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460 Kai On SUN, Henry Ka Fai TONG
herniated nucleus pulposus without neurological
deficits and herniated nucleus pulposus with
nerve root irritation or compression. It has also
been used for pain caused by degenerative joint
disease, spondylosis, scoliosis, spondylolisthesis,
post-laminectomy syndrome and spinal stenosis. A
favourable response has been reported in patients
with an advanced educational background, a
primary diagnosis of radiculopathy and pain of
less than 6 months’ duration. Factors associated
with poor outcome include constant pain, frequent
sleep disruption and being unemployed owing
to pain [29]. Despite the use of epidural steroid
injection for the clinical conditions listed above,
its efficacy varies. e most favourable clinical
predictor of good response is the presence of
radiculopathy in patients with back pain because
of the anti-inflammatory effects of corticosteroid
on compressed and/or inflamed nerve roots.
e rationale for epidural steroids focuses on
their strong anti-inflammatory action. Nerve root
oedema is seen in patients with herniated discs.
Herniated disc have been found to contain high
levels of the enzyme phospholipase A2, which
liberates arachidonic acid from cell membranes.
Steroids work by interfering with the inflammatory
process. Furthermore, administration of epidural
solutions clears or dilutes the chemical irritants.
Steroids also exert their effects in other ways,
including membrane stabilisation, inhibition of
neural peptide synthesis or action, suppression of
ongoing neuronal discharge and suppression of the
sensitisation of the dorsal horn neurons.
e most common steroids used in the epidural
space include methylprednisolone acetate 80 mg
and triamcinolone diacetate 50 mg. In general, a
total volume of 6 to 10 ml is adequate for lumbar
epidural administration, whereas 4 to 6 ml is used
for the cervical region. Larger volumes of 15 to
30 ml are required for administration through the
caudal space. In contrast, only 0.5 to 2 ml is used
for transforaminal injections.
e objective of epidural steroid injection is to
deliver corticosteroid close to the site of pathology,
presumably onto an inflamed nerve root. e
epidural space can be accessed through various
approaches: the interlaminar approach, caudal
approach and transforaminal approach. Caudal
and interlaminar epidural injections are affected
by the presence or absence of epidural ligaments
or scarring, which may prevent migration of
the posteriorly administered injectate to the
anterior epidural space. For optimum results, the
corticosteroid should reach the ventral epidural
space in front of the dural sac and behind the
disc. e transforaminal approach shows good
ventral flow, whereas the interlaminar method
predominantly shows dorsal flow, which is far
removed from the usual site of inflammation.
e response of the patient determines whether
repeated injections are required. It is preferable
to wait at least 2 weeks between injections. If the
patient has an excellent response, the epidural
steroid injection can be repeated on an as-needed
basis if the pain returns. If the patient has minimal
relief with the interlaminar epidural injection,
one transforaminal, site-specific, epidural steroid
injection may be tried. e epidural steroid injection
can be repeated every 3 months (maximum three
times per year) only if the patient gets at least 50%
relief for at least 6 weeks.
e interlaminar approach carries the disadvantages
of diluting the injectate, extra-epidural or
intravascular placement of the needle, preferential
cranial flow of the solution and preferential
posterior flow of the solution, technical difficulties
in postsurgical patients, dural puncture and trauma
to the spinal cord. e transforaminal epidural
injections carry the potential complications of
intraneural injection, neural trauma, intravascular
injection and spinal cord trauma. Other
complications of epidural steroid administration
include inadvertent intrathecal steroid injection
causing aseptic meningitis, adhesive arachnoiditis,
pachymeningitis, or conus medullaris syndrome.
Epidural steroids affect the hypothalamus-
pituitary-adrenal axis, resulting in depression of
the plasma cortisol levels for up to 3 to 5 weeks [3].
ey can also cause iatrogenic Cushing’s syndrome,
congestive heart failure secondary to fluid retention
and changes in blood glucose levels in susceptible
individuals. Fortunately, these side effects are
uncommon. Most of the side effects reported
are minor and transient [22] and are related to
systemic absorption; they include insomnia, rash
and pruritus.
e caudal epidural technique is useful in the
treatment of a variety of chronic benign pain
syndromes, including lumbar radiculopathy,
spinal stenosis and post-laminectomy syndrome.
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Interventional Procedures for Back and Neck Pain
Because of the simplicity and safety associated with
the caudal approach to the epidural space, this
technique is replacing the lumbar epidural approach
for these indications in some pain centres. e
caudal approach to the epidural space is especially
useful in patients who have previously undergone
low back surgery, which may make the lumbar
approach to the epidural space less efficacious. e
caudal approach to the epidural space may be used
in the presence of anticoagulation or coagulopathy,
so local anaesthetics, opioids and steroids can be
administered via this route even when spinal or
lumbar epidural approaches are contraindicated.
Potential risk of haematogenous spread via the
venous plexus, local infection and sepsis are the only
absolute contraindications to the caudal approach
to the epidural space.
In a recent review, there is limited evidence that
epidural steroid alone benefits the symptoms of
sciatica, either the condition alone or associated
with low back pain, in the short to intermediate
term (level 3) [4]. ere is also limited evidence that
epidural steroid injection alone does not affect the
long-term prognosis of sciatica (level 3). e caudal
epidural injection of steroid with local anaesthetic
benefits pain and function in low back pain in the
intermediate term (level 3).
Sleeve Root Injection
Just as discogenic pain can be studied by careful
blocks of the intervertebral disc, so too the central
neural elements can be investigated logically and
sequentially. e nerve root sleeve is particularly
accessible to precise local anaesthetic blocks.
Segmental information gained from such nerve
root blocks can be helpful in sorting out confusing
patterns of referred pain to the limbs. is may be
beneficial to those patients with contraindications
to neuraxial block.
ere are some regional differences in the approach
to each area of the spine, however, partly as a
result of the proximity of structures, such as the
lung or vertebral artery. Injectate volumes must be
restricted to 1 ml; a larger volume would ensure
spread to adjacent nerve roots via the epidural space,
resulting in loss of segmental specificity. Only the
lumbar and sacral nerve root sleeve injection will
be discussed here.
Numerous publications have discussed the anatomy
and approach to the lumbar nerve root sleeve [14,
16, 18]. Kikuchi and associates [17] have described
the anatomic variants of the dorsal root ganglia,
and Derby and colleagues [10] have reviewed the
techniques of blocking the lumbar nerve root
sleeve.
In general, the principles of approach to these
neural structures are little different from those of
the cervical approach. To avoid impalement of
the nerve root, the needle tip is directed to lie just
inferior to the midpoint of the pedicle. is can
be achieved by first aligning the fluoroscopy beam
to pass squarely through the disc space. For the
lumbosacral disc, a considerable degree of cranial
angulation may be required. e C-arm of the
fluoroscope is then rotated to an oblique position
so that the edges of the facet joint become clearly
defined. A spinal needle with a curve in the terminal
portion is then passed down the fluoroscopy beam
to strike the inferior margin of the pedicle without
contacting the nerve root. Derby and colleagues
[10] describe this as the “6 o’clock position”, with
the oblique view of the pedicle representing the
clock face. Small volumes of contrast and local
anaesthetic agents are then gently injected. If an
electrically insulated needle is used to approach the
nerve root, electrical stimulation can also be used
to study patterns of referral to the lower limbs.
Sacral nerve roots can easily be accessed by passing
a spinal needle through the appropriate posterior
sacral foramen. is route of access is visualised by
adjusting the fluoroscopy beam to align the round
posterior foramen with the curvilinear marking of
the anterior foramen. e needle is passed through
the epidural space onto the peripheral nerve at a
point just anterior to the anterior sacral plate.
Injection of contrast agents is best performed
under direct fluoroscopic guidance because veins
are easily entered in the vicinity of the sacral nerve
roots and can lead to false-negative block.
Facet Joint Syndrome
Approximately 15–40% of low back pain is
due to dysfunction or inflammation of the facet
(zygapophyseal) joints [8]. Among the roughly
13% of the population who go on to develop
chronic neck pain [13], the cervical zygapophyseal
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462 Kai On SUN, Henry Ka Fai TONG
joints have been postulated to account for between
50–60% of cases based on diagnostic, controlled
blocks [2, 21, 23]. Two factors which may account
for the high incidence of cervical facet joint pain in
chronic neck pain sufferers are the higher density
of mechanoreceptors in cervical compared with
lumbar facet joints [6] and their susceptibility to
injury during trauma. e precise pathophysiology
of facet joint syndrome is often unclear. Two medial
branches of the dorsal rami provide innervation.
ere is no pathognomonic symptom or sign,
laboratory, radiological, or electrophysiological
diagnostic test. By convention, the diagnosis is
based simply on a constellation of findings. Facet-
induced back pain is currently a diagnosis of
exclusion supported by reproduction of the pain
during arthrography and abolition of pain following
injection of local anaesthetic. erefore, there is no
facet syndrome per se as there is no combination of
clinical features which defines facet joint syndrome.
However, one recent retrospective study showed
that there is strong correlation between paraspinal
tenderness and radiofrequency treatment success in
cervical facet pain patients [9].
e facet joints are paired diarthrodial synovial
joints formed by the inferior articular process of
one vertebra and the superior articular process of
the subjacent vertebra. A tough fibrous capsule is
present on the posterolateral aspect of the facet
joint. Owing to the small volume of the lumbar
facet joint space, approximately 1 to 2 ml, volumes
of therapeutic agent in excess of this amount may
extravasate into the epidural space by the ventral
aspect of the joint. e poor localisation of facet
joint pain is explained by the pattern of profuse
overlapping of sensory innervation of these joints.
e medial branch of the posterior ramus supplies
the lower pole of the facet joint at its own level as
well as the upper pole of the facet joint below. Each
medial branch of the posterior primary ramus also
supplies the multifidus and interspinalis muscles,
as well as the ligaments and periosteum of the
neural arch. erefore, pain relief after lumbar
facet nerve block cannot be regarded as specific to
the facet joint. Because of the duality of segmental
innervation, each joint must be denervated at
two segmental levels, both at and above the level
of the involved joint. e medial branches of the
cervical posterior rami are somewhat different in
that they mainly supply the facet joints, with only
small discrete innervations of the posterior neck
muscles. erefore, if neck pain or headache is due
to cervical facet disease, it is likely to be relieved by
cervical facet joint or medial branch blocks. Please
also refer to Chapter 12 for more information on
neck pain.
In patients with lumbar facet joint disease, the
history is likely to include complaints of deep,
achy, nonspecific low back pain localised over
the affected facet joint. Radiation to the buttock
or proximal thigh is possible. Pain occasionally
radiates below the knee but not into the foot. e
patient may report that the symptoms are worse
with lumbar extension, extensive walking, or sitting
for long periods of time. ere is no bowel or
bladder dysfunction. On physical examination, the
patient demonstrates pain with deep palpation over
the affected facet joints. ere may be associated
paraspinal muscles spasm. e patient does not have
focal or segmental muscle atrophy, neural tension
signs, or true strength deficits. Facet joint changes
on radiography are nonspecific as they are almost
ubiquitous in adults. Some studies, however, have
suggested that computed tomography (CT) may be
very helpful in diagnosing significant abnormalities
of facet joints. Please also refer to Chapter 13 for
more information on back pain.
Once all myelopathic processes have been ruled
out, a 4- to 6-week course of conservative therapy
is indicated. Interventional procedures can be
considered if symptoms persist. Fluoroscopically
guided joint space or medial branch block injections
must reduce the pain by more than 50% to be
considered successful. ere are conflicting data
regarding the efficacy of radiofrequency ablation of
the nerve supply to the facet joint. e facet joint
can be blocked by local anaesthetics and steroid or
denervated with cryotherapy and radiofrequency
lesioning. e contraindications to facet blockade
are similar to those for any regional block. Facet
blocks should not be performed in patients with
coagulopathies, systemic infection, or infection at
the site of injection.
Injection of lumbar facet joints
and medial branch block
e normal lumbar facet joint has an S-shaped
contour in the oblique projection. e capacity of
the joint is 1 to 2 ml. Facet joints can be entered
from a posterior approach. e patient is placed in
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Interventional Procedures for Back and Neck Pain
the prone position on the X-ray table with a wedge
sponge placed beneath the abdomen, and with the
hip and knee flexed to decrease the lumbar lordosis.
e symptomatic side is rotated up while visualising
the facet joint under fluoroscopy to determine the
optimum obliquity. e minimum obliquity that
allows visualisation of the facet joint is usually best
for facet injection. Because this is often achieved
at nearly 45°, the C-arm is usually rotated to this
angle for better visualisation of the facet joints.
e joints to be blocked should be identified and
marked before initiation of the injection. When
the patient is properly positioned for lumbar
facet blockade, a “Scottie dog” configuration can
be clearly visualised under fluoroscopy. e joint
capsule is defined by the “ears” and “back” of the
head of one “Scottie dog” and the vertebra above
by the “dog’s” front feet (Fig. 28.01). At each
joint to be blocked, the caudal edge of the spinous
process corresponding to the level of the facet joint
is identified. After prone positioning and under
image intensifier guidance, a 22G or 25G x 35
mm spinal needle is then inserted into the joint
(Figs. 28.02 and 28.03). Radiocontrast 0.25 to 0.5
ml can be injected to visualise the S-shaped joint
space and confirm proper needle placement. is
is followed by injection of bupivacaine and 20 mg
methylprednisolone acetate (for each joint). Some
practitioners advocate the use of larger volumes
(2 to 5 ml) for pericapsular rather than intra-
articular injection. is type of injection bathes
the ligaments, paraspinal muscles and supporting
structures with local anaesthetics and steroid. is
has been beneficial to some patients with chronic
low back pain of multifactorial origin.
In medial branch blocks, a spinal needle is
introduced approximately 5 cm lateral from the
midline and directed obliquely, in order to avoid the
overhang of the articular process (Fig. 28.03). is
involves injecting a tiny amount of local anesthetic
(0.3 ml), under fluoroscopic control, onto each of
the medial branches. From L1 to L4, the medial
branch is blocked where it lies in a gutter on the
dorsal surface of the transverse process, just caudal
to the most medial end of the superior edge of the
transverse process. e posterior primary ramus of
L5 is blocked as it runs in the groove between the
ala of the sacrum and the superior articular process
of the sacrum (Fig. 28.04). e blocks require a
preliminary test dose of contrast medium, because
in about 8% of cases the injection can be into
Figure 28.01 Lumbar vertebra Scottie Dog
appearance
Figure 28.02 RF denervation of lumbar facet joint
positionin
Figure 28.03 RF denervation of lumbar facet joints
needle in
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464 Kai On SUN, Henry Ka Fai TONG
the vena comitans of the medial branch. Venous
uptake is usually not a major problem, given the
small volume of local anesthetic injected, but it
risks obtaining a false-negative response.
Lumbar medial branch block has a false-positive
rate of between 25% and 41% [30]. Placebo
controls provide the highest order of validity, but
they are difficult to implement in clinical practice
as multiple blocks would need to be performed on
separate occasions to assess response to placebo and
active agent. Less discriminating but more practical
are comparative local anesthetic blocks. On each of
two occasions, the patient receives an active agent,
but the agents are varied. When a short-acting
agent is used, the patient should obtain short-
lasting relief. When a long-acting agent is used,
the patient should obtain long-lasting relief. When
tested against placebo, this protocol has a sensitivity
of 54% and a specificity of 88% [20].
A transient exacerbation in pain (about 2%
incidence) can be experienced lasting as long as 6
weeks to 8 months in rare cases. Spinal anaesthesia
has occurred after facet joint injection.
Injection of cervical facet joint
and medial branch block
For medial branch nerve blocks of C3 through C8,
a 10 cm spinal needle should be inserted 1 to 2
cm lateral to the waist of the articular pillar as seen
by posteroanterior view under fluoroscopy. e
needle is advanced until it contacts the back of the
articular pillar and then is redirected laterally until
the needle tip is at the most lateral margin of the
articular pillar. Intra-articular blockade of cervical
facets C3 through C7 can be performed by using
a 10-cm spinal needle inserted one to two levels
below the joint to be blocked. e needle is then
advanced upwards and forwards into the middle of
the joint under the fluoroscopic guidance.
Blockade of the innervation of the C2–C3 facet
joint requires location of the third occipital nerve.
e needle is inserted until it contacts the C2–C3
facet joint and then is redirected laterally until
it reaches the lower half of the lateral margin of
the facet. Proper positioning of the needle should
be confirmed by fluoroscopy. After 1 to 2 ml of
medication is injected, the patient should be
assessed for suboccipital numbness, which indicates
adequate blockade of the third occipital nerve and
innervation of the C2–C3 facet joint.
e atlanto-axial joint can be blocked using a 22G
spinal needle to enter the joint posteriorly and
then directing the needle onto the lateral half of
the posterior capsule under fluoroscopic guidance.
Confirmation with both posteroanterior and lateral
X-ray views is needed to ensure that the needle
is in the middle of the joint before injection of
medication. e practitioner should be aware that
the epidural space lies immediately medial to the
joint capsule and that the vertebral artery lies just
lateral to it. Use of more than a total of 2 ml of
injectate may result in leakage outside the joint
capsule with subsequent blockade of the cervical
spinal nerve roots. is can lead to high spinal
block and respiratory arrest.
Bogduk and associates recommend the use of
medial branch nerve blocks rather than intra-
articular injections in the cervical area [5, 27].
is is because the medial branch nerve blocks are
easier to perform and possibly less traumatic than
intra-articular injections. Also, the medial branch
nerves are fairly superficial and easily accessible,
Figure 28.04 RF lesioning of lumbar facet joints
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Interventional Procedures for Back and Neck Pain
and the blocks can be successfully performed in
patients with facet joint disease which has resulted
in obliteration of the joint space. Furthermore,
theoretically, there is less risk of penetration of a
vertebral artery, the epidural space, or the dural sac
than with intra-articular injections.
Radiofrequency lesioning facet
joint
Radiofrequency (RF) lesion generation has
certain advantages over other techniques. Modern
RF generators (Fig. 28.05) and cannulas (Fig.
28.06) allow precision thermal lesion placement,
minimising damage to surrounding tissue.
Various cannulas are available to produce different
lesion sizes and shapes. Continuous temperature
monitoring gives the operator additional control
over lesion size. Impedance monitors detect electric
circuit malfunctions and may signal close proximity
to bone (high impedance) or blood vessels (low
impedance).
Radiofrequency heat lesions are produced by
exciting ions within a field of alternating electric
current at 500,000 Hz. As current density decreases
rapidly with distance from the electrode tip, the
volume of the lesion is limited. e determinants
of lesion size are electrode size, tissue conductivity
(water content), adjacent tissues (bone, blood
vessels and cerebrospinal fluid) and RF generator
output. Heating tissue to 80°C for 60 seconds
creates a maximal lesion. A clinical effect may also
be possible, without heating the tissue significantly,
using pulsed RF energy. Before RF lesioning, the
operator should always ensure that the temperature
meter reads body temperature at about 37°C. is
is the simplest check that the temperature monitor
is functioning.
e patient is placed in a prone position on a
fluoroscopic table (Fig. 28.02). It is important to
keep the patient awake enough so that they can co-
operate during the procedure. e patient’s back is
prepared and draped in a sterile fashion. A C-arm
fluoroscopic device is used for localisation of the
RF target sites.
Radiofrequency lesioning targeting the L5–S1
facet involves first positioning the RF probe at
the superior and lateral aspect of the S1 foraminal
opening (Fig. 28.07). A small branch exits the
superior lateral aspect of the S1 foraminal canal
and extends in a superior fashion towards the
base of the L5–S1 facet joint. At the S1 level, the
fluoroscopic unit needs to be angled in a cranial
fashion to correctly show the opening of the S1
foraminal canal. It is important to place the RF
Figure 28.05 Radiofrequency Machine with
permission from Baylis Medical Inc.
Figure 28.06 RF Probes
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466 Kai On SUN, Henry Ka Fai TONG
cannula in a parallel fashion to the X-ray beam
so that it touches the periosteum at the superior
lateral border of the S1 foramen. A second target
zone includes the superior and medial junction
of the sacral ala. (Fig. 28.07) A posteroanterior
fluoroscopic view usually gives correct imaging for
placement of the cannula. e cannula is advanced
until it touches the superior medial border of
the sacral ala and after the periosteum has been
contacted, the cannula is walked over the leading
edge and advanced approximately 2 to 3 mm in an
anterior fashion.
e other target zones include the superior and
medial aspect of the transverse processes at the
respectively involved L5, L4 and L3. at is, the
junction of the transverse process with the superior
articulating process of its respective facet joint (Fig.
28.04). An oblique fluoroscopic view between
5° and 15° is usually necessary to show the most
medial aspect of the transverse process. After the
cannula touches the periosteum at the superior
and medial border of the transverse process, the
cannula is walked over the leading edge and
advanced approximately 2 to 3 mm in an anterior
fashion. is is done to more correctly align the tip
of the cannula with the facet joint nerve. e idea
is to place the length of the cannula tip parallel to
the length of the nerve in order to create a longer
lesion which will hopefully produce a longer
clinical result. After the cannula has been placed
in the correct position, a lateral view is taken to
make certain that the cannulas at the L3, L4, L5
and alar levels are not too close to the opening of
the foraminal canals.
It is important to check impedance monitoring at
least one time after the cannula has been placed.
e average impedance during a facet rhizotomy
is between 400 to 700 ohms. Once the cannulas
are in the correct position, electrical stimulation is
performed at 50 Hz. Good paraesthesia to the back,
paravertebral, or hip region should be noted when the
medial branches at these levels are stimulated. Good
stimulation should be noted at less than 1 volt at 50
Hz if the electrode system is in correct alignment
with the medial branch. Next, electrical stimulation
is performed at 2 Hz and lower extremity motor
fasciculation should be absent at 3 volts stimulation.
After showing correct dissociation between sensory
and motor stimulation it can be assumed that the
cannulas are in the correct position. At that point,
1 ml of 2% lignocaine is injected through each
cannula and a 30-second delay is allowed to occur.
ermal lesions are then created at each level by
heating the nerve for a period of 90 seconds at a
temperature of 80°C. After the lesions are created,
the cannulas are removed and sterile bandages are
placed at the puncture sites.
Sometimes patients will notice lower extremity
weakness immediately following the procedure. is
is due to extravasation of local anaesthetic solution
onto the main nerve root. is phenomenon will
resolve within 1 to 2 hours after the procedure.
It can be expected that the patients will have up
to 2 weeks of discomfort involving pain in the
paravertebral regions and the upper buttock
following the procedure.
Cryoneurolysis of the facet joint
Cryoanalgesia, the relief of pain by application
of cold, has been used for millennia. Only gas
expansion (the Joule-ompson effect with CO
2
or
N
2
O) cryomachines are used for pain control today.
Important features of the cryomachine include a
thermocouple at the tip to monitor temperature,
a nerve stimulator at the tip allowing both motor
and sensory stimulation for nerve localisation,
a flowmeter to monitor high pressure gas flow, a
pressure gauge to monitor cylinder contents, and
freeze and defrost indicators.
A temperature of -20°C must be reached in the
tissues to result in uniform cell death. When using
Figure 28.07 RF lesioning of L5S1 facet joint
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467
Interventional Procedures for Back and Neck Pain
a gas expansion cryoprobe, which cools to -70°C
(using N
2
O), the center of the ice ball must be within
approximately 4 to 5 mm of the nerve for lethal
application. In contradistinction to the more severe
nerve injuries (induced by radiofrequency, phenol
and alcohol), cryoneurolysis preserves the fibrous
architecture, especially the endoneurium, allowing
more organised regeneration without neuroma
formation and a low incidence of neuritis.
e technique involved is similar to those for
RF lesioning of the facet joint. In medial branch
denervation, the silver-tipped 5-inch cryoprobe
can be used. e lesion needs to be frozen at -60°C
to -70°C for 2 to 4 minutes. It is repeated two to
three times, ensuring adequate thaw times between
freezes. e ice ball should not be removed from the
tissue. It is necessary to wait until it is completely
thawed before pulling out the cryoprobe. Since
the cryoprobes are relatively large, this may result
in significant intervening tissue trauma and for
this reason, radiofrequency neurolysis has largely
supplanted cryoneurolysis in most pain clinics.
Sacroiliac Joint Pain
e sacroiliac (SI) joint can produce symptoms
that are quite similar to facet joint pain. Areas of
referral include the hip, groin, anterior thigh and
calf. Examination usually shows distinct tenderness
over the middle and lower aspect of the SI joint.
Compression tests are frequently painful and
distraction tests often reveal a poorly mobile joint.
Other tests such as Faber and Patrick tests are also
useful. Sacroiliac joint problems frequently exist in
conjunction with other musculoskeletal disorders
such as myofascial pain syndrome, which must be
treated to ensure complete relief.
e SI joint can be a primary source of pain. Pain
may be referred to the SI joint or from the SI joint to
the lumbar facets, iliolumbar ligament, and gluteal,
piriformis, iliopsoas and adductor muscles. Visceral
pain referral may occur from the reproductive
organs and from the large intestine. Systemic
conditions such as ankylosing spondylitis, regional
ileitis and gout can also produce pain in the SI joint.
Primary SI problems are frequently the result of an
accident or injury, but they also can result from
an unguarded or unexpected movement, chronic
strain in the workplace, or repetitive activity such
as swinging a golf club. Sacroiliac joint pain is not
uncommon during or following pregnancy.
Sacroiliac joint problems can be treated by injection
or manipulation. Techniques used for manipulation
may involve high velocity, low amplitude thrust
techniques or muscle energy techniques, which
are a form of precise contract-relax stretching to
mobilise the joint.
With the patient lying in a prone position, the skin
entry point should be 1–3 cm below the inferior
margin of the SI joint. At this point, the skin is
infiltrated with 1% lignocaine. Under fluoroscopic
control, a 22/25G spinal needle is introduced and
directed cephalad to strike the ilium 1 cm above
the inferior margin of the target joint. e tip of
the needle is then manipulated until it enters the
joint space. One ml of contrast medium is injected.
e latter initially fills a small inferior, subcapsular
recess and then extends to the superior aspect of
the joint. Meanwhile, the injection can produce
similar pain to that which has been experienced by
the patient. After the injection of contrast medium,
the joint is infiltrated with 1 ml of 2% lignocaine.
For RF rhizotomy under image intensifier guidance
(Fig. 28.08), the fluoroscopy unit is angled in such
a way that the lines of the posterior and anterior
aspects of the joint are seen to overlap. e tube is
angled caudad and obliquely from the side opposite
Figure 28.08 Radiofrequency lesioning of
sacroiliac joint
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468 Kai On SUN, Henry Ka Fai TONG
the joint to be lesioned; that is, an oblique view
at 15° to 20° from the opposite side of the body
is used to correctly visualise the posterior joint
lines. e favoured technique used to denervate
the SI joint involves the production of multiple
connecting linear lesions along the entire length
of the posterior aspect of the joint and its capsule.
(Fig. 28.09) Each lesion is created by increasing the
temperature to 80°C for 60 seconds. It is important
to make certain that the lesions overlap slightly so
that a complete linear lesion is produced along the
entire posterior joint line. e S2 level contributes
heavily to the innervation of the SI joint. An S2
ganglionotomy can be an important adjunct to the
SI joint rhizotomy.
Patients usually experience 2 weeks of buttock
discomfort following the SI joint rhizotomy. Patchy
decreased skin sensation in the buttock is sometimes
seen and uniformly resolves within 2 to 6 weeks.
Discogenic Back Pain
Discogenic pain is typically a deep, dull midline
aching in the low back that might radiate to the
gluteal areas but is rarely experienced below the
knees or legs. It can be categorised into three entities:
internal disc disruption, degenerative disc disease,
and segmental instability. Internal disc disruption
should not be confused with disc herniation or disc
degeneration. Please also refer to Chapter 12 for
more information.
e aetiology of internal disc disruption has not been
definitively established, but it probably results from
a compression injury causing end-plate fracture;
this in turn triggers inflammatory degradation of
the nucleus pulposus and eventually of the annulus
fibrosus in the form of annular fissures. e disc
becomes painful as a result of chemical irritation of
nerve endings in the outer annulus. e condition
is sometimes not evident on CT and it does not
cause neurological symptoms. e annular fissures
can be demonstrated on magnetic resonance
imaging (MRI) scans with the use of gadolinium.
However, both CT and MRI do not tell us whether
the pathoanatomy is symptomatic. erefore, the
gold standard is still the discography procedure
[11].
Discography is an invasive diagnostic procedure
designed to ascertain whether a disc is intrinsically
painful, and is the single most important test for
diagnosing internal disc disruption. It stimulates
the disc by increasing the intervertebral pressure
and reproducing the patient’s pain. It can be done
anywhere in the cervical, thoracic, or lumbar discs,
with the lumbar being the most common. Patients
who are not candidates for definitive management of
discogenic pain (surgery, intradiscal electrothermal
therapy) are not candidates for discography. Broad
spectrum antibiotic are given before the procedure
[12].
e patient is placed in the prone position. Usually
one disc above and one below the suspected level
are also injected as control levels, and the suspected
level is injected last. e following parameters
are noted: resistance on entry to the annulus,
compliance of the nucleus on injection, pain
provocation on injection, and distribution of dye
inside and outside the disc. Antibiotics and local
anaesthetics are injected before withdrawing the
needle at each level. e administration of both
systemic and intradiscal antibiotics has been shown
to be necessary by Fraser et al. who in sheep studies
noted antibiotic levels in the annulus 30 minutes
after intravenous administration, but none was
demonstrated at 60 minutes [12]. Furthermore,
once the discitis is developed, it is very difficult
to treat. Anteroposterior and lateral discographic
images are then obtained as well as a post-procedure
CT scan within 2 hours to highlight the features of
the internal disc disruption. Replication of usual
pain at less than 50 psi above opening pressure
is considered positive for the test and can either
proceed to surgery (interbody fusion) or intradiscal
electrothermal annuloplasty/nucleoplasty,
Figure 28.09 SKJ RF denervation targets
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469
Interventional Procedures for Back and Neck Pain
radiofrequency lesioning and laser-assisted spinal
endoscopy.
Intradiscal electrothermal
procedure
e intradiscal electrothermal (IDET) procedure
utilises an intradiscal catheter designed to achieve
precise navigation and placement in the disc.
e catheter delivers intradiscal thermal energy.
e mechanism of analgesia is not entirely clear,
although there is evidence that the collagen fibres
in the annulus undergo structural changes, so
annular fissures can heal thereby reducing pain. It
is not recommended that more than two levels at
one time be treated. Signs of improvement usually
occur 6 to 12 weeks after the procedure. Exclusion
criteria for IDET are: intervertebral disc herniation
with radiculopathy, disc height decreased for more
than 50%, spinal stenosis, prior discectomy and
coagulopathy.
Radiofrequency procedures for
discogenic pain
Radiofrequency techniques developed for the
treatment of lumbar discogenic pain include
radiofrequency lesions of the ramus communicans
nerves as well as intradiscal RF lesions. e ramus
communicans nerve sends fibres to more than one
level and if discography has shown that the L4–L5
disc is the painful level, then lesions of the ramus
communicans nerves should be performed at L4
and L5. e patient is placed in the prone position
and RF cannulas measuring 150 mm in length
with 5 mm active tips are selected. e end plates
of the disc and the vertebral body should be clearly
visualised by fluoroscopy. Oblique angulation at
15° to 25° is used so that the body of the vertebra
just covers the lateral tip of the transverse process.
e ramus communicans nerve tends to run at the
lower third of the vertebral body. e RF cannula
is advanced until the periosteum at the lower third
of the vertebral body is contacted. e cannula
is advanced until halfway between the anterior
and posterior borders of the vertebral body in
the lateral fluoroscopic view. Direct contact with
the periosteum should be maintained at all times.
Electrical stimulation is then performed, which
produces a deep aching sensation in the back with
50 Hz stimulation at 1.0 volt. Stimulation with
2 Hz at 2.5 volts should fail to produce lower
extremity motor stimulation. One ml of 2%
lignocaine is then passed through the RF cannula
and a 60-second delay is allowed for it to take effect.
A thermal lesion is created by heating the lesion for
a period of 60 seconds at 80°C.
For the RF lumbar disc procedure, the patient is
again put into a prone position and preoperative
antibiotic is given to prevent postoperative disc
infection. e fluoroscopic unit is angled at 15° to
20° from an oblique approach to correctly image
the painful disc. e RF cannula is advanced in
a percutaneous manner until it contacts the disc
annulus. e cannula is passed into the disc and
advanced until it enters the central aspect of the
nucleus as seen by posteroanterior and lateral views.
Electrical stimulation is checked at 2 Hz for motor
stimulation. If a 10 mm active tip is used, then a
4-minute 80°C lesion is created; if a 15 mm active
tip is used, a 4-minute 70°C lesion is performed.
No intradiscal local anaesthetic is used.
It is not unusual to develop mild dysaesthesias
that last for 7 to 10 days following RF lesioning
of the ramus communicans nerve or intradiscal
procedure. ese are related to low-level heat
injury of the lumbar nerves. e vast majority of
such dysaesthesias resolve without complication
within 3 weeks.
Epiduroscopy and
Epidurolysis
Lumbosacral radiculopathy is suggested by
complaints of pain, sensory disturbance, weakness,
or reflex asymmetry in the distribution of a
distinct lumbosacral nerve root. Most lumbosacral
radiculopathies involve the L5 or S1 root and
most causes can be managed with conservative
care. Herniated intervertebral disc, spinal stenosis,
spondylolisthesis, infection and neoplasm can all
cause lumbosacral radiculopathy. Sinister causes
should be ruled out before treating the patient
conservatively.
Epidural endoscopy has been used in the diagnosis
and treatment of patients with chronic radicular
pain without evidence of disc injury. Visualisation
of inflammatory changes in the nerve roots
corresponding to the patient’s symptoms can be
useful in establishing mechanical compression as
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