epidural, TFE, INJECTION IN SPINE, STEROID

1. • Anatomy ->The epidural space commonly contains fat, abundant venous
plexus, spinal branches of the segmental arteries, and lymph vessels . Fat is the
major component of the epidural space and is the key factor in ESI because it
allows injected lipophilic medication to stay in the epidural space for a long
period and the action to be sustained . The nerve roots from the spinal cord
pass through the epidural space before they exit the spinal canal through the
intervertebral foramina.
• epidural venous plexus (EVP), H = posterior epidural space, tan areas = epidural fat (EF), white
dotted lines = pia mater, VA = vertebral artery, white solid lines = dura mater. radiculomedullary
artery (arrow and
red circle ) ,
blue solid areas =
PLL and LF

2. • * = sacral hiatus, blue dashed line = arachnoid mater, tan areas = epidural fat,
white line = dura mater.
• a, aorta; b, lumbar artery; c, radiculomedullary artery (artery of Adamkiewicz);
d, anterior spinal artery; e, spinal cord; f, nerve root; g, ascending lumbar vein;
h, lumbar vein; i, anterior internal vertebral venous plexus .

3. • Indications -> General indications for ESI include herniated disk disease
with or without radicular pain, spinal stenosis, axial low back pain, and post–
lumbar surgery syndrome.

4. • Contraindications -> Several pre existing conditions should be checked to avoid
complications. These conditions include coagulopathy or concurrent
anticoagulation therapy, systemic infection, local skin infection at the puncture
site, hypersensitivity to administered agents, and pregnancy .
• INR and platelet count should be adjusted to less than 1.5 and more than 50
000/μL, respectively (42). If a patient is taking anticoagulants, the medication
should be withheld in consultation with the prescribing physician.
• Warfarin should be withheld 5 days before ESI, and the patient’s INR should be
rechecked before the procedure. Low–molecular-weight heparin therapy should
be stopped 24 hours before ESI, whereas heparin does not need to be withheld
because it is a short-acting agent (the half-life of heparin is 23 minutes to 2.48
hours). Other medications that must be withheld include fondaparinux (Arixtra;
GlaxoSmithKline, London, England [withhold 2–5 days before the procedure]),
clopidogrel (Plavix; Handok, Seoul, Republic of Korea [withhold 5 days]), and
ticlopidine (Ticlid; Roche, Basel, Switzerland [withhold 5 days]). Nonsteroidal
anti-inflammatory drugs, including aspirin, do not have to be stopped before ESI.
• Relative contraindications include uncontrolled diabetes mellitus, congestive
heart failure, and an immunosuppressed state.

8. • Administered Medications ->
• Steroids and local anesthesia are generally used in combination for anti-
inflammatory and analgesic effects. It is theorized that the lipophilic characteristic
of the steroid permits sustained release from the abundant epidural fat, which is
where the steroid is injected .
• Particulate Steroid Injection ->The choice of steroid formula is a recent issue in
ESI. Particulate steroids, including triamcinolone acetonide, prednisolone acetate,
methylprednisolone acetate, and betamethasone acetate, may be responsible for
spinal cord infarction or cerebellar infarction after ESI, presumably due to particle
embolization . Particulate steroids are thought to work as emboli if there is
inadvertent puncture of small arteries that supply the spinal cord or brain.
• The recommendations included prohibition of particulate steroids in cervical
transforaminal ESI (55). In lumbar transforaminal ESI, a nonparticulate steroid
should be used for the initial injection, but there are situations in which
particulate steroids could be used .

10. Transforaminal lumbosacral needle placements. Schematic drawing of the lumbo-
sacral spine shows coronal relationships of nerve roots, nerve root ganglia, and
postganglionic spinal nerves. In stenotic foramina, extraforaminal needle placement
(N1) targets ventral ramus peripherally. In patent foramina, needle placement can
be supraneural (N2) in the safe triangle (∗) or infraneural (N3) in the Kambin
triangle (cross). At S1, the needle (N4) crosses posterior S1 foramen and enters
epidural space inferior to the S1 pedicle.

11. • (A) Cervical Interlaminar Injection ->A cervical interlaminar injection is usually
performed by using the C6–C7 or C7–T1 interlaminar spaces, where the
epidural fat is more adequate (14). Because the cervical epidural space has less
fat than the lumbar epidural space, special precautions are required to avoid
inadvertent dural puncture. Although the C7–T1 interlaminar space is wider,
our institution prefers to administer injections by using the C6–C7 interlaminar
approach because the shoulders can obscure the lower cervical spine on lateral
projections. On the basis of these studies and our experiences, we use a total
volume of 2–3 mL for cervical interlaminar ESI .
AP view with caudal angulation of the current
tube shows the interlaminar space of C6–C7 en
face (J). Dotted lines = bone landmarks,
double-headed arrow = interlaminar space (ILS)
of C5–C6, SP = spinous process

12. On a lateral view, the spinolaminar line (dashed line) is well identified. Arrow and H =
interlaminar space (ILS), DS = disk space, IAP = inferior articular process, IVF =
intervertebral foramen, SAP = superior articular process, SP = spinous process, VB =
vertebral body.

13. Lateral “true” epidurograms obtained with a test injection of contrast agent show
correct needle placement. A semilunar convexity (arrows in c) and a thin line of
contrast agent along the spinolaminar line (dashed line) are seen

14. AP view shows contrast agent
dispersion (arrows) that
outlines exiting nerve roots.
After confirming the puncture site on AP and lateral
views of the cervical spine, it is recommended that
the skin puncture be started with use of the AP
view, with caudal angulation of the current tube to
see the interlaminar space en face. The needle is
then advanced just ventral to the spinolaminar line
with use of the lateral view. The cervical epidural
space is only 1–2 mm in width. It is important to be
cautious and to use a small test dose of contrast
agent injected intermittently while the needle is
traversing the spinolaminar line. When the needle
tip arrives at the true epidural space, just ventral to
the spinolaminar line, contrast agent flows dorsally
along the spinolaminar line. With an interlaminar
ESI, a single line and a well-defined or smudged
convexity along the spinolaminar line on the lateral
view suggest that the needle tip is positioned
correctly in the epidural space . On the AP view,
contrast agent dispersion with drug injection may
outline exiting spinal nerves

15. • (B) Cervical Transforaminal Injection ->The cervical neural foramina are
aligned according to an axis oriented 45° forward; therefore, a cervical
transforaminal injection must be performed by using an oblique anterior
approach with the patient in the supine position .
• The level of targeting of the intervertebral foramen must be confirmed first .
The obliquity of the current tube, approximately 45° toward the symptomatic
side, allows the intervertebral foramina to enlarge. After tilting the current tube
to the angle at which the foramen is the most enlarged, a needle is advanced
parallel to the C-arm beam, targeting the dorsal and posterior aspect of the
foramen, with contact to the superior articular process of the lower cervical
spinal segment .
• Then, returning to the AP view, the needle tip is cautiously advanced further, to
the lateral third of the lateral mass (not beyond the midline of the lateral mass
on the AP view) . These approaches avoid unintended puncture of the vertebral
artery and dural sleeve of the nerve roots.
• With a tranforaminal ESI, if the needle tip is in the true epidural space, a test
dose of contrast agent will flow upward (occasionally downward) along the
medial margin of the pedicles and along the exiting nerve .

16. (a) Step 1: On an oblique image, the needle entry site is confirmed by contact with the
superior articular process of the lower cervical spinal segment. (b) Step 2: On an oblique
image, the needle is advanced parallel to the beam of the current tube. The intervertebral
foramen (IVF) is outlined by the top dotted line, and the lower dotted lines indicate bone
landmarks. FJ = facet joint, IAP = inferior articular process, SAP = superior articular process

17. Step 3: On a posteroanterior image, the
final needle advancement should not
pass the midline (solid white line) of the
lateral mass. Dotted lines = margins of
the lateral masses.
Anteroposterior fluoroscopic image in the supine
position shows the needle (arrow) targets right
C8 nerve at C7-T1 foramen. Pain provocation
prevented further needle advancement. Needle
trajectory was satisfactory, but the needle tip
terminated peripheral to lateral masses (black
lines), distant from the C8 nerve. Injected
contrast material (arrowheads) flowed along
nontarget C7 nerve into C6–7 foramen between
C6 and C7 pedicles. Black = pedicles from C6-T2.

18. Posteroanterior images show contrast agent flowing upward along the medial margin of
the pedicles (oval in d and dotted arrow in e) and the exiting nerve root (solid arrows).

19. • (C)Lumbar Interlaminar Injection ->The patient’s back should be flexed to
widen the epidural space. After checking the level on the AP view, the current
tube should be rotated caudally to open up the interlaminar space en face.
• Skin puncture is performed with use of the AP view at the center of the
interlaminar space along the midline , after which the needle is advanced just
ventral to the spinolaminar line (the base of the spinous process) seen on the
lateral view.
• In the paramidline approach, the tip of the needle may traverse the spinolaminar
line too deeply, and the test dose of contrast agent may not show the true shape
of the epidural space. When this is the case, the AP view must be rechecked to
confirm if the needle has escaped too laterally. When the ligamentum flavum is
thick, the tip of the needle may enter deep into the spinolaminar line .
• The loss of resistance as the needle traverses the ligamentum flavum, which
indicates that the needle is in the epidural space, can be unreliable, compared
with use of test injections of contrast material . A test injection of contrast
material would result in a vertical semilunar-shaped contrast agent deposit along
the spinolaminar line on the lateral view and a thick ipsilateral contrast agent
shadow along the medial margin of the upper and lower pedicles and the exciting
nerve sheath on the AP view .

20. Targeting midline posterior epidural fat in interlaminar
ESI. Midline sagittal reformatted CT image of the
lumbar spine and posterior epidural fat at L2–3 (white
∗) indicates safe zone for needle placement in ESI. As
a general rule, dorsal epidural fat is most prominent
between the bases of spinous processes (white line
between black ∗ at L4 and L5) at the disk space level
(intersection of white and black lines at L4–5). Needle
(N) at L3–4 shows desired tip location in dorsal
epidural fat. Needle trajectory projects cranial to disk
level (black line at L3–4). In normal spines, L5-S1 has
the least dorsal epidural fat.

21. Lateral “true” epidurograms show correct needle placement. (a) The needle tip is
placed just ventral to the spinolaminar line (dotted arrows), and contrast agent forms
a vertical semilunar shape (solid arrows). (b) When the ligamentum flavum is thick,
the needle tip may enter deep into the spinolaminar line (dotted arrows) to enter the
true epidural space (solid arrows). Dashed line = intervertebral foramen (IVF), DS =
disk space, ILS = interlaminar space, SP = spinous process, VB = vertebral body.

22. AP view shows a thick asymmetric contrast agent deposit that fades out at the periphery.
Contrast agent sometimes flows out into a neural foramen (solid arrows). Double-headed
arrow = interlaminar space (ILS)

23. • (D)Lumbar Transforaminal Injection ->
Schematic description for transforaminal
epidural steroid injection with the Kambin’s
triangle versus the subpedicular approach
(target L5 nerve root).
Schematic description of the “Kambin’s
triangle”. The triangle is defined by the
hypotenuse, base, and height. The hypotenuse
is the exiting nerve; the base is the caudad
vertebral body; and the height is the traversing
nerve root.

25. (a) Oblique radiograph of the lumbar spine shows the “Scotty dog” appearance (dotted
lines) of the posterior element of the vertebrae. × = subpedicular approach, + = retroneural
approach, IAP = inferior articular process, SAP = superior articular process, TP = transverse
process. (b) Lateral single-plane fluoroscopic image shows the proper location of the needle
tip in the subpedicular (×) and posterolateral (retroneural) (+) approaches. The needle is
placed to the retroneural space. White lines = imaginary outline of the ganglion and nerve
roots.

26. (c) AP image shows the subpedicular approach. Contrast agent
flows along the medial margin of the pedicle (arrow), and
lobulations (arrowheads) are seen outside the foramen. The
needle tip should not be advanced beyond the midpedicular line
(6-o’clock position on the clock face). Dotted outline = pedicle (P).

27. AP (d) and lateral (e) images in a different patient show the retroneural approach.
The needle tip (circle in e) is placed at the lower portion of the neural foramen,
and injected contrast agent is seen spreading into the intraneural and retroneural
epidural spaces. Dotted line in e = intervertebral foramen (IVF).

28. • (D.1)Kambin’s triangle approach(posterolateral (retroneural) ->
• Patients were placed in the prone position and were supported by pillows
under the abdomen to reduce lumbar lordosis. The X ray projection was
focused on the epiphyseal plate of the upper and lower vertebral body by
controlling the cranial-caudal angle of the and the right and left angle of the C-
arm was rotated by 20-35 degrees toward the region, so that the superior
articular process could be seen at the middle of the intervertebral disc.
• At that location, 22 Gauge spinal needle was inserted into the skin toward the
lateral lower part of the superior articular process and parallel to the X-ray
projection path, and the process was touched, directed laterally and advanced
by 2-3 mm. Th en, the needle was located medially in the 5 o’clock direction of
the upper pedicle at the anteroposterior view, without further advancement
and in the posteroinferior of the intervertebral foramen at lateral view. After
the final location of the needle was secured, 1 cc of non-ionic contrast agent
was administered to observe diffusion location and scope of the contrast agent,
and then 2 cc of the prepared agent (0.5% lidocaine 1.5ml + triamcinolone 20
mg) was administered .

29. (A) Anterior-posteior view of the lumbar spine, with superimposed line (1) bisecting
the pedicle. This line was draw halfway between the farthest medial (2) and farthest
lateral (3) points on the pedicle. (B) Lateral view of the lumbar spine, with the
quadrant system super-imposed. First, a line was drawn tangent to the curve of the
spine at the level of interest along the posterior vertebral line. (1) A second line (2)
was drawn parallel to the third at the posterior margina of the foramen. Next, two
lines perpendicular to lines 1 and 2 were drawn at the superior and inferior margins
of the foramen (3 and 4, respectively). Finally, line 5 was drawn bisecting 1 and 2,
and, likewise, line 6 bisecting 3 and 4. This divided the foramen into four quadrant,
Arrow: needle position.(for Kambin triangle)

30. (A) In the oblique view, the needle tip is advanced slowly and
cautiously past the superior articular process lateral surface.
(B) The anterior-posterior view will most often demonstrate the
tip in the interpedicular line.

31. (C) The lateral radiography should also be used while advancing past
the SAP to minimize the risk of the penetration until the needle tip is at
the posterior and inferior aspect of intervertebral neural foramen.
(D) A small amount of contrast is used to confirm epiduralspread.

32. • (D .2)Subpedicular approach(supraneural):->
All patients were in the prone position and were supported by pillows under the
abdomen to reduce lumbar lordosis. The relevant lumbar part was identified by
using the Scotty dog shadow oblique view. The lower endplate of the spine for
the C-arm was adjusted for accordance and rotated by 15- 30 degrees in the
oblique view to visualize the Scotty dog shadow. After the site was disinfected,
3.5-inch 22 Gauge spine needle was progressed toward the subjacent pedicle,
inferolateral inter-articularis (safe triangle) for the superior intervertebral
foramen. When the tip of the needle reached the inferolateral border, the C-
arm was rotated to the lateral view, and the needle was gradually progressed
toward the anterior and superior aspects ofthe intervertebral foramen. When
the needle reached the final location, an aspiration text test was conducted to
check for blood detection, and 1 cc of non-ionic contrast agent was
administered under real-time fluoroscopy, to identify whether the agent was
injected into the anterior epidural space. However, the “safe triangle” currently
is considered to be a misnomer because radiculomedullary arteries are located
almost in the triangle .

33. (A) In oblique view, needle tip lies directly inferior to the
pedicle and inferolateral to the pars interarticularis.
(B) The anteriorposterior view showing the proper location
of the needle at the base of pedicle.

34. (C) The lateral radiography should also be used while the needle is
advanced until the needle tip is at the anterior and superior aspect
of intervertebral neural foramen.
(D) A small amount of contrast is used to confirm epidural spread

35. • (E) Lumbosacral transforaminal injection->
• NRB at S1 requires epidural needle placement and poses unique access
challenges. Both transforaminal and transosseous techniques are feasible after
excluding Tarloff cysts and dural ectasia during MR image review. The dorsal S1
foramen is constant in location and orientation but variable in caliber. When the
foramen is narrow, transforaminal navigation can be difficult or impossible
without meticulous fluoroscopic set-up . A curved needle (5°–10° along the
distal centimeter) helps passage through a small angled foramen. Do not rotate
a curved needle in the foramen because of the risk of lacerating vessels,
including the lateral sacral artery. In patients with osteopenia, a 22-gauge
straight needle can be used to penetrate sacral plates with a twisting or
oscillating motion. Appropriate epidural depth is determined with lateral
fluoroscopy. Trajectory cannot be altered once the needle is drilled through
bone. The same transosseous technique can be used to advance a straight
needle through a paraspinal fusion mass for lumbar NRB

36. (a) Anteroposterior fluoroscopic image shows the detector was tilted cranio -
caudally to align the inferior margin of posterior S1 foramen (thin curved line) with
the superior margin of anterior S1 neural arch (arrowheads). Sacral orientation
determines the degree of craniocaudal tilt. The detector was rotated laterally to
align the medial margin (thick curved line) of S1 pedicle (∗) with lateral margin of
posterior S1 neural foramen along expected course of S1 nerve root. Curved needle
(arrow) improves foraminal navigation. Until it enters the foramen, the needle
must target the inferolateral border of the posterior S1 foramen.

37. (b) Subsequent anteroposterior fluoroscopic image shows the needle hub
(white arrow) and needle tip (white arrowhead) are oriented cranially along
the expected course of the S1 nerve root. Initially, contrast material flowed
retrograde into the posterior S1 foramen (black arrow). After advancing the
needle, contrast material (black arrowheads) spread favorably along S1
pedicle (∗) and S1 nerve root to the L5-S1 disk level.

38. • (F) caudal epidural block->
• It involves placing a needle through the sacral hiatus to deliver medications into
the epidural space. This approach to the epidural space is not only widely used
for surgical anesthesia and analgesia in pediatric patients but also popular in
managing a wide variety of chronic pain conditions in adults.
• Anatomy->
• Sacral Cornua->The sacral cornua are vestigial remnants of the inferior articular
processes of the 5th sacral vertebra and presented as two bony prominences at
the caudal end of sacrum. Palpating the bilateral sacral cornua is essential to
locate the sacral hiatus in the conventional
landmark-based technique. However, the
sacral cornua are not always palpable.

39. • Sacral Hiatus-> The sacral hiatus, resulting from failure of fusion of lamina and
spinous process of lower sacral vertebrae, is the caudal termination of the
sacral canal . The sacral hiatus is bordered laterally by two sacral cornua and
could be palpable as a dimple in between. Posteriorly, the sacral hiatus is
covered by the skin, subcutaneous fat, and sacrococcygeal ligament (SCL).
During caudal epidural block, inserting a needle into the sacral hiatus is
essential to access the sacral canal.
• Location of the Apex of the Sacral Hiatus->The apex of sacral hiatus is most
commonly located at the S4 level (65– 68%), followed by the S3 and S5 level
(around 15% at each level) and the S1 to S2 level in 3–5% of cases .

40. • Dural Sac -> The dural sac usually terminates between S1 and S2 vertebra,
with the majority at S2 . In 1 to 5% of patients, the dural sac terminates at S3
or below . In addition, 1 to 5% of patients with low back pain or sciatica have a
sacral Tarlov cyst , a perineural cyst that communicates with the dural sac and
is filled with cerebrospinal fluid (CSF). More than 40% of the sacral Tarlov cysts
are located at or below the S3 level.
• The lower the dural sac termination or the Tarlov cyst is located, themore likely
dural puncture or intrathecal injection might occur during caudal epidural
block.
• . Distance between the Dural Sac Termination and the Apex of the Sacral
Hiatus ->The distance between the dural sac termination and the apex of the
sacral hiatus was the interest of several studies, because the risk of dural
puncture is perceived to increase as this distance decreases . The average
distance varies markedly from studies conducted in different ethnics. In an
Indian cadaver study, the average distance is 32 ± 12 mm, ranging from5.8 to
60.0mm.

41. • Fluoroscopy-Guided Caudal Epidural Block-> Because of the inaccuracy of blind
technique, some authors have recommended that caudal epidural injection is
performed under fluoroscopic guidance . The patient is usually placed in prone
position for fluoroscopy-guided caudal epidural block. In lateral view of
fluoroscopy, the sacral hiatus could be identified as an abrupt drop off at the
end of S4 lamina .The block needle trajectory can be visualized and navigated
accordingly into the sacral canal. By injecting contrast medium under
fluoroscopy, the placement of needle tip within the sacral epidural space can be
verified , and intravascular or intrathecal needle tip placement can be detected.
During caudal epidural injection, intravascular injection was reported in 3–
14%of cases by conventional fluoroscopy even after negative aspiration .
Fluoroscopy guidance hasmarkedly improved the successful rate of caudal
epidural block and is now considered as the gold standard in performing caudal
block.

42. AP (a) and lateral (b) images show the needle advancing through the sacral hiatus (circle
in a and oval in b). (c) “True” epidurogram with correct placement of the needle tip
(circle) shows findings that resemble a Christmas tree

43. Pitfalls: False ESI
• (1)Staining of Paravertebral Muscles and Ligaments->
• This paravertebral muscular or ligamentous staining appears parallel to the
course of the muscle fiber or ligament. The so-called false staining is usually
located posterior to the spinolaminar line; therefore, it is easy to distinguish
from true epidural space staining . However, because muscular or ligamentous
staining diffuses slowly after injection, repetitive contrast agent injections can
conceal the needle tip and even the staining of the true epidural space. In this
case, further advancement of the needle carries risk for dural puncture, and it
is recommended to reposition the needle one level caudad or cephalad.
• If the needle tip is advanced too anteriorly and laterally during a lumbar
transforaminal injection, the psoas muscle can be stained with contrast agent .
Because of the obliquity of the psoas muscle fibers, the staining can mimic the
true contrast agent shadow of an exiting nerve root, but it will lack the upward
flow along the medial margin of the pedicle and lobulations along the nerve.
The needle should be repositioned in the medial direction.

44. (a) Lateral single-plane fluoroscopic image of the lumbar spine shows an irregular
cloud-shaped accumulation of contrast agent (open arrow) posterior to the
spinolaminar line. Solid arrows = true epidural space staining.

45. Psoas muscle staining. (b) AP single-plane fluoroscopic image of the lumbar spine
shows psoas muscle staining (arrows) that mimics the exiting nerve root shadow. (c)
Axial T2-weighted MR image of the lumbar spine shows the close relationship between
the psoas muscle (dark pink area) and the nerve root (yellow oval).

46. • (2)Intravascular Injection-> Intravascular contrast agent flows in a configuration
of curvilinear or thin straight lines and disappears at the moment of injection
without accumulation . If intravascular flow is observed, the needle is withdrawn
sufficiently and repositioned, targeting different locations.
Posteroanterior images show a linear contrast agent shadow (arrow in a) and
contrast agent flow that is still noted (arrow in b) when contrast agent is injected
after slight advancement of the needle tip. (c) Posteroanterior image shows that
the contrast agent shadow has rapidly dissipated and is no longer seen (oval).

47. • (3)Inadvertent Facet Joint Injection-> Huang and Palmer reported the incidence
of inadvertent lumbar facet joint injection as 1.2% during interlaminar ESI .
• (4)Dural Puncture->
• Dural puncture in epidural injection is a common and critical condition with a
reported incidence of up to 5% (81). Complications of dural puncture include
post–dural puncture headache, paresthesia, intracranial hemorrhage, cauda
equina syndrome, aseptic meningitis, and arachnoiditis .
• It usually develops within 5 days after dural puncture and typically manifests as a
postural headache that worsens within 15 minutes of sitting or standing and
improves within 15 minutes after lying down . It may be accompanied by neck
stiffness, tinnitus, or photophobia . For management of post–dural puncture
headache, hydration, oral nonopioid analgesics, and bed rest are frequently used
. An epidural blood patch is a relatively easy and effective option to treat post–
dural puncture headache by sealing the puncture site with 10–20 mL of
autologous blood.
• With an intradural injection, contrast material rapidly disperses and accumulates
at the ventral portion of the spinal canal, forming a cerebrospinal fluid–contrast
agent level (dorsal cerebrospinal fluid and ventral contrast agent) because of the
patient’s prone position. The AP view demonstrates a symmetric distribution of
contrast agent, similar to that seen at myelography

48. (a, b) L4–L5 interlaminar injection performed with single-plane fluoroscopy in a 34-year-old
woman. (a) Lateral image shows the needle tip (circle) deeply advanced into the
spinolaminar line. Test contrast agent accumulates at both the posterior epidural space
(arrows) and the ventral surface of the thecal sac. Contrast agent accumulation at the ventral
surface of the spinal canal forms a cerebrospinal fluid–contrast agent level (arrowheads) and
indicates dural puncture. (b) AP image shows that contrast agent is symmetrically
accumulated in the central portion of the spinal canal (arrowheads) but is faint.

49. (d) Sagittal T2-weighted MR image of the lumbar spine shows correlative large S2–S3
perineural cysts (arrows), findings that were missed on this image. (e) AP C-arm–guided
fluoroscopic image shows well-defined intrathecal contrast agent (arrowheads) and
perineural cysts (arrows), even though the needle tip is placed at the S4 level.

50. • (5)Nerve Injury-> The neurologic manifestations of nerve injection injury range
from minor but severe transient pain to severe transient sensory neurologic
deficit and, rarely, permanent neurologic deficit . With an intraepineural
injection, the patient would have severe radiating pain along the nerve
territory. Regarding intraneurally injected drugs, lidocaine was found to
produce hyperalgesia and much deposition of inflammatory cells in the dorsal
root ganglion of rats .
Fluoroscopic image shows
two sharp thin lines with a
feathery filling and “tram
track” appearance (open
arrows) along the C5
nerve root, suggesting an
intraepineural injection.
After the needle was
repositioned, a true
epidural contrast agent
shadow (solid arrows) is
seen through the C5–C6
foramen.

51. • (6)Disk Injury ->
• The incidence of intradiscal injection ranges from 0.002% (six in 2412 patients) to
2.4% (six in 251 patients) . Inadvertent intradiscal injections mostly occur during
transforaminal ESI, and ipsilateral foraminal stenosis and far-lateral disk
herniation are considered to be contributing factors. The most serious
complication of inadvertent disk injection is chemical inflammatory discitis, which
also carries risk for accelerating disk degeneration . Disk injury is likely to happen
when the needle advances too ventrally . Preprocedural intravenous antibiotics
have been used as in the recommendation for discography, but post procedural
antibiotics are barely used .