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Blake A Johnson MD is Director
of CNS Imaging at the Center for
Diagnostic Imaging. Dr. Johnson
completed his undergraduate work
and received his medical degree
from the University of Minnesota.
After radiology residency training,
he completed a neuroradiology
fellowship at the Barrow
Neurological Institute in Phoenix,
Arizona. His first appointment
brought him to California, where he
served as a staff neuroradiologist,
and subsequently as Chief of
Neuroradiology, at the David Grant
Medical Center at the Travis Air
Force Base. He was also an Assistant
Clinical Professor of Radiology at
the University of California,
San Francisco.
Dr. Johnson has authored and
co-authored numerous articles and
book chapters on topics including
intracranial pathology, head and
neck imaging and spine injection
procedures. He lectures extensively
on these areas of interest, at both
national and international forums. |
Image-guided pain management
Blake A Johnson, MD
Center for Diagnostic Imaging, St Louis Park, MN, USA
Address for correspondence:
Blake A Johnson, MD
Director of CNS Imaging
Center for Diagnostic Imaging
5775 Wayzata Boulevard, Suite 190
St. Louis Park, MN 55416, USA
Tel: +1 (952) 525-6304 Fax: +1 (952) 543-6524
Email: bjohnson@cdirad.com
Abstract
Image-guided spine injection procedures provide
a minimally invasive tool for the evaluation and
treatment of symptoms caused by degenerative
changes in the spine. Neck, back and radicular pain
typically represent a diagnostic challenge because
multilevel pathology is common and a number of
structures may be involved. Anatomical assessment of
intervertebral discs, ligaments, nerve roots, facet joints,
sacroiliac joints and paraspinous soft tissues is
important, but not conclusive, for evaluating the source
of pain symptoms. Spine injection procedures provide
functional and physiological information which are not
obtained from physical examination and imaging
studies, and therefore serve as an important adjunct
to the diagnostic process. Many of the procedures
performed are used for preoperative evaluation in
order to improve surgical outcomes through the
confirmation of suspected sources of symptoms and
the exclusion of adjacent levels or structures. In
addition, these procedures are utilised as pain
management modalities, in order to decrease
dependence on oral pain medication, increase physical
performance and facilitate rapid return to normal
activities of daily living and vocational pursuits.
Image-guided procedures are typically performed using
fluoroscopy, computed tomography and, less commonly,
magnetic resonance imaging. In this section, we review
a number of image-guided interventional spine
procedures utilised for pain management.
Epidurography and epidural steroid injections
Epidural steroid injections have been performed for
decades and are one of the most common spinal
injection procedures performed. This palliative
procedure is an effective means for treating neck and
back pain.1-3 The epidural space is in contact with a
number of nociceptors, which are stimulated in the
setting of degenerative spine disease. A number of
studies have shown the presence of inflammatory cells,increased CSF protein and neoneuralisation occurring
in the setting of degenerative changes in the spine.
Delivery of the therapeutic materials is performed after
placement of the needle in the epidural space, either in
the midline via an intralaminar approach (Figure 1) or
via a transforaminal approach (Figure 2) for patients
who suffer radicular symptoms in addition to neck or
back pain.
 |
 |
| Figure 1. Intralaminar lumbar epidurography performed prior to injection
of local anaesthetic and steroid suspension into the epidural space. (a)
Lateral radiograph demonstrates widespread dispersal of contrast within
the epidural space circumferentially, surrounding the unopacified thecal
sac. (b) Lateral epidurogram in another patient revealing severe stenosis
at the L2-3 level and moderately severe stenosis at L1-2. |
Figure 2. Transforaminal lumbar epidurography. (a) Contrast injected by
right transforaminal approach reveals opacification of proximal nerve
sheaths and extension into the right lateral epidural space. (b) Films
obtained following injection of therapeutic substances reveal widespread
dispersal of injected materials within the lumbar epidural space bilaterally. |
Epidurography is performed to assess the anatomy of the
epidural space and document the subsequent
delivery of therapeutic materials to the correct compartment. This helps prevent unintentional vascular
and intrathecal injections, as well as evaluate for
epidural scarring which may prevent delivery of
therapeutic substances diffusely within the epidural space.
This important component of
the examination improves
efficacy and helps avoid the potentially devastating complications of misguided administration
of therapeutic substances. Patients are monitored for
20–30 minutes following the injection and the initial
response to local anaesthetic is evaluated. Response to
steroids typically takes 1–2 days, and up to 10 days
before full efficacy of steroid response is appreciated.
Indications for epidural steroid injections
•Acute neck or back pain with or without radiculopathy
•Chronic neck or back pain with or without radiculopathy |
Selective nerve root injections
 |
 |
| Figure 3. Selective lumbar nerve
block. AP radiograph reveals
opacification of the proximal right
L4 nerve sheath with a small
amount of epidural reflux prior to
injection of anaesthetic and
steroid suspension. |
Figure 4. Selective cervical nerve
block. AP radiograph demonstrates
a 25 gauge needle in the lateral
aspect of the right C6-7 foramen
with opacification of the proximal
right C7 nerve sheath. After filming
and negative aspiration, local
anaesthetic (with steroid suspension
for therapeutic injections) is
injected. |
Selective nerve root blocks are used for the evaluation
and treatment of patients with radicular pain.4,5 It is
often clinically important to differentiate referred pain
in a radicular distribution from true nerve root pain,
secondary to irritation or compression of a specific
nerve root or ganglion. Imaging studies may not be
conclusive, as mechanical compression of a nerve root
is not required for the generation of pain symptoms.
Alternatively, there may be abnormalities on imaging
studies which do not result in the generation of pain or
other symptoms. By blocking the nerve in question, the
relative contribution to the patient’s pain can be
assessed. Local anaesthetic is administered for the
diagnostic component and a steroid suspension is
added to mitigate inflammation for the relief of pain
symptoms on a longer-term basis.
In the lumbar spine, the foramen is approached from a
posterolateral trajectory after sterile preparation of the
skin, draping and localisation using fluoroscopic
guidance. A radiculogram is obtained using watersoluble
nonionic contrast material to confirm accurate
placement within the nerve root sleeve (Figure 3) and
exclude vascular or intrathecal injection. Following
filming, an appropriate dose of local anaesthetic and
steroid is injected. The patient is monitored for response
and this is recorded in the diagnostic report. Cervical
nerve blocks (Figure 4) should only be performed by
experienced personnel. Due to the immediate proximity
of the vertebral artery and radicular arteries which
vascularise the spinal cord, real-time evaluation of
contrast distribution is required to prevent the
inadvertent injection of therapeutic substances into
these structures.
Indications for selective nerve block
•Acute radicular pain
•Chronic radicular pain |
Sacroiliac joint injections
 |
| Figure 5. Sacroiliac joint arthrography. Films obtained prior to injection of
therapeutic substances (local anaesthetic and steroid) reveal diffuse
opacification of the left sacroiliac joint and normal morphology. |
A number of studies have demonstrated the role of
the sacroiliac (SI) joint as a source of low back pain.6,7
The diagnosis of SI joint pain in patients who suffer
from low back, buttock or hip pain is often elusive based on history and medical examination alone.
The accurate assessment of this joint as a potential
pain generator can be done quickly, using image-guided
placement of therapeutic materials within the joint.
Prior to injection with these substances, SI joint
arthrography is performed to confirm accurate
placement within the joint and to assess joint
morphology (Figure 5).
Following filming of this study, a local anaesthetic and
steroid are injected and the patient is monitored for
initial response to the local anaesthetic. Transitional
joints at the lumbosacral junction may be evaluated
and treated using the same technique.
Indications for sacroiliac joint injection
•Chronic low back pain
•Buttock pain
•Hip pain (not secondary to hip joint pathology) |
Facet joint injections
The zygapophyseal joints (or facet joints) are richly
innervated and a frequent cause of neck and back
pain.8-12 Symptoms vary and the clinical evaluation may be difficult, even with the benefit of imaging studies.
The diagnostic evaluation of facet joint pain is best
performed using image-guided injections, which also
provide a minimally invasive therapeutic modality.
After needle placement within the joint, arthrography is
performed using a small amount of nonionic contrast
medium to confirm intraarticular delivery of the
injectate and to assess joint morphology (Figure 6).
The joint is then filled with a therapeutic mixture
consisting of local anaesthetic and steroid. A pars
interarticularis defect (spondylolysis) can be evaluated
and treated using the same technique.
 |
| Figure 6. Facet joint arthrography. (a) Oblique radiograph of a lumbar
facet joint arthrogram reveals intraarticular dispersal of contrast media
prior to injection of therapeutic substances. Joint morphology is normal.
(b) Lateral radiograph showing cervical facet joint arthrography. There is
uniform dispersal of contrast media revealing normal joint morphology. |
Facet joint injections may also be used therapeutically
for symptomatic synovial cysts (Figure 7). If the articular
space communicates freely with the cyst, the cyst can
be dilated and ruptured via a facet joint injection, often leading to relief of pain symptoms following
decompression.
Indications for cervical facet injection
•Neck pain
•Upper extremity radicular pain
•Suspected cervicogenic headache
Indications for thoracic and lumbar facet injections
•Back pain
•Lower extremity radicular pain |
Facet nerve injections and rhizotomy
 |
| Figure 7. Synovial cyst at L4-5. (a) Axial long TR MR image demonstrates a
right L4-5 facet joint effusion with a synovial cyst projecting into the spinal
canal, compressing the traversing right L5 nerve root within the subarticular
recess. (b) Lumbar facet joint arthrogram obtained during injection
reveals opacification of the L4-5 facet joint with extension of contrast
media into synovial cyst within the spinal canal. Following filming, a
therapeutic mixture consisting of local anaesthetic and steroid suspension
was injected, resulting in cyst rupture and relief of pain symptoms. |
 |
| Figure 8. Lumbar facet nerve (medium branch of the dorsal ramus) block.
AP radiograph reveals needle placement at the junction of the superior
articular process and transverse process, along the course of the medial
branch. |
Diagnostic medial branch blocks for the diagnosis and
treatment of posterior compartment or facet joint pain
are another diagnostic and therapeutic option.13,14
Rather than delivering therapeutic substances to the
joint, the sensory nerve to the facet joints can be
blocked. It is important to bear in mind that there is
dual innervation of facet joints, so the adjacent levels
should be blocked as well. Bony landmarks are utilised
to localise the nerves, which follow a predictable course
in the lumbar spine (Figure 8) and in the cervical spine
(Figure 9). After image-guided placement of the spinal
needle to the respective nerves, a mixture of local anaesthetic and steroid are injected. The patient’s pain
response is evaluated 20 minutes after the injection.
If the patient shows a significant response, a long-term
benefit may be achieved using a radiofrequency (RF)
facet nerve rhizotomy.
The approach to the nerve is similar for a facet nerve
rhizotomy, but instead of a small gauge spinal needle,
an RF probe is advanced to the nerve, with a trajectory
chosen to maximise contact between the small medial
branch (facet nerve) and the active tip of the probe.
Motor stimulation testing is performed to exclude
extremity motor activity (the medial branch is
immediately posterior to the motor nerve). Multifidus
contractions are typically observed if there is good contact with the medial branch, providing physiological
confirmation of accurate needle placement. After
filming and physiological testing have confirmed optimal
placement, lesioning is performed via the application of
RF energy to the nerve.
Indications for lumbar facet nerve injection
•Chronic low back pain
•Acute or chronic radicular pain
•Hip pain (not secondary to hip joint pathology)
Indications for cervical spine facet nerve injection
•Acute and chronic neck pain
•Cervicogenic headache
Indication for rhizotomy
•Significant pain relief (greater than 75%) provided
by facet nerve block |
Conclusion
The use of spinal injection procedures provides a
minimally invasive tool for the diagnosis and treatment
of spine related symptoms. These image-guided
procedures can be performed in an outpatient
setting and supplement clinical and imaging findings
for patient evaluation and pain management.
Key Learning
• Image-guided spine procedures provide physiological information not available from diagnostic
imaging studies
• Fluoroscopy provides the advantage of real-time observation during contrast injection to assess for
vascular opacification. CT and MR are additional modalities utilized for image-guided procedures
• Early intervention for spine pain sufferers helps to decrease dependence on oral pain medication,
improve physical performance and facilitate a rapid return to normal activities of daily living and
vocational pursuits
• Image-guided spine procedures are minimally invasive and can be performed on an outpatient basis
•With extensive training on imaging equipment safety and operation, and familiarity with image-based
anatomy and image-guided procedures, radiologists are best suited to perform these spine interventions |
References
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injections: technical considerations and experience with 5334 cases.
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2.White AH, Derby R,Wynne G. Epidural injections for the diagnosis and
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and treatment of lower back pain: diskography, facet-joint injection, and
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