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ORIGINAL
RESEARCH
CT-Guided Cervical Selective Nerve Root Block
with a Dorsal Approach
T. Wolter
S. Knoeller
A. Berlis
C. Hader
BACKGROUND AND PURPOSE: Cervical transforaminal blocks are frequently performed to treat cervical
radicular pain. These blocks are performed mostly under fluoroscopy, but a CT-guided technique has
also been described. The aim of this study was to review the results of CT-guided CSNRB by using a
dorsal approach, to describe the contrast patterns achieved with this injection technique, and to
estimate the degree of specificity and sensitivity.
MATERIALS AND METHODS: We used a CT-guided technique with a dorsal approach leading to a more
extra-than transforaminal but a selective nerve root block as well. Of 53 blocks, we performed 38 for
diagnostic and 15 for therapeutic indications. Pain relief was measured hourly on a VAS. The distribu-
tion of contrast and the angle of the trajectory of the injection needle were analyzed as well as the
degree of pain relief.
RESULTS: Contrast was found in the intraforaminal region in 8 (15%) blocks, extraforaminally in 40
(78%) blocks, and intraspinally in 3 (6%) blocks. The mean angle between the needle and the sagittal
plane was 26.6° (range, from 1° to 50°). The mean distance between needle tip and nerve root was
4.43 mm (range, 0 –20 mm). Twenty-six (68.4%) of the 38 diagnostic blocks led to a decrease in the
pain rating of ⬎50%. There were no complications or unintended side effects, apart from occasional
local puncture pain.
CONCLUSIONS: We conclude that CT-guided CSNRBs using a dorsal approach are feasible and that
they are sensitive and specific.
ABBREVIATIONS: CSNRB ⫽cervical selective nerve root block; VAS ⫽Visual Analog Scale
CSNRBs are commonly performed under fluoroscopic
guidance,
1-7
but CT guidance is also possible and has been
described.
8
CT guidance offers the advantage of enhanced an-
atomic resolution with a more precise needle-tip positioning.
9
It is, however, seen as more time-consuming and likely to
involve more radiation exposure. In both fluoroscopic and
CT-guided CSNRBs, the aim is to block the root in the fora-
men. The patient is, therefore, placed in a supine position, and
the foramen is reached from a lateral approach in a nearly
horizontal plane.
In recent years, there have been several reports of cata-
strophic complications of CSNRB under fluoroscopic guid-
ance, including cerebral edema
10
; cerebellar infarction
11-13
;
infarction of the cervical spinal cord
14,15
; and hemorrhagic
infarction of the pons, midbrain, cerebellum, and thalami
with intraventricular extension, subarachnoid hemorrhage,
and hydrocephalus.
16-18
There are similar reports of CT-
guided CSNRB complications of cerebellar and brain stem
infarction
19
and spinal cord infarction.
20
In all these cases, the
probable mechanism was arterial puncture leading to infarc-
tion. Live fluoroscopy has been advocated to detect vascular
uptake, but 2 of the above-mentioned cases were performed
with this technique.
12,15
There is a need, therefore, to modify the conventional tech-
nique to minimize the risks of the procedure.
We used a modification of the CT-guided technique in
which the patient is prone and the foramen is accessed from
the dorsal aspect, with the tip of the needle aimed at the outer
confines of the foramen. This technique leads to an extra-
foraminal but still selective nerve root block. It might involve a
smaller risk of devastating complications, such as spinal cord
infarction or cerebellar infarction.
The aim of the study was to review the results of CT-guided
CSNRB by using the dorsal approach, to describe the contrast
patterns achieved with this injection technique, and to esti-
mate the degree of specificity and sensitivity.
Materials and Methods
Patients
Between January 1, 2007, and December 31, 2007, thirty-one patients
underwent CT-guided CSNRB involving 53 blocks. The indication
was diagnostic in 38 blocks and therapeutic in 15 blocks. Eighteen
patients had only 1 diagnostic block, 7 patients had 2 blocks, 4 pa-
tients had 3 blocks, 1 patient had 4 blocks, and 1 patient had 5 blocks.
If patients had ⬎1 block, the blocks were usually performed at inter-
vals of 1 week and were typically done for therapeutic purposes.
Technique
Informed consent was obtained before the intervention. The proce-
dure, its benefits, and its risks were discussed with the patient. Risks
included infection, bleeding, and allergic reaction as well as a small
risk of a severe neurologic impairment, such as spinal cord stroke or
even death.
For the procedure, the patient was placed in the prone position.
The patient’s head was in a straight position with the forehead on a
pillow. After a lateral scout image was obtained, the designated level
was marked and images were obtained through the desired cervical
Received March 8, 2010; accepted after revision May 8.
From the Interdisciplinary Pain Centre (T.W.), Department of Orthopedic and Trauma
Surgery (S.K.), and Department of Neuroradiology (A.B., C.H.), University Hospital Freiburg,
Freiburg, Germany.
Please address correspondence to Tilman Wolter, MD, Interdisziplina¨res Schmerzzentrum,
Universita¨tsklinikum Freiburg, Breisacherstr 64, 79106 Freiburg, Germany; e-mail: tilman.
wolter@uniklinik-freiburg.de
DOI 10.3174/ajnr.A2230
SPINE ORIGINAL RESEARCH
AJNR Am J Neuroradiol 31:1831–36 兩Nov-Dec 2010 兩www.ajnr.org 1831
neural foramen. An appropriate needle-entry point was calculated
before it was identified and marked on the skin prior to its steriliza-
tion. The entry site was chosen to avoid the carotid and jugular vessels
and to gain access to the outer foramen. Usually, the needle was placed
in a 10°– 45° angle to the sagittal plane (a 45°– 80° lateral angle to the
table).
Once the site was sterilized and the skin and subcutaneous tissue
were anesthetized, a 22-ga 10-cm straight spinal needle (Seibel-
needle; William Cook Europe, Bjaeverskov, Denmark) was partially
inserted through a 19-ga 4-cm introducer needle, and an initial image
was obtained by using the minimum exposure the CT scanner could
provide. The straight spinal needle had marks to control the depth of
introduction.
After the initial image was obtained, the needle was adjusted and
advanced toward the posterior aspect of the neural foramen by using
an intermittent CT imaging technique. A multisection technique with
6 images per acquisition and a section thickness of 3 mm was used,
which could display the entire course of the needle and the surround-
ing anatomy. Usually 1 or 2 acquisitions were sufficient. The optimal
placement of the needle tip was at the outer edge of the posterior
aspect of the foramen, which was reached from the dorsal approach
typically at a 10°– 45° angle (range, 1°–50°) between the needle and the
sagittal plane (Figs 1 and 2). The facet joint capsule served as a confine
for the needle. The patients sometimes described reproduction of
their pain when the needle was in the correct position. Once the nee-
dle was in the desired position, 0.5 mL of a 1:1 mixture of iopamidol
(Solutrast 300; Bracco Altana Pharma, Konstanz, Germany) and bu-
pivacaine 0.75% (Bucain; Delta Select, Dreieich, Germany) was in-
jected. After the injection, an acquisition with 6 images was used
again, which then displayed the entire distribution of the contrast.
When the contrast was in an appropriate distribution, the nerve root
block was performed with 1 mL of bupivacaine. If no or an inappro-
priately small amount of contrast was detected, the procedure would
have been stopped. This, however, was never the case.
For therapeutic blocks, 8 mg (2 mL) of dexamethasone (Fortecor-
tin Inject; Merck, Darmstadt, Germany) was added.
Patient Assessment
Usually in our department, the patient’s history and a pain analysis
are recorded at the first presentation, a physical (neurologic) exami-
nation is conducted, and the CT/MR imaging scans of the cervical
Number of different nerve root blocks
a
Nerve Root
All Indications Diagnostic Indication Therapeutic Indication
No. ⫹⫺ No. ⫹⫺No. ⫹⫺
C3 1 1 0 1 1 0 0 0 0
C4 4 3 1 3 2 1 1 1 0
C5 3 1 2 3 1 2 0 0 0
C6 22 16 6 14 9 5 8 7 1
C7 13 10 2 12 9 3 1 1 0
C8 10 9 1 5 4 1 5 5 0
⌺53 40 13 38 26 12 15 14 1
a
⫹indicates evaluated as a positive block; ⫺, evaluated as a negative block.
Fig 1. Extraforaminal contrast distribution after CSNRB of the right C6 nerve root.
1832 Wolter 兩AJNR 31 兩Nov-Dec 2010 兩www.ajnr.org
spine are evaluated. When the assumed diagnosis is cervical radicular
pain, a cervical nerve root block is planned.
For this retrospective study, patients’ charts were assessed to as-
certain the nerve root and pathology involved. Furthermore, the pa-
tients’ charts were reviewed to discover whether, following a positive
diagnostic block, an operative intervention or subsequent therapeutic
blocks were performed and their effect on pain intensity.
Outcome Measurement
At our institution, all patients receive a standard form to fill in their
pain scores on the VAS before the block and after the block for 6 hours
in hourly intervals. Later, these standard forms were analyzed. The
block was regarded as positive if the following criteria were met: 1) the
pain level decreased ⬎50%, 2) the duration of the response was ⱖ4
hours, and 3) the pain in the arm decreased if one of the nerve roots
from C5 to C8 were blocked.
Neuroradiologic Analysis
Contrast patterns were analyzed to assess whether the spread of the
contrast agent was extraforaminal, intraforaminal, or intraspinal. To
this end, we analyzed each block by means of 6 axial sections in 3-mm
sections centered on the foramen.
Needle angulation was measured as the angle between the needle
and the sagittal plane. The distance between the needle tip and the
nerve root was measured, as well as the distance between the needle
tip and the entrance of the foramen. The foramen was defined as
being situated posteromedial to a line from the anterior confine of
the zygapophyseal joint to the anterior part of the uncinate process
(Fig 3).
Statistical Analysis
For statistical analysis, a computer software package (GraphPad
Prism, Version 5.01; GraphPad Software, La Jolla, California) was
used. A Pvalue ⬍.05 indicated a significant difference. For calcula-
tion of the statistical significance of the differences of mean VAS
scores, the Mann Whitney Utest was used. An unpaired ttest was also
used to determine if there were statistical differences in the distance
from the needle tip to the nerve root or to the foramen between the
group of positive and negative blocks. Angulation of the needle was
Fig 2. Extra- and intraforaminal contrast distribution after CSNRB of the right C6 nerve root.
Fig 3. Schematic illustration of the needle tip and entrance of the foramen. 1 indicates the
facet joint; 2, the uncinate process; 3, the line reaching from the anterior part of the
uncinate process to the anterior part of the zygapophyseal joint; 4, the area in which the
needle tip in the dorsal-approach technique is expected; and 5, the area in which the nerve
root and nerve supplying the artery are expected.
AJNR Am J Neuroradiol 31:1831–36 兩Nov-Dec 2010 兩www.ajnr.org 1833
correlated to the distance from the needle tip to the foramen and to
the nerve root by means of the Wilcoxon matched-pairs test. The
2
test was used to compare extra-/intraforaminal contrast patterns with
the results of the blocks.
Ethics Committee Approval
This retrospective study was approved by the Ethics Committee of the
University Hospital, Freiburg, Germany.
Results
Outcome Measurement
Overall 40 blocks fulfilled the criteria for positive blocks and
13 blocks were classified as negative. The positive blocks were
1 C3 block, 3 C4 blocks, 1 C5 block, 16 C6 blocks, 10 C7 blocks,
and 9 C8 blocks.
With 1 exception, the blocks that were considered negative
were performed for diagnostic indications. Among these
blocks, there were 1 C4 block, 2 C5 blocks, 6 C6 blocks, 3 C7
blocks, and 1 C8 block.
In those blocks not affecting pain relief, another pain
source, either radicular pain emerging from another level or a
different pathology (such as cervical facet joint pain or periph-
eral neuropathy) was later found.
Thirty-eight blocks were performed with diagnostic and 15
blocks with therapeutic indications (Table). Overall mean
VAS scores decreased from 5.57 ⫾1.57 (range, 2.5–10.0) pre-
intervention to 1.52 ⫾2.29 (range, 0.0 –7.0) postintervention.
In patients with positive blocks, mean VAS scores de-
creased from 5.42 ⫾1.57 (range, 2.5–10) to 0.52 ⫾1.04
(range, 0 – 4.5). In negative blocks, mean VAS scores were
6.08 ⫾1.44 preintervention (range, 5.0 –10.0) and 5.25 ⫾1.48
postintervention (range, 3.0 –7.0), respectively. No statisti-
cally significant difference was found between the preinter-
ventional VAS scores in positive and in negative blocks (P⫽
.14). Postinterventional VAS scores clearly differed in the 2
groups of blocks (P⬍.0001).
Twenty patients had osseous pathology (foraminal stenosis
due to osteophytes), 4 patients had a soft disk prolapse, and 6
patients had a combined pathology in the level of interest. One
patient who underwent 2 CSNRBs had a soft disk prolapse at
the C5– 6 level and osseous pathology in the C4–5 level. Over-
all 5, 37, and 11 CSNRBs were performed for osseous, soft disk,
and combined pathology, respectively.
Fourteen patients had subsequent surgery. Nine patients
had ventral spondylodesis. This was performed with bone ce-
ment in 7 patients, autologous bone grafts and ventral osteo-
synthesis in 1 patient, and a cage in another patient. Five pa-
tients had cervical foraminotomy as described by Frykholm.
21
All patients who underwent ventral fusion had a complete
resolution of the radicular pain, but 1 patient who had a sin-
gle-level fusion with Palacos had neck pain 3 months after the
operation. Those patients who underwent dorsal decompres-
sion had complete pain relief directly after the operation, but
after 3 months, 1 patient had radicular pain once again.
Most patients who had ⬎1 block had similar results each
time. One patient had the same level block performed 3 times
for therapeutic indications, and 5 patients had the same level
block performed twice.
In 1 patient, a C7 block and a C8 block were performed. He
had complete pain relief (VAS score, from 4.5 to 0) after the C7
block and partial pain relief after the C8 block (VAS score,
from 2.5 to 1), which was rated positive. After dorsal decom-
pression of the C7 nerve root foramen, the patient remained
pain-free.
One patient had a C6 block leading to complete pain relief
and subsequently underwent dorsal decompression, which
initially led to complete pain reduction. Three months later,
the patient once more had cervicobrachialgia, which now ir-
radiated into the C7 dermatome. A C7 block led to complete
pain relief, and a second therapeutic C7 block had a long-
lasting effect.
Neuroradiologic Analysis
The mean angle between the needle and the sagittal plane was
26.61° (range, 1°-50°). The mean distance between the needle
tip and the confines of the foramen was 10.02 mm (range,
1–20 mm). The mean distance between the needle tip and the
nerve root was 4.43 mm (range, 0 –20 mm).
The angle of the needle and the distance between the needle
and the nerve root did not correlate to the effect of the block
(P⫽.4915 and P⫽.2591). However, the distance between the
needle and the foramen was significantly higher in those
blocks that were rated positive (P⫽.007).
Angulation of the needle correlated with the distance be-
tween the needle tip and the foramen (P⫽.0009) and the
distance between the needle tip and the nerve root (P⫽.0132).
Contrast had an extraforaminal distribution pattern in 40
blocks. In 3 blocks, contrast was found intraspinally (epi-
durally), and in 8 blocks, the distribution of contrast was both
intra- and extraforaminal. Unfortunately in 2 blocks, the con-
trast scans were not archived. There were no correlations be-
tween extra- or intraforaminal distribution of contrast and a
positive or negative response to the block (
2
: extraforaminal,
34 of 40 positive blocks, 8 of 13 negative blocks; P⫽.12).
In 10 blocks (3 therapeutic and 7 diagnostic), no clear con-
tact between the contrast agent and the nerve root was found,
due to difficulty in identifying the exact position of the nerve
root in its extraspinal course. Nevertheless, 9 of these blocks
were positive. No correlation was seen between contrast in
clear contact with the nerve root and a positive or negative
response to the block.
Discussion
CSNRB is a technique frequently used in case of cervical radic-
ular pain, with estimates ranging in the magnitude of ⬎30,000
per year in the United States.
22
It can be used as a diagnostic
tool, but more often, it is performed therapeutically with local
application of corticosteroids as an alternative to medical
treatment or operative decompression of the nerve root. Indi-
cations for a diagnostic cervical block revolve around clinical
and MR imaging findings.
23
Lately, there is a growing awareness of possible devastating
complications of the procedure, such as spinal cord infarction
or cerebellar infarction. Also vertebral artery puncture has
been described.
16
In a recent survey conducted among pain
physicians about complications following cervical transfo-
raminal epidural steroid injections, 78 complications includ-
ing 16 vertebrobasilar brain infarcts, 12 cervical spinal cord
infarcts, and 2 combined brain and spinal cord infarcts were
1834 Wolter 兩AJNR 31 兩Nov-Dec 2010 兩www.ajnr.org
reported.
24
However, there is likely to be under-reporting of
complications.
25
Some complications have not been pub-
lished because they are still before the court or because lawyers
and patients refused to have their case records released into
the medical literature.
5
Among the published cases, there are 2
in which CSNRB was performed under CT guidance,
19,20
both
with a transforaminal access.
It is assumed that most complications involve an embolic
mechanism, with inadvertent injection of high-particulate
material into a nerve root artery.
26
Recently, after the known
adverse events were analyzed, the use of real-time fluoroscopy
to detect vascular uptake, a nonparticulate corticosteroid such
as dexamethasone, and microbore extension tubing (pigtail)
to minimize needle manipulation while changing syringes
have been proposed to reduce the probability of these adverse
events.
24
CT guidance with dorsal access offers the possibility of per-
forming a selective block, as the contrast distribution pattern
demonstrates. For the therapeutic efficiency of corticoste-
roids, it is not important if the target point is located slightly
more distally because there is a strong axonal transport of
corticoids.
27
If, however, an intraspinal epidural (less selec-
tive) distribution of the steroid is intended, the conventional
or even a translaminar approach is more suitable.
In our opinion, the technique we describe minimizes the
danger of inadvertent puncture of the nerve root artery be-
cause the target point of the needle tip lies posterior to the
region in which the radicular artery can be expected to run.
Recently, the technique has been described in a technical
note, but no information was supplied regarding the patterns
of contrast distribution, the angle of the trajectory, the dis-
tance between the needle tip and the nerve root, and pain relief
after the block.
9
In the present study, the angle of the needle
toward the sagittal plane correlated with the distance between
the needle tip and the foramen and the distance between the
needle tip and the nerve root but not with the distribution of
contrast. The pattern of contrast distribution did not correlate
with either a positive or negative response to the nerve block.
This indicates that intraforaminal distribution of the local an-
esthetic is not necessary for anesthesia of the nerve root. The
volumes used in our studies are within the ranges described in
the literature.
3,23,28
It is believed that posterior needle placement in the fora-
men might minimize the risk of intravascular injection by
avoiding the vertebral artery.
29
In a large series of 1036 ex-
traforaminal nerve root blocks, the posterior access was signif-
icantly safer than the anterior.
30
This finding may be because
the radicular artery normally runs anterior to the radicular
nerve. Nevertheless, Huntoon
31
could demonstrate that
branches of the deep cervical and ascending artery can enter
the foramen posteriorly and can supply the spinal cord. He
described the anatomy of the deep cervical arteries after exam-
ination of the cervical foramina of 10 embalmed cadavers and
found that of 95 intervertebral foramina dissected, 21 had an
arterial vessel proximal to the posterior aspect of the foraminal
opening and 7 of these 21 cases were spinal branches poten-
tially forming radicular or segmental medullary vessels to the
spinal cord. He concluded that these arteries may be vulnera-
ble to injection or injury during transforaminal epidural ste-
roid injection. This might explain why, in some published
cases of complications, the needle position was in the posterior
part of the foramen.
11,14,17
It is difficult to compare the CT technique with the fluoro-
scopic technique in terms of contrast use. First, vascular up-
take in the dorsal approach appears to be much more unlikely
because the final needle position is not in the region of the
suspected course of the radicular artery. Second, applying a
small volume of contrast as an initial step makes it possible to
correct the needle position in cases of insufficient contrast
distribution. Although the final volume of local anesthetic in-
jected is larger than the initial contrast volume, this difference
has a lower impact on the specificity of the block than the
position of the needle tip. By obtaining a block of 6 CT acqui-
sitions with 3-mm section thicknesses after contrast injection,
we could rule out contrast distribution to the adjacent nerve
root.
Because the complications stated above seem to occur at a
frequency of ⬍0.1%, the present study of 53 is insufficiently
powered to assess the risks associated with our technique. For
similar reasons, the sensitivity and specificity of the technique
when used for diagnostic purposes cannot be determined with
certainty. However, to our knowledge, precise estimates of the
sensitivity and specificity of other techniques of cervical nerve
root block studies do not exist; nevertheless, these techniques
are widely used. For methodologic and ethical reasons, a study
that would produce this information seems virtually impossi-
ble to perform. First, it would require that a precise diagnosis
for the pain be achieved by another method; this, however,
could make a diagnostic block unnecessary and could expose
the patient to an unnecessary risk. Second, the study design
would have to negate the possibility of a false-positive re-
sponse due to the patient’s expectations (placebo response; for
lumbar back pain, this issue has been reviewed by Saal
32
).
The only way to draw limited conclusions regarding spec-
ificity and sensitivity is to compare the results of serial (thera-
peutic) injections or to correlate them to the outcome of nerve
root decompression. We did this and found that blocks of the
same nerve root produced similar outcomes, with a low level
of variability in changes in pain scores, and that surgical de-
compression of the nerve root identified led to pain relief in all
except 1 case.
The technique is simple and not very time-consuming. It
induces a relatively low radiation dose, particularly if in the
future, dose-reduction strategies published recently
33,34
can
also be applied for intermittent CT acquisition.
Conclusions
CT-guided CSNRB by using a dorsal approach is feasible,
seems to have the same predictive value as other commonly
used techniques for cervical blocks, and, on the basis of tech-
nical considerations, can be assumed to have a higher degree of
safety.
References
1. Cluff R, Mehio AK, Cohen SP, et al. The technical aspects of epidural steroid
injections: a national survey. Anesth Analg 2002;95:403– 08
2. Vallee JN, Feydy A, Carlier RY, et al. Chronic cervical radiculopathy: lateral-
approach periradicular corticosteroid injection. Radiology 2001;218:886 –92
3. Cyteval C, Thomas E, Decoux E, et al. Cervical radiculopathy: open study on
percutaneous periradicular foraminal steroid infiltration performed under
CT control in 30 patients. AJNR Am J Neuroradiol 2004;25:441– 45
AJNR Am J Neuroradiol 31:1831–36 兩Nov-Dec 2010 兩www.ajnr.org 1835
4. Slipman CW, Lipetz JS, DePalma MJ, et al. Therapeutic selective nerve root
block in the nonsurgical treatment of traumatically induced cervical spondy-
lotic radicular pain. Am J Phys Med Rehabil 2004;83:446 –54
5. RathmellJP, Aprill C, Bogduk N. Cervical transforaminal injection of steroids.
Anesthesiology 2004;100:1595– 600
6. Kolstad F, Leivseth G, Nygaard OP. Transforaminal steroid injections in the
treatment of cervical radiculopathy: a prospective outcome study. Acta Neu-
rochir (Wien) 2005;147:1065–70. Epub 2005 Jun 9
7. Slipman CW, Lipetz JS, Jackson HB, et al. Outcomes of therapeutic selective
nerve root blocks for whiplash-induced cervical radicular pain. Pain Physician
2001;4:167–74
8. Wagner AL. CT fluoroscopic-guided cervical nerve root blocks. AJNR Am J
Neuroradiol 2005;26:43– 44
9. Wolter T, Mohadjer M, Berlis A, et al. Cervical CT-guided, selective nerve root
blocks: improved safety by dorsal approach. AJNR Am J Neuroradiol 2009;30:
336 –37
10. McMillan MR, Crumpton C. Cortical blindness and neurologic injury com-
plicating cervical transforaminal injection for cervical radiculopathy. Anes-
thesiology 2003;99:509 –11
11. Tiso RL, Cutler T, Catania JA, et al. Adverse central nervous system sequelae
after selective transforaminal block: the role of corticosteroids. Spine J 2004;
4:468 –74
12. Ludwig MA, Burns SP. Spinal cord infarction following cervical transforami-
nal epidural injection: a case report. Spine (Phila Pa 1976) 2005;30:E266 – 68
13. Beckman WA, Mendez RJ, Paine GF, et al. Cerebellar herniation after cervical
transforaminal epidural injection. Reg Anesth Pain Med 2006;31:282– 85
14. Brouwers PJ, Kottink EJ, Simon MA, et al. A cervical anterior spinal artery
syndrome after diagnostic blockade of the right C6-nerve root. Pain 2001;91:
397–99
15. Muro K, O’Shaughnessy B, Ganju A. Infarction of the cervical spinal cord
following multilevel transforaminal epidural steroid injection: case report
and review of the literature. J Spinal Cord Med 2007;30:385– 88
16. Rozin L, Rozin R, Koehler SA, et al. Death during transforaminal epidural
steroid nerve root block (C7) due to perforation of the left vertebral artery.
J Spinal Cord Med 2003;24:351–55
17. Ziai WC, Ardelt AA, Llinas RH. Brainstem stroke following uncomplicated
cervical epidural steroid injection. Arch Neurol 2006;63:1643– 46
18. Wallace MA, Fukui MB, Williams RL, et al. Complications of cervical selective
nerve root blocks performed with fluoroscopic guidance. AJR Am J Roentgenol
2007;188:1218 –21
19. Suresh S, Berman J, Connell DA. Cerebellar and brainstem infarction as a
complication of CT-guided transforaminal cervical nerve root block. Skeletal
Radiol 2007;36:449 –52
20. Rosenkranz M, Grzyska U, Niesen W, et al. Anterior spinal artery syndrome
following periradicular cervical nerve root therapy. J Neurol 2004;251:229 –31
21. Frykholm R. Cervical root compression resulting from disc degeneration and
root sleeve fibrosis. Acta Chir Scand 1951;160:1–149
22. Manchikanti L. The growth of interventional pain management in the new
millennium: a critical analysis of utilization in the Medicare population. Pain
Physician 2004;7:465– 82
23. Strobel K, Pfirrmann CW, Schmid M, et al. Cervical nerve root blocks: indica-
tions and role of MR imaging. Radiology 2004;233:87–92
24. ScanlonGC, Moeller-Bertram T, Romanowsky SM, et al. Cervical transforami-
nal epidural steroid injections: more dangerous than we think? Spine 2007;32:
1249 –56
25. Malhotra G, Abbasi A, Rhee M. Complications of transforaminal cervical epi-
dural steroid injections. Spine (Phila Pa 1976) 2009;34:731–39
26. Karasek M, Bogduk N. Temporary neurologic deficit after cervical transfo-
raminal injection of local anesthetic. Pain Med 2004;5:202– 05
27. Frolkis VV, Tanin SA. Peculiarities of axonal transport of steroid hormones
(hydrocortisone, testosterone) in spinal root fibres of adult and old rats. Neu-
roscience 1999;92:1399 – 404
28. Kumar N, Gowda V. Cervical foraminal selective nerve root block: a ‘two-
needle technique’ with results. Eur Spine J 2008;17:576 –84. Epub 2008 Jan 18
29. Lee JY, Nassr A, Ponnappan RK. Epidural hematoma causing paraplegia after
a fluoroscopically guided cervical nerve-root injection: a case report. J Bone
Joint Surg Am 2007;89:2037–39
30. MaDJ, Gilula LA, Riew KD. Complications of fluoroscopically guided extrafo-
raminal cervical nerve blocks: an analysis of 1036 injections. J Bone Joint Surg
Am 2005;87:1025–30
31. Huntoon MA. Anatomy of the cervical intervertebral foramina: vulnerable
arteries and ischemic neurologic injuries after transforaminal epidural injec-
tions. Pain 2005;117:104 –11
32. Saal JS. General principles of diagnostic testing as related to painful lumbar
spine disorders: a critical appraisal of current diagnostic techniques. Spine
2002;27:2538 – 45, discussion 2546
33. Smith AB, Dillon WP, Lau BC, et al. Radiation dose reduction strategy for CT
protocols: successful implementation in neuroradiology section. Radiology
2008;247:499 –506
34. Hohl C, Suess C, Wildberger JE, et al. Dose reduction during CT fluoroscopy:
phantom study of angular beam modulation. Radiology 2008;246:519 –25
1836 Wolter 兩AJNR 31 兩Nov-Dec 2010 兩www.ajnr.org
