Download Imaging-guided Injection Techniques with Fluoroscopy and CT for

EDUCATION EXHIBIT
927
Imaging-guided
Injection Techniques
with Fluoroscopy and
CT for Spinal Pain
Management1
Richard Silbergleit, MD2 ● Bharat A. Mehta, MD ● William P.
Sanders, MD ● Sanjay J. Talati, MD3
Local spinal pain and radiculopathy are common conditions that debilitate millions of Americans annually. Most cases are successfully
treated conservatively with rest or physical therapy. Chiropractic manipulation or, in some cases, surgery may also be performed. Percutaneous injection has been used for spinal pain management for many
years, but many of these procedures have historically been performed
without imaging guidance. Recently, however, newer minimally invasive, imaging-guided percutaneous techniques have been added to the
list of available treatment options for spinal pain. Imaging-guided techniques with fluoroscopy or computed tomography increase the precision of these procedures and help confirm needle placement. Cervical,
thoracic, lumbosacral, and sacroiliac pain can be evaluated and treated
safely and effectively with injections of local anesthetics or long-acting
steroids into facet joints, sacroiliac joints, selective nerve roots, spondylolytic areas, and the epidural space. Because imaging-guided techniques appear to provide better results and reduce complication rates,
they are becoming more popular despite controversy regarding their
effectiveness. Controversy will continue to surround these imagingguided techniques until large, double-blinded studies become available. In the meantime, there is an increased demand for these procedures from referring physicians, and it is important to be able to safely
perform them with a minimum of patient discomfort.
Index terms: Computed tomography (CT), guidance, 30.1211 ● Fluoroscopy, 30.11, 30.12989, 30.92 ● Nerves, roots, 30.11, 30.1211 ● Nerves, spinal, 30.11, 30.1211 ● Spine ● Spine, anatomy, 30.92 ● Spine, CT, 30.1211 ● Spine, facet joints, 30.11, 30.1211, 30.92
RadioGraphics 2001; 21:927–942
1From
the Department of Radiology, Henry Ford Hospital, Detroit, Mich (R.S., B.A.M., S.J.T.), and the Department of Diagnostic Radiology, William Beaumont Hospital, 3601 W Thirteen Mile Rd, Royal Oak, MI 48073-6769 (W.P.S.). From the 1999 RSNA scientific assembly. Received
November 3, 2000; revision requested December 8 and received December 28; accepted December 29. Address correspondence to R.S.
([email protected]).
2Current
address: Department of Diagnostic Radiology, William Beaumont Hospital, Royal Oak, Mich.
3Current
address: Department of Radiology, Covenant Health Care, Saginaw, Mich.
See the commentary by Zinreich and Murphy following this article.
©
RSNA, 2001
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Figure 1. (a) Drawing of a lumbar segment (axial view) shows the medial branch of the
dorsal ramus of the spinal nerve root innervating a facet joint. (b) Drawing of the midlumbar
spine (lateral view) shows branches from one nerve root innervating both the level of the exiting root and the next lower level.
Introduction
Local spinal pain and radiculopathy are very common conditions that debilitate more than half the
population of the United States at some time in
their lives. The prevalence of these conditions is at
least 5% annually (1,2). Most cases are successfully
treated conservatively with rest or physical therapy.
Chiropractic manipulation is also very common
although not frequently recommended to patients
by their allopathic physicians. Surgery is reserved
for a small percentage of cases. Because imaging
abnormalities do not correlate with symptoms in
most cases (3–5), many patients do not receive a
specific diagnosis and have continued pain.
Percutaneous injection techniques have been
used to treat back pain for many years—and have
been controversial. Many of these procedures
have historically been performed without imaging
guidance. Imaging-guided techniques with fluoroscopy or computed tomography (CT) increase
the precision of these procedures and help confirm needle placement. Because imaging-guided
techniques should lead to better results and reduced complication rates, they are now becoming
more popular. These improvements are probably
due in part also to better patient selection by experienced spine physicians.
Cervical, thoracic, lumbosacral, and sacroiliac
pain can be evaluated and treated with interventional procedures including injections of local
anesthetics or long-acting steroids into facet
joints, sacroiliac joints, selective nerve roots,
spondylolytic areas, and the epidural space.
In this article, we discuss and illustrate techniques for CT- and fluoroscopy-guided percuta-
neous injections used at our institution for spinal
pain management. These include techniques for
facet joint injection, selective nerve root injection,
epidural injection, sacroiliac joint injection, and
injection for spondylolysis.
Technique
All of the procedures discussed in this article are
routinely performed on an outpatient basis. The
patient is questioned regarding previous steroid
use (oral, cutaneous, or injected) to avoid causing
iatrogenic Cushing syndrome. We usually wait
2–3 months before administering repeat injections. This is particularly important when multilevel injections (eg, bilateral L3-4, L4-5, and
L5-S1 facet joint injections) are performed. Relative contraindications include hemorrhagic diathesis, local skin infection, and pilonidal cyst as
well as progressive neurologic disorder, which
may be masked by the procedure.
The procedure as well as possible benefits and
complications are explained to the patient, and
informed consent is obtained. Because it is often
difficult to determine the origin of spinal pain, the
patient is advised that the procedure may not be
effective. Possible complications that are discussed include Cushing syndrome, infection,
hemorrhage, pneumothorax, anaphylactic (idiosyncratic) reaction to iodinated contrast material
or anesthetic, and nerve damage.
Baseline vital signs are obtained. Physiologic
monitoring (pulse oximetry and intermittent automatic blood pressure and pulse rate monitoring) is
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used if conscious sedation is administered to the
patient. Physiologic monitoring is not necessary in
otherwise healthy patients if sedation is not used
(6). Intravenous sedation is required in less than
20% of patients and consists of low doses of opioids
or anxiolytic drugs. Midazolam hydrogen chloride
(initial dose, 1 mg) is used for sedation and anxiolysis. In healthy adults, additional doses of 1 mg are
given as needed up to a total of 4 mg with an interval of at least 2 minutes between doses. In patients
over 60 years of age and in chronically ill or debilitated patients, additional doses are reduced to 0.5
mg up to a total of 3 mg. Morphine sulfate (initial
dose in healthy adults, 1–2 mg) is used for pain relief. Additional doses of 1–2 mg are given as needed
up to a total of 10 mg with an interval of at least 2
minutes between doses. Resuscitation equipment
should be readily available.
Sterile procedure is followed. For cutaneous
and tract local anesthesia, we use 1% lidocaine.
We use triamcinolone acetonide suspension (Kenalog 10 or 40 [Apothecon, Princeton, NJ ]) as a
long-acting steroid and bupivacaine hydrochloride (Sensorcaine 0.25% [Astra USA, Westborough, Mass ]) as a long-acting local anesthetic.
After the procedure, the patient is observed in the
recovery room or short stay unit for 1–2 hours
depending on his or her condition.
Most of these procedures can be performed
with either CT guidance or fluoroscopic guidance. The imaging technique used is largely a
matter of personal preference. Different steroids
and anesthetics may also be used.
Facet Joint Injection
Facet joint pain is attributed to segmental instability, inflammatory synovitis, or degenerative arthritis
(1,7,8). Cavanaugh et al (9) conducted a study using New Zealand white rabbits and demonstrated
that the facet joints are heavily innervated, that sensitization and excitation of nerves occurs in the facet
joints when the joint is inflamed or exposed to certain chemicals that are released during injury and
inflammation, and that injection of hydrocortisone
and lidocaine results in a marked reduction in this
nerve activity. The signs of facet joint syndrome are
local paraspinal tenderness; pain on hyperextension,
rotation, and lateral bending; absence of neurologic
deficit; absence of root tension sign; and hip, buttock, or back pain with straight leg raising (8).
Symptoms include hip and buttock pain, cramping
leg pain involving the thigh but not radiating below
the knee, low back stiffness, and absence of paresthesias (8). The back stiffness is typically most
marked in the morning.
According to a study by Schwarzer et al (10), the
degree of degenerative change identified on CT
scans is a poor indicator of the presence or degree
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of facet joint syndrome. However, Lewinnek and
Warfield (11) found radiographic evidence of facet
joint disease to correlate with the initial success of
facet joint injections. Helbig and Casey (12) described four clinical criteria that led to a high longterm success rate, including back pain associated
with groin or thigh pain, well-localized paraspinal
tenderness, reproduction of pain with extensionrotation toward the symptomatic side, and significant facet joint arthrosis seen at radiography. Largevolume injections may cause joint rupture and extravasation into the epidural space, which may
account for part of their therapeutic effect (13).
There is disagreement as to whether intraarticular
injection is preferable to periarticular injection
(14,15). The true success of facet joint injections is
uncertain despite numerous studies because of
questions regarding patient selection, uncertainty as
to whether the injections were intraarticular or periarticular, and use of different medications. Facet
joint injection may be considered either diagnostic
or therapeutic (1,16). CT guidance (7,16) or fluoroscopic guidance (8,10,11,13,14) may be used for
facet joint injections. Levels for injection are selected on the basis of local pain or tenderness and
imaging evidence of disease. It is often difficult to
localize the pain to one level, so that generally two
and occasionally three levels are injected. If the pain
is bilateral, injections are performed bilaterally.
There are reports of long-term (3– 6 months) success and failure (14 –17). Denervation of the facet
joint may also be performed with CT guidance or
fluoroscopic guidance. This procedure has been
performed with 95% ethanol or with radio-frequency techniques (7,18). Gangi et al (7) denervate
facet joints using CT guidance with 95% ethanol.
Twenty-two– gauge spinal needles are advanced
into the internal superior borders of the transverse
processes above and below the target facet joint.
One mL of nonionic contrast material is injected to
predict ethanol diffusion, and 1.5 mL of 95% ethanol is injected at each level. Van Kleef et al (18) denervated facet joints using C-arm fluoroscopic guidance and 60-second 80° C treatment with a radiofrequency generator. Bogduk and Long (19)
studied the anatomy of facet joint innervation and
found that the most commonly used techniques
usually result in injury to the medial branch of the
dorsal ramus rather than to the small nerves of the
facet joints. A facet joint is supplied by the nerve
exiting at the level of the facet joint as well as at the
next higher level (Fig 1). Denervating a facet joint
requires that two rhizotomies be performed. For
example, denervation of the right L3-4 facet joint
requires rhizotomy of right L2 and L3.
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Figure 2. (a) Frontal oblique radiograph obtained with fluoroscopic guidance (standard posterior approach) demonstrates angulation of the tube to open the facet joints for cervical facet injection. (b) Lateral radiograph obtained with fluoroscopic guidance helps confirm the needle position.
Figure 3. (a) Frontal oblique radiograph obtained with fluoroscopic guidance for optimal visualization of the facet joints demonstrates a needle in the L3-4 joint. (b) Drawing of the L3-4 level
(oblique view) shows the needle at an exaggerated angle.
Fluoroscopic Guidance
We routinely use fluoroscopic guidance for the
injection of cervical facet joints. The patient is
placed in the supine oblique position at an approximately 45° angle with the side to be injected
facing up. The head is turned away from the side
to be injected. The frontal tube is angled to open
the facet joint, and a 22-gauge needle is advanced
into the joint (Fig 2a). The patient is then placed
flat, and true lateral and anteroposterior views are
obtained to confirm the needle position (Fig 2b).
A posterior approach is usually used to avoid the
vertebral arteries. If the shoulders are large, an
anterior approach may be required. A 25-gauge
needle is usually used for this approach. For
therapeutic injection, 0.5 mL of triamcinolone
acetonide suspension (Kenalog 40) and 1–2 mL
of 0.25% bupivacaine hydrochloride are used.
For diagnostic purposes, only the latter is injected. If more than four joints are being injected,
the dose of triamcinolone acetonide is reduced to
keep the total dose below 80 mg.
We prefer CT guidance for the injection of
lumbar facet joints and use a technique that is
described in the next section; however, fluoroscopic guidance may also be used. The patient is
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Figures 4 – 6. (4) CT scans demonstrate a bilateral L4-5 facet joint injection with the vertical approach (a)
and an L5-S1 facet joint injection with the angled approach (b). (5) CT scan shows a T6-7 facet joint
injection. (6) CT scan shows a C5-6 facet joint injection.
placed in the prone oblique position with the side
to be injected facing up slightly. The patient is
then rotated until the facet joint is best visualized
(Fig 3). A 22-gauge needle is advanced vertically
into the joint, and its position is confirmed with
true lateral and anteroposterior views. Our therapeutic and diagnostic injections are identical to
those used for cervical facet joints. Gangi et al (7)
use 3.75 mg (1.5 mL) of cortivazol mixed with
1.5 mL of 0.25% bupivicaine hydrochloride for
every two facet joints. Sarazin et al (20) have described a fluoroscopically guided technique for
injecting the inferior articular recess of the facet
joint that does not require profiling the joint.
CT Guidance
CT guidance is our preferred technique for lumbar facet joint injection. The patient is placed in
the prone position, and several images are ob-
tained at the level of interest to determine entry
site and angle of approach. The entry site is
marked on the skin, and a 22-gauge needle is advanced into the joint (Fig 4). A coaxial system
may be used to approach a horizontally oriented
joint. Injections are identical to those performed
with fluoroscopic guidance. We also prefer CT
guidance for thoracic facet joint injections. In the
thoracic region, the horizontal orientation of the
facet joints and overlying ribs usually limits access. Access may be limited in other areas by
bridging spurs. In such cases, periarticular injection is performed (Fig 5). The steroid and anesthetic doses are the same as for other facet joint
injections. Cervical facet joint injections may also
be performed with CT guidance (Fig 6).
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Figure 7. (a) Lateral oblique radiograph obtained with
fluoroscopic guidance with the patient’s head turned to
the left demonstrates
a cervical nerve root
injection with the
needle projecting
into the C6-C7 neural foramen. (b) On a
frontal radiograph
obtained with fluoroscopic guidance, the
needle tip has been
advanced to the
pedicle.
Figure 8. Frontal
(a) and lateral
(b) radiographs obtained with fluoroscopic guidance
demonstrate a C2
nerve root injection.
Selective Nerve Root Injection
Nerve root injection is indicated in patients with
radicular symptoms in the cervical, thoracic, lumbar, or sacral region; acute diskogenic symptoms
without nerve paralysis that is resistant to conventional medical therapy; and post-diskectomy syndrome (1). Inflammation of the nerve root is presumed to be the cause of the pain. In a study by
Zennaro et al (21), selective nerve root injection
provided pain relief in 70% of all patients and in
95% of patients with foraminal stenosis secondary
to degenerative stenosis rather than disk herniation.
These authors used CT guidance and injected 0.8
mL of 1% lidocaine with 75 mg of hydrocortisone.
Selective nerve root injections often result in a degree of epidural injection, which may play a role in
pain relief. Typically, injection is performed at a
single level that correlates with the radiculopathy.
Fluoroscopic Guidance
Cervical nerve root injections may be performed with
CT guidance or fluoroscopic guidance. For a fluoroscopically guided selective cervical nerve root injection, the patient is placed in the supine oblique
position with the side to be injected facing up. The
head is turned slightly to the opposite side. Obliquity is
adjusted until the foramina are well seen (Fig 7a). A
22-gauge spinal needle is advanced toward the foramen. The patient is placed flat, and anteroposterior
and lateral views are obtained to confirm the needle
position (Fig 7b). The needle should not project
medial to the medial margin of the pedicle on the
frontal view. The patient often reports reproduction
of symptomatic pain along the nerve distribution as
the needle nears the appropriate location. For C1
and C2 nerve root injections, the patient is placed in
the prone position and the needle is advanced under
frontal and lateral fluoroscopic guidance (Fig 8).
The stylet is then removed, and absence of cerebro-
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Figure 9. Frontal (a) and lateral (b) radiographs obtained with fluoroscopic guidance
demonstrate a T10 nerve root injection. Arrow in b indicates the needle tip.
Figures 10, 11. (10a) Prone oblique radiograph obtained with fluoroscopic guidance demonstrates a needle tip
under the pedicle of L1. (10b) Lateral radiograph obtained with fluoroscopic guidance helps confirm needle placement in the L1 neural foramen. (11) Prone oblique radiograph obtained with fluoroscopic guidance demonstrates the
angled approach to the L5 foramen.
spinal fluid flow is verified with aspiration. Two mL
of Kenalog 10 and 2 mL of Sensorcaine 0.25% are
injected. If the dura mater is perforated, the procedure is terminated and subsequently rescheduled.
Similarly, for fluoroscopically guided selective
thoracic nerve root injections, the patient is
placed in the prone position and the needle is
advanced under frontal and lateral fluoroscopic
guidance (Fig 9). Care is taken to keep the needle
posterior and medial to avoid the pleural space.
Although we have used this technique in many
patients without causing a pneumothorax, this is
a serious concern, and CT guidance may be safer,
particularly in thin patients. Injections are the
same as for cervical nerve roots.
For a fluoroscopically guided selective lumbar
nerve root injection, the patient is placed in the
prone oblique position with the side to be injected
facing up. A 22-gauge needle is advanced under the
pedicle with the patient in this position (Fig 10a).
The patient is then placed flat, and needle position
is confirmed with frontal and lateral views (Fig
10b). L5 nerve root injections require marked angulation of the needle to avoid the iliac crest (Fig 11).
Injections are the same as for cervical nerve roots.
Selective sacral nerve root injections may be performed with a dorsal approach using the same technique used for a sacral foraminal epidural injection.
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Figures 12–17. (12) CT scan (posterior angled approach) obtained with the patient in the prone position demonstrates needles positioned at both exiting C2 nerve roots. (13) On a CT scan (anterior angled approach), a needle is
seen posterior to the carotid and vertebral (cursor) arteries for a C7 nerve root injection. (14) CT scan obtained with
the patient in the prone position shows a T12 nerve root injection. (15) CT scan obtained with the patient in the
prone position shows an L4 nerve root injection. (16) CT scan obtained with the patient in the prone position shows
an L5 nerve root injection. (17) CT scan (posterior sacral foramen approach) shows an S1 nerve root injection.
CT Guidance
For selective lumbar and thoracic nerve root injections, the area of interest is scanned with the
patient in the prone position. For selective cervical nerve root injections, the procedure can be
performed with the patient in the supine, prone,
or lateral decubitus position. The skin entry site
and the angle of approach are determined, and
a 22-gauge needle is advanced adjacent to the
exiting nerve root. Patients usually report repro-
duction of pain along the distribution of the
nerve. Cervical (Figs 12, 13), thoracic (Fig 14),
lumbar (Figs 15, 16), and sacral (Fig 17) nerve
roots may be injected under CT guidance.
Epidural Injection
Patient selection for epidural injections is poorly
described in the literature. We have used epidural
injections for treatment of local pain or radiculopathy in the settings of documented disk herniation, central or foraminal stenosis, and absent
imaging findings. The technique is usually used if
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rest has failed to relieve the symptoms or if the
patient is considered a surgical candidate but
does not desire to undergo surgery. The technique is infrequently used in acute situations.
Various combinations of saline solution, local
anesthetics, and steroids have been injected (22–
25). Theories for explaining the method of relief
include lysis of adhesions, change in relationship
between the disk and the nerve root, anesthetic
breaking the pain cycle, and reduction of inflammation and swelling (23,24). Epidural injection
has been performed mostly by anesthesiologists.
White (22), using both sacral hiatus and lumbar
interlaminar approaches, documented that even
in experienced hands, the needle was not in the
epidural space 25% of the time when the procedure was performed without imaging guidance.
The needle may be inadvertently placed intradurally or intravascularly or may not even be in
the canal. Fluoroscopic guidance is recommended for all epidural injections. Injection of
nonionic contrast material to confirm the needle
position is also recommended.
The choice of steroid is controversial. Methylprednisolone acetate (Pharmacia & Upjohn,
Kalamazoo, Mich) was used extensively prior to the
early 1980s (23,26,27). This steroid mixture contains polyethylene glycol, which is neurotoxic. The
most common complications associated with methylprednisolone acetate injection include aseptic
meningitis and arachnoiditis (26). These complications are probably related to intrathecal injection;
however, there may also be toxicity from epidural
injection. In a comprehensive literature review,
Abram and O’Connor (27) concluded that epidural
injection of steroid preparations containing polyethylene glycol is safe. Because of the slight risk of intrathecal injection, even with fluoroscopic guidance,
we do not inject methylprednisolone for spinal procedures. El-Khoury and Renfrew (1) inject 3 mL
(18 mg) of betamethasone (Celestone Soluspan;
Schering, Kenilworth, NJ) followed by 5–10 mL of
sterile saline solution or diluted 0.25% bupivacaine
hydrochloride via the sacral hiatus. Bush and Hillier
(24) inject 80 mg of triamcinolone acetonide with
0.5% procaine hydrochloride in saline solution via
the sacral hiatus. Gangi et al (7) use 3.75 mg of cortivazol with or without 2 mL of 0.5% lidocaine.
We use fluoroscopic guidance for epidural injections. Gangi et al (7) describe CT guidance for
lumbar epidural injections. Dorsal interlaminar,
Silbergleit et al
935
sacral hiatus, and foraminal approaches may be
used for lumbosacral epidural injection. Epidurography with nonionic myelography-approved
iodinated contrast material (iopamidol [Isovue
200; Bristol-Myers Squibb, Wallingford, Conn])
is performed to document epidural position and
evaluate the distribution pattern. If the area of
clinical concern is not opacified, the needle position is changed. The plica medianis is a midline
dural reflection that may be complete or incomplete. If complete, it may confine the contrast material and steroid to one side. If the patient has
bilateral symptoms, one-half of the dose is injected followed by repositioning of the needle to
opacify the contralateral epidural space and injection of the other half of the dose. If the pain is
unilateral, we attempt to inject all the medication
on the ipsilateral side in the presence of a complete plica medianis.
For a dorsal interlaminar approach, the patient
is placed in the prone position. 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. Standard plastic syringes are usually not
adequate; instead, glass syringes or special lowresistance plastic syringes (Pulsator Loss of Resistance Syringe; Sims Portex, Keene, NH) may be
used. Absence of cerebrospinal fluid flow is verified with aspiration. Epidurography is performed
with 2–3 mL of nonionic myelography-approved
iodinated contrast material.
The sacral hiatus approach described by ElKhoury et al (25) is the one most frequently used
at our institution. The patient is placed in the
prone position. The sacral cornua (ie, the border
of the sacral hiatus) and median sacral crest are
palpated and localized fluoroscopically. Gauze
pads are placed between the buttocks to prevent
povidone-iodine (Betadine; Purdue Frederick,
Norwalk, Conn) from irritating the perineum and
genitals. A 5-inch-long, 22-gauge spinal needle is
advanced via the sacral hiatus into the sacral canal
until its tip reaches the S3 level (Fig 18). Keeping
the needle below the S2-3 disk space minimizes
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Figures 18, 19. (18) Frontal (a) and lateral (b) radiographs obtained with fluoroscopic guidance show a needle inserted into the sacral canal via the sacral hiatus. (19) Frontal epidurogram shows an epidural injection via the sacral hiatus.
Figures 20, 21. (20) Frontal epidurogram demonstrates an epidural injection with the S1 foraminal approach. This approach is also used for selective sacral nerve root injections. (21a) Frontal radiograph obtained with
fluoroscopic guidance (dorsal interlaminar approach) shows a needle in the
posterior epidural space at C7-T1. (21b) Subsequent frontal radiograph
obtained with fluoroscopic guidance demonstrates contrast material dispersion. (21c) Drawing shows the needle directed medially over the T1
lamina.
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Figure 22. (a) Supine oblique radiograph obtained with fluoroscopic guidance (transforaminal approach) demonstrates an open foramen. (b) Lateral radiograph obtained with fluoroscopic guidance demonstrates opacification of
the anterior epidural space. (c) Frontal radiograph obtained with fluoroscopic guidance shows the needle tip just medial to the pedicle.
the risk of dural puncture. It is helpful to keep the
needle as horizontal as possible. The needle is
usually advanced primarily under lateral fluoroscopic guidance with intermittent frontal guidance. On a frontal projection, the needle should
lie between the pedicles of the sacral segments.
The stylet is removed, and absence of cerebrospinal fluid flow is confirmed with aspiration. Epidurography is performed with injection of 3 mL of
nonionic myelography-approved iodinated contrast material (Fig 19). The lumbosacral epidural
space is usually opacified to the L4 level and occasionally higher.
The needle bevel is directed to the symptomatic side, and 5–7 mL of Kenalog 10 is injected.
We do not usually inject local anesthetic into the
epidural space because of the possibility of postural hypotension, particularly in older patients.
Many authors use local anesthetic in lower thoracic and lumbosacral epidural injections (1,6,7).
If the dura mater is accidentally punctured, we do
not perform the injection, and the procedure is
rescheduled.
For a lumbar foraminal approach, the patient is
placed in the prone position and a 22-gauge needle
is advanced under the pedicle of the appropriate
segment, similar to the approach used for lumbar
nerve root injection (Figs 10, 11). Sacral foraminal
injection is performed with a direct dorsal approach,
a technique that can also be used for selective sacral
nerve root injection (Fig 20).
For a cervical epidural injection, a dorsal interlaminar (Fig 21) or transforaminal (Fig 22) ap-
proach can be used. The patient is placed in the
prone position for the dorsal interlaminar approach.
This procedure is performed only at the C7-T1 disk
space, where the dorsal epidural space is larger (1–2
mm thick) than at the higher cervical levels (6). A
22- or 25-gauge Whitacre needle with a blunt tip
and side hole is advanced through an 18-gauge
needle using a paramedian approach. The needle is
directed to the top of the T1 lamina in the midline.
The needle contacts the bone and is then slowly
advanced into the epidural space with the loss-ofresistance technique. Test injections of contrast material may also be performed while advancing the
needle. An epidurogram is obtained to document
needle position and evaluate the extent of opacification. We inject 5– 6 mL of Kenalog 10. Local anesthetic is not used in upper thoracic or cervical epidural injections because of the risk of spinal anesthesia and respiratory suppression. A similar
approach may be used for thoracic epidural injections (6). In the transforaminal approach, a 25gauge spinal needle is advanced into the inferior
neural foramen with the patient in an oblique position to open the foramen. The needle is positioned
in the anterolateral epidural space with the loss-ofresistance technique. This approach carries the risk
of nerve root or vertebral artery injury. It is used
primarily when the dorsal interlaminar approach does
not result in opacification of the area of interest.
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Figure 23. Oblique radiograph obtained with
fluoroscopic guidance shows two needles in the
sacroiliac joint. We now routinely use only one
needle at the level of the lower needle.
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Figure 24. CT scan shows a needle positioned in the
sacroiliac joint.
22-gauge spinal needle is used, and 0.5 mL of
Kenalog 40 and 1 mL of Sensorcaine 0.25% are
injected on each side.
Sacroiliac Joint Injection
The indications for sacroiliac joint injection are
acute or chronic sacroiliac joint pain that is not
adequately controlled with nonsteroidal anti-inflammatory agents. The procedure is frequently
performed in patients with seronegative inflammatory sacroiliitis. Maugars et al (28) inject 1.5
mL of cortivazol, the equivalent of 62.5 mg of
prednisone, without local anesthetic.
Fluoroscopy or CT may be used for guidance.
With fluoroscopic guidance, the patient is placed
in the prone oblique position with the side to be
injected facing down to create a vertical pathway
to the inferior synovial joint (Fig 23). The patient
is then turned to the prone position, and 22gauge spinal needle placement is confirmed with
lateral fluoroscopy. Five mL of Kenalog 10 and
1–2 mL of Sensorcaine 0.25% are injected. With
CT guidance, the middle third of the joint is usually most accessible and is accessed with a dorsal
angulated approach (Fig 24).
Injection for Spondylolysis
Injection for spondylolysis is used for otherwise
unexplained local pain at the affected level. We
perform injections directly into the spondylolytic
area. El-Khoury and Renfew (1) have demonstrated that injection of adjacent facet joints
opacifies the affected area and can be used for
therapeutic injections.
CT guidance is used because pars defects are
easily identified at CT. The procedure is similar
to a CT-guided facet joint injection (Fig 25). A
Conclusions
Our preference for a given technique is largely
due to our training and experience and does not
necessarily mean that we consider the alternatives
to be inferior or more dangerous. Further experience with fluoroscopically guided CT may show it
to be superior to fluoroscopy for many of the procedures for which we now routinely use the latter
modality.
We recommend using the smallest needle that
can be effectively directed to the target site (usually 22-gauge or smaller). For cervical procedures, a 25-gauge needle is preferred if a sharp tip
is used. Occasionally, a 20-gauge needle will be
used in the lumbar region in a very large patient
in whom it is difficult to maneuver the needle.
Contrast material should be injected to confirm
needle placement for epidural injections unless
the patient has a history of contrast material sensitivity. Contrast material injection is also useful
for this purpose in the other procedures, although
it is not as critical. We usually do not inject contrast material for the other procedures unless we
are unsure of the needle position. Studies similar
to that of White (22) on needle placement for
epidural injections may be useful in evaluating
whether contrast material should be routinely
injected for these procedures. We have safely used
Kenalog as our choice of steroid and Sensorcaine
as a local anesthetic. Celestone Soluspan appears
to be a good alternative steroid.
Controversy will continue to surround these
imaging-guided techniques until large, doubleblinded studies become available. The contradic-
RG f Volume 21
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Number 4
Figure 25. CT scan (posterior angled approach)
demonstrates an injection for spondylolysis.
tory results of the existing small studies are likely
caused by differing patient selection methods,
questions about accurate needle placement, and
varying definitions of success. Despite the controversy, there is an increased demand for these procedures from referring physicians, and it is important to be able to safely perform them with a
minimum of patient discomfort.
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