us-guided interventional techniques at the cervical region · 2010-11-02 · approach, the needle...
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US-guided interventional techniques at the cervical region
서울 학교 의과 학 마취통증의학교실
김 용 철
Fig. 1. Anatomy of the stellate ganglion.
최근 들어서 음 가 통증 역의 치료에 도입되면서 신속 정확하게 시술을 시행할 수 있게 되었고 그 만큼 시술에 따른
합병증도 어들게 되었다. 한 C-arm 유도 하에서 시행되었던 많은 술기들이 음 유도 하에서 시술이 가능해짐으로써
의료인과 환자의 방사선 노출도 어들게 되었다.
본 강의에서는 경추부에서 음 유도 하에 시술할 수 있는 표 인 질환들인 stellate ganglion block, brachial plexus
block with interscalene approach, superficial cervical plexus block, cervical facet joint injection, cervical medial branch block, spinal
accessory nerve block에 해서 간략히 설명하고자 한다. SGB는 prevertebral fascia 아래, longus colli 에 치하고 있다.
Stellate ganglion block
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Fig. 2. Annotated version of US anatomy of SGB.
Fig. 3. US anatomy at the C6 and C7 levels. A yellow arrow depicts path of needle. Place US probe medial to the anterior
tubercle of C6 to avoid any obstacle of the needle advancement. Block at the C7 level is not recommended. Using the anterior
approach, the needle is inserted through the thyroid gland, adjacent to the carotid artery and close to the inferior thyroid artery
and the recurrent laryngeal nerve. In addition, this approach requires the application of pressure to the anterior neck, which is
troubling for most patients [2].
Longus colli muscle의 근막을 뚫자 마자 5 ml 정도를 주사하면 즉시 블록이 일어 난다[1].
김용철:US-guided interventional techniques at the cervical region
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Fig. 4. US anatomy at the mid level interscalene region.
Arrowheads = nerve roots. The ASM is now larger in
size at this level and more NRs are seen in the
interscalene groove.
Fig. 5. US anatomy at the lower level interscalene
region. Move the transducer caudad to visualize
branching of NRs (arrowheads) into trunks which travel
superficially towards the skin surface. The vertebral
artery (VA) usually becomes visible below the C6
transverse process.
Fig. 6. In Plane Approach (LEFT PANEL) and Out of Plane Approach (RIGHT PANEL). Clear identification of the needle
tip can be technically challenging in out of plane approach. It is advantageous to inject a small volume of local anesthetic (1
mL) during needle advancement to facilitate tracking of the needle tip [3].
Brachial plexus block with interscalene approach
Mid level interscalene region (C6 level)
Lower interscalene region (Below C6)
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Fig. 8. Schematic drawings of greater auricular nerve from the superficial cervical plexus and its US image. The plexus lies
on the SCM just posterior to the EJV.
Fig. 7. US image (RIGHT PANEL) and its annotated version (RIGHT PANEL) for injection during BPB [3].
주사 시에는 그림에서 보는 바와 같이 이상감각을 유발하지 않고 신경 주 에 주사를 하여야 신경 손상을 피할 수 있다.
Superficial cervical plexus block
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Fig. 9. Landmarks for superficial cervical plexus block: mastoid process, sternocleidomastoid muscle, posterior border of the
clavicular head, and transverse process of C6.
Fig. 10. A schematic drawing of spinal accessory nerve from the superficial cervical plexus and its US image. The nerve have
motor innervation of the SCM and TZ. However, it has no sensory component. It emerges under the SCM to lie on the levator
scapulae and middle scalene muscles ventral to the anterior border of the TZ.
Spinal accessory NB
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Fig. 12. Targets for cervical facet joints (LEFT PANEL) and medial
branch blocks (RIGHT PANEL).Fig. 11. A schematic drawing of the referred pain area of cervical facet
joints.
Fig. 13. A schematic illustrations of the location of medial branches (LEFT PANEL) and an annotated version of lateral image
of C-spine for the paths of cervical medial branches.
Cervical facet joint injection
문진 시에 어디로 연 통이 발생했느냐에 따라 블록을 시행할 경추 이나 후지들을 결정한다.
Cervical medial branch block
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Table 1. The Diameter and Distance from Bone of the Cervical
Medial Branches
Fig. 14. A US image of cervical spine. Yellow straight arrows indicates cervical facet joints and dark yellow arrows indicates
medial branches.
References
1. Shibata Y, Fujiwara Y, Komatsu T. A new approach of ultrasound-guided stellate ganglion block. Anesth Analg 2007; 105: 550-1.
2. Gofeld M, Bhatia A, Abbas S, Ganapathy S, Johnson M. Development and Validation of a New Technique for Ultrasound-Guided Stellate
Ganglion Block. Reg Anesth Pain Med 2009; 34: 475-9.
3. http://www.neuraxiom.com/index.php: useful internet site for US-guided techniques.
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가톨릭 학교 의과 학 마취통증의학교실
문 동 언
Ultrasound guided neuroaxial block and Ultrasonography in
pain medicine (USPM) is a rapidly growing medical field in
interventional pain management. Traditionally, spine interven-
tional procedures for pain management are performed with
imaging guidance such as fluoroscopy and computed tomog-
raphy (CT) scan. In the last few years, there has been tremen-
dous growth in USPM interest as evidenced by the remarkable
increase in the publication of literature on ultrasound (US)
guided injections. There is a growing trend in using ultra-
sonography in pain medicine as evident by the plethora of
published reports. Ultrasound (US) provides direct visualization
of various soft tissues and real-time needle advancement and
avoids exposing both the health care provider and the patient
to the risks of radiation. The US machine is more affordable
and transferrable than fluoroscopy, computed tomography scan,
or magnetic resonance imaging machine. In a previous review,
we discussed the challenges and limitations of US, anatomy,
sonoanatomy, and techniques of interventional procedures of
peripheral structures. In the present lecture, I will discuss the
sonoanatomy, and US-guided techniques of interventional pain
procedures for axial structures, paraspinal structure for example
quadrates lumborum muscle block, piriformis muscle block and
sacroiliac joint block.
Ultrasound imaging of the lumbar spine
For a transverse scan of the lumbar spine, the US transducer
is positioned over the spinous process with the patient in the
sitting or lateral position. On a transverse sonogram the spi-
nous process is seen as a hyperechoic reflection under the skin
and subcutaneous tissue, anterior to which there is a dark
acoustic shadow that completely obscures the underlying spinal
canal and thus the neuraxial structures. Therefore, this view is
not ideal for imaging the neuraxial structures but is useful for
identifying the midline when the spinous processes cannot be
palpated (obesity and in those with edema in their backs).
However, if one now slides the transducer slightly cranially or
caudally, it is possible to perform a transverse scan of the
lumbar spine with the US beam being insonated through the
interspinous space (interspinous view). Because the US signal
is now not impeded by the spinous process, the ligamentum
flavum, posterior dura, thecal sac, and the anterior complex
(discussed below) are visualized in the midline (from a posteri-
or-to-anterior direction) within the spinal canal, and laterally
the articular process of the facet joints and the transverse
processes are visible. The resultant sonogram produces a pat-
tern that Carvalho likens to a “flying bat. The interspinous
view can also be used to determine whether there is any rota-
tion in the vertebra, such as in scoliosis. Normally, the articu-
lar processes of the facet joint on either side are symmetrically
located. However, if they are asymmetrical or either one of
the articular processes is not visible, then one should suspect
rotation of the spine (provided the transducer is correctly posi-
tioned and aligned) and anticipate a potentially difficult spinal
or epidural. For a sagittal scan of the lumbar spine, the author
prefers to position the patient in the left lateral position with
the knees and hips slightly flexed. The transducer is positioned
1−2 cm lateral to the spinous process (midline) at the lower
back on the nondependent side with its orientation marker di-
rected cranially. The transducer is also tilted slightly medially
during the scan so the US beam is insonated in a PMOS
plane. During the scout scan, the L3/4 and L4/5 interlaminar
spaces are located as described above. On a PMOS sonogram
of the lumbar spine, the erector spinae muscles are clearly de-
lineated and lie superficial to the lamina. The lamina appears
hyperechoic and is the first osseous structure visualized.
Because bone impedes the passage of US, there is an acoustic
shadow anterior to each lamina. The sonographic appearance of
the lamina produces a pattern that resembles the head and
neck of a horse, which we refer to as the “horse head sign”.
The interlaminar space is the gap between the adjoining
lamina. In contrast, the articular processes of the facet joints
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appear as one continuous hyperechoic wavy line with no inter-
vening gaps as seen at the level of the lamina and are the
usual clues to differentiate the lamina from the articular
processes. In between the dark acoustic shadows of adjacent
lamina, there is a rectangular area in the sonogram where the
neuraxial structures are visualized. This is the “acoustic win-
dow” and results from reflections of the US signal from the
neuraxial structures within the spinal canal. The ligamentum
flavum is also hyperechoic and is often seen as a thick band
across two adjacent lamina. The posterior dura is the next hy-
perechoic structure anterior to the ligamentum flavum, and the
epidural space is the hypoechoic area (few millimeters wide)
between the ligamentum flavum and the posterior dura. The
thecal sac with the cerebrospinal fluid is the anechoic space
anterior to the posterior dura. The cauda equina, which is lo-
cated within the thecal sac, is often seen as multiple horizontal
hyperechoic shadows within the anechoic thecal sac, and their
location can vary with posture. Pulsations of the cauda equina
are also identified in some patients. The anterior dura is also
hyperechoic, but it is often difficult to differentiate it from the
posterior longitudinal ligament and the vertebral body as they
are of the same echogenicity (isoechoic) and very closely ap-
posed to each. This often results in a single, composite, hyper-
echoic reflection anteriorly that is also referred to as the
“anterior complex”.
Lumbar epidural injection
During lumbar epidural access, US imaging can be used to
preview the underlying spinal anatomy or to guide the needle
in real-time. As described above, real-time US guidance for
epidural access is performed either as a twooperator or as a
single-operator technique. In the former technique, which was
described by Grau and coworkers for combined spinal epidural
anesthesia, the first operator performs the US scan via the par-
amedian axis while the second operator performs the epidural
access via the midline using the traditional “loss-of-resistance”
technique. Grau and coworkers were able to visualize the ad-
vancing needle in all their cases despite the axis of the US
scan and the needle insertion being different. Moreover, they
were also able to visualize the dural puncture in all their pa-
tients and dural tenting in a few cases during the nee-
dle-through-needle spinal puncture. Recently, Karmakar have
described the successful use of real-time US guidance in con-
junction with loss of resistance to saline for paramedian epi-
dural access, performed by a single operator, with the epidural
needle inserted in the plane of the US beam. With this techni-
que, because the epidural needle is inserted in-plane, it is pos-
sible to visualize the advancing needle in real-time until it is
seen to engage in the ligamentum flavum. Anterior displace-
ment of the posterior dura and widening of the posterior epi-
dural space were the most frequently visualized changes within
the spinal canal, but compression of the thecal sac was also
seen in a few patients. These are objective signs of a correct
epidural injection and have previously been described in
children. The neuraxial changes that occur within the spinal
canal following the “loss of resistance” to saline may have
clinical significance and are discussed in detail in our report.
Despite our success with real-time USG epidural access, we
haven’t been able to visualize an indwelling epidural catheter
to date in adults. However, Karmakar has occasionally ob-
served changes within the spinal canal, for example, anterior
displacement of the posterior dura and widening of the posteri-
or epidural space, after an epidural bolus injection via the
catheter. These are surrogate markers of the location of the
catheter tip and are of limited value in clinical practice. There
is a need to develop new epidural catheter designs with im-
proved echogenicity.
Currently, there are limited outcome data following USG
lumbar epidural access, and the majority of the publications
have evaluated the use of performing a prepuncture US scan
or scout scan. A scout scan allows one to identify the midline
and accurately determine the interspace for needle insertion,
which are useful in patients in whom anatomical landmarks are
difficult to palpate, such as in those with obesity, edema of
the back, or abnormal anatomy (scoliosis, post laminectomy
surgery, or spinal instrumentation).
It also allows the operator to preview the neuraxial anatomy
accurately predict the depth to the epidural space, and de-
termine the optimal site and trajectory for needle insertion.
Cumulative evidence suggests that, when an US examination is
performed before the epidural puncture, it improves the success
rate of epidural access on the first attempt, reduces the number
of puncture attempts or the need to puncture multiple levels,
and also improves patient comfort during the procedure.
Lumbar medial-branch block
The patient is placed in the prone position, and a low-
frequency curvilinear transducer is used. First, a longitudinal
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midline sonogram is obtained to identify the correct spinal
level. The dorsal surface of the sacrum is easily identified, and
the lumbar spinal processes can be counted from caudal to
cephalad. By sliding the transducer laterally, a longitudinal par-
avertebral image is obtained, and the corresponding transverse
processes can be easily seen. Once the appropriate level is
identified, the transducer can be rotated transversely to obtain
a short-axis view showing the transverse process and the corre-
sponding SAP. The target is the groove at the junction be-
tween the base of the SAP and the superior border of the
transverse process. A 20-gauge needle is advanced in-plane
with the US beam from lateral to medial under real-time ultra-
sonography aiming toward the target. Once the bone is con-
tacted, a longitudinal paravertebral image is obtained to make
sure that the needle is at the cephalad margin of the corre-
sponding transverse process. L5 dorsal ramus block is usually
more difficult secondary to the US bony artifacts from the
iliac bone.
Lumbar facet intra-articular injection
The patient is placed in the prone position, and a low-
frequency curvilinear transducer is used. Once the appropriate
level is identified as above, the transducer can be rotated
transversely to obtain a short-axis view showing the facet joint
space between the inferior articular process and SAP. The tar-
get is the midpoint of the joint space. A 20-gauge needle is
advanced in-plane with the US beam from lateral to medial
under real-time ultrasonography aiming toward the target. Often
it is difficult to see the entire needle shaft clearly while it is
advanced because the needle angle is usually between 45 and
60 degrees.
As mentioned earlier, the major limitation of ultrasonography
is the inability to obtain a high-resolution image at such depth
needed for facet injections. That is why visualizing the sacral
hiatus, and as the lateral edge of the sacrum is identified, the
transducer is moved laterally and cephalad until the bony con-
tour of the ileum is identified. The cleft between the ileum
and the lateral sacral edge represents the SIJ, and the target is
the most inferior part. A 22-gauge needle is then inserted at the
medial end of the transducer and advanced laterally under direct
vision in-plane with the US beam until it enters the joint.
The major limitation is the potential for periarticular rather
than intra-articular injection compared with fluoroscopy, where
one can reliably obtain an arthrogram with contrast agent in-
jection in most cases. Also, US is not entirely reliable in de-
tecting intravascular injection while performing SIJ injections
secondary to the bony artifacts casted by the iliac bone.
Caudal epidural injection
With the patient in the prone position, the sacral hiatus is
palpated, and a linear high-frequency transducer (curved low-
frequency transducer in obese patients) is placed transversely at
the midline to obtain a sonographic transverse view of the sa-
cral hiatus. The 2 bony prominences of sacral cornua appear
as 2 hyperechoic reversed U-shaped structures. Between the 2
cornua, one can identify 2 hyperechoic band-like structures: the
sacrococcygeal ligament on top and the dorsal bony surface of
the sacrum at the bottom and the sacral hiatus as the hypo-
echoic area in between. A 22-gauge needle is then inserted be-
tween the 2 cornua into the sacral hiatus. A Bpop is usually
felt as the sacrococcygeal ligament is penetrated. The trans-
ducer was then rotated 90 degrees to obtain a longitudinal
view of the sacrum and sacral hiatus, and the needle is ad-
vanced into the sacral canal under real-time sonographic in the
longitudinal view. In adults, it is usually difficult to follow the
needle once in the sacral canal secondary to the bony artifacts
from the sacrum wall. After negative aspiration for cere-
brospinal fluid and blood, injection is carried out under re-
al-time sonography, where one can notice turbulence in the sa-
cral canal and monitor the spread of the injectate cephalad,
which is not an easy task in adults. Color Doppler mode may
be used as discussed above; however, it is very subjective and
unreliable because turbulence from the injectate can be in-
terpreted as flow in many directions with different colors and
can be misinterpreted as intravascular injection. The best way
to rule out unintentional intravascular or intrathecal injection is
still by contrast fluoroscopy. Ultrasound can be used if fluoro-
scopy is not available or to guide needle placement into the
sacral canal as an adjuvant to fluoroscopy.
Limitations of US in neuroaxial applications are discussed
earlier, and the authors feel that neuroaxial (intrathecal and
spinal) applications of US should be limited to regional anes-
thesia and obstetric anesthesia practice where fluoroscopy is
not readily available. Until we have better technology, US
should have no role in neuroaxial (intrathecal, epidural) blocks
in chronic pain practice as fluoroscopy (which is superior) is
readily available; hence, these applications will not be dis-
cussed in this review.
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Piriformis muscle injection
The key to successful needle placement is to locate the sci-
atic notch. Proximal to the sciatic notch is the ilium, which is
visualized as a hyperechoic line running across the scan image
from medial to lateral positions. Moving the probe medially,
the sacrum and SIJ are visualized. When the scan is in the
sciatic notch, the hyperechoic shadow of bone (ischium) is
seen only in the lateral part of the scan image. At this level,
2 layers of muscles, gluteus maximus muscle dorsally and pir-
iformis ventrally, will be visualized. By rotating the hip in-
ternally and externally with the knee flexed, the piriformis
muscle will be seen gliding underneath the gluteus maximus
muscle. By moving the probe in a medial-to-lateral position,
the origin and the insertion of the piriformis muscle can be
traced.
The ultrasound-guided techniques described in the literature
are quite similar. The patient is placed in the prone position.
With the use of a curvilinear probe with low frequency (2−5
Hz), scanning is performed in the transverse plane with the
probe placed caudad to the posterior superior iliac spine so
that the SIJ can be seen. The probe is then moved caudally to
the sciatic notch. The piriformis muscle is demonstrated by ro-
tating the hip internally and externally with the knee flexed.
The needle is inserted from medial to lateral using an in-plane
technique. It is important to scan from the ilium and move the
probe caudally to ensure the location of the sciatic notch, as
an inexperienced practitioner may mistake the other external
hip rotators (obturator externus, superior and inferior gemellus
muscle forming the tricipital tendons below the ischial spine)
for the piriformis.
Because of the anatomic anomalies of the sciatic nerve with-
in and below the piriformis muscle, we strongly suggest the
use of the nerve stimulator in preventing unintentional injection
in the vicinity of the sciatic nerve. For injection outside the
piriformis muscle, a small amount of normal saline (<0.5 mL)
isinjected, which will confirm the location between the 2 mus-
cle layers (gluteus maximus and piriformis). If intramuscular
injection is attempted, the needle should be advanced further to
elicit strong muscle contractions. A very small amount of nor-
mal saline (<0.5 mL) is injected to confirm the intramuscular
location of the needle. It is not uncommon for sciatic nerve
stimulation to be observed when the needle is advanced
through the piriformis muscle.
Sacroiliac joint injection
US was performed with a curved array transducer and oper-
ating at a gray-scale frequency between 2.5 and 6.0 MHz, ad-
justed to the frequency needed according to the penetration
depth. US scanning and needle insertion were performed by a
musculoskeletal radiologist with 5 years of experience in
US-guided injections. An axial US scan of the posterior area
of the cadavers was used to identify landmarks of the 2 dif-
ferent levels (puncture sites).
Upper level. For primary orientation, the posterior superior
iliac spine was visualized laterally, and the spinous process of
the fifth lumbar vertebra medially. Then the transducer was
moved caudally, depicting the dorsal surface of the sacrum
with the median and lateral sacral crest, the gluteal surface of
the ilium, and the posterior sacral foramen 1. The needle was
inserted into the hypoechoic cleft located between the surface
of the sacrum and the contour of the ilium
Lower level. For the lower level, the transducer was moved
downward by delineation of the median and lateral sacral crest,
at the dorsal surface of the sacrum and the gluteal surface of
the ilium until the posterior sacral foramen 2 was visualized.
As with the upper level, the needle was inserted into the hy-
poechoic cleft between the sacrum and ilium.
The SI joint consists of ear-shaped auricular surfaces of the
ilium and sacrum, resulting in a mainly vertical and antero-
lateral orientation. The posterosuperior compartment is fibrous,
whereas the anteroinferior compartment is synovial. The carti-
lage-lined portion extends more superiorly along the anterior
aspect of the joint, so that the few inferior centimeters repre-
sent a chondral joint from front to back. The transition line
between the cartilage and syndesmotic portions is inferiorly
convex. The entire joint is superficially stabilized by strong an-
terior and posterior ligaments to the interosseous ligaments and
the joint capsule.
Needle insertion using a 21-gauge needle was performed at
both levels under US guidance by freehand needle placement.
The tip of the needle was placed cranially to the puncture lev-
el by using a paraaxial transducer position first. Angulations of
needle insertion were determined according to the orientation
of the hypoechoic cleft. The hypoechoic cleft of the SI joint
shows cranially a more medial to lateral orientation, which be-
comes slightly more caudally vertically oriented. Therefore,
needle orientation is mainly vertical with only slight angula-
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tions from medial at the upper level and vertical at the lower
level. After needle positioning under the skin by a paraaxial
US scan, the needle was inserted toward the SI joint using a
longitudinal transducer position, visualizing the needle parallel
to the US beam. After reaching the entrance of the SI joint
with the tip of the needle, a paraaxial transducer position al-
lowed for further vertically oriented needle introduction under
a perpendicular US beam, so that the tip of the needle could
be visualized in the hypoechoic cleft. Care was taken to insert
the needle directly toward the hypoechoic cleft, to avoid any
bony spurs. Once the needle tip was depicted in the hypo-
echoic cleft, a further insertion of less than 1 cm was at-
tempted by pushing the needle into the joint space.