Ultrasound-Guided Techniques
Facet Joints
- •
The facet joints (zygapophyseal or Z joints) can be targeted individually for isolated pathology or targeted in combination with treating other components of the functional spinal unit, , along with ligaments (supraspinous/interspinous, intertransverse, iliolumbar, ligamentum flavum), paraspinal multifidus muscles, the thoracodorsal fascia, nerve roots in the epidural space, and the intervertebral discs.
- •
Injections can be accomplished using a low-frequency curvilinear transducer with similar accuracy as fluoroscopy- or CT-or computed tomography (CT)-guided techniques. ,
- •
Fluoroscopic contrast-dye confirmation may be used to ensure accurate placement of the injectate.
Pertinent Anatomy
- •
The facet joints or zygapophyseal Z joints are the synovial interface between the inferior and superior articular processes (SAPs) of adjacent vertebral bodies ( Figs. 14.1–14.4 ).
- •
The orientation of facet joints may cause or be otherwise associated with degenerative processes such as spondylosis, spondylolisthesis, and/or disc degeneration.
Common Pathology
- •
Facet arthropathy, facet capsule sprain, tropism.
Equipment
- •
Ultrasound machine with low-frequency curvilinear probe
- •
22 to 25 gauge, 2- to 3-inch needle
Common Injectate
- •
Local anesthetics with or without corticosteroid
- •
Prolotherapy
- •
Orthobiologics (platelet-rich plasma [PRP], bone marrow concentrate, etc.)
Injectate Volume
- •
0.25 to 0.5 mL into the joint, +/− peppering the capsule outside of the joint
Technique
Patient Position
- •
Prone with a pillow under the lower abdomen/pelvis to allow lumbar spine to be in a flattened or rounded kyphotic position. This allows the spinous processes to be gapped and the ligaments to be taut.
Clinician Position
- •
Standing at the side of the patient with the ultrasound screen on the opposite side.
Transducer Position
- •
Short axis with visualization of spinous process, lamina, and facet joint. Identification of levels should be done by starting in the region of the sacrum. The L5 spinous process and lamina are much steeper, and together with the bilateral facets and transverse processes further laterally form the appearance of a “crown.” This is just cephalad to the S1 spinous process which comes off of a relatively flat sacral base that has more of a “tiara” appearance. After identifying your target level, scan so that the lateral aspect of the lamina is midline to the probe, then scan cephalad/caudad incrementally to visualize the facet joint which is lateral to the lamina but medial to the deeper transverse process—with the appearance of two small teeth (the superior and inferior articular processes). You may or may not be able to visualize a thin hyperechoic joint capsule overlying the facets ( Figs. 14.5–14.7 ).
- •
Identification of levels can also be done with long-axis view; visualizing spinous processes from a midline axial position helps identify levels, starting caudally with the shallow relatively flat sacral spinous processes, cephalad to the steeper lumbar spinous processes. With target level in mid-screen, turn the probe 90 degrees.
- •
Switching back and forth may optimize targeting of needle tip.
Needle Position
- •
In-plane
- •
With spine in short axis, introduce the needle lateral to medial at a steep angle with or without gel stand-off, directed into the gap between the superior and inferior articular processes ( Fig. 14.6 ).
- •
- •
Out-of-plane
- •
With spine in short axis, introduce the needle out-of-plane just caudad to the mid-point of the transducer which is placed just lateral to the facet joint. Needle tip should be advanced superficially at first, withdrawn back from the plane of the transducer, and walked down to the gap between the superior and inferior articular processes ( Fig. 14.8 ).
- •
Target
- •
Direct placement into the desired facet joint and or capsule.
Pearls and Pitfalls
- •
The facet joint may be difficult to visualize in situations with significant facet hypertrophy.
- •
For in-plane injections, a gel stand-off may be beneficial at reducing anisotropy.
- •
Care must be taken to stay midline when doing an out-of-plane injection with a curvilinear probe because straying to one direction or the other can be skewed drastically due to the convex nature of the ultrasound beam.
- •
Supraspinous and Interspinous Ligaments
- •
The supraspinous and interspinous ligaments can be targeted in isolation for specific injuries, but more commonly are targeted in combination with treating other components of the functional spinal unit, , along with other ligaments (intertransverse, iliolumbar, ligamentum flavum), paraspinal multifidus muscles, the thoracodorsal fascia, zygapophysial (Z joints or facet) joints, nerve roots in the epidural space, and the intervertebral discs.
- •
Injections can be accomplished using a high-frequency linear transducer; however, a low-frequency curvilinear transducer is preferred to have a wider visualization of the region and allow for steeper in-plane injections with minimized anisotropy.
Pertinent Anatomy
- •
The supraspinous ligament (SSL) is a strong fibrous cord-like structure that adjoins and overlies adjacent spinous processes. The SSL is contiguous dorsally with the thoracodorsal fascia and ventrally with the interspinous ligament (ISL).
- •
The ISL is a thin membranous structure that traverses adjacent spinous processes from the root to the apex. The ISL connects dorsally with the SSL and ventrally with the ligamentum flavum (see Figs 14.2 and 14.3 ).
Common Pathology
- •
Ligament strain, partial tear, relative laxity secondary to or underlying disc, and facet pathology.
Equipment
- •
Ultrasound machine with low-frequency curvilinear probe. Alternatively, a high-frequency linear probe can be utilized in individuals with low body fat and minimal subcutaneous tissue.
- •
22 to 25 gauge, 2- to 3-inch needle.
Common Injectate
- •
Prolotherapy
- •
Orthobiologics (PRP, bone marrow concentrate, etc.)
Injectate Volume
- •
0.25 to 1 mL at each site
Technique
Patient Position
- •
Prone with a pillow under the lower abdomen/pelvis to allow lumbar spine to be in a flattened or rounded kyphotic position. This allows the spinous processes to be gapped and the ligaments to be taut.
Clinician Position
- •
Standing at the side of the patient with the ultrasound screen on the opposite side.
Transducer Position
- •
Short and/or long axis to the ligaments, with visualization of spinous processes ( Figs 14.9 and 14.16 ).
- •
Switching back and forth may optimize targeting of needle tip.
- •
In short-axis view, identification of levels should be done by starting in the region of the sacrum. The L5 spinous process and lamina are much steeper and together with the bilateral facets and transverse processes further laterally form the appearance of a “crown.” This is just cephalad to the S1 spinous process, which comes off of a relatively flat sacral base that has more of a “tiara” appearance ( Figs 14.9 and 14.13 ).
- •
Identification of levels can also be done with long-axis view; visualizing spinous processes from a midline axial position helps identify levels, starting caudally with the shallow relatively flat sacral spinous processes, cephalad to the steeper lumbar spinous processes ( Figs 14.11 and 14.15 ).
Needle Position
- •
In-plane
- •
With ligaments in short axis, introduce the needle in-plane lateral to medial to SSL superficial to the spinous process. Needle tip is walked cephalad or caudad and anteriorly into the interspinous gap. This is done while pivoting or fanning the ultrasound transducer to maintain the needle length in-plane ( Fig. 14.10 ).
- •
With ligaments in long axis, introduce the needle in-plane with the transducer from caudad to cephalad, with or without a gel stand-off to minimize anisotropy. Needle tip should be advanced to the spinous process to inject at the SSL, then walked cranially into the interspinous space for the ISL ( Fig. 14.12 ).
- •
- •
Out-of-plane
- •
With ligaments in short axis, introduce the needle out-of-plane just caudad to the mid-point of the transducer. Needle tip should be advanced to the spinous process to inject at the SSL, then walked cranially into the interspinous space for the ISL. This is done while the transducer glides cephalad to follow the needle tip ( Fig. 14.14 ).
- •
With ligaments in long axis, introduce the needle out-of-plane just lateral to the mid-point of the transducer. Advance needle tip to the SSL superficial to or between the dorsal aspect of the spinous processes, then walk anteriorly into the interspinous space for the ISL ( Fig. 14.16 ).
- •
Target
- •
Diffusely through the SSL and ISL as deep as can safely be visualized.
- •
These ligaments may be difficult to visualize entirely, so adjacent and adjoining anatomy need to be visualized.
- •
For in-plane injections, needle angle and anisotropy need to be considered. With the ligaments in short axis, the needle can be obscured in the thoracodorsal fascia while approaching the SSL. With the ligaments in long axis, a gel stand-off may be required to limit anisotropy.
- •
For out-of-plane injections, the needle tip could inadvertently be advanced beyond the plane of the transducer Use doppler to see injectate flow can help (see Fig. 14.17 ).
Multifidus Muscles
- •
The multifidus muscles can be targeted in isolation for specific injuries, but more commonly are targeted in combination with treating other components of the functional spinal unit, including ligaments (supraspinous/interspinous, intertransverse, iliolumbar, ligamentum flavum), the thoracodorsal fascia, zygapophysial (Z joints or facet) joints, nerve roots in the epidural space, and the intervertebral discs.
- •
Injections can be accomplished using a low-frequency curvilinear transducer.
Pertinent Anatomy
- •
The multifidus muscles are the most medial column of the three main lumbar paraspinal muscles, which are all enclosed between the thoracodorsal fascia posteriorly, the lamina, facet joints, transverse processes, and intertransverse (IT) ligaments anteriorly, and the spinous processes and ISLs medially. Unlike the erector spinae (the other two columns of the paraspinal muscles that run the length of the spine), the multifidus muscles consist of several fascicles that traverse three to six vertebral segments, attaching the spinous processes to the vertebral bodies, sacrum, posterior superior iliac spine (PSIS). and posterior sacroiliac ligaments. ,
- •
The multifidus muscles provide functional stabilization, with deep and superficial fibers playing different roles in segmental motion.
Common Pathology
- •
The multifidus muscles have been controversially linked to various low back conditions, , but ultimately they are involved as a part of the functional spinal unit. Pathology includes multifidus muscle atrophy associated with chronic degenerative spine pathology, , chronic low back pain, , chronic radiculopathy, or iatrogenically from radiofrequency denervation, , or prior surgery.
- •
While often not mentioned in magnetic resonance imaging (MRI) radiology reports, pathology of the multifidus muscles is readily visible.
Equipment
- •
Ultrasound machine with low-frequency curvilinear probe. Alternatively, a high-frequency linear probe can be utilized in individuals with low body fat and minimal subcutaneous tissue
- •
22 to 27 gauge, 1.5- to 3-inch needle
Common Injectate
- •
Local anesthetic for trigger point injection
- •
Orthobiologics (PRP, platelet-poor plasma [PPP])
Injectate Volume
- •
0.25 to 2 mL at each site
Technique
Patient Position
- •
Prone with a pillow under the lower abdomen/pelvis to allow lumbar spine to be in a flattened or rounded kyphotic position.
Clinician Position
- •
Standing at the side of the patient with the ultrasound screen on the opposite side.
Transducer Position
- •
Short axis to the multifidus muscles, with visualization of spinous processes and lamina ( Figs 14.18A and 14.19A ).
- •
In short-axis view, identification of levels should be done by starting in the region of the sacrum. The L5 spinous process and lamina are much steeper and together with the bilateral facets and transverse processes further laterally form the appearance of a “crown.” This is just cephalad to the S1 spinous process, which comes off of a relatively flat sacral base that has more of a “tiara” appearance.
- •
Identification of levels can also be done with long-axis view, visualizing spinous processes from a midline axial position helps identify levels, starting caudally with the shallow relatively flat sacral spinous processes, cephalad to the steeper lumbar spinous processes. Turn 90 degrees at desired level.
Needle Position
- •
In-plane
- •
Introduce the needle in-plane lateral to medial directed to lamina. Needle tip is walked anterior/ posterior and cephalad/caudad while injectate is administered ( Fig 14.18B ).
- •
- •
Out-of-plane
- •
Introduce the needle out-of-plane just caudad to the mid-point of the transducer, which is centered over the spinous process. Needle tip should be advanced to the spinous process, then walked off laterally into the multifidus muscle ( Fig. 14.19B ).
- •
Target
- •
Multifidus lying just lateral to the spinous process and just superficial to the laminae.
- •
Take care to keep track of the needle tip. If a longer needle is used, the tip could be advanced into the interlaminar epidural space.
- •
For out-of-plane injections, the needle tip could inadvertently be advanced beyond the plane of the transducer. As the needle tip is advanced deeper, it can be tracked by tilting the probe in the direction of advancement.
Thoracodorsal Fascia
- •
The thoracodorsal fascia (also called the thoracolumbar fascia) can be targeted in isolation for focal injuries, but more commonly is targeted in combination with treating other components of the functional spinal unit, , along with ligaments (supraspinous/interspinous, intertransverse, iliolumbar, ligamentum flavum), paraspinal multifidus muscles, zygapophysial (Z joints or facet) joints, nerve roots in the epidural space, and the intervertebral discs.
- •
Injections can be accomplished using a low-frequency curvilinear transducer.
Pertinent Anatomy
- •
The thoracodorsal fascia is a thick retinaculum around the paraspinal muscles of the lumbar and sacral regions, composed of aponeurotic fascial tissue continuous with the paraspinal fascia throughout the spine from the cranial base to the sacrum.
- •
Several muscles of the trunk and extremities insert into the thoracodorsal fascia.
- •
Laterally, the thoracodorsal fascia is in continuity with the fascia of all of the abdominal muscles, ultimately providing synchronization throughout the core muscles between the rectus abdominis and paraspinals.
- •
Medially, the bilateral thoracodorsal fascia converges into the midline SSL, which in turn is contiguous ventrally with the ISLs into the ligamentum flavum (see Fig. 14.3) .
Common Pathology
- •
The thoracodorsal fascia can be injured spontaneously with a hernia or iatrogenically from even minimally invasive procedures like vertebroplasty or LASER spine surgery.
- •
In the absence of specific injury, the thoracodorsal fascia is ultimately involved as a part of the functional spinal unit.
Equipment
- •
Ultrasound machine with low-frequency curvilinear probe. Alternatively, a high-frequency linear probe can be utilized in individuals with low body fat and minimal subcutaneous tissue.
- •
22 to 25 gauge, 2- to 3-inch needle.
Common Injectate
- •
Prolotherapy solution
- •
Orthobiologics (PRP, etc.)
Injectate Volume
- •
0.25 to 10 mL at each site
Technique
Patient Position
- •
Prone with a pillow under the lower abdomen/pelvis to allow lumbar spine to be in a flattened or rounded kyphotic position.
Clinician Position
- •
Standing at the side of the patient with the ultrasound screen on the opposite side.
Transducer Position
- •
Short axis to the SSL, ISL, and multifidus muscles, with the thoracodorsal fascia arching laterally off the midline spinous processes and SSL ( Figs 14.20 and 14.22 ).
- •
In short-axis view, identification of levels should be done by starting in the region of the sacrum. The L5 spinous process and lamina are much steeper and together with the bilateral facets and transverse processes further laterally form the appearance of a “crown.” This is just cephalad to the S1 spinous process, which comes off of a relatively flat sacral base that has more of a “tiara” appearance.
- •
Identification of levels can also be done with long-axis view; visualizing spinous processes from a midline axial position helps identify levels, starting caudally with the shallow relatively flat sacral spinous processes, cephalad to the steeper lumbar spinous processes. Turn 90 degrees at desired level.
Needle Position
- •
In-plane
- •
Introduce the needle in-plane lateral to medial directed along the thoracodorsal fascia. Can redirect superior and inferior to get broader coverage ( Fig. 14.21 ).
- •
- •
Out-of-plane
- •
Introduce the needle out-of-plane just caudad to the mid-point of the transducer, which is centered over the spinous process. Needle tip should be advanced to the spinous process, then walked off laterally and superficially into the thoracodorsal fascia ( Fig. 14.23 ).
- •
Target
- •
TDF fibers overlying the erector spinae muscles from the spinous process out as lateral as desired.
- •
For in-plane injections, needle angle and anisotropy need to be considered. With the ligaments in short axis, the needle can be obscured in the thoracodorsal fascia while approaching the SSL. With the ligaments in long axis, a gel stand-off may be required to limit anisotropy.
- •
For out-of-plane injections, the needle tip could inadvertently be advanced beyond the plane of the transducer.
Iliolumbar, Intertransverse Ligaments
- •
Injured iliolumbar intertransverse ligaments may or may not be primary pain generators but should be considered as part of the spinal functional unit (adjacent vertebrae, intervertebral disc, ligaments, and facet joints) in which injury to any part can cause biomechanical alterations leading to degeneration and pain.
- •
These ligaments can get stressed with scoliosis.
Pertinent Anatomy
- •
The IT ligaments course between and just anterior to the transverse processes.
- •
The iliolumbar (IL) ligament can have several anatomic variations but mostly courses between the transverse processes of the lowest lumbar vertebra (typically L5) and the iliac crest.
Common Pathology
- •
Traumatic injury.
- •
Lumbar ligament injuries are common after motor vehicle accidents (MVAs) or traumas.
- •
Lumbar spondylosis, degenerative disease, and loss of lordosis can cause lumbar ligament laxity and vice versa.
- •
Scoliosis: for a lateral curve the IT ligaments are stretched/lax at the convexity of the curve at that segment and are the targets for injection.
- •
Buckling and hypertrophy of the ligamentum flavum associated with degenerative disk disease, segmental motion abnormalities, spondylosis, and contributes to spinal stenosis.
- •
Iliolumbar syndrome has been described as unilateral low back pain at the posterior iliac crest, reproduced by hip flexion and the Patrick test. One small study showed that 25% dextrose solution helped pain in 6/7 patients.
Equipment
- •
Ultrasound machine with low-frequency curvilinear probe
- •
22 to 25 gauge, 2- to 3-inch needle
Common Injectates
- •
Prolotherapy, orthobiologics (PRP, bone marrow concentrate, etc.)
- •
Avoid intraligamentous corticosteroids
Injectate Volume
- •
0.5 to 1 mL per area/ligament
Technique
Patient Position
- •
Prone with a pillow under the lower abdomen/pelvis to allow lumbar spine to be in a flattened or rounded kyphotic position.
Clinician Position
- •
Standing at the side of the patient with the ultrasound screen on the opposite side.
Transducer Position
- •
Long axis to spine, short axis to the transverse processes ( Fig. 14.24 ).
- •
Start scanning at the sacrum and count L5 up to targeted region.
- •
Scan laterally until the most lateral aspect of the transverse process are visualized.
Needle Position
- •
In-plane, distal to proximal or proximal to distal approach ( Fig. 14.25 ).
- •
Alternatively, can inject out-of-plane medial to lateral ( Figs 14.26 and 14.27 ).
Target
- •
IL ligament distal to the L5 spinous process.
- •
IT ligaments at levels above L5.
- •
Target the fibers traversing between the spinous processes just deep to bony tip.
- •
Heel toe maneuver with gel stand-off can be helpful to visualize the needle better.
- •
Always visualize needle tip and be careful not to go deep into the retroperitoneal space (higher risk with out-of-plane injections).
Quadratus Lumborum Origins Off the Iliac Crest
- •
The quadratus lumborum (QL) has great anatomic variability; thus, ultrasound to visualize it is the best modality
- •
QL injury or pain syndromes are likely an underdiagnosed problem but typically result in myofascial pain.
- •
The injection describes the tendon injections if typical myofascial treatments for QL pain fail or there is suspected tendon injury form trauma.
Pertinent Anatomy
- •
Originates on the superior wing of the posterior iliac crest (extends up to 5 to 7 cm laterally) and IL ligament
- •
Inserts on the anterior inferior border of the 12th rib (extending 4.5 to 7 cm laterally) and off the lateral borders of the L1-4 transverse processes
- •
There is great variability to its locations and can have interwoven fibers of the different intrinsic spinal muscles
- •
The iliohypogastric and ilioinguinal nerves course along the ventral muscle fibers
- •
The QL lies posterior to the colon, kidneys, and diaphragm and deep to the spinal erectors
- •
The anterior primary ramus of the 12th thoracic spinal nerve runs in the abdominal wall inferior to the 12th rib, known as the subcostal nerve
- •
Unilateral contraction causes ipsilateral trunk flexion; bilateral contraction extends the trunk and flexes the 12th rib during inspiration
- •
These muscle actions are small and so may play more of a role in lumbar stability.
Common Pathology
- •
Muscle and tendon injury after traumatic event via hyper-flexion or hyper-contralateral flexion mechanisms.
Equipment
- •
Ultrasound machine with low-frequency curvilinear probe
- •
22 to 25 gauge, 2- to 3-inch needle
Common Injectates
- •
Local anesthetics for diagnostics or for muscle trigger point or QL blocks
- •
Orthobiologics (PRP, platelet poor plasma, bone marrow concentrate, etc.)
Injectate Volume
- •
0.5 to 1 mL per tendon area
Technique
Patient Position
- •
Prone with a pillow under the lower abdomen/pelvis to allow lumbar spine to be in a flattened or rounded kyphotic position.
Clinician Position
- •
Standing at the side of the patient with the ultrasound screen on the opposite side.
Transducer Position
- •
Long axis to spine and QL ( Fig. 14.28 ).
- •
Can rotate to visualize more medial or lateral fibers.
- •
Identify the posterior medial superior border of the iliac crest.
- •
Scan up to 5 to 7 cm laterally from the medial border.
Needle Position
- •
In-plane, proximal to distal approach ( Fig. 14.29 ).
- •
May use two to four different needle entry sites to target multiple areas of the tendons.
Target
- •
Tendon fibers at and proximal to the iliac crest.
- •
Hypoechoic fibers and the enthesopathy points.
- •
Heel toe maneuver with gel stand-off can be helpful to visualize the needle better.
Fluoroscopy-Guided Techniques
Lumbar Transforaminal Epidurals
- •
Real-time live fluoroscopy is key for visualizing intravascular injection. Inject contrast slowly and carefully and assess the flow pattern. Do not rely on aspiration.
- •
Digital subtraction can be considered if there is a question of aberrant flow pattern or difficulty with visualization due to other factors such as contrast or hardware obscuring the view with live fluoroscopy.
- •
Particulate steroids are not recommended due the risk of catastrophic consequences thought to be from particulate steroid embolization via the arterial supply to the brain and spinal cord.
- •
Particulate steroids have not been found to be consistently superior to soluble steroids (dexamethasone or betamethasone) in efficacy.
- •
Platelet lysate epidural injections for lumbar radicular pain have evidence that they can help pain and function.
Pertinent Anatomy
- •
The intervertebral foramen is bordered by:
- •
Posterior: the inferior and superior articular processes
- •
Superior/Inferior: The pedicles superiorly and inferiorly
- •
Anterior: Vertebral body and intervertebral disc anteriorly from a lateral view
- •
- •
The spinal canal (dural sac) lies medial from an anterior-posterior perspective
- •
Would add anatomy of vascularization of the spinal cord ( Fig. 14.30 )
- •
Pedicle (P)—Eye
- •
Pars interarticularis (PI)—Neck
- •
Superior articulating process (SAP)—Ear
- •
Transverse process—Nose
- •
Spinous process (SP)—Tail
- •
Lamina (L)—Body
- •
Inferior articulating process (IAP)—Legs
- •
Common Pathology
- •
Lumbar disc herniation
- •
Facet arthrosis or synovial cyst with nerve root impingement
- •
Disc osteophyte, resulting in subarticular narrowing
- •
Spinal stenosis with symptomatic neurogenic claudication
Equipment
- •
C-arm fluoroscope
- •
Extension tubing
- •
22 to 25 gauge, 3.5- to 7-inch needle depending on body habitus
- •
Contrast
Common Injectates
- •
Local anesthetic and non-particulate corticosteroids
- •
Orthobiologics (platelet lysate)
- •
Avoid particulate steroids
Injectate Volume
- •
2 to 5 mL, pending the degree of stenosis and patient tolerance
- •
Prior studies have shown that with an injectate volume of 2.8 mL, 95% of the lumbar transforaminal epidurals will spread to the superior aspect of the superior intervertebral disc and with 3.6 mL total volume, 95% with reach to the inferior aspect of the inferior intervertebral disc.
Technique: Subpedicular Approach
Patient Position
- •
Prone with abdomen on a pillow to reduce lumbar lordosis.
C-Arm Position
- •
Confirm the level using the anteroposterior (AP) view and counting down from the 12th rib.
- •
Line up the superior endplate corresponding to the correct vertebrae by tilting the C-arm cephalad or caudal. This should “square off” the target segment.
- •
Oblique the C-arm ipsilateral to visualize the “Scotty Dog.”
- •
The SAP of the level below will be below the 6 o’clock position of the pedicle above.
- •
Obtain a non-obstructed view of the chin of the “Scotty Dog” or 6 o’clock position of the pedicle.
- •
If the iliac crest obstructs the trajectory to the L5-S1 foramen, a more cephalad tilt and a less oblique angle may be required.
- •
It is recommended to have a more lateral rather than medial bias to decrease the risk of neural injury (6:30 if procedure is on the right side, or 5:30 if procedure is on the left side).
- •
Will use the AP view to triangulate the needle position. Optimal position in the AP view requires:
- •
“Squaring” of superior and inferior endplate of the target level using a cephalad or caudal tilt.
- •
The spinous process should be midline using an oblique tilt.
- •
- •
Optional to use “true” lateral view to ascertain depth. Optimal position in the lateral view requires:
- •
“Squaring” the superior and inferior endplate of the target level using a wigwag.
- •
Needle Position
- •
Slight bend in the needle can help with navigation.
- •
Start slightly inferior lateral to the final target as this starting point will make it easier to navigate around potential osteophytes off the SAP or transverse process.
- •
Place the needle coaxial to the fluoroscopic beam using intermittent fluoroscopic guidance in the oblique view, guiding the needle towards the 6 o’clock position of the pedicle.
- •
Do not advance too deep in the oblique view without checking an AP view.
- •
Authors recommend in the oblique view to gently touch os at the inferior aspect of the pedicle to ascertain depth.
- •
Withdraw the needle slightly; then redirect just inferior to the pedicle.
- •
Obtain an AP view to ascertain depth and medial trajectory. The needle tip should not pass the midpedicular line (6 o’ clock of the pedicle) in the AP to avoid dural puncture.
- •
Optional to obtain lateral view to ascertain depth.
Target
- •
The target point is also known as the “safe triangle” formed by the pedicle superiorly and the spinal nerve that passes in a tangent inferomedially.
- •
By staying in the superior one-sixth of the “safe triangle” there is less risk of neural injury; however, vascular penetration can still occur.
- •
In the AP view the needle should not pass the 6 o’clock position of the pedicle.
- •
In the lateral view the needle should land close to the facet joint silhouette within the superior aspect of the foramen.
- •
The anterior or ventral aspect of the foramen should be avoided due to increased risk of vascular injury or vascular injection as the radicular arteries and intervertebral veins typically lie dorsal to the vertebral body.
- •
Attach extension tubing, keeping the needle still.
- •
Aspirate to ensure no vascular uptake; then inject a small amount of contrast under live fluoroscopy.
- •
In the AP view, contrast should flow epidurally along the medial pedicle border with or without peripheral extension around the spinal nerve.
- •
In the lateral view, contrast should flow against the posterior margin of the vertebral body.
- •
If the needle is adjusted in the lateral view, the AP view should also be checked to confirm that the needle has not advanced past the mid-pedicular line (6 o’clock of the pedicle).
- •
If at any point, neuropathic pain is elicited, the needle should be withdrawn and repositioned. If the pain does not resolve, the procedure should be aborted. Pain should not be used as an indicator of needle placement.
- •
The injection of contrast should be done under live fluoroscopy.
- •
Extension tubing should be used for stability to avoid inadvertent movements.
- •
Ideal flow should outline the desired spinal nerve and then flow medially into the epidural under the pedicle.
- •
Avoid intrathecal or subdural flow patterns.
- •
Avoid all vascular flow patterns.
- •
Be aware of the characteristic downward “hairpin” turn of the artery of Adamkiewicz (arteria radicularis magnus). This vessel supplies the spinal cord from T8 to the conus medullaris. It has a high degree of anatomic variation but typically enters the canal between T12-L3 and is more commonly found on the left side ( Figs. 14.31–14.34 ).
Technique: Infraneural Transforaminal Epidural
Patient Position
- •
Prone with abdomen on a pillow to reduce lumbar lordosis.
C-Arm Position
- •
Square off of vertebrae at injection level.
- •
Identify the pedicle, pars interarticularis, transverse process, spinous process.
- •
Ipsilateral oblique to rotate the SAP to approximately one-half to one-third of the width of disc space.
Needle Position
- •
The initial target is the lateral aspect of the SAP of the inferior vertebral level.
- •
For example, when targeting the L4-5 foramen, one should target the SAP of the L5 vertebrae.
- •
The needle is inserted just lateral to the SAP and advanced in a coaxial position.
- •
Once the needle contacts the SAP or is felt to be at the depth of the SAP, a lateral view should be obtained.
- •
Intermittent AP and lateral multiplanar views should be utilized to assess depth in relation to the foramen.
- •
The needle can slowly be advanced past the SAP with care to note any changes in “feel” consistent with inadvertent disc access.
Target
- •
In the AP view, the needle should not be advanced past the 6 o’ clock position of the superior pedicle to avoid intrathecal or subdural needle placement.
- •
In a true lateral view, the needle should be just anterior to the SAP in its final position.
- •
Attach extension tubing, keeping the needle still.
- •
Aspirate to ensure no vascular uptake; then inject a small amount of contrast under live fluoroscopy. Confirm epidural flow in both AP and lateral views.
- •
Multiplanar imaging is essential.
- •
If the needle is found too ventral on lateral view, the initially set up was likely not oblique enough. A less oblique trajectory results in a more ventral position on lateral view and a less medial needle position on AP.
- •
If the needle is found too medial on AP but has not reached the foramen on lateral, the initial trajectory was likely too oblique, and readjustment is required to make the trajectory less medial and more ventral. A more oblique trajectory results in a more medial needle position on AP and a less ventral position on lateral view.
- •
Do not advance too deep in the oblique or lateral view without checking an AP view.
- •
The needle tip should not pass the mid-pedicular line (6 o’ clock of the pedicle) in the AP to avoid dural puncture.
- •
Be aware of the characteristic downward “hairpin” turn of the artery of Adamkiewicz.
- •
Beware of placing the needle too inferior and ventral to avoid intradiscal puncture. This is more common with an infraneural approach.
- •
Caution with needle advancement past the SAP given proximity of the intervertebral disc. With proper technique, Levi et al. reported intradiscal needle placement 4.7% occurrence.
- •
Pre-procedure MRI review is imperative to confirm adequate epidural space for needle placement. Dural ectasia or Tarlov cysts should be noted prior to injection.
- •
Be aware of intrathecal, subdural, and vascular flow patterns ( Figs 14.35 and 14.36 ).
Lumbar Interlaminar Epidural Injection
- •
Aseptic technique should be followed during the performance of any epidural injection.
- •
A fluoroscope should be used for routine performance of interlaminar epidural injections for the management of painful conditions.
- •
A loss of resistance technique is commonly performed to access the epidural space from an interlaminar approach.
- •
Contrast spread should cover the target of interest to ensure appropriate injectate delivery.
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
