapeutic facet nerve blocks using anatomical landmarks have been described 17 [85].[86].
As described by Hoerster et al 44, a
larger volume of local anesthetic administered at the lamina of the vertebral
arch will spread along the muscles of the frontal plane, cranially, caudally
and laterally, blocking the deep areas supplied by the medial and lateral
branches of the dorsal rami of the spinal nerves, including the adjacent
component of the vertebral joints up to the region of the ventral rami of the
spinal nerves. There
are no studies that have compared the safety, efficacy and outcome of facet
joint nerve blocks guided by fluoroscopy or guided by anatomical landmarks. However,
clinicians perform thousands of epidural injections, joint, nerve blocks and
regional anesthetic procedures safely and effectively every day without
fluoroscopy and often on women in labor. A study of spinal anatomy will reveal
that the facet joint nerve block has a lower risk profile than many other
spinal procedures and regional anesthetic blocks that are performed utilizing
anatomical landmarks. Success
of the technique will occur if the anesthetic blocks the medial or lateral
branch nerves that are involved in the inflammatory process or blocks the
medial branch innervation to the facet joint or posterior spinal structures
that are inflamed. Performance of facet joint nerve blocks
utilizing anatomical landmarks require the same training, skills and caution as
for other spinal or
paravertebral nerve blocks in order to avoid complications such as nerve injury
and inadvertent epidural or spinal anesthesia. It should be noted that there is
a greater risk of spinal cord injury from epidural blocks wherein the tip of
the needle is 10-16 mm away from the spinal cord. Procedures utilizing
anatomical landmarks should not be performed where such landmarks cannot be
identified as in obese patients or where there is a narrow margin of safety as
in the elderly. Safety of blocks utilizing anatomical landmarks is enhanced by
aspiration before injection, and use of low concentration, preservative-free
local anesthetic solutions.
NEEDLE POSITION AND SUCCESS OF A NERVE BLOCK
It has been stated by advocates of fluoroscopy that
fluoroscopic verification of needle position gives inconsistent results when
the facet joint nerve is blocked or the epidural space is injected using
anatomical landmarks (“blind technique”)14. Nerve blocks are often performed
utilizing local anesthetics and steroid. Inconsistent needle position does not
correlate with the success of a block or relief of pain and is not unique to a
facet joint nerve block. It is a characteristic of the simplest joint injection
procedures. Intra-articular knee and shoulder joint procedures are some of the
commonest procedures performed by primary care physicians and specialists. A
study by Jackson and Evans in the Journal of Bone and Joint Surgery determined
the accuracy of needle placement in the intra-articular space of the knee, by
orthopedic surgeons performing intra-articular knee injections. Out of eighty
injections performed through an anterolateral portal, fifty-seven were
confirmed to have been placed in the intra-articular space on the first attempt
(an accuracy rate of 71%)[87].
Needle position does not predict the success of a nerve
block. The success rate of a nerve block or joint injection with or without
fluoroscopy is higher than is predicted by accuracy of needle placement because
of the diffusion and perineural transport of the local anesthetic and steroid. One study
characterized the local anesthetic spread of injectate resulting from a
single-injection technique of deep cervical plexus block.
The authors showed that the spread of injectate had
a large volume exceeding twice that of the injectate[88].
Studies have been published that have utilized fluoroscopy
to verify needle placement and success of the regional anesthetic or epidural
procedure utilizing anatomical landmarks. Fredman
et al examined the effect of fluoroscopy on improving the accuracy and possible
efficacy of an epidural steroid injection. In the study, the epidural steroid
reached the anatomical level of pathology only 26% of the time despite
fluoroscopic guidance[89]. However the effect of the steroid
extends beyond the anatomical level visualized under fluoroscopy. Renfrew
found that 14.2% of caudal epidurals and 34% of interlaminar epidurals placed
by experienced physicians using anatomical landmarks are found to be misplaced
when verified by fluoroscopy[90]. These figures are often quoted in
the pain and radiology literature, and one
article stated that even in experienced hands, blind epidural steroid
injections result in inaccurate needle placement in up to 30% of cases[91].
Another article stated that epidural injection of steroid and local anesthesia
used to treat low back pain is best performed with fluoroscopic control, with
needle placement documented by means of a limited epidurogram16.
None of these articles provide any documentation of the success or failure rate
of the epidural injection. In fact, a study in the journal Reg
Anesth Pain Med showed a 95% success rate of labor epidurals placed using
anatomical landmarks that were reactivated at a later time for postpartum tubal
ligation[92]
[93].
Several studies have verified the success of nerve or epidural blocks utilizing
anatomical landmarks. In one study of
caudal epidural injections, fluoroscopy revealed incorrect placement by staff
physicians confident of their anatomical landmarks 14.2% of the time (seven of
49 procedures)90. In addition, when the needle was
positioned within the sacral canal and no blood was evident on Valsalva
maneuver or aspiration, the injection was venous in 29 of 316 procedures
performed by both staff physicians and residents (9.2%). In another study, the
combination of two anatomical landmark signs predicted a successful caudal epidural
injection in 91.3% of attempts[94].
In yet another study, radiological studies confirmed the clinical impression
that the epidural space had been successfully identified using anatomical
landmarks in 91.6% of the time. The authors stated that because of
ever-increasing medical expenditures, the cost-benefit of routine fluoroscopy
should be critically evaluated89 One study examined the site of catheter tips and the spread of contrast
material in the epidural space using computed tomographic (CT) imaging in
patients receiving successful epidural analgesia. Catheter tips were
most often found lateral to the dura in the intervertebral foramen. In these
subjects with normally functioning epidural analgesia, there was remarkable
inter-individual variability in patterns of spread, including various amounts
of anterior passage, layering along the dura, and compression of the dura
creating a posterior fold. The author concluded that non-uniform distribution
of injectate is common and is compatible with uniform anesthesia[95]. Success of a nerve block requires a needle to be within the vicinity of
a nerve and not exactly on the nerve.
CONCLUSION
There is no physiological or biomechanical evidence for a single pain trigger in the spine where inflammation is confined. Inflammation and the inflammatory process are characterized by recruitment and spread. There is evidence to revise the current focus on searching for one pain trigger at a time to acknowledging the existence of and targeting multiple pain triggers responsible for spinal pain. There is evidence for the therapeutic utility of blockade of the medial branch nerve innervation of the posterior spinal structures that are involved in inflammation and pain. There is a need for more research and clinical trials to improve the current structural pathology based diagnosis and treatment of spinal pain to biochemical imaging and interventions that address the role of cytokine and inflammatory mediators, neuroplasticity and central/peripheral sensitization in the biochemical pathology of spinal pain. In the hands of a skilled physician, a facet medial branch nerve block or epidural injection is similar to other spinal nerve block procedures. These procedures can be performed safely and effectively with or without fluoroscopy. There is no evidence to support a requirement for the use of fluoroscopy to perform facet medial branch nerve blocks or epidural injections. Use of fluoroscopy for facet medial branch nerve blocks and epidural injections should be optional and depend on the skill, training and comfort of the individual clinician and a cost-benefit analysis.
Fluoroscopy should be utilized when anatomical landmarks are unreliable or difficult to discern and in the performance of procedures that bring the needle close to vital structures such as a celiac plexus block or with nerve destruction procedures such as radiofrequency lesioning.
We have found no evidence to support the performance of intra-capsular facet joint injections for either diagnosis or treatment. As a diagnostic tool, the facet intra-capsular injection is meaningless and this procedure should be discontinued. There is no evidence that fluoroscopic guidance can result in a controlled or limited block of the medial branch innervation to the facet joint. A facet joint nerve block administered as a diagnostic test cannot localize the pain to the facet joint. In the absence of systemic analgesia, the block localizes the pain to any or several of the posterior spinal structures innervated by the medial branch nerve. Lack of diagnostic localization to the facet joint does not affect the therapeutic utility of medial branch blocks, as inflammation subsequent to injury is not confined to a single posterior spinal structure. There is evidence for the therapeutic utility of a blockade of the medial branch nerve and the posterior spinal structures that are involved in inflammation and pain. Fluoroscopy enables better structural accuracy of needle positioning over a bony landmark, but structural accuracy may not correlate with efficacy or outcome of neural blockade or pain relief. Structural accuracy enables blockade of the nerve branches in close proximity. However, the nerve branches being blocked may or may not innervate the posterior spinal structures that are involved in inflammation and pain. There is no evidence that a block utilizing fluoroscopy translates into a greater therapeutic advantage than a block performed utilizing anatomical landmarks. Techniques of facet joint nerve blockade utilizing fluoroscopy or anatomical landmarks are both biochemically and electro-diagnostically blind. Neither technique can visualize or target the branches of the facet joint nerve that are involved in the inflammatory process. EMG guidance during a facet joint nerve block - whether performed with fluoroscopic guidance or by utilizing anatomical landmarks - is the only objective method of confirming accuracy of the procedure. Technologies such as MRI spectroscopy that can image inflammation are currently experimental. There is no evidence of any studies that demonstrate increased safety, efficacy or outcome of facet medial branch nerve blocks or epidural injections using fluoroscopy compared with the use of anatomical landmarks. However it should be noted that the absence of proof for facet joint nerve blocks, i.e. the fact that there are no controlled studies comparing blocks with and without imaging, does not necessarily mean that the success rate is not different.
The increased use of fluoroscopy should translate into a better safety record and decrease the frequency and payments of claims associated with chronic pain management procedures but the opposite has occurred. Research is required to determine if this increase in chronic pain claims reflects a change in liability or an increase in the number of procedures performed. Research should determine the correlation of claims to the level of training and experience of those performing these procedures. Safety dividends that should accrue from the use of fluoroscopy may be offset by complacency due to a false sense of security, increased risk of spinal cord injury with the prone position required in fluoroscopic epidurals and increased performance of procedures with a greater risk of nerve or spinal cord injury, yet unproven and questionable therapeutic advantage, such as transforaminal epidurals. More cost-benefit and risk-benefit analysis of some of these procedures are required. The constant questioning of “established” truths is necessary for progress in the specialty of pain medicine and improvement in outcome at optimum cost.
Figure 1 – Anatomy of the Facet Medial
Branch Nerve44
1.
Ventral
branch of the dorsal ramus
2.
Dorsal
ramus of spinal nerve
3.
Ascending
branch of spinal nerve
4.
Medial
branch of dorsal ramus
5.
Inferior
articular branch of medial branch
6.
Superior
articular branch of medial branch
7.
Sinuvertebral
nerve of Luschka
REFERENCES